JP2009203198A - Method for producing polyisocyanate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polyisocyanate, which sufficiently improves hue of a polyisocyanate and controls formation of precipitate during purification. <P>SOLUTION: The method for producing a polyisocyanate comprises a contact process of reacting a polyamine with phosgene to give a reaction solution and bringing the reaction solution into contact with zeolite at 60-230°C and a heating process of heating the reaction solution at 180-230°C after the contact with the zeolite in the contact process. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a polyisocyanate. In more detail, this invention relates to the manufacturing method which manufactures polyisocyanate with little coloring.

  Polyisocyanates are produced industrially by reacting a polyamine mixture with phosgene in the presence of a solvent, followed by separation of distillate and non-distillate components by vacuum distillation. The non-distilled component obtained by this method contains an acid content and a hydrolyzable chlorine-containing compound as impurities, and it is known that the reactivity during urethane production deteriorates when these impurities are large. As a method for reducing these impurities, heat treatment at 180 to 230 ° C. is performed under reduced pressure. However, this high-temperature treatment deteriorates the color of the polyisocyanate, which causes the coloring of the urethane product. Therefore, development of a method for producing a polyisocyanate having a small coloring is desired.

  There are many reports on improving the hue of polyisocyanate (for example, Patent Document 1 and Patent Document 2), but a method of heat-treating a reaction product of polyamine and phosgene in the presence of hydrogen chloride gas is industrially effective. It is said that.

On the other hand, a method has been proposed in which diphenylmethane diisocyanate (hereinafter sometimes referred to as “MDI”) is treated with a microporous adsorbent having an internal surface area of at least 100 m ² / g to reduce the iron content. (See Patent Document 3).

Japanese Patent Publication No.57-15827 Japanese Patent No. 3222914 JP-A-8-99946

  However, even the above method does not sufficiently improve the hue of the polyisocyanate, and a further improvement in hue is desired. Further, if the polyisocyanate to be produced contains a component having low solubility, there is a problem that a precipitate is formed when cooled to room temperature.

  Therefore, an object of the present invention is to provide a method for producing a polyisocyanate capable of sufficiently improving the hue of the polyisocyanate and suppressing the formation of precipitates during purification.

  As a result of intensive studies on a method for producing a polyisocyanate with little coloration, the present inventors have heated the polyisocyanate reaction liquid at a predetermined temperature in the presence of zeolite, and then reheated it at the predetermined temperature. As a result, the present inventors have found that sedimentation can be suppressed while improving the present invention.

  That is, in the present invention, a contact step in which a reaction solution obtained by reacting polyamine with phosgene is brought into contact with zeolite at 60 to 230 ° C., and a reaction solution after being brought into contact with zeolite in the contact step is heated at 180 to 230 ° C. And a heating step to provide a method for producing polyisocyanate.

  By the production method of the present invention, a polyisocyanate in which the hue is significantly improved and the sediment is suppressed is obtained. Although the present inventors are not bound by a specific theory, it is thought that the improvement in hue is caused by heating the reaction solution at 60 to 230 ° C. in the presence of zeolite in the contact step. Moreover, it is estimated that heating at 180-230 degreeC in a heating process has contributed to suppression of a sediment. In addition, the method of the present invention is far superior to the conventional method in terms of energy consumption. That is, conventionally, after completely removing phosgene and hydrogen chloride, it was disadvantageous in terms of energy consumption by refining it by adding hydrogen chloride or the like to improve the hue again. In the present invention, hydrogen chloride gas is added again. Therefore, since the hue can be improved, energy consumption can be kept low.

The zeolite used in the present invention is preferably a zeolite having a SiO ₂ / Al ₂ O ₃ (molar ratio) of 5/1 to 500/1. Since such zeolite has sufficient durability against hydrogen chloride, phosgene and the like, the effect of improving hue is sufficiently exhibited.

  The reaction solution contains a solvent, and it is preferable that the solvent and / or unreacted phosgene is removed in the contacting step. With such a configuration, hue improvement and impurity removal proceed simultaneously, which is advantageous in terms of energy and hue improvement efficiency.

  Since the effect mentioned above is exhibited notably, it is preferable that the reaction solution is brought into contact with zeolite at 100 to 160 ° C. in the contact step.

  The polyamine preferably used in the present invention is a mixture of polyamines obtained by addition condensation of aniline and formaldehyde and having different skeletons derived from aniline. Examples of such polyamines include methylene dianiline and higher analogs (polynuclear bodies) thereof.

  According to the present invention, it is possible to produce a polyisocyanate that is excellent in hue (that is, very little colored) and that suppresses the formation of precipitates during purification, and is useful as a method for producing polyisocyanate.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  The method for producing a polyisocyanate according to the present invention comprises a contact step in which a reaction solution obtained by reacting polyphosphine with phosgene (phosgenation) is contacted with zeolite at 60 to 230 ° C., and a reaction after contacting with zeolite in the contact step A heating step of heating the liquid at 180 to 230 ° C.

As the polyamine used for the phosgenation reaction in the contacting step, a polyamine having any skeleton such as an aliphatic polyamine, an aromatic polyamine, or an alicyclic polyamine can be used. In the present invention, it is preferable to use a polyamine obtained by addition condensation of aniline and formaldehyde, that is, a polyamine represented by the following general formula (1), because a polyisocyanate having excellent reactivity and safety can be obtained. In the formula, n represents 0 or a number of 1 or more.

  In the above, when n = 0, the polyamine represented by the general formula (1) is methylenedianiline (MDA) and corresponds to a binuclear body. Further, when n = 1, it is a trinuclear body, when n = 2, it is a tetranuclear body, and when n = m, it is a (m + 2) nucleus. The polyamine represented by the general formula (1) may be a mixture of different skeletons derived from aniline (skeletons composed of one amino group and one benzene ring). That is, it may be a mixture of binuclear, trinuclear, tetranuclear, pentanuclear and higher polynuclear bodies.

  Phosgenation can be carried out by dissolving polyamine in an inert solvent as a reaction solvent and introducing phosgene into this. Examples of the inert solvent include aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as chlorotoluene, chlorobenzene, and dichlorobenzene, esters such as butyl acetate and amyl acetate, and ketones such as methyl isobutyl. . The phosgenation can be carried out by using a method such as a hydrochloride method, a cold two-stage method, a phosgene pressurization method, and the like, and a method of causing a reaction continuously from an industrial standpoint.

  When phosgenation is carried out by the hydrochloride method, polyamine is dissolved in the above-mentioned inert solvent, hydrogen chloride gas is introduced at a temperature below the boiling point of this solvent, polyamine hydrochloride is formed, and phosgene gas is further introduced. Thus, for example, the phosgenation reaction can be caused at 100 to 180 ° C.

  When the phosgenation is carried out by a cold two-stage method, the polyamine is dissolved in the above-mentioned inert solvent, and about 5 to 20 times moles of phosgene of the polyamine is introduced into the solution. Subsequently, the second stage reaction is carried out at 100 to 150 ° C., for example, in the presence of about 0.5 to 10 moles of phosgene with respect to the polyamine.

  When phosgenation is carried out by the phosgene pressurization method, the polyamine is heated to the boiling point or a temperature higher than the boiling point, for example, phosgene (about 1 to 10 times mole of the polyamine) under a pressure of 100 to 500 kPa is a carrier such as nitrogen or argon. It can introduce | transduce with gas and can react.

  In the contacting step, it is preferable to reduce the contents of residual phosgene and reaction solvent before contacting the reaction solution obtained by phosgenating polyamine with zeolite at 60 to 230 ° C.

  As a method of reducing the content of residual phosgene and reaction solvent, a reaction solution obtained by phosgenation of polyamine is charged with an inert gas such as nitrogen, helium, argon, or the reaction solvent under reduced pressure. A method of heating to the boiling point (decompression method) can be mentioned, and the decompression method is preferable from the viewpoint of cost. In this case, it is preferable to reduce the content until the amount of residual phosgene in the reaction solution is about 100 ppm and the amount of residual reaction solvent is about 10%.

  It is preferable to reduce the contents of residual phosgene and reaction solvent by heating at 100 to 160 ° C. in order to maintain the reduction efficiency and the color of the polyisocyanate. If heating is continued for a long time at a temperature higher than 160 ° C, the hue of the polyisocyanate may be deteriorated, and if the temperature is lower than 100 ° C, the reduction efficiency may be insufficient.

  The reaction solution obtained by reacting polyamine with phosgene is preferably heated at 60 to 230 ° C. in the presence of zeolite after reducing the residual phosgene to 100 ppm and the residual reaction solvent to about 10%. It is advantageous in terms of energy consumption that the heating in the presence of zeolite is performed at 100 to 160 ° C. from the flow of the production process. When the heating temperature is lower than 60 ° C., the hue improving effect tends to decrease, and when the heating temperature is higher than 230 ° C., the polyisocyanate is thermally decomposed and the hue tends to deteriorate.

  The temperature of the heat treatment in the contact step is more preferably from 100 to 200 ° C, particularly preferably from 100 to 160 ° C. Heating is preferably performed in an inert gas atmosphere such as nitrogen in order to prevent moisture and the like from being mixed.

  When such heat treatment is performed, the zeolite can be used in a batch mode, a continuous mode or a semi-continuous mode, but a continuous mode is preferable from the viewpoint of equipment, labor saving and the like when industrially implemented.

  The amount of zeolite used is in the range of 0.01 to 10 parts by mass with respect to 100 parts by mass of the reaction solution in a batch mode. The treatment time varies depending on the treatment temperature and varies depending on the amount of zeolite used, but it is usually preferable to give about 20 minutes at 150 ° C.

  The zeolite used in the contacting step may be natural zeolite or synthetic zeolite, but synthetic zeolite is preferable from the viewpoint of composition and uniformity of pores. Examples of natural zeolites include chabasite, mordenite, erionite, faujasite, clinoptilolite, and synthetic zeolites include A type, B type, D type, L type, X type, Y type, and Z type. Omega type (Omega type), beta type (Beta type), mordenite type (Mordenite type), ferrierite type (Ferrierite type) and the like. As a synthetic zeolite, a beta type (Beta type) and a mordenite type (Mordenite type) are preferable.

The zeolite used in the contacting step is preferably a zeolite having a SiO ₂ / Al ₂ O ₃ (molar ratio) of 5/1 to 500/1. That is, the composition of zeolite is M _{2 / X 2} O ₃ · Al ₂ O ₃ · mSiO ₂ · nH ₂ O (where M is a x-valent metal element, x is a valence of M, and m is a number of 2 or more. , N represents a number of 0 or more), and is preferably a zeolite having a SiO ₂ / Al ₂ O ₃ (molar ratio) of 5/1 to 500/1. In addition, as M, metal elements, such as Na, K, Ca, Ba, Mg, are mentioned, As x, 1 or 2 is mentioned. Note that n is a number determined according to the number of water molecules contained in the voids in the skeleton of the compound represented by M _{2 / X 2} O ₃ · Al ₂ O ₃ · mSiO ₂ , for example, a value of 10 to 300 (13 16, 21, 22, 24, 27, 235, 250, 264, etc.).

When the molar ratio of SiO ₂ / Al ₂ O ₃ is smaller than 5/1, durability against acids such as hydrogen chloride and phosgene tends to be inferior. Moreover, when the molar ratio of SiO ₂ / Al ₂ O ₃ is larger than 500/1, durability against acids such as hydrogen chloride and phosgene is improved, but the hue improving effect tends to be reduced.

  The cation type of zeolite is preferably a proton type. In metal types such as sodium type and calcium type, these metals are eluted in the polyisocyanate component, which may cause problems in the reactivity and storage stability of the product.

The zeolite is preferably in the form of particles, and the average particle size is preferably 2 to 20 μm. BET value of the zeolite is preferably 150~800m ² / g, more preferably 200~800m ² / g, more preferably 400-600m ² / g.

The phosgenation reaction of amine can be represented by R—NH ₂ + COCl ₂ → R—NCO + 2HCl, but as side reactions, R—NH ₂ + COCl ₂ → R—NHCOCl + HCl, R—NH ₂ + HCl → R—NH _2. HCl, R—NH ₂ + R—NCO → R—NHCONH—R, and the like are conceivable (R is an isocyanate residue, and examples thereof include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alicyclic hydrocarbon group. ). It is preferable that the substance generated by such a side reaction is removed during the contacting step.

When the polyamine represented by the above general formula (1) is used as the polyamine, the substance obtained by the reaction with phosgene is a polyisocyanate represented by the following general formula (2). In the formula, n represents 0 or a number of 1 or more.

  When the polyamine represented by the general formula (1) is a polynuclear mixture, the resulting polyisocyanate is also a polynuclear mixture. The polyisocyanate represented by the general formula (2) is monomeric MDI when n = 0 (binuclear), and polymeric MDI when n ≧ 1 (trinuclear or more). In this case, the polyisocyanate obtained is a mixture comprising a monomeric MDI that is a binuclear body of n = 0 and a polymeric MDI that is a trinuclear body of n ≧ 1.

  After the contact process described above, a heating process is performed in which the reaction liquid after contacting with zeolite is heated at 180 to 230 ° C.

  In the heating step, it is necessary to remove the zeolite from the reaction solution and heat to 180 to 230 ° C. For this purpose, the supernatant of the reaction solution may be collected. The heating temperature is more preferably 190 to 230 ° C, and further preferably 200 to 230 ° C. In addition, the heating temperature should just be 180-230 degreeC, and there may exist temperature rise or temperature fall in this range. Heating is preferably performed in an inert gas atmosphere such as nitrogen in order to prevent moisture and the like from being mixed.

  By performing such a heating process, not only can the hue of the generated polyisocyanate be improved, but also the sedimentation of trace components with low solubility that occur in the reaction solution is suppressed (the generation of sediment is suppressed). )can do. Thus, although the reason for suppressing sedimentation of the trace component with low solubility is not necessarily clear, it is considered that the generated trace component is decomposed by heating. In addition, when the reaction liquid is heated to a temperature higher than 230 ° C., not only the above trace components but also the polyisocyanate itself intended for the present invention is decomposed and should be avoided. Further, when the reaction solution is heated at a temperature lower than 180 ° C., it should be avoided because a precipitate is generated due to insufficient decomposition of the trace components.

  The heating time is not particularly limited and can be, for example, 1 minute to 30 minutes, but it is preferable to end the heating time within 10 minutes in order to prevent denaturation or decomposition. The heating time is preferably 5 to 10 minutes in order to ensure the above effects and prevent excessive heating.

  The polyisocyanate obtained after carrying out the heating step is very little colored and has high purity because the production of precipitates during production is suppressed. Therefore, for example, if it is used for the production of polyurethane, a light-colored polyurethane with reduced coloring can be obtained, and the stability of performance is also improved.

  The manufacturing method of the polyisocyanate of this invention should just be provided with the contact process and heating process which were mentioned above, and may be provided with another process before and after the process. For example, a storage step for storing the reaction liquid after contacting with zeolite may be performed between the contact step and the heating step, and after the heating step, a step of rapidly cooling to near room temperature (for example, 30 ° C.) is performed. May be.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not construed as being limited to these examples. In the following, “%” means “% by mass” unless otherwise specified.

  The polyisocyanate mixture is reacted with phosgene in the presence of a solvent, followed by a step of separating a distillate component and a non-distillate component by distillation under reduced pressure, and is abbreviated as polyisocyanate shown below (hereinafter referred to as “raw material MDI”). ) Each Example and each Comparative Example shown below were performed using this raw material poly-MDI.

<Details of raw material poly MDI>
MDI peak area (PA) ratio (measured by GPC)
Dinuclear body: Trinuclear body: Tetranuclear body: More than pentanuclear body = 66.4: 16.7: 6.9: 10.0 PA%
Here, the nucleus indicates a benzene ring in the molecule.
For example, binuclear refers to MDI having two benzene rings in the molecule.
Ratio of 4,4′-MDI in MDI (measured by GC) = 98.7 PA%, isomers other than 4,4′-MDI in MDI (2,4′-MDI and 2,2′-MDI) Ratio (measured by GC) = 1.3 PA%
Phosgene content = 100 ppm
Monochlorobenzene content = 8%

In Examples and Comparative Examples, the hue of polyisocyanate was measured as follows.
<Solution hue measurement method>
In a 450 ml colorless transparent bottle, 2 g of sample and 400 ml of acetone were added and dissolved, and the color of the solution was visually measured at 23 ° C. The value is indicated by APHA (Hazen unit color number). The solution hue of the raw material poly-MDI was 10 APHA.

In Examples and Comparative Examples, the presence or absence of sediment was evaluated by visual confirmation.
Example 1
200 g of raw poly MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 ° C. for 20 minutes at 150 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 20 APHA.

(Example 2)
200 g of raw poly MDI and 10 g of zeolite 660HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 rpm for 20 minutes at 150 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 20 APHA.

(Example 3)
200 g of raw poly MDI and 10 g of zeolite 640HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 ° C. for 20 minutes at 150 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 20 APHA.

Example 4
200 g of raw poly MDI and 10 g of zeolite 690HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 rpm for 20 minutes at 150 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 30 APHA.

(Example 5)
200 g of raw poly MDI and 10 g of zeolite 390HUA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 ° C. for 20 minutes at 150 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 30 APHA.

(Example 6)
200 g of raw poly MDI and 10 g of zeolite 320HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 ° C. for 20 minutes at 150 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. The container was then immersed in an ice bath and quenched until the solution temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 30 APHA.

(Example 7)
200 g of raw poly-MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 100 rpm for 20 minutes at 150 rpm in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 30 APHA.

(Example 8)
200 g of raw poly MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 160 rpm for 20 minutes at 160 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 20 APHA.

Example 9
200 g of raw poly MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 60 rpm at 60 ° C. for 20 minutes in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 40 APHA.

(Example 10)
200 g of raw poly MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 rpm for 20 minutes at 230 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 40 APHA.

(Comparative Example 1)
200 g of raw poly-MDI was added to a 300 ml four-neck separable flask equipped with a distillation outlet, and stirred at 150 rpm at 150 ° C. for 20 minutes in a nitrogen atmosphere. 50 ml of the solution was added to a stainless steel 100 ml container which had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen of 50 ml / min. The container was then immersed in an ice bath and quenched until the solution temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample is 80 APHA, and the solution hue is inferior to Examples 1 to 10 of the present invention.

(Comparative Example 2)
200 g of raw poly MDI was added to a 300 ml four-necked separable flask equipped with a distillation outlet, and stirred at 150 rpm at 150 ° C. for 20 minutes while bubbling 100 ml / min of hydrogen chloride gas. 50 ml of the solution was added to a stainless steel 100 ml container which had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen of 50 ml / min. The container was then immersed in an ice bath and quenched until the solution temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 60 APHA.

(Comparative Example 3)
200 g of raw poly MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and stirred at 150 rpm for 20 minutes at 23 ° C. in a nitrogen atmosphere. 50 ml of the supernatant was added to a stainless 100 ml container that had been heated to 220 ° C. in advance, and left for 7 minutes while bubbling with nitrogen at 50 ml / min. Next, this container was immersed in an ice bath and rapidly cooled until the liquid temperature reached 30 ° C. No sediment was observed in this treatment liquid. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 80 APHA.

(Comparative Example 4)
200 g of raw poly MDI and 10 g of zeolite 930HOA (manufactured by Tosoh Corporation) were added to a 300 ml four-necked separable flask equipped with a distillation outlet, and the mixture was stirred at 150 rpm for 20 minutes at 150 ° C. in a nitrogen atmosphere. Thereafter, the heating was stopped and left standing. The liquid temperature after 24 hours was 30 ° C. Sediment was confirmed in this treatment solution. Thereafter, the treatment liquid was filtered to obtain a sample. The solution hue of the obtained sample was 20 APHA.

  Examples 1 to 10 and Comparative Examples 1 to 4 are summarized in Tables 1 to 3 below. In addition, the detail of each zeolite used in the Example and the comparative example is as follows.

<Zeolite 930HOA>
Beta type zeolite trade name “HSZ-930HOA” (manufactured by Tosoh Corporation)
Cation type: H
SiO ₂ / Al ₂ O ₃ (molar ratio): 27/1
Na ₂ O content (% by mass): 0.03
Surface area (BET, m ² / g): 600
Crystal size (μm): 0.04
Average particle diameter (μm): 5

<Zeolite 660HOA>
Mordenite type zeolite trade name “HSZ-660HOA” (manufactured by Tosoh Corporation)
Cation type: H
SiO ₂ / Al ₂ O ₃ (molar ratio): 33/1
Na ₂ O content (% by mass): 0.03
Surface area (BET, m ² / g): 400
Crystal size (μm): 0.1 × 0.5
Average particle diameter (μm): 13

<Zeolite 640HOA>
Mordenite type zeolite trade name “HSZ-640HOA” (manufactured by Tosoh Corporation)
Cation type: H
SiO ₂ / Al ₂ O ₃ (molar ratio): 18/1
Na ₂ O content (% by mass): 0.05
_{NH 3 N-TPD (mmol /} g): 0.7
Surface area (BET, m ² / g): 400
Crystal size (μm): 0.1 × 0.5
Average particle diameter (μm): 13

<Zeolite 690HOA>
Mordenite type zeolite trade name "HSZ-690HOA" (manufactured by Tosoh Corporation)
Cation type: H
SiO ₂ / Al ₂ O ₃ (molar ratio): 240/1
Na ₂ O content (% by mass): 0.05
_{NH 3 N-TPD (mmol /} g): 0.2
Surface area (BET, m ² / g): 450
Crystal size (μm): 0.1 × 0.5
Average particle diameter (μm): 13

<Zeolite 390HUA>
Y-type zeolite trade name “HSZ-390HUA” (manufactured by Tosoh Corporation)
Cation type: H
SiO ₂ / Al ₂ O ₃ (molar ratio): 470/1
Na ₂ O content (% by mass): 0.05
Ultra Clean Call (ASTM): 24.26
_{NH 3 N-TPD (mmol /} g): 0.1
Surface area (BET, m ² / g): 620
Crystal size (μm): 0.3

<Zeolite 320HOA>
Y-type zeolite trade name “HSZ-320HOA” (manufactured by Tosoh Corporation)
Cation type: H
SiO ₂ / Al ₂ O ₃ (molar ratio): 5/1
Na ₂ O content (% by mass): 4
Ultra Clean Call (ASTM): 24.50
_{NH 3 N-TPD (mmol /} g): 0.7
Surface area (BET, m ² / g): 550
Crystal size (μm): 0.3
Average particle diameter (μm): 6

The polyisocyanate with very little coloration that can be obtained by the present invention is a field using this polyisocyanate as a raw material (such as a binder), or any field where a polyurethane resin obtained using this polyisocyanate as a raw material is used ( This is useful when low coloration is required in foams, paints, adhesives, sealants, elastomers, and the like.

Claims (5)

  A contact step in which a reaction solution obtained by reacting polyamine with phosgene is brought into contact with zeolite at 60 to 230 ° C., and a heating step in which the reaction solution after contact with zeolite in the contact step is heated at 180 to 230 ° C., A process for producing a polyisocyanate. The method for producing a polyisocyanate according to claim 1, wherein the zeolite is a zeolite having a SiO ₂ / Al ₂ O ₃ (molar ratio) of 5/1 to 500/1.   The said reaction liquid contains the solvent, The manufacturing method of the polyisocyanate of Claim 1 or 2 with which the said solvent and / or the said unreacted phosgene are removed in a contact process.   The manufacturing method of the polyisocyanate as described in any one of Claims 1-3 which makes the said reaction liquid contact the said zeolite at 100-160 degreeC in the said contact process. The said polyamine is a polyamine obtained by addition condensation of aniline and formaldehyde, Comprising: It is a mixture of what differs in the number of frame | skeleton derived from aniline, The manufacturing method of the polyisocyanate as described in any one of Claims 1-4 .