JP3292857B2 - Method for producing diphenylmethane diisocyanate-based polyisocyanate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing diphenylmethane diisocyanate-based polyisocyanate (hereinafter referred to as MDI-based polyisocyanate) having improved coloring.

[0002]

2. Description of the Related Art Diphenylmethane diisocyanate (hereinafter referred to as "MDI"), various MDI polynuclear condensates having three or more benzene rings obtained by phosgenation of a condensation product of aniline and formaldehyde, or MDI based on this. Polyphenylenepolymethylene polyisocyanate (hereinafter referred to as Polymeric M)
MDI-based polyisocyanates such as DI) are widely used industrially to react with active hydrogen-containing compounds such as polyols and amines to produce elastomers, foams, synthetic leathers, spandex, paints, adhesives, and the like. It is used.

[0003] MDI is colorless, transparent or slightly yellow immediately after its production, but becomes 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 paints, and is also difficult to use as a raw material for elastomers and the like. Therefore, it is purified by distillation or the like under precise conditions. Further, in order to prevent coloring during storage, an antioxidant, an ultraviolet absorber and the like are added. In order to prevent coloring during storage of aromatic isocyanate, specifically, conventionally,
Among aromatic isocyanates, in addition to antioxidants such as 2,6-di-tert-butyl-4-methylphenol (hereinafter referred to as BHT), triphosphites such as triphenylphosphite (hereinafter referred to as TPP). Addition of trialkyl phosphates such as reel ester and triethyl phosphate is known. Further, as a mixture thereof, a method of adding a dialkyl monoaryl phosphite and a mixture of three kinds of TPP and BHT (Japanese Patent Laid-Open No. 5-65264), or a pentaerythritol trialkyl phosphite, BHT and an ultraviolet absorber 2 (2'-hydroxy-3 ', 5'-di-
A method of adding a mixture of three kinds of (tert-amylphenyl) benzotriazole (Japanese Patent Publication No. 3-4062) and the like are known.

[0004] Unlike MDI, polymeric MDI cannot be purified by distillation. Therefore, coloring due to heat history or the like in the production process directly results in coloring of the product. Therefore, generally, the polymeric MDI has a brown color. Until now, this coloring has been unavoidable, but in recent years, polymeric MDI has also been required to have low coloring.

[0005]

However, all of the above-mentioned addition methods relate to the prevention of coloration of distilled and purified colorless transparent or pale yellow polyisocyanate during storage. No simple method has yet been found to simultaneously solve the problem of polymeric MDI obtained as a can and its reduction in color during storage.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve such problems, and as a result, by adding an organic phosphite before the phosgenation step of the polyamine, it is possible to obtain It has been found that the reduction in the degree of coloring of the MDI-based polyisocyanate and the degree of coloring during storage thereof can be simultaneously achieved, and the present invention has been completed.

That is, the method for producing an MDI-based polyisocyanate of the present invention is characterized in that a diaminodiphenylmethane-based polyamine is phosgenated in an inert solvent, wherein an organic phosphite is added before the phosgenation reaction. And

The process for producing an MDI-based polyisocyanate according to the present invention is a process comprising subjecting a condensation product obtained by condensation of aniline and formaldehyde in the presence of a catalyst to phosgenation in an inert solvent. Wherein the organic phosphite is added at any time of the above.

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

[0010] The diaminodiphenylmethane-based polyamine in the present invention is produced, for example, as follows.
An organic phosphite is optionally added to 1 mol of aniline in the presence of 0.01 to 0.1 mol of an acid catalyst such as hydrochloric acid or sulfuric acid as a catalyst, and aniline: formaldehyde = 3: 2 to 6 In a molar ratio of 1: 1
After the reaction is completed, the condensation product is neutralized and washed with water, then water and aniline are distilled off to obtain diaminodiphenylmethane, a diaminodiphenylmethane polynuclear condensate having three or more benzene rings, Alternatively, a diaminodiphenylmethane-based polyamine such as a mixture thereof is obtained. Phosgenation in the present invention can be performed, 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). The MDI-based polyisocyanate such as MDI, MDI-based polynuclear condensate having three or more benzene rings, polymeric MDI, isomers thereof, and crude mixture thereof is obtained by distillation. If necessary, MDI and polymeric MDI are separated and purified by distillation or the like.

The organic phosphite used in the present invention is preferably a phosphite 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 phosphite group. Phosphoric acid triesters are preferred, particularly, for example, triaryl phosphites such as triphenyl phosphite, alkyldiaryl phosphites having an alkyl group having 4 to 20 carbon atoms, and alkyl group having 4 to 20 carbon atoms.
A dialkylaryl phosphite having a carbon number of 20 to 20; a trialkyl phosphite having an alkyl group having 4 to 20 carbon atoms;
Phosphorous triester with a hydrocarbon group having an rt-butyl) phenyl structure, for example, tris (2,4-di-
tert-butylphenyl) phosphite (hereinafter referred to as 24
P) or bis (2,6-di-tert-butyl-4)
-Methylphenyl) pentaerythritol phosphite (hereinafter referred to as 26P), one having two phosphite groups in one molecule and a skeleton linking the phosphite groups having a bisphenol A structure, for example, tetrabutyl -4, 4 '
-Isopropylidene diphenyl diphosphite, which has two or four phosphite groups in one molecule, and a skeleton linking the phosphite groups has a pentaerythritol structure, for example, diisodecyl pentaerythritol diphosphite, tetra Phenyltetradecylpentaerythritol tetraphosphite and the like can be mentioned. These phosphites may be used as a mixture of two or more. 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 phosphite group, the boiling point is low, so that it is easy to volatilize during the production of the polymeric MDI, and the effect of preventing coloring is small. . These organic phosphites may be used in combination with an antioxidant such as BHT.

[0012] The step of adding the organic phosphite is
The addition of the raw material to aniline, the reaction system before the condensation reaction, the addition to each or one of the diaminodiphenylmethane-based polyamine and the inert solvent, 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 step, the step in which it is added, and the like, but is preferably 10 to 2000 ppm, particularly preferably 50 to 1000 ppm, per part by weight of aniline or diaminodiphenylmethane-based polyamine. .

[0013]

According to the present invention, it is possible to produce an MDI-based polyisocyanate which is uncolored or has significantly reduced coloration, and at the same time, prevents coloration during storage. It became possible to provide. Specifically, for example, it is possible to improve both the coloration during production and storage of the final product MDI and polymeric MDI. In particular, for example, unlike isocyanates which can be easily purified by distillation or the like, it is possible to reduce the coloring of the polymeric MDI which is difficult to purify 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,
Means "parts by weight" and "%" means "% by weight".

Example 1 Into a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid, and 100 ppm of TPP per 1 part of aniline were added and mixed at 10 ° C., and 100 parts of a 30% aqueous solution of formaldehyde was further added thereto. added. After condensing by reacting at 130 ° C. for 120 minutes, the condensation product is taken out and neutralized with caustic soda, and then passed through a thin film evaporator to remove water and unreacted aniline to obtain 94 parts of diaminodiphenylmethane polyamine. Was. MCB33 is added to 80 parts of this polyamine.
After addition of 0 parts, an excess of phosgene 1 is added at 0-10 ° C.
20 parts were blown, the temperature was raised after 90 minutes, and then 60 to 8
The phosgenation reaction was carried out at 0 ° C for 90 minutes and further at 110 to 130 ° C for 90 minutes. After completion of the reaction, MCB was removed from the phosgenation reaction solution by distillation, and M
DI and polymeric MDI were separated. M obtained
DI was 33 parts and polymeric MDI was 68 parts.
Table 1 shows the colors of the polyamine, the reaction solution after phosgenation (after removing the 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 1 part of aniline were added and mixed at 10 ° C., and 100 parts of a 30% aqueous formaldehyde 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 a diaminodiphenylmethane-based polyamine. MCB330 is added to 80 parts of this polyamine.
Of phosgene 12 at 0-10 ° C.
0 parts were blown. Phosgenation reaction, MC from reaction solution
MDI and polymeric MD by removal of B and distillation
Separation of I was performed 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 A reaction vessel equipped with a stirrer was charged with 500 pp per part of aniline.
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 an aqueous formaldehyde solution were added. After condensation and neutralization in the same manner as in Example 1, water and unreacted aniline were removed through a thin film evaporator to obtain 94 parts of a diaminodiphenylmethane-based polyamine. After adding 330 parts of MCB to 80 parts of the polyamine, an excess equivalent of 120 parts of phosgene was blown at 0 to 10 ° C. The phosgenation reaction, removal of MCB from the reaction solution, and separation of MDI and polymeric MDI by distillation were carried out in the same manner as in Example 1. The obtained MDI was 29 parts and the polymeric MDI was 71 parts. Reaction solution after the polyamine and phosgenation (MCB
Table 1 shows the colors of the MDI and the polymeric MDI.

Example 4 Diaminodiphenylmethane 8 was placed in a reaction vessel equipped with a stirrer.
0 parts, 500 ppm per 1 part of diaminodiphenylmethane
After adding and mixing 330 parts of 24P and MCB,
At 0 ° C., an excess of 120 parts of phosgene was blown. Example 1 Phosgenation Reaction and Removal of MCB from Reaction Solution
In the same manner as described above, 100 parts of polymeric MDI was obtained.
Polyamine (in this case, diaminodiphenylmethane), reaction solution after phosgenation (after removal of MCB), polymeric MDI (in this case, MDI containing a small amount of by-products obtained as bottoms, not as distillates) ),
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 500 ppm of 24P per 1 part of aniline were added and mixed at 10 ° C., and 100 parts of a 30% aqueous formaldehyde 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 a diaminodiphenylmethane-based polyamine. After adding 330 parts of MCB to 80 parts of the polyamine, an excess of phosgene 120 is added at 0 to 10 ° C.
I blew the part. Phosgenation reaction, MCB from reaction solution
Of MDI and polymeric MDI
Was carried out in the same manner as in Example 1. The obtained MDI is 3
2 parts, polymeric MDI was 69 parts. The polyamine, the reaction solution after phosgenation (after removing MCB), MD
Table 2 shows the colors of I and polymeric MDI.

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

Example 7 To a reaction vessel equipped with a stirrer, 465 parts of aniline, 50 parts of 36% hydrochloric acid, and 500 ppm of 26P per 1 part of aniline were added and mixed at 10 ° C., and 100 parts of a 30% aqueous formaldehyde 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 a diaminodiphenylmethane-based polyamine. After adding 330 parts of MCB to 80 parts of the polyamine, an excess of phosgene 120 is added at 0 to 10 ° C.
I blew the part. Phosgenation reaction, MCB from reaction solution
Of MDI and polymeric MDI
Was carried out in the same manner as in Example 1. The obtained MDI is 3
0 parts and 71 parts of polymeric MDI. The polyamine, the reaction solution after phosgenation (after removing MCB), MD
Table 2 shows the colors of I and polymeric MDI.

Example 8 To 80 parts of an additive-free diaminodiphenylmethane-based polyamine obtained from the condensation reaction in Example 6, 26 ppm of 500 ppm per part of polyamine and 330 parts of MCB were added, and then an excess equivalent at 0 to 10 ° C. 120 parts of phosgene was blown. Phosgenation reaction, removal of MCB from the 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 diaminodiphenylmethane-based polyamine without additive obtained from the condensation reaction of Example 6, an excess equivalent of phosgene 120 was added at 0 to 10 ° C.
I blew the part. Phosgenation reaction, MCB from reaction solution
Of MDI and polymeric MDI
Was carried out in the same manner as in Example 1. The obtained MDI is 3
3 parts and 68 parts of polymeric MDI. The polyamine, the reaction solution after phosgenation (after removing MCB), MD
Table 3 shows the colors of I and polymeric MDI.

COMPARATIVE EXAMPLE 2 5 parts of the reaction solution after the phosgenation of Comparative Example 1 was added to the reaction solution.
TPP of 00 ppm was added, and removal of MCB and distillation separation of MDI and polymeric MDI were performed in the same manner as in Example 1. 33 parts of MDI obtained, 6 parts of polymeric MDI
7 parts. Reaction solution after polyamine and phosgenation (M
Table 3 shows the colors of MDI and polymeric MDI (after CB removal).

Comparative Example 3 The reaction solution after phosgenation of Comparative Example 1 was added to the reaction solution in an amount of 5 parts per part.
After adding 00 ppm of 24P, removal of MCB and distillation separation of MDI and polymeric MDI were performed in the same manner as in Example 1. 33 parts of MDI obtained, 6 parts of polymeric MDI
7 parts. Reaction solution after polyamine and phosgenation (M
Table 3 shows the colors of MDI and polymeric MDI (after CB removal).

Comparative Example 4 The reaction solution after phosgenation of Comparative Example 1 was added
The removal of MCB and the separation by distillation of MDI and polymeric MDI were performed in the same manner as in Example 1 by adding 00 ppm of 26P. 34 parts of MDI obtained, 6 parts of polymeric MDI
6 parts. Reaction solution after polyamine and phosgenation (M
Table 3 shows the colors of MDI and polymeric MDI (after CB removal).

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-211641 (JP, A) JP-A-51-48619 (JP, A) JP-A-4-159259 (JP, A) JP-B-46 2091 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 18/00-18/87 C07C 263 / 10,265 / 14

Claims (4)

(57) [Claims] 1. A method for producing a diphenylmethane diisocyanate-based polyisocyanate obtained by phosgenating a diaminodiphenylmethane-based polyamine in an inert solvent, wherein an organic phosphite is added before the phosgenation reaction. 2. A method for producing a diphenylmethane diisocyanate-based polyisocyanate obtained by subjecting a condensation product obtained by condensation of aniline and formaldehyde in the presence of a catalyst to phosgenation in an inert solvent. The above method, wherein an organic phosphite is added at a point in time. 3. A condensation product obtained by condensation of 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. The method for producing a diphenylmethane diisocyanate-based polyisocyanate described above, wherein an organic phosphite is added at any point before the phosgenation reaction. 4. The organic phosphite wherein the total number of carbon atoms of the hydrocarbon group bonded to the oxygen atom of the phosphite is 12 to 60 per phosphite. The method according to claim 1, 2 or 3, further comprising an antioxidant as required.