JPH0920744A - Prevention of discoloration of organic isocyanate compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-quality organic isocyanate compound by adding a specific three component-based discoloration inhibitor to the compound, useful as a raw material for an elastic material, a foam, an adhesive, etc., while effectively preventing discoloration. SOLUTION: The method for preventing discoloration of an organic isocyanate compound comprises blending (A) an organic isocyanate compound with (B) a compound of the formula [R1 and R2 are each a 1-10C (branched) saturated hydrocarbon group; R3 is R1 or (thio) ether group] [e.g. 4,4'- butylidenebis(3-methyl-6-tert-butyphenol)] (B1 ), 2,6-di-tert-butyl-4-methylphenol (B2 ) and triphenyl phosphite (B3 ), for example, in the ratio of 100 pts.wt. of the component A, 0.005-1 pt.wt., especially 0.01-0.05 pt.wt. of the component B1 , the component B2 and the component B3 , respectively.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for improving the stability of an isocyanate compound against air, light, heat and the like. Isocyanate compounds such as tolylene diisocyanate, diphenylmethane diisocyanate, and hexamethylene diisocyanate are extremely reactive and react with many polyols having active hydrogen to produce elastic bodies, foams, adhesives, paints. It is used for various purposes such as textiles.

[0002]

2. Description of the Related Art Isocyanate compounds are substances that are easily colored, and are almost colorless immediately after purification, but if they are exposed to air or light or are heated during storage, trace amounts of impurities and isocyanate groups contained therein will change over time. It becomes colored due to oxidation. It becomes a problem especially when used for paints, and when using isocyanate compounds for paints, it is usually used as a so-called modified isocyanate in which the isocyanate compound is adducted or biuretized, but these compounds are stored. Not only does it exhibit coloring inside, but it also becomes a colored product due to heating during the denaturation reaction, significantly impairing the commercial value. In addition, the hue of the product changes due to the coloring of the isocyanate compound for other purposes,
A solution was desired because it caused a problem.

[0003]

As a method for preventing the coloration of the isocyanate compound, a purification method such as rectification under precise conditions is not sufficient. Therefore, usually 2,6- Compounds generally known as antioxidants such as di-tert-butyl-4-methylphenol (hereinafter referred to as BHT) and 2- (3,5-di-ter).
Stabilization of the isocyanate compound is carried out by adding a compound generally known as an ultraviolet ray inhibitor such as t-amyl-2-hydroxyphenyl) benzotriazole (hereinafter referred to as tinuvin). In addition to these stabilizers, the addition of triallyl phosphite such as triphenyl phosphite (hereinafter referred to as TPP) to U.S. Pat. No. 2,957,903 is a method for preventing coloration of isocyanate compounds. No. 49-75505, the addition of ethyl triphosphate is also disclosed in
-98050 and JP-A-5-65264 describe addition of organic phosphites, respectively.

However, according to the additional tests of the present inventors, it cannot be said that the prevention of coloration of the isocyanate compound by the addition of these known compounds is necessarily sufficient. Further, the one-sided hindered phenol used in the present invention is a known compound for synthetic resin applications such as synthetic rubber, polyolefin, ABS resin, AS resin and urethane resin.
The prevention of coloration of the isocyanate compound is not known, and further, according to the studies by the present inventors, the hindered phenol alone cannot be said to have a sufficient coloration prevention effect.

[0005]

In order to solve this problem, the present inventors have made a detailed screening of the effects of addition of various compounds, and as a result, certain compounds of mono-hindered phenol were Although it has only a known anti-coloring effect, it was found that the synergistic effect becomes extremely large when it is used in combination with a specific stabilizer, and the present invention has been completed based on this finding.

That is, the present invention provides a novel three-component color preventive agent as a method for preventing coloration of an isocyanate compound, as shown in the following (1) and (2). (1) General formula (I) for the isocyanate compound

Embedded image [In the formula, R ₁ and R ₂ are the same or different and have 1 to 1 carbon atoms.
10 straight-chain or branched saturated hydrocarbon groups can be used as R ₃
Represents a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an ether group or a thioether group. ] Hindered phenols represented by the formula 2,6-di-ter
A method for preventing coloration of an isocyanate compound, which comprises adding t-butyl-4-methylphenol and triphenylphosphite. (2) In the general formula (I), R ₁ is a methyl group and R ₂ is tert.
A butyl group and R ₃ is a butylidene group, that is, the one-hindered phenol represented by the general formula (I) is 4,4 ′.
-A method for preventing coloration of an isocyanate compound according to (1), which is butylidene bis (3-methyl-6-tert-butylphenol).

The one-sided hindered phenol used in the method of the present invention is a known compound used as an antioxidant for synthetic rubbers, synthetic resins and the like. For example, 4,4'-butylidenebis (3-methyl-6-). tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 4,
4'-thiobis (3-methyl-6-tert-butylphenol) and the like can be mentioned. In the method of the present invention, the addition amount of the one-hindered phenol is usually 0.005 to 100 parts by weight of the isocyanate compound, although it depends on the type and composition of the isocyanate compound.
About 1.0 part by weight, preferably 0.01 to 0.05 part by weight is added. The amount of BHT added is usually about 0.005 to 1.0 part by weight, preferably 0.01 to 0.05 part by weight, per 100 parts by weight of the isocyanate compound. The amount of TPP added is usually about 0.005 to 1.0 part by weight, preferably 0.01 to 0.05 part by weight, per 100 parts by weight of the isocyanate compound.

As a method of addition, the three-component compounds may be directly added separately, or the three-component compounds may be mixed in advance and then added. These three-component compounds are uniformly dissolved and mixed even at room temperature by adding and stirring, and the effects are sufficiently exhibited. Alternatively, the compound may be dissolved in a small amount of an isocyanate compound in advance to form an isocyanate compound having a high additive concentration, and then added to a large amount of the isocyanate compound so as to adjust the concentration of the three-component additive. .

Isocyanate compounds applicable to the present invention include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and naphthylene diisocyanate, hexamethylene diisocyanate,
Butyl diisocyanate, aliphatic isocyanate such as dicyclohexylmethane diisocyanate, alicyclic isocyanate such as dicyclohexylmethane diisocyanate, and mixtures thereof, as well as biuret modified isocyanate, urethane modified isocyanate, carbodiimide modified isocyanate It can also be applied to modified isocyanate compounds.

[0010]

The method of the present invention will be described in more detail with reference to the following examples, but these examples do not limit the present invention. Unless otherwise specified, all parts and ratios are by weight.

Example 1 To the purified tolylene diisocyanate (hue APHA 5) having a purity of 99.9% obtained from a rectification column, the additives shown in Table 1 were added, and the mixture was stirred and mixed. Put each in a container made of nitrogen, seal with nitrogen, and then seal,
The specimen was left exposed to light in a room and a coloring test was performed by aging.
Table 1 shows the results.

Example 2 Additives shown in Table 2 were added to purified diphenylmethane diisocyanate (hue APHA 5) having a purity of 99.9% obtained from a rectification column, and the mixture was stirred and mixed, and 300 g of the transparent glass was added. After putting each in a container made of nitrogen and sealing with nitrogen,
It was hermetically sealed and left to stand in a room for light, and a coloring test was performed by aging. Table 2 shows the results.

Example 3 200 g of 2,4-tolylene diisocyanate containing 99.9% of purity and 0.004% of hydrolyzable chlorine was added to 167 g of ethyl acetate, and 51 g of trimethylolpropane was added at 60 ° C. Stir for 4 hours, NCO% 12.2%
Was prepared. The additives shown in Table 3 were added to this prepolymer solution (hue APHA 10), and the degree of coloring was examined in the same manner as in Example 1. The results are shown in Table 3.

Example 4 BHT, triphenyl phosphite and 4,4'-
Equal amounts of butylidene bis (3-methyl-6-tert-butylphenol) (Sumitomo Chemical Co., Ltd. trade name, Sumilizer BBM) were mixed in advance and added to hexamethylene diisocyanate to contain 300 ppm. After stirring, 300 g of the mixture was heated to 140 ° C., 5.0 g of steam was sucked in for 4 hours, and a biuretization reaction of hexamethylene diisocyanate was performed.
After completion of the reaction, unreacted hexamethylene diisocyanate was removed by a Smith evaporator, and the reaction product was diluted with a solvent of xylene and cellosolve acetate in a ratio of 1: 1 to prepare a 75% solution. This product was slightly yellow and transparent and had a hue of APHA40. It should be noted that it was obtained by subjecting hexamethylene isocyanate to a biuretization reaction without addition and treating and preparing it in the same manner.
The hue of the 5% solution was APHA200.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

EFFECTS OF THE INVENTION According to the method of the present invention, it is possible to effectively prevent the coloration of the isocyanate, which is suitable as a method for producing an isocyanate compound having a high commercial value.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Taniguchi 30 Asamu-cho, Omuta-shi, Fukuoka Mitsui Toatsu Kagaku Co., Ltd. (72) Inventor Hiroshi Takayanagi 1190 Kasama-cho, Sakae-ku, Yokohama, Kanagawa Within the corporation

Claims (2)

[Claims] 1. An isocyanate compound represented by the general formula (I): [In the formula, R ₁ and R ₂ are the same or different and have 1 to 1 carbon atoms.
10 straight-chain or branched saturated hydrocarbon groups can be used as R ₃
Represents a linear or branched hydrocarbon group having 1 to 10 carbon atoms, an ether group or a thioether group. ] Hindered phenols represented by the formula 2,6-di-ter
A method for preventing coloration of an isocyanate compound, which comprises adding t-butyl-4-methylphenol and triphenylphosphite. 2. In the general formula (I), R ₁ is a methyl group and R ₂ is t.
an ert-butyl group and R ₃ is a butylidene group, that is, the one-hindered phenol represented by the general formula (I) is 4,
The method for preventing coloration of an isocyanate compound according to claim 1, which is 4'-butylidene bis (3-methyl-6-tert-butylphenol).