JPH0782230A - Production of diphenylmethanediisocyanate-based polyisocyanate - Google Patents

Abstract

PURPOSE:To provide a producing method not only producing a MDI-based polyisocyanate which is not colored or remarkably reduced in coloring, but simultaneously capable of also preventing coloring during storage. CONSTITUTION:In producing diphenylmethanediisocyanate-based polyisocyanate by subjecting a condensation product obtained by condensing aniline with formaldehyde in the presence of a catalyst or a diaminodiphenylmethane-based polyamine to phosgenation, this producing method is carried out by adding an organic phosphorous acid before carrying out phosgenation reaction. As necessary, the phosgenation product is separated into diphenylmethanediisocyanate and polyphenylenepolymethylenepolyisocyanate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a diphenylmethane diisocyanate polyisocyanate (hereinafter referred to as MDI polyisocyanate) having improved coloring.

[0002]

2. Description of the Related Art Diphenylmethane diisocyanate (hereinafter referred to as MDI), various MDI-based polynuclear condensates having three or more benzene rings obtained by phosgenating a condensation product of aniline and formaldehyde, or MDI mainly composed of this A mixture containing polyphenylene polymethylene polyisocyanate (hereinafter referred to as Polymeric M
MDI-based polyisocyanates such as DI) are widely used industrially for producing elastomers, foams, synthetic leather, spandex, paints, adhesives, etc. by reacting with active hydrogen-containing compounds such as polyols and amines. It is used.

Immediately after production, MDI is colorless and transparent or slightly yellow, but it is colored when exposed to air or light or heated during storage. Colored MDI cannot be used as a raw material for white or pale yellow artificial leather or paint, and it is also difficult to use it as a raw material for elastomer or the like. Therefore, it is purified by distillation or the like under precise conditions. Further, in order to prevent coloration during storage, antioxidants, ultraviolet absorbers and the like are added. In order to prevent coloration during storage of aromatic isocyanates, specifically,
In addition to antioxidants such as 2,6-di-tert-butyl-4-methylphenol (hereinafter referred to as BHT) in aromatic isocyanate, triphenylphosphite (hereinafter referred to as TPP) and phosphite tria Addition of trialkyl phosphates such as reel ester and triethyl phosphate is known. As a mixture of these, a method of adding a dialkyl monoaryl phosphite, a mixture of three kinds of TPP and BHT (JP-A-5-65264), or a pentaerythritol-based trialkyl phosphite, BHT and an ultraviolet absorber. 2 (2'-hydroxy-3 ', 5'-di-
A method of adding a mixture of three types of tert-amylphenyl) benzotriazole (Japanese Patent Publication No. 3-4062) is known.

By the way, unlike MDI, polymeric MDI cannot be purified by distillation, so that coloring due to heat history in the manufacturing process directly results in coloring of the product. Therefore, in general, the polymeric MDI has a brown color. Up to now, this coloring has been unavoidable, but in recent years, low coloring of the polymeric MDI has also been demanded.

[0005]

However, all of the above addition methods relate to the prevention of coloration of distilled and purified colorless transparent or pale yellow polyisocyanate during storage, and to prevent the coloration of MDI separated by distillation. However, a simple method of simultaneously solving the polymeric MDI obtained as a can and the reduction of the coloring degree during storage thereof has not been found yet.

[0006]

Means for Solving the Problems As a result of intensive studies for solving such problems, the present inventors have found that by adding an organic phosphite ester before the phosgenation step of polyamine, immediately after the production. It was found that the reduction of the coloring degree of the MDI-based polyisocyanate and the reduction of the coloring degree during the storage thereof were simultaneously achieved, and the present invention was completed.

That is, the method for producing an MDI-based polyisocyanate of the present invention is a method of phosgenating a diaminodiphenylmethane-based polyamine in an inert solvent, characterized by adding an organic phosphite ester before the phosgenation reaction. And

The method for producing the MDI polyisocyanate of the present invention is a method in which a condensation product obtained by condensing aniline and formaldehyde in the presence of a catalyst is phosgenated in an inert solvent before phosgenation reaction. The organic phosphite ester is added at any one time.

Further, the MDI-based polyisocyanate production method of the present invention comprises phosgenating a condensation product obtained by condensing aniline and formaldehyde in the presence of a catalyst in an inert solvent, and then obtaining the obtained phosgenation product. To MD
In the method of separating I and polymeric MDI,
It is characterized in that the organic phosphite is added at any point before the phosgenation reaction.

The diaminodiphenylmethane type polyamine in the present invention is produced, for example, as follows.
Organic phosphite is optionally added in the presence of 0.01 to 0.1 mol of an acid catalyst such as hydrochloric acid or sulfuric acid as a catalyst to 1 mol of aniline, and aniline: formaldehyde = 3: 2 to 6 80 to 150 at a molar ratio of 1: 1
After the reaction is completed, the condensation product is neutralized and washed with water, and then water and aniline are distilled off and separated, and diaminodiphenylmethane and a diaminodiphenylmethane-based polynuclear condensate having three or more benzene rings, Alternatively, a diaminodiphenylmethane-based polyamine such as a mixture thereof is obtained. The phosgenation in the present invention can be carried out, for example, by reacting a diaminodiphenylmethane-based polyamine with an excess amount of phosgene in an inert solvent such as monochlorobenzene (hereinafter referred to as MCB), and then reacting with an inert solvent. By distilling and separating, MDI, an MDI polynuclear condensate having three or more benzene rings, a polymeric MDI, isomers thereof, a crude mixture thereof, and other MDI polyisocyanates are obtained. If necessary, the product is further purified by separation into MDI and polymeric MDI.

In the organic phosphite used in the present invention, the total number of carbon atoms of the hydrocarbon group bonded to the oxygen atom of the phosphite group is 12 to 60 per phosphite group. Phosphoric acid triesters are preferable, and particularly, for example, triaryl phosphites such as triphenyl phosphite, alkyl diaryl phosphites having an alkyl group having 4 to 20 carbon atoms, and alkyl groups having 4 to 20 carbon atoms.
A dialkylaryl phosphite having 20 carbon atoms, a trialkyl phosphite having an alkyl group having 4 to 20 carbon atoms, and a di (te
A phosphite triester bearing a hydrocarbon group having an rt-butyl) phenyl structure, such as tris (2,4-di-).
tert-butylphenyl) phosphite (hereinafter 24
P) and bis (2,6-di-tert-butyl-4)
-Methylphenyl) pentaerythritol phosphite and the like (hereinafter referred to as 26P) having two phosphite groups in one molecule and having a skeleton linking the phosphite groups with a bisphenol A structure, for example, tetrabutyl -4,4 '
-Isopropylidene diphenyl diphosphite, having 2 or 4 phosphite groups in one molecule and having a skeleton connecting the phosphite groups with a pentaerythritol structure, such as diisodecyl pentaerythritol diphosphite, tetra Examples thereof include phenyl tetradecyl pentaerythritol tetraphosphite. You may use these phosphorous acid ester in mixture of 2 or more types. Particularly preferred organic phosphites are 24P and 26P. When the total number of carbon atoms of the hydrocarbon group bonded to the oxygen atom of the phosphite group is 11 or less per one phosphite group, the boiling point is low, so that volatilization easily occurs during the production of the polymeric MDI, and the coloring preventing effect is small. . An antioxidant such as BHT may be used in combination with these organic phosphites.

The step of adding the organic phosphite ester is
The raw material may be added to aniline, the reaction system before the condensation reaction, the diaminodiphenylmethane-based polyamine and / or the inert solvent, or the reaction system immediately before the phosgenation reaction, or any time before the phosgenation reaction. Good. The addition amount of the organic phosphite varies depending on the residence time of the production process, which process is added, and the like, but is preferably 10 to 2000 ppm, particularly preferably 50 to 1000 ppm, per 1 part by weight of aniline or diaminodiphenylmethane-based polyamine. .

[0013]

Industrial Applicability According to the present invention, it is possible not only to produce an MDI-based polyisocyanate which is not colored or whose coloring is remarkably reduced, but at the same time it is possible to prevent coloring during storage thereof. It has become possible to provide. Specifically, for example, it is possible to improve the coloring of the final product MDI and the polymeric MDI during manufacture and storage. Especially, for example, unlike isocyanate which is easily purified by distillation or the like, it is possible to reduce coloring of the polymeric MDI which is difficult to be purified by a simple method such as distillation. Can be applied to a wider range of applications.

[0014]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In Examples and Comparative Examples, "part"
Means all "parts by weight" and "%" means "% by weight".

Example 1 In a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid, and 100 ppm of TPP per 100 parts of aniline were added and mixed at 10 ° C., and 100 parts of 30% aqueous formaldehyde solution was added to the mixture. added. After reacting at 130 ° C. for 120 minutes for condensation, the condensation product was taken out, neutralized with caustic soda, passed through a thin film evaporator to remove water and unreacted aniline, and 94 parts of diaminodiphenylmethane-based polyamine was obtained. It was MCB33 in 80 parts of this polyamine
After addition of 0 part, excess equivalent of phosgene 1 at 0-10 ° C.
Blowing 20 parts, heating after 90 minutes, then 60-8
The phosgenation reaction was performed at 0 ° C. for 90 minutes and at 110 to 130 ° C. for 90 minutes. After completion of the reaction, MCB is removed from the phosgenation reaction solution by distillation, and M is removed by distillation.
Separation of DI and polymeric MDI was performed. Obtained M
The DI was 33 parts and the polymeric MDI was 68 parts.
Table 1 shows the colors of the polyamine, the reaction solution after phosgenation (after removing MCB), MDI, and polymeric MDI.

Example 2 To a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid, and 1000 ppm of TPP per part of aniline were added and mixed at 10 ° C., and 100 parts of a 30% aqueous formaldehyde solution was added thereto. added. After condensation and neutralization in the same manner as in Example 1, water and unreacted aniline were removed by passing through a thin film evaporator to obtain 95 parts of diaminodiphenylmethane-based polyamine. MCB330 to 80 parts of this polyamine
After addition of 10 parts of phosgene 12
I blew 0 copies. Phosgenation reaction, MC from reaction solution
Removal of B and further distillation by MDI and polymeric MD
Separation of I was carried out as in Example 1. The obtained MDI was 30 parts and the polymeric MDI was 71 parts. The polyamine, the reaction solution after phosgenation (after removing MCB), M
Table 1 shows the colors of DI and Polymeric MDI.

Example 3 500 pp / part of aniline was placed in a reaction vessel equipped with a stirrer.
465 parts of aniline to which 24P of m was added, and 50 parts of 36% hydrochloric acid were added and mixed at 10 ° C.
100 parts of formaldehyde aqueous solution was added. After condensation and neutralization in the same manner as in Example 1, water and unreacted aniline were removed by passing through a thin film evaporator to obtain 94 parts of diaminodiphenylmethane-based polyamine. After adding 330 parts of MCB to 80 parts of this polyamine, 120 parts of excess equivalent of phosgene was blown in at 0 to 10 ° C. The phosgenation reaction, the removal of MCB from the reaction solution, and the separation of MDI and polymeric MDI were carried out in the same manner as in Example 1 by distillation. The obtained MDI was 29 parts and the polymeric MDI was 71 parts. The polyamine, the reaction solution after phosgenation (MCB
The colors of MDI and polymeric MDI (after removal) are shown in Table 1.

Example 4 Diaminodiphenylmethane 8 was placed in a reaction vessel equipped with a stirrer.
0 parts, 500ppm per 1 part of diaminodiphenylmethane
24P and 330 parts of MCB were added and mixed, and then 0-1
120 parts of excess equivalent of phosgene was bubbled in at 0 ° C. Example 1 for phosgenation reaction and removal of MCB from reaction solution
The same procedure was followed to obtain 100 parts of Polymeric MDI.
Polyamine (in this case diaminodiphenylmethane), reaction solution after phosgenation (after MCB removal), Polymeric MDI (in this case MDI with a small amount of by-product obtained as bottom product, not as distillate) Is),
The colors are shown in Table 1.

Example 5 In a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid and 24P were added at 500 ppm per 1 part of aniline and mixed at 10 ° C., and 100 parts of 30% formaldehyde aqueous solution was further added thereto. added. After condensation and neutralization in the same manner as in Example 1, water and unreacted aniline were removed by passing through a thin film evaporator to obtain 95 parts of diaminodiphenylmethane-based polyamine. After adding 330 parts of MCB to 80 parts of this polyamine, an excess equivalent of phosgene 120 was added at 0 to 10 ° C.
The part was blown in. Phosgenation reaction, MCB from reaction solution
Of MDI and Polymeric MDI
Was separated in the same manner as in Example 1. The MDI obtained is 3
2 parts, Polymeric MDI was 69 parts. The polyamine, the reaction solution after phosgenation (after removing MCB), MD
The colors of I and Polymeric MDI are shown in Table 2.

Example 6 To a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid and 100 parts of 30% aqueous formaldehyde solution were added. After condensation and neutralization in the same manner as in Example 1, water and unreacted aniline were removed by passing through a thin film evaporator to obtain 94 parts of diaminodiphenylmethane-based polyamine. 24P to 80 parts of this polyamine is 500p per 1 part of polyamine
After adding 330 parts of pm and MCB, 120 parts of excess equivalent of phosgene was blown in at 0 to 10 ° C. MD by phosgenation reaction, removal of MCB from reaction solution, and further distillation
Separation of I and polymeric MDI was carried out as in Example 1. The obtained MDI is 35 parts, and the polymeric MDI is 6 parts.
It was 5 parts. Table 2 shows the colors of the polyamine, the reaction solution after phosgenation, MDI (after removing MCB), and polymeric MDI.

Example 7 In a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid, and 26P were added at 500 ppm per 1 part of aniline and mixed at 10 ° C., and 100 parts of a 30% formaldehyde aqueous solution was further added thereto. added. After condensation and neutralization in the same manner as in Example 1, water and unreacted aniline were removed by passing through a thin film evaporator to obtain 96 parts of diaminodiphenylmethane-based polyamine. After adding 330 parts of MCB to 80 parts of this polyamine, an excess equivalent of phosgene 120 was added at 0 to 10 ° C.
The part was blown in. Phosgenation reaction, MCB from reaction solution
Of MDI and Polymeric MDI
Was separated in the same manner as in Example 1. The MDI obtained is 3
0 part, polymeric MDI was 71 parts. The polyamine, the reaction solution after phosgenation (after removing MCB), MD
The colors of I and Polymeric MDI are shown in Table 2.

Example 8 To 80 parts of an additive-free diaminodiphenylmethane-based polyamine obtained from the condensation reaction of Example 6, was added 26P (500 ppm per part of polyamine, 330 parts of MCB), and then an excess equivalent weight at 0 to 10 ° C. Blow 120 parts of phosgene. Phosgenation reaction, removal of MCB from reaction solution,
Further, MDI and polymeric MDI were separated by distillation in the same manner as in Example 1. The obtained MDI was 34 parts and the polymeric MDI was 67 parts. The polyamine,
Table 2 shows the colors of the reaction solution after phosgenation (after removal of MCB), MDI, and polymeric MDI.

Comparative Example 1 After adding 330 parts of MCB to 80 parts of the additive-free diaminodiphenylmethane-based polyamine obtained from the condensation reaction of Example 6, 330 parts of MCB was added, and an excess equivalent of phosgene 120 was obtained at 0 to 10 ° C.
The part was blown in. Phosgenation reaction, MCB from reaction solution
Of MDI and Polymeric MDI
Was separated in the same manner as in Example 1. The MDI obtained is 3
3 parts, Polymeric MDI was 68 parts. The polyamine, the reaction solution after phosgenation (after removing MCB), MD
The colors of I and Polymeric MDI are shown in Table 3.

Comparative Example 2 The reaction solution after the phosgenation of Comparative Example 1 contained 5 parts per 1 part of the reaction solution.
00 ppm of TPP was added, MCB was removed, and MDI and polymeric MDI were separated by distillation in the same manner as in Example 1. The obtained MDI was 33 parts, and the polymeric MDI was 6 parts.
It was 7 copies. Reaction solution after polyamine and phosgenation (M
Table 3 shows the colors of MDI, after removing CB, MDI, and polymeric MDI.

Comparative Example 3 The reaction solution after the phosgenation of Comparative Example 1 contained 5 parts per 1 part of the reaction solution.
00P of 24P was added, MCB was removed, and MDI and polymeric MDI were separated by distillation in the same manner as in Example 1. The obtained MDI was 33 parts, and the polymeric MDI was 6 parts.
It was 7 copies. Reaction solution after polyamine and phosgenation (M
Table 3 shows the colors of MDI, after removing CB, MDI, and polymeric MDI.

Comparative Example 4 The reaction solution after the phosgenation in Comparative Example 1 contained 5 parts per 1 part of the reaction solution.
00P of 26P was added, MCB was removed, and MDI and polymeric MDI were separated by distillation in the same manner as in Example 1. The obtained MDI was 34 parts, and the polymeric MDI was 6 parts.
It was 6 parts. Reaction solution after polyamine and phosgenation (M
Table 3 shows the colors of MDI, after removing CB, MDI, and polymeric MDI.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

In Table 1, Table 2 and Table 3, the reaction solution after phosgenation (after MCB removal) and the polymeric MDI
The color number of the product is 200 times diluted with acetone (APH
A). The color number of the diaminodiphenylmethane-based polyamine is the color number (APHA) of a 2-fold diluted acetone product.

Claims (4)

[Claims] 1. A method for producing a diphenylmethane diisocyanate-based polyisocyanate obtained by phosgenating a diaminodiphenylmethane-based polyamine in an inert solvent, wherein the organic phosphite ester is added before the phosgenation reaction. 2. A method for producing a diphenylmethane diisocyanate-based polyisocyanate obtained by phosgenating a condensation product obtained by condensing aniline and formaldehyde in the presence of a catalyst, which is used before any phosgenation reaction. The above method, characterized in that an organic phosphite is added at this point. 3. A condensation product obtained by condensing aniline and formaldehyde in the presence of a catalyst is phosgenated in an inert solvent, and then diphenylmethane diisocyanate and polyphenylene polymethylene polyisocyanate are separated from the obtained phosgenation product. In the method for producing a diphenylmethane diisocyanate-based polyisocyanate as described above, the organic phosphite ester is added at any point before the phosgenation reaction. 4. The organic phosphite ester wherein the total number of carbon atoms of the hydrocarbon group bonded to the oxygen atom of the phosphite group is 12 to 60 per one phosphite group. The method according to claim 1, 2 or 3, further comprising an antioxidant if necessary.