JP2017031114A - Method for producing pentamethylene diisocyanate and apparatus for producing pentamethylene diisocyanate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing pentamethylene diisocyanate capable of efficiently removing hydrolyzable chlorine, and an apparatus for producing pentamethylene diisocyanate in which a method for producing the pentamethylene diisocyanate is carried out. SOLUTION: A reaction product containing pentamethylene diisocyanate and hydrolyzable chlorine is obtained by reacting carbonyl chloride with pentamethylenediamine (reaction step), and then the reaction product is heat-treated (heat treatment step). Then, the reaction product after the heat treatment is distilled to purify the pentamethylene diisocyanate (purification step). Further, in the heat treatment step, the tar component obtained by distilling the reaction product in the purification step is introduced into the reaction product before the heat treatment and heated. [Selection diagram] Fig. 1

Description

  The present invention relates to a method for producing pentamethylene diisocyanate and an apparatus for producing pentamethylene diisocyanate, and more particularly to a method for producing pentamethylene diisocyanate and an apparatus for producing pentamethylene diisocyanate in which the method for producing pentamethylene diisocyanate is carried out.

  Conventionally, it is known to produce a polyisocyanate which is a raw material of a polyurethane resin by reacting a polyamine and carbonyl chloride (phosgene).

  For example, pentamethylene diisocyanate as polyisocyanate can be produced by reacting pentamethylenediamine as polyamine with carbonyl chloride.

  On the other hand, such pentamethylene diisocyanate contains hydrolyzable chlorine as an impurity.

  Since hydrolyzable chlorine causes coloration of the polyurethane resin, it is desired to reduce hydrolyzable chlorine in pentamethylene diisocyanate.

  As a method for reducing such hydrolyzable chlorine, for example, it is proposed to distill pentamethylene diisocyanate after heat treatment at 150 to 220 ° C. (see, for example, Patent Document 1).

JP 2010-254664 A

  However, in the heat treatment described in Patent Document 1, hydrolyzable chlorine having a relatively high decomposition rate can be decomposed while hydrolyzable chlorine having a relatively low decomposition rate (for example, cyclic carbamoyl chloride, dichloroimine, etc.) is decomposed. In order to achieve this, it is necessary to lengthen the processing time. However, if the treatment time is increased, pentamethylene diisocyanate may cause a polymerization loss, and therefore the treatment time cannot be increased. As a result, hydrolyzable chlorine (for example, cyclic carbamoyl chloride) having a relatively slow decomposition rate. , Dichloroimine, etc.) may not be decomposed. Therefore, in pentamethylene diisocyanate, further reduction of the hydrolyzable chlorine concentration is required.

  The objective of this invention is providing the manufacturing method of the pentamethylene diisocyanate which can remove hydrolyzable chlorine efficiently, and the manufacturing apparatus of the pentamethylene diisocyanate by which the manufacturing method of the pentamethylene diisocyanate is implemented.

The present invention
[1] A reaction step of reacting carbonyl chloride with pentamethylenediamine to obtain a reaction product containing pentamethylene diisocyanate and hydrolyzable chlorine, a heat treatment step of heat-treating the reaction product, and after the heat treatment A purification step of purifying the pentamethylene diisocyanate by distilling the reaction product of the step, wherein in the heat treatment step, a tar component obtained by distilling the reaction product in the purification step is subjected to the heat treatment before the heat treatment. A process for producing pentamethylene diisocyanate, which is introduced into the reaction product and heated.
[2] In the heat treatment step, an addition ratio of the tar component is 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the reaction product. Production method of pentamethylene diisocyanate,
[3] The method for producing pentamethylene diisocyanate according to [1] or [2] above, wherein the heat treatment temperature in the heat treatment step is 180 ° C. or higher and 245 ° C. or lower.
[4] An apparatus for producing pentamethylene diisocyanate for carrying out the method for producing pentamethylene diisocyanate according to any one of [1] to [3], wherein carbonyl chloride and pentamethylenediamine are reacted. A reaction unit for obtaining a reaction product containing pentamethylene diisocyanate and hydrolyzable chlorine, a heat treatment unit for heat-treating the reaction product, and distilling the reaction product after the heat treatment, And a heat treatment unit for introducing a tar component for introducing the tar component obtained by distillation of the reaction product in the purification unit into the reaction product before the heat treatment. Pentamethylene diisocyanate, characterized by comprising a line It is a manufacturing equipment.

  In the pentamethylene diisocyanate production method and the pentamethylene diisocyanate production apparatus of the present invention, the tar component obtained in the purification step is introduced into the reaction product before the heat treatment and heated in the heat treatment step. Hydrolyzable chlorine can be removed efficiently.

FIG. 1 is a schematic configuration diagram showing one embodiment of the pentamethylene diisocyanate production apparatus of the present invention.

  The method for producing pentamethylene diisocyanate according to the present invention includes a reaction step of reacting carbonyl chloride and pentamethylenediamine to obtain a reaction product containing pentamethylene diisocyanate and hydrolyzable chlorine, and a heat treatment for heat-treating the reaction product. And a purification step of distilling the reaction product after the heat treatment.

1. Reaction Step In this method for producing pentamethylene diisocyanate, first, carbonyl chloride and pentamethylenediamine are reacted to prepare a reaction product.

  Examples of pentamethylenediamine include 1,5-pentamethylenediamine, 1,4-pentamethylenediamine, and the like.

  These pentamethylenediamines can be used alone or in combination of two or more.

  As the pentamethylenediamine, 1,5-pentamethylenediamine is preferable.

  In addition, although pentamethylenediamine can also be obtained as a commercial item, it can also be obtained by biochemical techniques, such as a decarboxylase reaction of lysine and / or its salt, for example.

  In the reaction step, for example, carbonyl chloride and pentamethylenediamine are reacted in the presence of a reaction solvent.

  The reaction solvent is an organic solvent inert to carbonyl chloride, pentamethylenediamine and pentamethylene diisocyanate (described later), and includes, for example, aromatic hydrocarbons (for example, toluene, xylene, etc.), halogenated aromatics Hydrocarbons (for example, chlorotoluene, chlorobenzene, dichlorobenzene, etc.), esters (for example, butyl acetate, amyl acetate, etc.), ketones (for example, methyl isobutyl ketone, methyl ethyl ketone, etc.) and the like can be mentioned.

  Such reaction solvents can be used alone or in combination of two or more.

  Moreover, in such a reaction solvent, Preferably, a halogenated aromatic hydrocarbon is mentioned, More preferably, a dichlorobenzene is mentioned.

  Examples of the method of reacting carbonyl chloride with pentamethylenediamine include, for example, a method of reacting pentamethylenediamine directly with carbonyl chloride (hereinafter referred to as a direct method), or a hydrochloride of pentamethylenediamine with the above reaction solvent. And the like, and a method of reacting with carbonyl chloride (hereinafter referred to as the hydrochloride method).

  Among such methods, the hydrochloride method is preferable.

  In order to react pentamethylenediamine hydrochloride with carbonyl chloride by the hydrochloride method, first, a diamine solution in which pentamethylenediamine is dissolved in a reaction solvent is stirred in a reaction vessel equipped with a hydrogen chloride introduction tube. Then, hydrogen chloride is supplied to the reaction vessel and stirred. As a result, pentamethylenediamine and hydrogen chloride react to form pentamethylenediamine hydrochloride, and the contents of the reaction vessel become a slurry liquid (hydrochloric acid chlorination reaction).

  The content ratio of pentamethylenediamine in the diamine solution is not particularly limited, but is, for example, 3.0% by mass or more, preferably 4.5% by mass or more, for example, 20% by mass or less, preferably 17% by mass or less. is there.

  The supply ratio of hydrogen chloride is, for example, 1 time mol or more, for example 10 times mol or less, preferably 6 times mol or less with respect to one amino group of pentamethylenediamine.

  At this time, the pressure in the reaction vessel is, for example, normal pressure or more, for example, 1.0 MPa or less, preferably 0.5 MPa or less, and the temperature in the reaction vessel is, for example, 0 ° C. or more, for example, 180 ° C. Less than, preferably 160 ° C. or less.

  Next, the inside of the reaction vessel is maintained at the above temperature and pressure, and unreacted hydrogen chloride is released out of the reaction system (outside of the reaction vessel).

  Next, the pressure in the reaction vessel is, for example, normal pressure or higher, for example, 1.0 MPa or lower, preferably 0.5 MPa or lower, and the temperature in the reaction vessel is raised to, for example, 80 ° C. or higher and 180 ° C. or lower. . And after temperature rising, carbonyl chloride is supplied, for example, continues supply of carbonyl chloride for 30 minutes or more and 20 hours or less, and is made to react (isocyanation reaction).

  The progress of the isocyanate reaction can be estimated from the amount of generated hydrogen chloride gas and the fact that the slurry in the reaction solvent disappears and the reaction solution (reaction product) becomes clear and uniform.

  As a result, carbonyl chloride and pentamethylenediamine hydrochloride react to produce pentamethylene diisocyanate as a main component.

  The obtained pentamethylene diisocyanate usually corresponds to the above-described pentamethylenediamine used as a raw material component, and more specifically 1,5-pentamethylene diisocyanate, 1,4-pentamethylene diisocyanate, and the like. For example, when 1,5-pentamethylenediamine is used, 1,5-pentamethylene diisocyanate is usually obtained.

  Thus, a reaction product (reaction solution) is prepared.

  Further, preferably, gas such as surplus carbonyl chloride and by-product hydrogen chloride is removed from the reaction product (reaction solution) (degassing step).

  Examples of the method for removing the gas include a method in which an inert gas is supplied and ventilated, and a method in which the gas is separated from the reaction product (reaction liquid) using a known flash tank.

  In order to remove the gas from the reaction product (reaction liquid) by supplying an inert gas and venting, for example, the reaction product at 80 to 160 ° C., preferably 100 to 140 ° C. For example, at a feed rate of 60 to 140 L / h, preferably 80 to 120 L / h.

  Examples of the inert gas include carbon dioxide, nitrogen, argon, helium, and preferably nitrogen is used. Such inert gases can be used alone or in combination of two or more.

  Further, in order to separate the gas from the reaction product (reaction liquid) using the flash tank, for example, the reaction product (reaction liquid) containing the gas is allowed to flow into the flash tank, and the pressure is rapidly reduced. Separate components (eg, pentamethylene diisocyanate, reaction solvent, etc.).

  In this embodiment, the reaction product (liquid component) contains pentamethylene diisocyanate, a reaction solvent, hydrolyzable chlorine, and a tar component.

  The content ratio of pentamethylene diisocyanate is, for example, 0.9% by mass or more, preferably 5% by mass or more, for example, 20% by mass or less, preferably 15% by mass or less, with respect to 100% by mass of the reaction product. is there.

  The content ratio of the reaction solvent is, for example, 80% by mass or more, preferably 85% by mass or more, for example, 99% by mass or less, preferably 95% by mass or less, with respect to 100% by mass of the reaction product.

  Hydrolyzable chlorine is an organic chlorine compound by-produced in the reaction process, and is a compound that generates hydrogen chloride by hydrolysis. Hydrolyzable chlorine contains a light boiling component having a relatively low boiling point and a high boiling point component (such as chloro-hydroxypyridine-carbamoyl chloride) having a relatively high boiling point (a boiling point close to that of pentamethylene diisocyanate). .

  The concentration (HC concentration) of hydrolyzable chlorine in the reaction product is, for example, 1000 ppm or more, preferably 1200 ppm or more, more preferably 1400 ppm or more, for example, 10000 ppm or less, preferably 5000 ppm or less. In addition, the density | concentration (HC density | concentration) of hydrolysable chlorine is measured based on the method of calculating | requiring hydrolysable chlorine described in JISK1603-3 (2007).

  The hydrolyzable chlorine contains, for example, cyclic carbamoyl chloride, dichloroimine and the like. That is, the reaction product contains cyclic carbamoyl chloride and dichloroimine as hydrolyzable chlorine.

  The concentration of the cyclic carbamoyl chloride in the reaction product is, for example, 200 ppm or more, preferably 300 ppm or more, more preferably 400 ppm or more, for example, 1000 ppm or less, preferably 800 ppm or less. In addition, the density | concentration of cyclic carbamoyl chloride is measured by the gas chromatography based on the Example mentioned later (hereinafter the same).

  The concentration of cyclic carbamoyl chloride is, for example, 3% as a percentage of the concentration of cyclic carbamoyl chloride (concentration measured by gas chromatography) with respect to the concentration of hydrolyzable chlorine (concentration in accordance with JIS K-1603-3 (2007)). % Or more, preferably 5% or more, for example, 45% or less, preferably 40% or less.

  The concentration of dichloroimine in the reaction product is, for example, 200 ppm or more, preferably 300 ppm or more, more preferably 400 ppm or more, for example, 1000 ppm or less, preferably 800 ppm or less. In addition, the density | concentration of dichloroimine is measured by the gas chromatography based on the Example mentioned later (hereinafter the same).

  The concentration of dichloroimine is, for example, 3% or more as a percentage of the concentration of dichloroimine (concentration measured by gas chromatography) with respect to the concentration of hydrolyzable chlorine (concentration in accordance with JIS K1603-3 (2007)). Preferably, it is 5% or more, for example, 45% or less, preferably 40% or less.

  The tar component is a polyisocyanate residue by-produced in the reaction step, and contains a high molecular weight polyisocyanate. Examples of the high molecular weight polyisocyanate include multimers of pentamethylene diisocyanate (eg, polyisocyanate trimer or higher multimer), carbodiimide, uretdione, uretonimine, and the like.

  The content ratio of the tar component is, for example, 0.1% by mass or more, preferably 0.2% by mass or more, for example, 5% by mass or less, preferably 3% by mass or less, relative to 100% by mass of the reaction product. It is.

  Thus, in this embodiment, the reaction product contains a reaction solvent and a tar component in addition to pentamethylene diisocyanate and hydrolyzable chlorine.

  Therefore, the method for producing pentamethylene diisocyanate preferably includes a solvent removal step of removing the reaction solvent as a post-step of the reaction step and a pre-step of the heat treatment step.

  In order to remove the reaction solvent in the solvent removal step, the reaction solvent is distilled off from the reaction product, for example, by distillation.

  Normally, when producing a polyisocyanate, if the tar component is contained in the above reaction product, a polymerization loss of the polyisocyanate may occur in the heat treatment step described later, resulting in a decrease in production efficiency. There is a case. Therefore, for example, the tar component can be removed from the reaction product by a known thin film evaporator, and the production efficiency can be improved.

  However, in the case of producing pentamethylene diisocyanate, even if a tar component is contained in the reaction product, it is difficult to cause polymerization loss of polyisocyanate in the heat treatment step described later. Heat treatment is performed without removing the tar component.

  In the case of producing a polyisocyanate different from pentamethylene diisocyanate (for example, hexamethylene diisocyanate), if a tar component is contained in the reaction product, the polymerization loss of the polyisocyanate is reduced in the heat treatment step described later. It is likely to occur. Therefore, the tar component is preferably removed from the reaction product as a pre-process of heat treatment.

2. Heat treatment step Next, the reaction product is heat-treated to remove hydrolyzable chlorine.

  That is, in this method, among the hydrolyzable chlorine contained in the reaction product, hydrolyzable chlorine having a relatively high thermal decomposition rate is decomposed by heating, and the chlorine content is removed as a gas component. In addition, hydrolyzable chlorine having a relatively low thermal decomposition rate is increased in molecular weight by heating, and is converted into a high molecular weight product that can be easily separated in a purification step described later.

  At this time, a tar component obtained in a purification step described later is added to the reaction product.

  More specifically, in this method for producing pentamethylene diisocyanate, a tar component obtained by distilling the reaction product in the purification step described later is introduced (added) to the reaction product before the heat treatment, and then heated. To process.

  By adding the tar component to the reaction product before heat treatment, it is possible to promote the high molecular weight of hydrolyzable chlorine, and as a result, the hydrolyzable chlorine in the reaction product is particularly efficiently converted into high molecular weight. It can be converted into a thing.

  The tar component is added in an amount of, for example, 0.5 parts by mass or more, preferably 1 part by mass or more, more preferably, 100 parts by mass of the reaction product before the tar component is added. It is 5 parts by mass or more, for example, 50 parts by mass or less, preferably 40 parts by mass or less, and more preferably 30 parts by mass or less.

  If the addition ratio of the tar component is in the above range, hydrolyzable chlorine can be removed from the reaction product particularly efficiently.

  In this method, the reaction product into which the tar component has been introduced (added) is heated while introducing an inert gas if necessary.

  In order to heat the reaction product while introducing the inert gas in the heat treatment step, for example, first, the reaction product is charged into the heat treatment container, and then the inert gas is introduced (supplied) into the heat treatment container. An active gas is blown into the reaction product, and the inside of the heat treatment container is purged with an inert gas.

  The heat treatment container is not particularly limited as long as it is heat resistant to the heat treatment temperature (described later) in the heat treatment step.

  Examples of the inert gas include the inert gas described above, and preferably nitrogen. Such inert gases can be used alone or in combination of two or more. The supply rate per unit volume of the heat treatment liquid (reaction product) of the inert gas is, for example, 0.001 / min or more, preferably 0.005 / min or more, for example, 0.2 / min or less, preferably 0.1 / min or less.

  Next, the reaction product is stirred and heat-treated as necessary while continuously introducing an inert gas. Thereby, a part of the reaction product is diffused in the heat treatment container, and the reaction product is heat-treated.

  The heat treatment temperature in the heat treatment step is, for example, 140 ° C. or higher, preferably 160 ° C. or higher, more preferably 180 ° C. or higher, for example 260 ° C. or lower, preferably 245 ° C. or lower, more preferably 240 ° C. or lower, Preferably, it is 220 degrees C or less.

  If the heat treatment temperature in the heat treatment step is not less than the above lower limit, hydrolyzable chlorine in the reaction product can be reliably reduced, and if it is not more than the above upper limit, pentamethylene diisocyanate in the reaction product can be polymerized (poly (Polymerization loss of isocyanate) can be suppressed.

  The heat treatment time (residence time) of the heat treatment step is, for example, 0.1 hour or more, preferably 0.5 hour or more, more preferably 1 hour or more, for example, 12 hours or less, preferably less than 10 hours. More preferably, it is 8 hours or less, and particularly preferably 6 hours or less.

  If the heat treatment time of the heat treatment step is not less than the above lower limit, hydrolyzable chlorine in the reaction product can be reliably reduced, and if it is not more than the above upper limit, pentamethylene diisocyanate in the reaction product is polymerized (poly (Polymerization loss of isocyanate) can be suppressed.

  The pressure in the heat treatment step is, for example, 1 kPa or more, preferably 10 kPa or more, for example, 1000 kPa or less, preferably 500 kPa or less, and more preferably normal pressure.

  As a result, the hydrolyzable chlorine having a relatively high thermal decomposition rate in the reaction product is decomposed, and the chlorine content is removed as a gas component. In addition, hydrolyzable chlorine having a relatively low thermal decomposition rate is increased in molecular weight by heating, and is converted into a high molecular weight product that can be easily separated in a purification step described later.

  After the heat treatment step, the HC concentration in the reaction product is, for example, 100 ppm or more, preferably 200 ppm or more, for example, 1000 ppm or less, preferably 800 ppm or less.

  In addition, after the heat treatment step, the concentration of the cyclic carbamoyl chloride in the reaction product is, for example, 20 ppm or more, preferably 50 ppm or more, for example, 200 ppm or less, preferably 100 ppm or less.

  The concentration of the cyclic carbamoyl chloride is, for example, 1% as a percentage of the concentration of the cyclic carbamoyl chloride (concentration measured by gas chromatography) with respect to the concentration of hydrolyzable chlorine (concentration in accordance with JIS K-1603-3 (2007)). % Or more, preferably 2% or more, for example, 20% or less, preferably 15% or less.

  The concentration of dichloroimine in the reaction product is, for example, 20 ppm or more, preferably 50 ppm or more, for example, 200 ppm or less, preferably 100 ppm or less.

  The concentration of dichloroimine is, for example, 1% or more as a percentage of the concentration of dichloroimine (the concentration measured by gas chromatography) with respect to the concentration of hydrolyzable chlorine (the concentration based on JIS K-1603-3 (2007)). Preferably, it is 2% or more, for example, 20% or less, preferably 15% or less.

  The HC concentration in the reaction product in the heat treatment step is, for example, 1% by mass or more, preferably 5% by mass or more, for example, 50% by mass or less, with respect to the HC concentration in the reaction product before the heat treatment step. Preferably, it is 40 mass% or less.

  That is, the reduction rate of hydrolyzable chlorine in the heat treatment step ([HC concentration in the reaction product before the heat treatment step−HC concentration in the reaction product after the heat treatment step] / HC concentration in the reaction product before the heat treatment step) × 100) is, for example, 50% by mass or more, preferably 60% by mass or more, for example, 99% by mass or less, preferably 95% by mass or less.

  In the above heat treatment step, a catalyst or an additive can be added to the reaction product.

  Examples of the additive include metals such as iron, copper, and zinc. These metals can be used alone or in combination of two or more. The metal is preferably copper.

  The addition amount of the metal is not particularly limited, and is appropriately set according to the purpose and application. For example, the addition amount of metal is, for example, 0.01% by mass or more with respect to 100 parts by mass of pentamethylene diisocyanate. 1% by mass or more, more preferably 0.15% by mass or more, for example, 0.50% by mass or less, preferably 0.40% by mass or less, and more preferably 0.30% by mass or less.

  Further, the timing of addition of the metal is not particularly limited, and may be, for example, before heat treatment, during heat treatment, or both of them.

  Further, when a metal is added in the heat treatment step, a metal chloride (for example, copper chloride, iron chloride, zinc chloride) may be generated due to a reaction between the metal and a chlorine atom of hydrolyzable chlorine.

  The content ratio of the metal chloride is, for example, 0.015% by mass or more, preferably 0.15% by mass or more, for example, 1.0% by mass or less, preferably 100% by mass with respect to the reaction product after heat treatment. Is 0.7 mass% or less.

3. Purification Step Next, the reaction product is distilled to purify pentamethylene diisocyanate.

  In the purification step, pentamethylene diisocyanate is separated from the reaction product by distillation, and for example, hydrolyzable chlorine (hydrolyzable chlorine having a high molecular weight) and tar components are removed.

  As distillation temperature, it is 100 degreeC or more, for example, Preferably, it is 120 degreeC or more, for example, 160 degreeC or less, Preferably, it is 140 degreeC or less. The distillation pressure is, for example, 1.0 kPa or more, preferably 1.7 kPa or more, for example, 3.0 kPa or less, preferably 2.4 kPa or less.

  The distillation time (residence time) is, for example, 0.1 hour or more, preferably 0.5 hour or more, more preferably 1 hour or more, for example, 12 hours or less, preferably less than 10 hours, more preferably. Is 8 hours or less.

  As described above, high-purity pentamethylene diisocyanate (fine pentamethylene diisocyanate) is produced from the reaction product.

  The purity of purified pentamethylene diisocyanate is, for example, 95% by mass or more, preferably 98% by mass or more, for example, 100% by mass or less, preferably 99.999% by mass or less.

  The purified pentamethylene diisocyanate is a composition containing pentamethylene diisocyanate and a small amount of hydrolyzable chlorine, and the concentration (HC concentration) of hydrolyzable chlorine in the purified pentamethylene diisocyanate is, for example, 10 ppm or more. Preferably, it is 20 ppm or more, for example, 150 ppm or less, preferably 100 ppm or less, and more preferably 90 ppm or less.

  Further, the concentration of HC in the purified pentamethylene diisocyanate is, for example, 0.05% by mass or more, preferably 0.1% by mass or more, for example, 15% by mass with respect to the HC concentration in the reaction product before the heat treatment step. % Or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

  That is, the reduction ratio of hydrolyzable chlorine in purified pentamethylene diisocyanate ([HC concentration in the reaction product before the first step−HC concentration in purified pentamethylene diisocyanate] / HC in the reaction product before the first step) Concentration × 100) is, for example, 85% by mass or more, preferably 90% by mass or more, more preferably 92% by mass or more, for example, 99.95% by mass or less, preferably 99.9% by mass or less. .

  The concentration of the cyclic carbamoyl chloride in the purified pentamethylene diisocyanate is, for example, 1 ppm or more, preferably 5 ppm or more, for example, 150 ppm or less, preferably 100 ppm or less.

  The concentration of the cyclic carbamoyl chloride is, for example, 0% as a percentage of the concentration of the cyclic carbamoyl chloride (concentration measured by gas chromatography) with respect to the concentration of hydrolyzable chlorine (concentration in accordance with JIS K-1603-3 (2007)). 0.1% or more, preferably 0.2% or more, for example, 95% or less, preferably 90% or less.

  Moreover, the density | concentration of the dichloroimine in refined pentamethylene diisocyanate is less than 1 ppm, for example, Preferably, it is 0.1 ppm or less.

  The concentration of dichloroimine is, for example, less than 1% as a percentage of the concentration of dichloroimine (concentration measured by gas chromatography) with respect to the concentration of hydrolyzable chlorine (concentration in accordance with JIS K1603-3 (2007)). Preferably, it is 0.1% or less.

4). Plant Such a method for producing pentamethylene diisocyanate is industrially continuously performed, for example, by a plant 1 as shown in FIG.

  The plant 1 is a pentamethylene diisocyanate production apparatus that produces pentamethylene diisocyanate by the above-described method, and includes a reaction unit 2, a gas removal unit 7, a solvent removal unit 3, a heat treatment unit 5, and a purification unit 6. It has.

  The reaction unit 2 is configured to perform a reaction process. The reaction unit 2 includes a reaction vessel 10, a hydrogen chloride supply line 13, a carbonyl chloride supply line 11, an amine supply line 12, and a reaction product transport line 14.

  The reaction vessel 10 is a reaction vessel for reacting pentamethylenediamine and hydrogen chloride, and pentamethylenediamine hydrochloride and carbonyl chloride, and includes, for example, a heat-resistant pressure-resistant vessel whose temperature and pressure can be controlled.

  The hydrogen chloride supply line 13 is a pipe for supplying hydrogen chloride to the reaction vessel 10, and its downstream end is connected to the reaction vessel 10. The upstream end is connected to a hydrogen chloride tank that stores hydrogen chloride, although not shown.

  The carbonyl chloride supply line 11 is a pipe for supplying carbonyl chloride to the reaction vessel 10, and its downstream end is connected to the reaction vessel 10. The upstream end is connected to a carbonyl chloride tank that stores carbonyl chloride, although not shown.

  The amine supply line 12 is a pipe for supplying pentamethylenediamine to the reaction vessel 10, and its downstream end is connected to the reaction vessel 10. Further, the upstream end is connected to an amine tank that stores pentamethylenediamine (diamine solution), although not shown.

  The reaction product transport line 14 is a pipe for transporting the reaction product generated in the reaction vessel 10 to the gas removal unit 7, and its upstream end is the lower end (bottom) of the reaction vessel 10. It is connected to the.

  Although not shown, the reaction unit 2 can include a stirring device for stirring the inside of the reaction vessel 10 if necessary.

  The gas removal unit 7 is configured to perform a degassing step, and includes a flash tank 40, an outflow line 41, and an exhaust line 42.

  The flash tank 40 is a known flash tank, and examples thereof include a flash tank described in Japanese Patent Application Laid-Open No. 2009-119346. The downstream end of the reaction product transport line 14 is connected to the substantially vertical center of the flash tank 40.

  The outflow line 41 is a pipe for transporting the reaction product from which the gas has been removed to the solvent removal unit 3, and its upstream end is connected to the tower bottom of the flash tank 40.

  The exhaust line 42 is a pipe for discharging the gas separated from the reaction product by the flash tank 40, and its upstream end is connected to the top of the flash tank 40.

  The solvent removal unit 3 is configured to perform a solvent removal step, and includes a distillation column 18, a can line 19, and a distillation line 20.

  The distillation column 18 is, for example, a known distillation column whose temperature and pressure can be controlled, and is preferably a continuous distillation column. A downstream end portion of the outflow line 41 is connected to a substantially central portion in the vertical direction of the distillation column 18.

  The bottom line 19 is a pipe for transporting the bottom liquid from the distillation column 18, that is, the reaction product from which the reaction solvent has been removed, to the heat treatment unit 5. Connected to the bottom of the tower.

  The distillation line 20 is a pipe for distilling the distillate from the distillation column 18, that is, the reaction solvent, and its upstream end is connected to the top of the distillation column 18. Further, although not shown, the downstream end is connected to a solvent tank for recovering the solvent or connected to the reaction vessel 10 so that the reaction solvent can be reused.

  The heat treatment unit 5 is configured to perform a heat treatment step, and includes a heat treatment tank 30, a gas supply line 32, a reaction product transport line 33, an exhaust line 34, and a tar component introduction line 31. Yes.

  The heat treatment tank 30 includes, for example, a horizontal spring type stirrer and includes a heat and pressure resistant container capable of controlling temperature and pressure. A downstream end portion of the take-out line 19 is connected to a substantially central portion in the vertical direction of the heat treatment tank 30.

  The gas supply line 32 is a pipe for supplying the inert gas to the heat treatment tank 30, and its downstream end is connected to the heat treatment tank 30.

  The reaction product transport line 33 is a pipe for transporting the reaction product heat-treated in the heat treatment tank 30 to the purification unit 6, and its upstream end is connected to the lower end (bottom) of the heat treatment tank 30. Has been.

  The exhaust line 34 is a pipe for discharging the inert gas supplied from the gas supply line 32 from the heat treatment tank 30, and its upstream end is connected to the upper end (top) of the heat treatment tank 30. Yes.

  The tar component introduction line 31 is a pipe for introducing a tar component (specifically, a tar component obtained by distilling the reaction product in the purification unit 6 described later) into the reaction product before the heat treatment. And the upstream end part is connected to the middle part of the flow direction of the take-out line 45 in the refinement | purification unit 6 mentioned later. That is, the tar component introduction line 31 is connected so as to branch from the take-out line 45. A distribution valve 25 (described later) is provided at a branch portion where the tar component introduction line 31 branches from the take-out line 45.

  Further, the downstream end portion of the tar component introduction line 31 is connected to a middle portion in the flow direction of the can line 19 in the solvent removal unit 3.

  That is, the tar component introduction line 31 is constructed between the bottom line 45 in the purification unit 6 and the bottom line 19 in the solvent removal unit 3, and the tar component in the bottom line 45 in the purification unit 6 is removed. It can be introduced into the take-out line 19 in the solvent removal unit 3 and added to the product before the heat treatment.

  The purification unit 6 is configured to perform a purification process, and includes a distillation column 44, a take-out line 45, and a distillation line 46.

  The distillation column 44 is, for example, a known distillation column capable of controlling temperature and pressure, and is preferably a continuous distillation column. A downstream end portion of the reaction product transport line 33 is connected to a substantially vertical central portion of the distillation column 44.

  The bottom line 45 is a pipe for discharging bottom liquid (tar component) from the distillation tower 44, and its upstream end is connected to the bottom of the distillation tower 44.

  Further, the tar component introduction line 31 is connected so as to branch from an intermediate portion of the take-out line 45, and a distribution valve 25 is provided at the branch portion.

  The distribution valve 25 is a known distribution valve, and the bottom liquid (tar component) in the bottom line 45 is discharged to the downstream side of the bottom line 45 (downstream side of the connecting portion of the tar component introduction line 31). , For distribution to the tar component introduction line 31.

  Thereby, a part of the bottom liquid (tar component) in the bottom line 45 can be supplied to the tar component introduction line 31, and the remaining part is downstream of the bottom line 45 (tar component introduction line 31). It can be transported to the downstream side).

  The distillation line 46 is a pipe for discharging the distillate from the distillation column 44, that is, pentamethylene diisocyanate, and its upstream end is connected to the top of the distillation column 44.

  The purification unit 6 may be configured such that the reaction product after the heat treatment is filtered under reduced pressure using a known filter, and the filtrate is then distilled using a known distillation apparatus.

  Next, the operation of the plant 1 will be described.

  In the plant 1, first, hydrogen chloride is continuously supplied to the reaction vessel 10 through the hydrogen chloride supply line 13, and the amine supply line 12 is used as a diamine solution in which pentamethylenediamine is dissolved in the reaction solvent. To the reaction vessel 10 continuously. Further, carbonyl chloride is continuously supplied to the reaction vessel 10 via the carbonyl chloride supply line 11.

  Then, carbonyl chloride and pentamethylenediamine hydrochloride react in the reaction vessel 10 under the above reaction conditions to produce pentamethylene diisocyanate, and hydrolyzable chlorine, hydrogen chloride and tar components are by-produced ( Reaction step).

  As described above, a reaction product containing pentamethylene diisocyanate, hydrolyzable chlorine, a reaction solvent, and a tar component is prepared.

  Thereafter, the reaction product flows into the flash tank 40 via the reaction product transport line 14 and is separated into excess gas such as carbonyl chloride and hydrogen chloride and liquid components such as pentamethylene diisocyanate and reaction solvent. Is done.

  Then, the gas is discharged from the flash tank 40 via the exhaust line 42, and the reaction product from which the gas has been removed flows out of the flash tank 40 via the outflow line 41 and is pressure transported to the distillation column 18. The

  Next, the reaction product is distilled in the distillation column 18 (solvent removal step).

  The column bottom temperature of the distillation column 18 is, for example, 120 ° C. or more, preferably 130 ° C. or more, for example, 160 ° C. or less, preferably 150 ° C. or less, and the column top temperature is, for example, 60 ° C. or more, preferably 70 ° C. or higher, for example, 100 ° C. or lower, preferably 90 ° C. or lower.

  The pressure in the distillation column 18 is, for example, 1 kPa or more, preferably 2 kPa or more, for example, 10 kPa or less, preferably 5 kPa or less.

  Then, the reaction solvent is distilled off from the distillation column 18 through the distillation line 20. The reaction solvent distilled off is collected in a solvent tank for collecting the solvent, or directly transported to the reaction vessel 10 and can be reused as necessary.

  On the other hand, the reaction product from which the reaction solvent has been distilled off is pressure-transported from the distillation tower 18 to the heat treatment tank 30 of the heat treatment unit 5 as a bottoms of the distillation tower 18 via the bottom line 19.

  At this time, a part of the tar component generated in the purification unit 6 described later is transported to the take-out line 19 by the distribution valve 25 and the tar component transport line 31, and the reaction product in the take-out line 19 is It is added in the above ratio.

  In addition, an inert gas is supplied to the heat treatment tank 30 through a gas supply line 32, and the inert gas passes through the heat treatment tank 30 and is then discharged from the heat treatment tank 30 through an exhaust line 34. .

  The reaction product (including the tar component) supplied to the heat treatment tank 30 is heat-treated in the heat treatment tank 30 under the above conditions while introducing an inert gas as necessary (heat treatment step). Thereby, among hydrolyzable chlorine, a light boiling component having a relatively high thermal decomposition rate is thermally decomposed, and the chlorine component is removed as a gas component. In addition, a high-boiling fraction having a relatively low thermal decomposition rate is thermally decomposed, or is converted into a high molecular weight product that can be easily separated in a purification process by increasing the molecular weight by heating.

  Thereafter, the heat-treated reaction product is transported to the distillation column 44 via the reaction product transport line 33.

  Next, the heat-treated reaction product is distilled in a distillation column 44 (purification step).

  The column bottom temperature of the distillation column 44 is, for example, 120 ° C. or more, preferably 130 ° C. or more, for example, 160 ° C. or less, preferably 150 ° C. or less, and the column top temperature is, for example, 80 ° C. or more, preferably 90 ° C. or higher, for example, 150 ° C. or lower, preferably 140 ° C. or lower.

  The pressure in the distillation column 44 is, for example, 1 kPa or more, preferably 2 kPa or more, for example, 10 kPa or less, preferably 5 kPa or less.

  Then, a distillate distilled from the distilling line 46 is collected as pentamethylene diisocyanate. In addition, the kettle residue (tar component) of the distillation column 44 is removed from the distillation column 44 through a can line 45 as a bottom liquid.

  A part of the kettle residue (tar component) discharged from the distillation column 44 is transported to the take-out line 19 by the distribution valve 25 and the tar component transport line 31, and becomes a reaction product in the take-out line 19. On the other hand, it is added at the above-mentioned ratio. The remaining portion is transported to the downstream side of the take-out line 45 (downstream side of the connecting portion of the tar component introduction line 31) and discharged from the plant 1.

  As described above, pentamethylene diisocyanate (fine pentamethylene diisocyanate) is continuously produced.

  According to such a method for producing pentamethylene diisocyanate, the tar component obtained in the purification step is introduced into the reaction product before the heat treatment and heated in the heat treatment step, so that hydrolyzable chlorine is removed from the reaction product. It can be removed efficiently.

  In the above-described embodiment, in the heat treatment step, heating is performed while introducing (purging) an inert gas into the reaction product. However, the present invention is not limited to this, and the inert gas is not introduced (purged) into the reaction product. It can also be heated.

  In the above-described embodiment, the downstream end of the tar component introduction line 31 is connected to the take-out line 19 and the tar component is introduced into the reaction product between the solvent removal step and the heat treatment step. The timing for introducing the tar component is not particularly limited as long as it is before the heat treatment step. For example, the downstream end of the tar component introduction line 31 is connected to the middle part in the flow direction of the reaction product transport line 14 and the tar component is introduced into the reaction product between the reaction step and the degassing step. it can. Further, for example, the downstream end portion of the tar component introduction line 31 is connected to the middle portion in the flow direction of the outflow line 41, and the tar component is introduced into the reaction product between the degassing step and the solvent removal step. it can.

  Preferably, as shown in FIG. 1, the downstream end portion of the tar component introduction line 31 is connected to the take-out line 19, and the tar component is introduced into the reaction product between the solvent removal step and the heat treatment step.

  The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to them. Specific numerical values such as blending ratio (content ratio), physical property values, and parameters used in the following description are described in the above-mentioned “Mode for Carrying Out the Invention”, and the corresponding blending ratio (content ratio) ), Physical property values, parameters, etc. The upper limit value (numerical value defined as “less than” or “less than”) or lower limit value (number defined as “greater than” or “exceeded”) may be substituted. it can. “Part” and “%” are based on mass unless otherwise specified.

  In addition, methods for measuring various physical properties described below are described below.

<Concentration of pentamethylene diisocyanate and reaction product hydrolyzable chlorine (unit: ppm)>
The concentration of hydrolyzable chlorine (HC concentration) was measured based on the method for obtaining hydrolyzable chlorine described in JIS K-1603-3 (2007).

  The concentration of cyclic carbamoyl chloride and the concentration of dichloroimine were measured by gas chromatography.

  Moreover, the measurement conditions of gas chromatography are shown below.

Injection temperature: 250 ° C
Carrier gas; N ₂ / Air gas flow rate; 40 mL / min
Column: DB-1 (Agilent Technology) 0.53 mm × 30 m × 1.5 μm
Split ratio: 10
Temperature: 120-280 ° C., heating rate 7 ° C./min
<Polymerethylene diisocyanate polymerization loss>
The concentration (mass%) of pentamethylene diisocyanate before and after the heat treatment was measured by gas chromatography, and the polymerization loss of pentamethylene diisocyanate was calculated by the following formula.

Polymerization loss = 100 − ([Pentamethylene diisocyanate concentration after heat treatment] / [Pentamethylene diisocyanate concentration before heat treatment]) × 100
Moreover, the measurement conditions of gas chromatography are shown below.

Injection temperature: 250 ° C
Carrier gas; N ₂ / Air gas flow rate; 40 mL / min
Column: DB-1 (Agilent Technology) 0.53 mm × 30 m × 1.5 μm
Split ratio: 10
Temperature: 120-280 ° C., heating rate 7 ° C./min
Detector: FID
Comparative Example 1
(1) Preparation of reaction product (reaction process)
1,5-pentamethylene in a jacketed pressure reactor equipped with an electromagnetic induction stirrer, automatic pressure control valve, thermometer, nitrogen introduction line, hydrogen chloride introduction line, carbonyl chloride introduction line, condenser and feed pump A diamine solution in which 380 parts by mass of diamine was dissolved in 5000 parts by mass of o-dichlorobenzene was charged. Stirring was then started and steam was passed through the reactor jacket to keep the internal temperature at about 130 ° C. Thereto was added 400 parts by mass of hydrogen chloride from a hydrogen chloride introduction line, and a hydrochloric acid chlorination reaction was started at 130 ° C. or lower and normal pressure. After the feed was completed, the inside of the pressurized reactor became a pale brown white slurry.

  Next, the internal solution of the reactor was gradually heated to 160 ° C., and isocyanated at a pressure of 0.25 MPa and a reaction temperature of 160 ° C. for 6 hours while adding 1350 parts by mass of carbonyl chloride. In the course of the reaction, the liquid in the pressurized reactor became a light brown clear solution.

  After the end of the isocyanate conversion, nitrogen gas was passed at 100 L / hour at 100 to 140 ° C. to remove excess carbonyl chloride and by-product hydrogen chloride (degassing).

  Thus, a reaction product was obtained. The reaction product contained 1,5-pentamethylene diisocyanate, hydrolyzable chlorine, o-dichlorobenzene, and a tar component.

  Then, o-dichlorobenzene was distilled off from the reaction product under reduced pressure (desolvation).

  Thereafter, the tar component was separated and removed from the reaction product by a known thin film evaporator.

  In this reaction product, the content of 1,5-pentamethylene diisocyanate was 95% by mass, and the concentration of hydrolyzable chlorine (hereinafter referred to as HC concentration) was 1417 ppm.

(2) Heat treatment step Next, 200 parts by mass of the reaction product was charged into a flask (heat treatment vessel) equipped with a stirrer, a thermometer and a nitrogen introduction tube, and after introducing nitrogen into the flask for 30 minutes, Nitrogen was introduced at 10 mL / min (feed rate of nitrogen reaction product per unit volume: 0.05 / min), and heat treatment was started at 200 ° C. under normal pressure while stirring at 250 rpm. The heat treatment time was 4 hours.

  A part of the reaction product is sampled every hour from the start of the heat treatment, and the HC concentration, cyclic carbamoyl chloride concentration, dichloroimine concentration, and pentamethylene diisocyanate concentration of the reaction product at each time are sampled. Polymerization loss was measured. The results are shown in Table 1.

  Thus, the reaction product was heat-treated. Then, it cooled to 40 degrees C or less, and obtained the reaction product after heat processing.

  The reaction product after the heat treatment contained 1,5-pentamethylene diisocyanate and hydrolyzable chlorine.

(3) Purification step Next, the reaction product after the heat treatment was filtered under reduced pressure (filter paper: model No. 5A), and then the filtrate was filtered at 120 to 140 ° C. with a distillation apparatus equipped with a stirrer, a flask and a condenser. Distillation (rectification) was carried out under conditions of 1.7 to 2.4 kPa.

  And after distilling 12 mass% (12 mass parts) of an initial fraction, the main fraction (main fraction) 76 mass% (76 mass parts) was extract | collected as refined pentamethylene diisocyanate. The residue of the kettle (tar component) was 12% by mass (12 parts by mass).

  The concentration of HC in the purified pentamethylene diisocyanate was 305 ppm, the concentration of cyclic carbamoyl chloride was 128 ppm, and the concentration of dichloroimine was 178 ppm.

Example 1
206 parts by mass of the reaction product obtained in the preparation of the reaction product (1) of Comparative Example 1 and 11 parts by mass of the residue (tar component) obtained in the purification step (3) of Comparative Example 1 Were introduced into a flask (heat treatment vessel) equipped with a stirrer, a thermometer and a nitrogen introduction tube, nitrogen was introduced into the flask for 30 minutes, and then nitrogen was added at 10 mL / min (reaction product of nitrogen). At a feed rate of 0.05 / min), and heat treatment was started at 200 ° C. under normal pressure while stirring at 250 rpm. The heat treatment time was 4 hours. Moreover, when the HC concentration of the reaction product to which the tar component was added was measured before the start of the heat treatment, it was 1455 ppm, the concentration of cyclic carbamoyl chloride was 569 ppm, and the concentration of dichloroimine was 659 ppm.

  A part of the reaction product is sampled every hour from the start of the heat treatment, and the HC concentration, cyclic carbamoyl chloride concentration, dichloroimine concentration, and pentamethylene diisocyanate concentration of the reaction product at each time are sampled. Polymerization loss was measured. The results are shown in Table 1.

  Thus, the reaction product was heat-treated. Then, it cooled to 40 degrees C or less, and obtained the reaction product after heat processing.

  The reaction product after the heat treatment contained 1,5-pentamethylene diisocyanate and hydrolyzable chlorine.

  Next, the reaction product after the heat treatment was filtered under reduced pressure (filter paper: model No. 5A), and then the filtrate was subjected to 120 to 140 ° C. and 1.7 to 2 with a distillation apparatus equipped with a stirrer, a flask and a condenser. Distillation (rectification) was carried out at a condition of 4 kPa.

  And after distilling 19 mass% (19 mass parts) of the first fraction, 70 mass% (70 mass parts) of the main fraction (main fraction) was extract | collected as refined pentamethylene diisocyanate. The residue of the kettle (tar component) was 12% by mass (12 parts by mass).

  The concentration of HC in the purified pentamethylene diisocyanate was 90 ppm, the concentration of cyclic carbamoyl chloride was 73 ppm, and the concentration of dichloroimine was less than the detection limit (1 ppm).

1 Plant 2 Reaction Unit 3 Solvent Removal Unit 5 Heat Treatment Unit 6 Purification Unit 31 Tar Component Transport Line

Claims (4)

A reaction step of reacting carbonyl chloride with pentamethylenediamine to obtain a reaction product containing pentamethylene diisocyanate and hydrolyzable chlorine;
A heat treatment step for heat-treating the reaction product;
A step of distilling the reaction product after the heat treatment to purify the pentamethylene diisocyanate,
In the heat treatment step,
A tar component obtained by distilling the reaction product in the purification step,
It introduce | transduces into the said reaction product before the said heat processing, It heats. The manufacturing method of the pentamethylene diisocyanate characterized by the above-mentioned. In the heat treatment step,
2. The method for producing pentamethylene diisocyanate according to claim 1, wherein an addition ratio of the tar component is 1 part by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the reaction product. The method for producing pentamethylene diisocyanate according to claim 1 or 2, wherein a heat treatment temperature in the heat treatment step is 180 ° C or higher and 245 ° C or lower. An apparatus for producing pentamethylene diisocyanate for carrying out the method for producing pentamethylene diisocyanate according to any one of claims 1 to 3,
A reaction unit that reacts carbonyl chloride with pentamethylenediamine to obtain a reaction product containing pentamethylene diisocyanate and hydrolyzable chlorine;
A heat treatment unit for heat-treating the reaction product;
A distillation unit for purifying the pentamethylene diisocyanate by distillation of the reaction product after the heat treatment,
The heat treatment unit includes:
A pentamethylene diisocyanate comprising a tar component introduction line for introducing a tar component obtained by distillation of the reaction product in the purification unit into the reaction product before the heat treatment. Manufacturing equipment.

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