JP3518052B2 - Method for producing organic isocyanate with reduced coloring - Google Patents

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 an organic isocyanate in which coloring is remarkably reduced, and a method for bleaching a colored organic isocyanate.

[0002]

2. Description of the Related Art Conventionally, organic isocyanates have been manufactured and stored by sealing with nitrogen gas and shielding from air. Further, at that time, an ultraviolet absorber, an antioxidant and the like were used together. This is because it was thought that the organic isocyanate was oxidized by oxygen in the air to be deteriorated and colored.
However, Japanese Patent Application Laid-Open No. 2-228317 discloses a technique of producing a modified polyisocyanate for a light-colored polyurethane lacquer, in which the organic diisocyanate is modified and then positively treated with a peroxide.

[0003]

However, the above-mentioned Japanese Unexamined Patent Application Publication No.
In the production of the modified polyisocyanate disclosed in JP-A-228317, the treatment with peroxide requires heating for a long time, and the decomposed product of the peroxide remains after the treatment, which adversely affects the quality of the modified polyisocyanate. There is a problem.

An object of the present invention is to provide an organic isocyanate in which coloring is significantly reduced by bleaching the colored organic isocyanate by a simple treatment.

[0005]

In order to achieve the above object, the method for producing an organic isocyanate having reduced coloring of the present invention is characterized by including a step of bringing an ozone-containing gas into contact with the colored organic isocyanate.

The method for bleaching a colored organic isocyanate of the present invention is characterized in that an ozone-containing gas is blown into the colored organic isocyanate.

The colored organic isocyanate in the present invention is a crude organic isocyanate colored in the manufacturing process, the remaining organic isocyanate obtained by distillation of the crude organic isocyanate, a modified organic isocyanate obtained by partially modifying the organic isocyanate, or a long-term organic isocyanate. Organic isocyanates that are more colored than pure products for various reasons, such as organic isocyanates that are colored by storage. Among these, since the organic isocyanate has a high degree of coloring by the manufacturing process or distillation, it is preferable to use the crude organic isocyanate, the canned organic isocyanate, or the modified organic isocyanate in the present invention. Most preferably used.

Examples of the crude organic isocyanate include crude tolylene diisocyanate. As the bottom organic isocyanate, a condensation product obtained by condensing aniline and formaldehyde in the presence of a catalyst is phosgenated in an inert solvent, and this is distilled to distill diphenylmethane diisocyanate (hereinafter referred to as MDI). And polymethylene polyphenylene polyisocyanate (also referred to as polymeric MDI). As the modified organic isocyanate, a urethane bond, a carbodiimide bond, an allophanate bond, a urea bond, a buret bond, a uretdione bond, a uretoimine bond, an isocyanurate bond, an oxazolidone bond, or the like is used in a part of the molecule. The modified product of the organic isocyanate contained can be mentioned, and an isocyanate prepolymer is included.

Specific examples of the organic isocyanate include 2,4-tolylene diisocyanate and 2,2-tolylene diisocyanate.
6-tolylene diisocyanate, xylene-1,4-diisocyanate, xylene-1,3-diisocyanate, 4,4'-MDI, 2,4'-MDI, 2,2'-
MDI, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-
4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-
1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3′-dimethoxydiphenyl-4,
Aromatic diisocyanates such as 4'-diisocyanate,
Further, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter referred to as HDI) , 2-methyl
Pentamethylene diisocyanate, lysine diisocyanate, aliphatic diisocyanates such as tetramethyl xylene diisocyanate or isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene <br/> diisocyanate, hydrogenated diphenylmethane iso <br/> cyanate over preparative And other polyisocyanates such as alicyclic diisocyanates.

A method in which an ozone-containing gas is brought into contact with the above-mentioned colored organic isocyanate, a solution of the colored organic isocyanate dissolved in an inert solvent, or a reaction liquid for producing the colored organic isocyanate is described.
This is a feature of the present invention . When the ozone-containing gas is brought into contact with the reaction solution for producing a colored organic isocyanate, it is preferably carried out in the final step. This reaction solution is
The solvent type or solvent-containing type may be used, and as the solvent or the inert solvent, an inert solvent commonly used in the polyurethane industry, for example, an aromatic solvent such as toluene, xylene, and monochlorobenzene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. Ketone solvents, ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, etc. Examples thereof include glycol ether ester type solvents, and ether type solvents such as tetrahydrofuran and dioxane, or a mixed solution of two or more types thereof.

Ozone-containing gas includes pure ozone,
It is a gas containing ozone in a gas inert to isocyanate groups such as air, oxygen, nitrogen, argon gas, and helium gas. Ozone concentration in gas is 0.1g / N (standard condition
(State: 0 ° C., 1 atm) ・ m ³ or more is preferable, and particularly 1 to
It is preferably 200 g / N · m ³ . As a method of contacting the ozone-containing gas and the colored organic isocyanate,
Any method may be used as long as it can bring them into contact with each other, and various conventionally known gas-liquid contact methods can be adopted. As such a method, for example, a method of bubbling by blowing an ozone-containing gas into a solution of a colored organic isocyanate, a solution of a colored organic isocyanate,
As a liquid film, for example, a method of bringing an ozone-containing gas into contact with the liquid film in a cocurrent or countercurrent manner while flowing down on an inner wall surface of a cylinder, in a transportation pipeline that conveys a solution of a colored organic isocyanate. , And a method of adding and mixing an ozone-containing gas.

The contact time between the ozone-containing gas and the solution of the colored organic isocyanate depends on the contact method and the ozone in the gas.
It depends on the concentration and cannot be uniquely determined,
When it is blown into the solution of the colored organic isocyanate, it is usually preferably 5 minutes or longer, more preferably 10 to 60.
Minutes, most preferably 10 to 30 minutes. Further, when a solution of a colored organic isocyanate is flown down on a wall surface as a liquid film and an ozone-containing gas is brought into contact therewith in a cocurrent or a countercurrent, preferably 10 to 120 seconds, particularly preferably 3
0 to 90 seconds. The contact temperature between the solution of the colored organic isocyanate and the ozone-containing gas is not particularly limited, but it is economically preferably room temperature. The supply amount of ozone-containing gas is usually 1.0 to 1.0 g of oxygen gas having an ozone concentration of 100 to 200 g / N · m ³ with respect to 500 g of a colored organic isocyanate.
It is preferable to supply at 2.0 liters (standard state) / minute.

[0013]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Synthesis Example 4650 g and 36 of aniline were placed in a reaction vessel equipped with a stirrer.
% Hydrochloric acid (500 g) was added and mixed at 10 ° C., and 30% formaldehyde aqueous solution (1000 g) was further added thereto. 1
After reacting at 30 ° 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 940 g of diaminodiphenylmethane-based polyamine was obtained. . After adding 3300 g of monochlorobenzene to 800 g of this polyamine, 1200 g of excess equivalent of phosgene was blown in at 0 to 10 ° C., the temperature was raised after 90 minutes, and then 9 to 60 ° C. at 80 ° C.
The phosgenation reaction was carried out for 0 minutes and further at 110 to 130 ° C. for 90 minutes. After completion of the reaction, monochlorobenzene was removed from the phosgenation reaction solution by distillation, and MDI and polymeric MDI were further separated by distillation. The obtained MDI was 330 g and the polymeric MDI was 680 g. The brightness and number of colors (APH of this polymeric MDI
A) and NCO content were measured. The brightness is JIS
Measured according to the method of Z8701 or JIS Z8729
The color number is measured according to the method of JIS K6901.
It was

Example 1 500 g of the polymeric MDI obtained in the synthesis example was placed in a container of a gas-liquid mixing apparatus (Muenke type gas cleaning bottle (with ball) 1464-500 manufactured by Shibata Scientific Instruments Co., Ltd.) at room temperature (about 17 C.), ozone-containing oxygen having an ozone concentration of 170 g / m ³ (ozone generator:
Nihon Ozone Co., Ltd., generated using Q-ZONE) was introduced at a supply rate of 2.0 liters / minute for 10 to 40 minutes. Ozone-containing oxygen is jetted as small bubbles into the polymeric MDI (liquid) from a gas outlet hole below the container, and is exhausted from the gas outlet. 10 minutes, 20 minutes,
The lightness, color number (APHA), and NCO content (% by weight) of each of the ozone-treated solutions for 30 minutes and 40 minutes were measured.
Table 1 collectively shows these results and the measurement results of the raw material polymeric MDI.

Example 2 In Example 1, urethane, uretdione and isocyanurate modified HDI were used instead of the polymeric MDI.
(Nippon Polyurethane Industry Co., Ltd.) was used, and the same operation was carried out except that the ozone-containing gas was introduced for 20 minutes. Lightness and color number (APH) of raw material modified HDI (liquid) and ozone treatment liquid
The measurement results of A) and NCO content (% by weight) are summarized in Table 1.

Comparative Example 1 Polymeric M obtained in the Synthesis Example was placed in a reaction vessel equipped with a stirrer.
DI (500 g) and butanone peroxide (1.25 g) were added, and the mixture was stirred at 100 ° C. for 60 minutes for treatment. The brightness, color number (APHA) and NCO content (% by weight) of the treatment liquid for 60 minutes were measured. These results and raw material MD
The measurement results of I are summarized in Table 1.

Comparative Example 2 In Comparative Example 1, urethane, uretdione and isocyanurate modified HDI was used instead of polymeric MDI.
It carried out similarly except having used ( made by Nippon Polyurethane Industry Co., Ltd. ) . The measurement results of the lightness, the color number (APHA) and the NCO content (wt%) of the raw material modified HDI (liquid) and the ozonized liquid are summarized in Table 1.

[0018]

[Table 1]

[0019]

As described above, according to the present invention, it is possible to provide an organic isocyanate in which coloring is significantly reduced by bleaching a colored organic isocyanate by a simple treatment. Moreover, since no reaction decomposition products remain in the organic isocyanate obtained by the present invention, the quality is excellent.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-41044 (JP, A) JP-A-6-9538 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C07C 263/18-263/20 C07C 265/00-265/14

Claims (2)

(57) [Claims] 1. A method for producing an organic isocyanate having reduced coloration, which comprises the step of bringing an ozone-containing gas into contact with the colored organic isocyanate. 2. A method for bleaching a colored organic isocyanate, which comprises blowing an ozone-containing gas into the colored organic isocyanate.