KR101982608B1 - Process for the preperation of Aliphatic Diisocyanates - Google Patents

Abstract

The present invention relates to a process for producing aliphatic diisocyanates, and more particularly to a process for producing aliphatic diisocyanates by thermally decomposing an aliphatic dicarbamate in the presence of a catalyst of a tin compound, And a method for producing an aliphatic diisocyanate capable of improving the yield of diisocyanate by efficiently removing high-boiling by-products produced using a reaction system comprising a separator.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing an aliphatic diisocyanate,

More particularly, the present invention relates to a process for producing an aliphatic diisocyanate by thermally decomposing an aliphatic dicarbamate in a pyrolysis reactor in the presence of a catalyst of a tin compound , High boiling point byproducts having a specific molecular weight or higher during the thermal decomposition of the aliphatic dicarbamate are removed by centrifugation in a centrifuge connected to the heat exchanger through a heat exchanger after mixing with the alcohol to improve the yield of aliphatic diisocyanate and to produce an aliphatic diisocyanate To a process for producing an aliphatic diisocyanate capable of securing long-term operability.

Isocyanates, widely used as raw materials for producing polyurethane foams, paints and adhesives, can be roughly divided into aromatic isocyanates and aliphatic isocyanates, both of which are used as useful industrial raw materials.

The above-mentioned aliphatic isocyanates and isocyanates of aromatic isocyanates have been synthesized from amines and phages. However, due to the toxicity characteristic of phosgene in the production of isocyanate from amines and phogens, hydrochloric acid (HCl), which is a byproduct which is generated in large quantities during the reaction as well as phosgene leakage and device corrosion, There has been a demand for a new environmental friendly isocyanate production method which does not use phosgene. In addition, given the increasingly stringent regulations on hazardous substances globally, the research and development of environmentally friendly technologies to synthesize isocyanates by the Bifosgen process is a very attractive area for the chemical industry.

Among the most economical and most widely studied methods of producing environmentally friendly isocyanates by the presently known non-phosphazene method, carbamates are synthesized by reacting amines with dialkyl carbonate or urea / alcohol, pyrolyzed them to obtain isocyanate . However, a large amount of high-boiling by-products generated by pyrolysis reaction in the production of isocyanate by pyrolysis of carbamate causes lowering of isocyanate yield, and the polymer by-product is immersed in the wall of the reactor, Long-term production of isocyanate is interfered with, and various studies for improving it have been attempted.

Accordingly, the inventors of the present invention have found that aliphatic diisocyanate is produced by pyrolyzing an aliphatic dicarbamate in the presence of a catalyst of a tin compound in a pyrolysis reactor to produce an aliphatic diisocyanate, The high boiling point byproduct is removed by centrifugation in a centrifuge connected to the heat exchanger after mixing with the alcohol, thereby improving the yield of aliphatic diisocyanate and securing long-term operability for producing aliphatic diisocyanate. ≪ / RTI >

As a prior art related to the present invention, U.S. Patent No. 3,962,302 discloses a method of pyrolyzing toluene diethyl carbamate to synthesize toluene diisocyanate (TDI), and flowing nitrogen into the reactor at a temperature of 250 ° C in a cetane solvent Was used to synthesize TDI at a yield of 83.4%. However, since this method uses nitrogen, there is a problem that can not be applied in an actual process.

In the case of EP-A 92 738, a liquid phase pyrolysis of carbamate was attempted by using a thin film evaporator or a falling film evaporator, but there is insufficient application of a large capacity due to the characteristics of the film evaporator , Which has the problem that when the column temperature is increased to increase the column temperature to pyrolyze the carbamate at high speed, wall deposit adheres to the column section or when the column temperature is lowered, the residence time of the reactant becomes longer and high boiling point by-products are produced .

U.S. Patent No. 4,294,774 describes the use of N, N-dimethylaniline as a solvent and catalyst to obtain methylenediphenyl diisocyanate (MDI) in a yield of 46%, and U.S. Patent No. 4,349,484 discloses that diisobutylene (MDI) was obtained at a yield of 76.5% by decomposing diphenylmethanedimethylurethane at a high temperature (310 DEG C) using a zinc flake as a catalyst. However, low methylene diphenyldiisocyanate (MDI ) In addition to the decomposition and loss of the solvent in accordance with the yield, vacuum and high temperature, there is a problem that a large amount of high boiling point material is produced as a byproduct.

As another method for reducing the production of high-boiling point by-products in the production of diisocyanate, U.S. Patent No. 4,388,246 discloses a process for producing a diisocyanate by using an inorganic acid salt of an alkyl ester or an alkyl ester as a stabilizer and using an organic tin chloride compound as a catalyst, Mate is pyrolyzed to produce diisocyanate. However, the formation of high boiling point byproducts is not significantly reduced and the yield of diisocyanate is not high, even though catalyst and stabilizer are used.

The present invention and the above prior arts are different from each other in the technical features of the invention, and thus the inventions have different configurations.

DISCLOSURE OF THE INVENTION The present invention relates to a process for continuously removing high boiling point by-products which are inevitably generated during the thermal decomposition of an aliphatic dicarbamate to prevent the production of a polymer by-product attached to a pyrolysis reactor in which the aliphatic dicarbamate is pyrolyzed, And to provide a process for producing an aliphatic diisocyanate which can improve the yield of the isocyanate.

The present invention relates to a process for producing an aliphatic diisocyanate by thermally decomposing an aliphatic dicarbamate in the presence of a catalyst of a tin compound in a pyrolysis reactor to produce an aliphatic diisocyanate, The present invention provides a process for preparing an aliphatic diisocyanate which is capable of improving the yield of an aliphatic diisocyanate and securing a long-term operability for producing an aliphatic diisocyanate by centrifugally removing the aliphatic diisocyanate in a centrifuge connected to the heat exchanger through a heat exchanger after mixing with the alcohol I want to.

The present invention effectively removes the high boiling point by-products which are necessarily generated when the aliphatic dicarbamate is pyrolyzed without using the phosgene method used in the production of the conventional diisocyanate, thereby achieving long-term operation stability in the process of producing the aliphatic dicarbamate The aliphatic diisocyanate can be produced at a high yield.

1 is a schematic view illustrating a process for producing an aliphatic diisocyanate produced in Example 1 of the present invention through a reaction apparatus.
FIG. 2 is a schematic view illustrating the process for producing an aliphatic diisocyanate prepared in Comparative Example 1 of the present invention through a reaction apparatus. FIG.
FIG. 3 is a schematic view showing a process for producing an aliphatic diisocyanate prepared in the process 2 of the present invention through a reaction device.

The present invention shows a process for producing an aliphatic diisocyanate.

The present invention relates to a process for producing an aliphatic diisocyanate by thermally decomposing an aliphatic dicarbamate in the presence of a catalyst of a tin compound in a pyrolysis reactor to produce an aliphatic diisocyanate, The aliphatic dicarbamate is removed by centrifugal separation in a centrifugal separator connected to the heat exchanger through a heat exchanger to effectively remove the generated high boiling point byproducts generated during pyrolysis of the aliphatic dicarbamate, thereby attaching the high boiling point byproduct to the reactor in which the aliphatic dicarbamate is pyrolyzed Thereby improving the yield of the isocyanate in addition to the stable operation of the process. The present invention also provides a process for producing an aliphatic diisocyanate.

The aliphatic dicarbamate may be at least one selected from among aliphatic dicarbamates having 4 to 12 carbon atoms and cycloaliphatic dicarbamates having 4 to 12 carbon atoms.

The aliphatic dicarbamate is selected from the group consisting of 1,3-bis (methoxycarbonylamino) propane, 1,4-bis (methoxycarbonylamino) butane, 1,6-bis (methoxycarbonylamino) (Methoxycarbonylamino) hexane, 1,8-bis (ethoxycarbonylamino) hexane, 1,6-bis (butoxycarbonylamino) (Methoxycarbonylamino) cyclohexane, 1,2-bis (butoxycarbonylamino) cyclohexane, 1,3-bis (methoxycarbonylamino) cyclohexane, (Butoxycarbonylamino) cyclohexane, 1,4-bis (methoxycarbonylamino) cyclohexane, 1,4-bis (butoxycarbonylamino) (Methoxycarbonylaminomethyl) cyclohexane, 1,2-bis (butoxycarbonylaminomethyl) cyclohexane, 1,3-bis (methoxycarbonylaminomethyl) Cyclohexane, 1,4-bis (methoxycarbonylamino (Methoxycarbonylaminocyclohexane), 4.4-methylene di (butoxycarbonylaminocyclohexane), bis (butoxycarbonylaminomethyl) cyclohexane, (Methoxycarbonyl) isophorone, and bis (butoxycarbonyl) isophorone may be used.

The tin compound catalyst may be a divalent tin compound or a tetravalent tin compound.

The catalyst may be at least one selected from the group consisting of bis (tri-n-butyltin) oxide, bis (tri-n-butyltin) sulfate, di- di-n-butyltin dilaurate, di-n-butyl tin oxide, dimethyl diphenyl tin, dimethyl tin dichloride, diphenyl (2-ethylhexanoate) Tin (II) acetate, tin (II) acetylacetonate, tin (II) chloride, tin chloride, diphenyltin oxide, hexa-n-butyltin, hexaphenyltin, tetra- At least one tin compound selected from tin (II) iodide and tin (II) oxalate can be used.

The catalyst may be used in an amount of 0.01 to 5% by weight, preferably 0.02 to 3% by weight, more preferably 0.05 to 1% by weight, based on the weight of the aliphatic dicarbamate.

When the amount of the catalyst to be used is less than 0.01% by weight based on the weight of the aliphatic dicarbamate, the rate of thermal decomposition of the aliphatic dicarbamate is too slow. When the amount of the catalyst is more than 5% by weight, There is no economic advantage since the yield of production of isocyanate is not improved.

The thermal decomposition reaction of the aliphatic dicarbamate can be carried out in a solvent.

In the above, the pyrolysis reaction of the aliphatic dicarbamate may be carried out by using one or more aliphatic hydrocarbons selected from dodecane and hexadecane; At least one aromatic hydrocarbon selected from biphenyl, terphenyl, benzyltoluene, triphenylmethane, phenylnaphthalene and benzylnaphthalene; At least one ester selected from dioctyl phthalate and didecyl phthalate; Or diphenyl sulfone, and a solvent of at least one ether selected from diphenyl ether and dibenzyl ether.

The pyrolysis reaction of the aliphatic dicarbamate may be performed using a commercially available solvent. As an example of such a solvent, Malotherm SH can be used.

The solvent may be used in an amount of 0.5 to 20 times the weight of the aliphatic dicarbamate, preferably 2 to 10 times the weight of the aliphatic dicarbamate.

When the amount of the solvent used is less than 0.5 times the weight of the aliphatic dicarbamate, the viscosity of the solvent is less than 0.5 times the weight of the aliphatic dicarbamate, so that the risk of generation of high boiling point by-products is increased. The amount of the solvent to be recovered after the reaction becomes large, and the energy consumption becomes large.

The pyrolysis of the aliphatic dicarbamate in the pyrolysis reactor may be carried out at a temperature of 180 to 300 ° C, preferably 220 to 270 ° C.

When the pyrolysis temperature of the aliphatic dicarbamate is less than 180 ° C., the pyrolysis rate of the aliphatic dicarbamate is lowered and the yield of the diisocyanate is lowered. When the pyrolysis temperature of the aliphatic dicarbamate exceeds 300 ° C. There is a problem in that the production of high-boiling point by-products due to the side reaction occurring in the pyrolysis reaction of the aliphatic dicarbamate is increased.

The pyrolysis of the aliphatic dicarbamate in the pyrolysis reactor may be carried out at a pressure of 0.1 to 100 mmHg, preferably 1 to 50 mmHg.

If the pyrolysis reaction pressure of the aliphatic dicarbamate in the pyrolysis reactor is less than 0.1 mmHg, there is a problem that the solvent used as the solvent vaporizes as the product diisocyanate and exits the reactor. In the first reactor, the aliphatic dicarbamate The pyrolysis reaction pressure of the diisocyanate exceeds 100 mmHg, the diisocyanate stays in the reactor for a long time, which increases the possibility of becoming a polymer.

In the pyrolysis reactor, pyrolysis of the aliphatic dicarbamate can be carried out for a residence time of 10 to 200 minutes.

When the residence time of the aliphatic dicarbamate in the pyrolysis reactor is less than 10 minutes, the yield of the diisocyanate decreases. When the residence time of the aliphatic dicarbamate in the pyrolysis reactor exceeds 200 minutes, There is a problem that the isocyanate is likely to remain in the reactor for a long time and become highly polymerized.

The pyrolysis of the pyrolysis reactor may be performed at a temperature of 180 to 300 DEG C, a pressure of 0.1 to 100 mmHg, and a residence time of 10 to 200 minutes.

High boiling point byproducts are necessarily formed during the course of diisocyanate production through pyrolysis of dicarbamate. Such high-boiling byproducts may become a cause of deterioration of the production yield of diisocyanate due to the increase in the molecular weight, which may appear as adherend on the wall surface or adhere to the pump or the like, thereby interfering with long-term stable operation of the process. Therefore, it is necessary to reduce the production of high-boiling point by-products generated during the production of the diisocyanate using pyrolysis of dicarbamate, or to remove the produced high boiling point by-products, in order to improve long-term stable operation and yield of the process . However, such high boiling point byproducts are difficult to separate, and when they are separated through a filter or the like, high-boiling point byproducts have already started to be produced in a large amount and it is difficult to effectively remove them.

Accordingly, it was confirmed that the high-boiling by-product can be easily removed even at a relatively high temperature through the reaction of the high-boiling by-product with the alcohol. More specifically, the mixture containing the alcohol and the high boiling point by-product is passed through a heat exchanger, It was confirmed that the high-boiling point by-product can be removed through the reaction.

Therefore, the present invention is characterized in that alcohol is added to a pyrolysis reactor for thermal decomposition of an aliphatic dicarbamate, a heat exchanger and a centrifugal separator connected to the pyrolysis reactor, and a high-boiling by-product generated upon pyrolysis of an aliphatic dicarbamate in a pyrolysis reactor is mixed with an alcohol , The mixture is centrifuged in a centrifugal separator through a heat exchanger to remove high boiling point byproducts, thereby improving the production yield of the aliphatic diisocyanate produced upon pyrolysis of the aliphatic dicarbamate and improving the long-term operability by removing the high boiling point byproduct .

The alcohol may be a lower alcohol having 3 to 6 carbon atoms.

The alcohol may be selected from the group consisting of isopropylalcohol, n-propanol, n-butanol, isobutanol, sec-butanol, tert- butanol, 2-methylpropanol, pentan-1-ol, pentan-2-ol, pentan- 2-methylbutan-1-ol, 3-methylbutan-1-ol and 2,2-dimethylpropan- 1-ol, 2-Methylbutan-2-ol, 3-Methylbutan-2-ol, Alcohol such as 2-hexanol, 3-hexanol and the like can be used.

The alcohol may be used in an amount of 0.1 to 100% by weight based on the weight of the aliphatic dicarbamate.

The alcohol may be added to any one or more selected from among a pyrolysis reactor, a heat exchanger and a centrifugal separator, in which the aliphatic dicarbamate is pyrolyzed, and the alcohol added to the pyrolysis reactor, the heat exchanger and the centrifugal separator, 0.1 to 100% by weight based on the weight of the aliphatic dicarbamate can be used.

The heat exchanger connected to the pyrolysis reactor may be maintained at a temperature lower than the pyrolysis condition temperature of the pyrolysis reactor by 0 to 200 ° C.

The mixture temperature of the mixture passing through the heat exchanger after mixing the by-product and the alcohol generated in the pyrolysis of the aliphatic dicarbamate may be 50-150 ° C.

The by-products and the alcohol generated during thermal decomposition of the aliphatic dicarbamate passing through the heat exchanger can be removed by centrifugation at 1500 to 3000 rpm in a centrifugal separator.

The byproducts and alcohol generated during thermal decomposition of the aliphatic dicarbamate passing through the heat exchanger can be returned to the pyrolysis reactor by centrifuging the mixture at 1500 to 3000 rpm in the centrifugal separator and then finely decomposing the aliphatic dicarbamate.

The process for producing an aliphatic diisocyanate of the present invention is carried out under various conditions. In order to achieve the object of the present invention, it is preferable to provide a process for producing an aliphatic diisocyanate by the above-mentioned conditions.

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. However, these are for the purpose of illustrating the present invention in more detail, and the scope of the present invention is not limited thereto.

≪ Example 1 >

A system including a plurality of columns C100, C150 and C200 to which a pyrolysis reactor T100, a heat exchanger HT150 and a centrifuge Cy200 are sequentially connected and the pyrolysis reactor T100 is connected as shown in FIG. , Aliphatic diisocyanate was prepared by pyrolyzing aliphatic dicarbamate under tin compound catalyst.

Hereinafter, the process for producing an aliphatic diisocyanate by pyrolyzing an aliphatic dicarbamate under a tin compound catalyst will be described in more detail.

A thermal decomposition reactor (T100), a heat exchanger (HT150), and a centrifuge (Cy200) were charged with maltosol SH (a solvent) and di-n-butyltin dilaurate and n-butanol as catalysts. The catalyst was made to a concentration of 0.01 wt% with respect to the solvent and a concentration of 1.0 wt% of n-butanol. The temperature of the pyrolysis reactor (T100) was maintained at 240 DEG C and the pressure was maintained at 20 mmHg. The temperature of the heat exchanger was kept at 200 DEG C, and the discharge temperature of the reactants of the high- boiling point by- product passing through the pyrolysis reactor and the heat exchanger and n-butanol was 120 Deg.] C, and the centrifuge was operated at a rotation speed of 2000 rpm.

Bis (methoxycarbonylamino) hexane (HDC) was fed into the pyrolysis reactor (T100) at a feed rate of 100 g / hr for 20 hours when the respective reaction temperatures and reaction pressures for the pyrolysis reactor and the centrifuge were maintained And the catalyst di-n-butyltin dilaidolate was fed at a rate of 0.01 g / hr for 20 hours, and 1,6-bis (methoxycarbonylamino) hexane (HDC) and di- The residence time of tin dilaurate was 30 minutes, and 1,6-bis (methoxycarbonylamino) hexane (HDC) was pyrolyzed for 22 hours.

1,6-Hexamethylene diisocyanate (HDI) and methanol produced by pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) in a pyrolysis reactor were separated into a column (C100) and a column (C200) Methanol is collected in the collector R100, 1,6-hexamethylene diisocyanate (HDI) is collected in the collector R200, n-butanol is collected in the collector R150 via the column C150, In the case of n-butanol, it is sent back to the heat exchanger by means of a purifying pump and transformed into a mixture which is easily separated by reaction with high-boiling by-products.

On the other hand, the high boiling point byproducts produced in the pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) in the pyrolysis reactor (T100) are mixed with n-butanol in the pyrolysis reactor and heat exchanger, After centrifugation in a centrifuge, the high boiling point byproduct was removed in the form of waste (L200-1) at 2 g / hr, and some of the mixture of high boiling point byproduct and n-butanol was sent back to the pyrolysis reactor.

After pyrolysis reaction for 22 hours after the introduction of HDC, the products collected in the collector (R200) after completion of the pyrolysis reaction were analyzed by gas chromatography. As a result, 1,6-hexamethylene diisocyanate (HDI) collected in the collector (R200) The yield was 92.2%.

On the other hand, after the pyrolysis reaction, the solvent adhered to the wall deposit collected from the pyrolysis reactor (T100) was weighed 15 g.

≪ Comparative Example 1 &

As shown in FIG. 2, an aliphatic diisocyanate was prepared by pyrolyzing an aliphatic dicarbamate under a tin compound catalyst using a reactor structure having only a thermal decomposition reactor (T100).

The thermal decomposition reactor (T100) was charged with the solvent Malotherm SH (SH) and di-n-butyl tin dilaurate as a catalyst. The catalyst was made to a concentration of 0.01 wt% with respect to the solvent, and the temperature of the pyrolysis reactor (T100) was maintained at 240 DEG C and the pressure was maintained at 20 mmHg.

Bis (methoxycarbonylamino) hexane (HDC) was fed at a feeding rate of 100 g / hr to the pyrolysis reactor (T100) for 20 hours when the reaction temperature and the reaction pressure for the pyrolysis reactor (T100) were maintained, The catalyst di-n-butyltin dilaurate was fed at a rate of 0.01 g / hr and pyrolyzed 1,6-bis (methoxycarbonylamino) hexane (HDC) for 22 hours.

1,6-Hexamethylene diisocyanate (HDI) produced by pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) in the reactor T100 passes through column C100 and column C200 Methanol produced by pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) in the reactor (T100) was collected in column (R200) by collecting 1,6-hexamethylene diisocyanate (R100) through the separator (100).

After pyrolysis reaction for 22 hours after the introduction of HDC, the product collected by the collector (R400) after completion of the pyrolysis reaction was analyzed by gas chromatography. As a result, 1,6-hexamethylene diisocyanate (HDI) collected in the collector (R200) The yield was 62.7%.

On the other hand, after the pyrolysis reaction, the solvent adhered to the wall deposit collected from the pyrolysis reactor (T100) was removed and the weight of the dried deposit was 576 g.

≪ Comparative Example 2 &

A system including a plurality of columns C100 and C200 to which a pyrolysis reactor T100, a heat exchanger HT150 and a centrifuge Cy200 are sequentially connected and the pyrolysis reactor T100 is connected as shown in FIG. 3 Aliphatic diisocyanate was prepared by pyrolyzing aliphatic dicarbamate under tin compound catalyst.

The thermal decomposition reactor (T100), the heat exchanger (HT150) and the centrifuge (Cy200) were charged with the solvent Malotherm SH and the catalyst di-n-butyl tin dilaurate. The temperature of the pyrolysis reactor (T100) was maintained at 240 DEG C and the pressure was maintained at 20 mmHg. The temperature of the discharge reactant of the heat exchanger (HT150) was 120 DEG C and the pressure was 20 mmHg Respectively.

Bis (methoxycarbonylamino) hexane (TLC) was added to the pyrolysis reactor (T100) for 20 hours when the reaction temperature and the reaction pressure for the pyrolysis reactor (T100), the heat exchanger (HT150) and the centrifuge HDC) was fed at a feed rate of 100 g / hr and the catalyst di-n-butyltin dilaidolate was fed at a rate of 0.01 g / hr and 1,6-bis (methoxycarbonylamino) hexane (HDC ) Was pyrolyzed.

1,6-Hexamethylene diisocyanate (HDI) and methanol produced by pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) in a pyrolysis reactor (T100) Methanol was collected in a collector R100 through a filter C200 and 1,6-hexamethylene diisocyanate (HDI) was collected in a collector R200.

On the other hand, the high boiling point byproducts produced in the pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) in the pyrolysis reactor (T100) are mixed with n-butanol in the pyrolysis reactor and heat exchanger, After centrifugation in a centrifuge, the high boiling point byproduct was removed in the form of waste (L200-1) at 2 g / hr, and some of the mixture of high boiling point byproduct and n-butanol was sent back to the pyrolysis reactor.

After pyrolysis reaction for 22 hours after the introduction of HDC, the products collected in the collector (R200) after completion of the pyrolysis reaction were analyzed by gas chromatography. As a result, 1,6-hexamethylene diisocyanate (HDI) collected in the collector (R200) The yield was found to be 75.2%.

On the other hand, after the pyrolysis reaction was completed, the weight of the adhered material was 273 g after removing the solvent from the wall deposit collected from the pyrolysis reactor (T100).

As mentioned in the above Example 1 and Comparative Examples 1 and 2, in Example 1 of the present invention, 1,6-hexamethylene (1,6-bis (methoxycarbonylamino) hexane The yield of diisocyanate (HDI) is higher than that of 1,6-hexamethylene diisocyanate (HDI) produced by the method mentioned in Comparative Examples 1 and 2, and the content of adherents attached to the pyrolysis reactor is small (Methoxycarbonylamino) hexane (HDC) through heat exchanger and centrifugal separator, it is possible to remove the high-boiling by-product formed during thermal decomposition of 1,6-bis (methoxycarbonylamino) hexane The removal efficiency of high boiling point byproducts was further increased by the use of alcohol in the removal of the high boiling point byproduct produced during thermal decomposition of methoxycarbonylamino) hexane (HDC).

≪ Examples 2 to 5 >

The amount of 1,6-bis (methoxycarbonylamino) hexane (HDC) introduced into the pyrolysis reactor (T100) was the same at 100 g / hr, and the temperature of the reactant introduced into the centrifuge through a heat exchanger was measured in accordance with Table 1 HDI was produced by pyrolyzing HDC under the same conditions as in Example 1, and the HDI yield and the adhered content of the pyrolysis reactor (T100) were measured. The results are shown in Table 1 below .

Example Through a heat exchanger
Reactant Discharge Temperature HDI yield Pyrolysis reactor
Weight of attachment 2 200 ℃ 81.0% 118g 3 150 ℃ 87.4% 54g 4 80 ℃ 90.3% 13g 5 50 ℃ 86.2% 12g

In Table 1, when the discharge temperature of the heat exchanger reactant is high, the HDI yield and the amount of deposit of the pyrolysis reactor are both increased. However, when the discharge temperature of the reactant of the heat exchanger is lowered, . However, in the case of the yield, it can be confirmed that the optimum value exists at the discharge temperature of the heat exchanger reaction.

≪ Examples 6 to 9 >

HDI was produced by pyrolyzing HDC under the same conditions as in Example 1 except that the speed of the centrifugal separator was changed as shown in Table 2 below, and the yield of HDI and the content of adherents of the pyrolysis reactor (T100) were measured The following results are shown in Table 2 below.

Example Centrifugal separator
Speed (rpm) HDI yield Pyrolysis reactor
Weight of attachment 6 1,000 85.9% 134 g 7 1,500 86.7% 97g 8 2,500 83.5% 13g 9 3,000 81.2% 11g

In Table 2, when the centrifugal separator rotation speed is high, the amount of the high boiling point product is increased, and the adherence of the pyrolysis reactor is decreased while the HDI yield is increased due to the increase of the HDI yield and the attachment of the pyrolysis reactor depending on the rotation speed of the centrifugal separator. I can confirm that it is shrinking. Also, when the rotation speed of the centrifuge was too low, both HDI yield and adhesion to the pyrolysis reactor showed deterioration.

≪ Example 10 >

bis (methoxycarbonylamino) hexane (HDC) was pyrolyzed in the same manner as in Example 1, except that n-propanol was used in place of n-butanol to obtain 1 , 6-hexamethylene diisocyanate (HDI) was prepared and by-products generated during the thermal decomposition of 1,6-bis (methoxycarbonylamino) hexane (HDC) were removed.

≪ Example 11 >

bis (methoxycarbonylamino) hexane (HDC) was prepared in the same manner as in Example 1, except that pentan-1-ol was used instead of n-butanol. 1,6-hexamethylene diisocyanate (HDI) was prepared by pyrolysis to remove by-products generated upon pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC).

≪ Example 12 >

bis (methoxycarbonylamino) hexane (HDC) was pyrolyzed using the same method as in Example 1 except that 1-hexanol was used instead of n-butanol 1,6-hexamethylene diisocyanate (HDI) was prepared and the by-products formed during pyrolysis of 1,6-bis (methoxycarbonylamino) hexane (HDC) were removed.

Although the present invention has been described with reference to the preferred embodiments and the comparative examples, those skilled in the art will appreciate that various modifications, substitutions, and alterations can be made hereto without departing from the spirit and scope of the present invention as defined by the following claims It will be understood that the invention may be modified and varied without departing from the scope of the invention.

The present invention can produce an aliphatic dicarbamate by pyrolysis of an aliphatic dicarbamate in the presence of a catalyst of a tin compound without using a phosgene process used in the production of a conventional diisocyanate, It is possible to efficiently remove the high boiling point byproducts generated and to ensure long-term operation stability in the process of producing the aliphatic dicarbamate. Thus, aliphatic diisocyanate can be produced at a high yield, It can contribute to the development of related industries, and there is possibility of industrial use.

T100: Pyrolysis reactor
HT150: heat exchanger
Cy200: Centrifuge
C100, C200: column,
R100: Methanol Collector
R200: Diisocyanate collector

Claims (12)

An aliphatic diisocyanate is produced by thermally decomposing an aliphatic dicarbamate in the presence of a catalyst of a tin compound in a pyrolysis reactor and the byproducts generated upon pyrolysis of the aliphatic dicarbamate are mixed with an alcohol and passed through a heat exchanger Wherein the aliphatic diisocyanate is removed by centrifugation in a centrifuge connected to a heat exchanger,
The alcohol is introduced into at least one selected from a pyrolysis reactor, a heat exchanger and a centrifugal separator, and the alcohol to be fed is 0.1 to 100% by weight based on the weight of the aliphatic dicarbamate.
Wherein the temperature of the mixture discharged from the mixture after passing through the heat exchanger after mixing the by-product generated in the thermal decomposition of the aliphatic dicarbamate with the alcohol is 50 to 150 ° C. The method according to claim 1,
Wherein the aliphatic dicarbamate is at least one selected from an aliphatic dicarbamate having 4 to 12 carbon atoms and a cycloaliphatic dicarbamate having 4 to 12 carbon atoms. The method according to claim 1,
The aliphatic dicarbamates include 1,3-bis (methoxycarbonylamino) propane, 1,4-bis (methoxycarbonylamino) butane, 1,6-bis (methoxycarbonylamino) Bis (ethoxycarbonylamino) hexane, 1,6-bis (butoxycarbonylamino) hexane, 1,8-bis (methoxycarbonylamino) (Methoxycarbonylamino) cyclohexane, 1,2-bis (butoxycarbonylamino) cyclohexane, 1,3-bis (methoxycarbonylamino) (Butoxycarbonylamino) cyclohexane, 1,4-bis (methoxycarbonylamino) cyclohexane, 1,4-bis (Butoxycarbonylaminomethyl) cyclohexane, 1,3-bis (methoxycarbonylaminomethyl) cyclohexane, 1,3-bis (butoxycarbonyl) (Aminomethyl) cyclohexane, 1,4-bis (methoxycarbonylaminomethyl) (Methoxycarbonylaminocyclohexane), 4,4-methylene di (butoxycarbonylaminocyclohexane), bis (methoxycarbonylaminomethyl) cyclohexane, Carbonyl) isophorone, and bis (butoxycarbonyl) isophorone. The method for producing an aliphatic diisocyanate according to claim 1, The method according to claim 1,
The tin compound catalyst may be selected from the group consisting of bis (tri-n-butyltin) oxide, bis (tri-n-butyltin) sulfate, di- di-n-butyltin dilaurate, di-n-butyl tin oxide, dimethyl diphenyl tin, dimethyl tin dichloride, diphenyl (2-ethylhexanoate) Tin (II) acetate, tin (II) acetylacetonate, tin (II) chloride, tin chloride, diphenyltin oxide, hexa-n-butyltin, hexaphenyltin, tetra- Wherein at least one selected from tin (II) iodide and tin (II) oxalate is used in an amount of 0.01 to 5 wt% based on the weight of the aliphatic dicarbamate. The method according to claim 1,
The pyrolysis reaction of the aliphatic dicarbamate may be carried out by using any one or more of aliphatic hydrocarbons selected from dodecane and hexadecane; At least one aromatic hydrocarbon selected from biphenyl, terphenyl, benzyltoluene, triphenylmethane, phenylnaphthalene and benzylnaphthalene; At least one ester selected from dioctyl phthalate and didecyl phthalate; Or diphenylsulfone, and a solvent of at least one ether selected from diphenyl ether and dibenzyl ether, wherein the solvent is used in an amount of 0.5 to 20 times the weight of the aliphatic dicarbamate. Gt; delete The method according to claim 1,
Alcohols include isopropylalcohol, n-propanol, n-butanol, isobutanol, sec-butanol, tert-butanol, Pentan-2-ol, Pentan-3-ol, 2-methylbutane- 1-ol, 3-methylbutan-1-ol and 2,2-dimethylpropan-1- ol, 2-methylbutan-2-ol, 3-methylbutan-2-ol, 1-hexanol, At least one selected from 2-hexanol, 3-hexanol and the like is introduced into at least one selected from a pyrolysis reactor, a heat exchanger and a centrifugal separator, To 100% by weight, based on the weight of the amorphous aliphatic diisocyanate. The method according to claim 1,
Wherein pyrolysis of the aliphatic dicarbamate in the pyrolysis reactor is carried out at a temperature of 180 to 300 DEG C, 0.1 to 100 mmHg, and 10 to 200 minutes. The method according to claim 1,
Wherein the heat exchanger is kept at a temperature lower than the pyrolysis condition temperature of the pyrolysis reactor by 0 to 200 ° C. delete The method according to claim 1,
Wherein the by-product and the alcohol generated in the pyrolysis of the aliphatic dicarbamate passing through the heat exchanger are centrifuged at 1500 to 3000 rpm for 10 to 60 minutes in a centrifugal separator to remove the byproducts. The method according to claim 1,
The by-products and the alcohol generated in the pyrolysis of the aliphatic dicarbamate passing through the heat exchanger are centrifuged at 1500 to 3000 rpm in a centrifugal separator and the undifferentiated aliphatic dicarbamate is recycled to the pyrolysis reactor. Way.

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