KR101215428B1 - Process for the preparation of methylene？bridged polyphenylene polyisocynate - Google Patents

Abstract

It is an object of the present invention to provide a production method for easily and effectively suppressing the coloring of methylene crosslinked polyphenylene polyisocyanate. In the solution, the condensation reaction between aniline and formaldehyde in the presence of an acid catalyst is provided. In the method of producing the methylene crosslinked polyphenylene polyisocyanate by reacting the polyamine mixture produced by reacting with phosgene in the presence of an inert solvent,

(1) After the said phosgenation reaction, after removing the remaining phosgene from the reaction mixture containing the obtained methylene crosslinked polyphenylene polyisocyanate,

(2) To the above-mentioned prepared methylene crosslinked polyphenylene polyisocyanate, the following formula (I)

[Formula 1]

(In formula, R <^1> , R <^2> , R <^3> and R <^4> is respectively independently hydrogen or a C1-C6 hydrocarbon group.)

It is characterized by adding a hydroxyl group-containing aromatic compound having a carboxyl group to the ortho position represented by the following and heat treatment.

Description

Process for producing methylene crosslinked polyphenylene polyisocyanate {PROCESS FOR THE PREPARATION OF METHYLENE? BRIDGED POLYPHENYLENE POLYISOCYNATE}

The present invention relates to a method for producing methylene crosslinked polyphenylene polyisocyanate.

Methylene crosslinked polyphenylene polyisocyanate (hereinafter abbreviated as "poly MDI") industrially reacts a polyamine mixture produced by condensation of aniline with formaldehyde with phosgene under a solvent in the presence of an acid catalyst, Subsequently, after removing the solvent, it is generally prepared by separating diphenylmethane diisocyanate (hereinafter abbreviated as MDI) by vacuum distillation, and adjusting to poly MDI having a desired MDI content and viscosity. However, since the poly MDI obtained by this method cannot be purified by distillation, the coloration in the manufacturing process becomes the coloration of the product as it is, and shows a dark color. As a result, the foam formed from this poly MDI is also colored and does not become colorless. This coloration does not adversely affect the mechanical properties, but the user prefers colorless in nature, and the colorless one has a wider range of use than coloration.

Many methods are known for improving the color of poly MDI. For example, Patent Document 1 discloses a method of removing a colored component from poly MDI. This method is a method of extracting poly-MDI at 80-180 degreeC using a C8 or more aliphatic hydrocarbon as an extraction solvent, and removing tar powder. However, the removal of the extraction solvent and the treatment of tar powder which has not been extracted are necessary, and therefore it is not a preferred method as an industrial production method. In addition, Patent Document 2 discloses a method of adding an additive to a product of a phosgenated preparation. This method is a method in which water is added after completion of phosgenation and before completion of removal of phosgene from the reaction mixture. However, this method is not preferable at the point of causing the fall of the isocyanate content of poly MDI obtained, and the increase of a viscosity. As a method of suppressing the coloring of poly MDI, there is also a method of adding various additives to the phosgene-containing mixture after the completion of phosgenation. Patent Document 3 describes a method of adding a low molecular weight alkanol and / or a polyhydric alcohol, Patent Document 4 describes a method of adding a polyoxyalkylene alcohol, and Patent Document 5 describes a method of adding a carboxylic acid. However, these methods are all unfavorable in that the quality of the obtained poly MDI falls with the secondary reaction which raises the acidity of MDI of the preparation agent obtained.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 60-58955

[Patent Document 2]

Japanese Patent Application Laid-Open No. 59-141553

[Patent Document 3]

Japanese Patent Application Laid-Open No. 4-211641

[Patent Document 4]

Japanese Patent Application Laid-Open No. 4-253952

[Patent Document 5]

European Patent No. 538500

The present invention is an improvement of the conventional method for producing methylene crosslinked polyphenylene polyisocyanate, in which the coloration in the manufacturing process is the cause of the coloration of the product as it is difficult to purify by distillation. An object of the present invention is to provide a production method for suppressing coloring of phenylene polyisocyanate.

The present inventors earnestly studied to solve the above problems, and surprisingly, after completion of the phosgenation reaction in the conventional method for producing a methylene crosslinked polyphenylene polyisocyanate, phosgene was removed from the phosgene-containing reaction mixture, By a simple and economical method of adding a specific aromatic compound containing a hydroxyl group and a carboxyl group to a poly MDI and heat-treating, it is possible to produce a low-pigmented methylene-crosslinked polyphenylene polyisocyanate. The present inventors have found that the present invention can be produced without an increase in acidity, and have completed the present invention.

That is, in the method for producing methylene crosslinked polyphenylene polyisocyanate according to the present invention, a polyamine mixture produced by condensation reaction between aniline and formaldehyde in the presence of an acid catalyst is reacted with phosgene in the presence of an inert solvent, In the method for producing a crosslinked polyphenylene polyisocyanate,

(1) after the said phosgenation reaction, after removing the remaining phosgene from the reaction mixture containing the obtained methylene crosslinked polyphenylene polyisocyanate,

(2) To the above-mentioned prepared methylene crosslinked polyphenylene polyisocyanate, the following formula (I)

[Formula 2]

(In formula, R <^1> , R <^2> , R <^3> and R <^4> is respectively independently hydrogen or a C1-C6 hydrocarbon group.)

It is characterized by adding a hydroxyl group-containing aromatic compound having a carboxyl group to the ortho position represented by the following and heat treatment.

The amount of the aromatic compound having a hydroxyl group represented by the above-mentioned (I) is preferably 1 part by weight or less, and more preferably 0.4 part by weight or less based on 100 parts by weight of the methylene crosslinked polyphenylene polyisocyanate. It is desirable to.

In the step (1), it is preferable to remove the remaining phosgene by heating at a temperature of preferably 180 ° C or lower, more preferably 140 ° C or lower.

In the said process (2), Preferably it heat-processes at the temperature of 30-180 degreeC, More preferably, 50-140 degreeC range.

BEST MODE FOR CARRYING OUT THE INVENTION [

Hereinafter, the manufacturing method of the methylene crosslinked polyphenylene polyisocyanate which concerns on this invention is demonstrated in detail.

[Production of prepared poly MDI]

The polyamine mixture used for the phosgenation reaction is a mixture containing methylene crosslinked polyphenylene polyamine (hereinafter abbreviated as "poly MDA") produced by the condensation reaction of aniline with formaldehyde in the presence of an acid catalyst such as hydrochloric acid. to be. Although the composition of poly MDA varies depending on the mixing ratio and condensation temperature of aniline / acid / formaldehyde at the time of condensation, poly MDA of any composition can be used in the present invention.

By reacting such a polyamine mixture with phosgene in the presence of an inert solvent, a crude methylene crosslinked polyphenylene polyisocyanate (hereinafter abbreviated as "prepared poly MDI") can be obtained. The prepared poly MDI contains 4,4-MDI, 2,4-MDI, 2,2-MDI, poly MDI homologue having three or more isocyanate groups, and unclassified by-products.

The inert solvent used for phosgenation will not be restrict | limited especially if it is a solvent normally used for manufacture of organic isocyanate. For example, Aromatic hydrocarbons, such as toluene and xylene; Halogenated aromatic hydrocarbons such as chlorotoluene, chlorobenzene and dichlorobenzene; Esters such as butyl acetate and amyl acetate; Ketones, such as methyl isobutyl, etc. are mentioned.

The method of phosgenation is not specifically limited as long as it is a method generally used, Any method, such as a hydrochloride method, a cold heat | fever two-stage method, a phosgene pressurization method, is applicable.

[Removal of remaining phosgene]

The reaction mixture after the phosgenation reaction contains the prepared poly MDI, an inert solvent, and the remaining phosgene. In the present invention, the remaining phosgene can be removed from the reaction mixture by a method of heating, depressurizing or charging an inert gas, or a combination thereof. Specifically, the reaction mixture in which the phosgene remains is preferably heated to a range of 100 ° C or more and 180 ° C or less, charged with an inert gas such as nitrogen, helium or argon, or heated to the boiling point of the inert solvent under reduced pressure. By doing so, the remaining phosgene can be removed. Among them, the reduced pressure method is preferable in that the remaining phosgene can be removed efficiently. By such an operation, the amount of phosgene remaining in the reaction mixture can be 1% by weight or less.

When removing phosgene remaining by heating, heating temperature is 180 degrees C or less normally, Preferably it is 140 degrees C or less. When the reaction mixture in which phosgene remains is heated at a temperature higher than 180 ° C, the reaction mixture may be colored, and the effect by the addition of a specific hydroxyl group-containing aromatic compound described below may not be sufficiently obtained. This is because discoloration does not occur even when a specific hydroxyl group-containing aromatic compound is added to the reaction mixture which has already been colored.

The heating time is appropriately set depending on the amount of remaining phosgene, and is usually 1 minute to 1 hour. The remaining phosgene removal method can appropriately use a method generally used for this kind of removal treatment, and can be carried out either batchwise or continuously.

[Addition of aromatic compounds and heat treatment]

The remaining phosgene is removed as described above, and the following formula (I) is added to the reaction mixture containing at least the prepared poly MDI.

(3)

(In formula, R <^1> , R <^2> , R <^3> and R <^4> is respectively independently hydrogen or a C1-C6 hydrocarbon group.)

A hydroxyl group-containing aromatic compound having a carboxyl group is added to the ortho position represented by the following to be heat treated.

As the hydroxyl group-containing aromatic compound represented by the formula (I), for example, salicylic acid, 3-methyl salicylic acid, 4-methyl salicylic acid, 5-methyl salicylic acid, 3-isopropyl salicylic acid, 3,5-di-t-butyl Salicylic acid, 3-methyl-6-isopropylsalicylic acid, 3-isopropyl-6-methylsalicylic acid, 3,5-diisopropylsalicylic acid, 2-hydroxy-3-phenylbenzoic acid, etc. are mentioned.

The aromatic compound represented by the formula (I) may be added to the reaction mixture containing the prepared poly MDI and the inert solvent without removing the inert solvent from the reaction mixture, or after removing the inert solvent from the reaction mixture. You may add to poly MDI.

The addition amount of the aromatic compound represented by said Formula (I) is 5 weight part or less normally, Preferably it is 1 weight part or less, More preferably, it is 0.4 weight part or less with respect to 100 weight part of prepared poly MDI.

The aromatic compound represented by the formula (I) may be added to the reaction mixture containing the prepared poly MDI or the prepared poly MDI as it is, or may be dissolved in an inert solvent and added. The inert solvent used herein is not particularly limited as long as it does not react with isocyanate and is stable in the heat treatment temperature range and does not inhibit the heat treatment reaction. For example, hexane, cyclohexane, toluene, xylene, chlorobenzene, dichloro Benzene and the like. Preferably, it is an inert solvent used in the phosgenation reaction.

Thus, after adding the aromatic compound represented by the above formula (I) to the reaction mixture containing at least the prepared poly MDI, the reaction mixture is usually at a temperature in the range of 30 to 180 ° C, preferably 50 to 140 ° C. Heat treatment. When heat processing temperature exceeds 180 degreeC, coloring may advance, the effect which added the said aromatic compound may become small, and it is not preferable to heat-process at temperature exceeding 180 degreeC. Moreover, even if it heat-processes at the temperature lower than 30 degreeC, there is no problem in particular, but the said aromatic compound may not melt completely, and it is not preferable.

The heat treatment time is appropriately set by the amount of the phosgenated by-product in the reaction mixture, the amount of the aromatic compound added, and the temperature of the heat treatment, and is usually in the range of 1 minute to 1 hour.

As the method of heat treatment, a method generally used for this kind of heat treatment can be appropriately used, and either a batch type or a communication type can be performed.

As mentioned above, when the inert solvent is contained in the reaction mixture heated by adding the aromatic compound represented by said Formula (I), this is removed. As a removal method, the method generally used for this kind of removal process can be used suitably.

The acid M and HC of the poly MDI can be reduced by heating the obtained MDI or the MDI separated from the poly MDI in this manner at 180 ° C to 240 ° C. Poly MDI manufactured by the manufacturing method which concerns on this invention can suppress deterioration of color to the minimum even if it heat-processes at such high temperature.

In addition, an acid content is a general term of the acid origin substance contained in an isocyanate, The quantity is calculated | required by the acidity measurement method defined in JISK1603 (polymethylene polyphenylene polyisocyanate test method), and converted into the amount of hydrogen chloride. Value.

In addition, HC is called hydrolyzable chlorine, and is a general term of the substance contained in an isocyanate and producing hydrochloric acid by hydrolysis, and the quantity is the hydrolyzable chlorine measurement defined in JIS K1556 (tolylene diisocyanate test method). It is the value calculated | required by the method and converted into the amount of chlorine.

[Example]

Hereinafter, although an Example demonstrates this invention, this Example demonstrates this invention concretely, and this invention is not limited at all by this Example. In addition, "part" and "%" in an Example shall represent "weight part" and "weight%", respectively, unless there is particular notice. Below, the manufacturing method of the poly MDI of the preparation used by the Example and the comparative example and the evaluation method of the color of poly MDI are shown.

(Production method of prepared poly MDI)

Aniline and formalin were condensed in the presence of hydrochloric acid, and purification such as neutralization and dehydration was performed to obtain a polyamine mixture. The polyamine mixture is reacted with phosgene in o-dichlorobenzene, flash distillation is carried out, 470 parts of o-dichlorobenzene solvent, 18 parts of remaining phosgene, and 100 parts of prepared poly MDI (prepared poly MDI is , 4,4-MDI, 2,4-MDI, 2,2-MDI, poly MDI consisting of homologues having three or more isocyanate groups, and unclassified by-products). Of the poly MDIs contained in the prepared poly MDI, MDI (4,4-MDI, 2,4-MDI, and 2,2-MDI) was 56.3%, and the poly MDI homologue having three or more isocyanate groups was 43.7%.

(Color Evaluation Method of Poly MDI)

1 weight part of obtained poly MDI was melt | dissolved in 50 weight part of toluene, the absorbance in wavelength 430nm and 520nm was measured at 20 degreeC, and the value evaluated.

(Measuring method of acid content)

The acid content of the obtained poly MDI measured acidity based on JISK1603, and evaluated it by the value converted into the amount of hydrogen chloride.

(Measurement method of HC)

HC of obtained poly MDI was measured based on the measuring method of hydrolyzable chlorine described in JISK1556, and it evaluated by the value converted into the amount of chlorine.

&Lt; Example 1 >

500 parts of the reaction mixture (85 parts of the prepared poly MDI was charged) into a 50 mL four-neck flask equipped with a condenser, and the mixture was reduced to 17.3 kPa while stirring, and the temperature was increased to 120 ° C. The mixture was stirred at this temperature for 10 minutes to completely remove the remaining phosgene.

Next, using the dropping lot, the solution which melt | dissolved 0.85 parts of salicylic acid in 10 parts of o-dichlorobenzene was charged at 120 degreeC under atmospheric pressure, and it stirred and heat-processed at 120 degreeC for 30 minutes under atmospheric pressure. Then, it cooled to 80 degreeC and removed most o-dichlorobenzene on the conditions of 1.3-4.0 kPa using a single distillation apparatus.

The reaction mixture from which phosgene and most of the solvents were removed as described above was heated at 215 ° C for 13.3 kPa for 20 minutes to completely remove o-dichlorobenzene to obtain poly MDI. As shown in Table 1, the absorbance at 430 nm of the obtained poly MDI was 0.062, the absorbance at 520 nm was 0.009, the acid content was 0.016%, and the HC was 0.10%.

<Example 2>

Poly MDI was obtained in the same manner as in Example 1 except that salicylic acid was changed from 0.85 part to 0.17 part. As shown in Table 1, the absorbance at 430 nm of the obtained poly MDI was 0.081, the absorbance at 520 nm was 0.023, the acid content was 0.015%, and HC was 0.10%.

<Example 3>

In the same manner as in Example 1, the remaining phosgene was completely removed from 500 parts of the reaction mixture (of which the prepared poly MDI was 85 parts), and the obtained reaction mixture was cooled to 50 ° C. The solution which melt | dissolved 0.17 parts of salicylic acid in 10 parts of o-dichlorobenzene was charged at 50 degreeC under atmospheric pressure using this dropping lot, and it stirred and heat-processed at the said temperature for 30 minutes under atmospheric pressure. Thereafter, most of o-dichlorobenzene was removed using a single distillation apparatus at 80 ° C and 1.3 to 4.0 kPa.

From the reaction mixture in which phosgene and most of the solvents were removed as described above, o-dichlorobenzene was completely removed in the same manner as in Example 1 to obtain poly MDI. As shown in Table 1, the absorbance at 430 nm of the obtained poly MDI was 0.063, the absorbance at 520 nm was 0.015, the acid content was 0.015%, and HC was 0.11%.

&Lt; Comparative Example 1 &

In the same manner as in Example 1, the remaining phosgene was completely removed from 500 parts of the reaction mixture (of which 85 parts of the prepared poly MDI). After stirring and heat-processing this at 120 degreeC for 30 minutes under atmospheric pressure, it cooled to 80 degreeC and removed most o-chlorobenzene on the conditions of 1.3-4.0 kPa using a single distillation apparatus.

From the reaction mixture in which phosgene and most of the solvents were removed as described above, o-dichlorobenzene was completely removed in the same manner as in Example 1 to obtain poly MDI. As shown in Table 1, the absorbance at 430 nm of the obtained poly MDI was 0.103, the absorbance at 520 nm was 0.040, the acid content was 0.015%, and HC was 0.11%.

Comparative Example 2

Poly MDI was obtained in the same manner as in Example 1 except that 0.85 part of benzoic acid was used instead of salicylic acid. As shown in Table 1, the absorbance at 430 nm of the obtained poly MDI was 0.063, the absorbance at 520 nm was 0.012, the acid content was 0.096%, and HC was 0.17%.

&Lt; Comparative Example 3 &

Poly MDI was obtained in the same manner as in Example 1 except that the hydroxyl group used 0.85 part of 1200 mg KOH / g polyethylene glycol instead of salicylic acid. As shown in Table 1, the absorbance of 430 nm of the obtained poly MDI was 0.107, the absorbance of 520 nm was 0.041, the acid content was 0.040%, and HC was 0.13%.

&Lt; Comparative Example 4 &

Poly MDI was obtained in the same manner as in Example 1 except that 0.17 part of p? Hydroxy benzoic acid was used instead of salicylic acid. As shown in Table 1, the absorbance of 430 nm of the obtained poly MDI was 0.067, the absorbance of 520 nm was 0.018, the acid content was 0.041%, and HC was 0.14%.

Below, the evaluation result of the test of the obtained poly MDI is put together in Table 1, and is shown.

Absorbance Acid content (%)
HC (%)
Remarks
430 nm 520 nm Example 1 0.062 0.009 0.016 0.10 Good Example 2 0.081 0.023 0.015 0.10 Good Example 3 0.063 0.015 0.015 0.11 Good Comparative Example 1 0.103 0.040 0.015 0.11 Bad
(High absorbance) Comparative Example 2 0.063 0.012 0.096 0.17 Bad
(High acid and HC) Comparative Example 3 0.107 0.041 0.040 0.13 Bad
(Absorbance, acid and
HC high) Comparative Example 4 0.067 0.018 0.041 0.14 Bad
(High acid and HC)

※ Note:

   ㆍ Absorbance: 0.090 or less → Good color during visual inspection

             0.100 or more → Poor color during visual inspection

   ㆍ Acid: 0.025 or less → good, 0.030 or more → bad

   ㆍ HC: 0.12 or less → good, 0.13 or more → bad

As shown in Table 1, in Examples 1, 2, and 3, absorbance, acid content, and HC all showed appropriate values, while good poly MDI was obtained, whereas in Comparative Examples 1, 2, 3, and 4, It can be seen that poor poly MDI is obtained by showing at least one of the high values.

Industrial availability

According to the present invention, methylene crosslinked polyphenylene polyisocyanate having excellent color can be easily produced as compared with the conventional method, and the deterioration in quality due to secondary by-products can also be prevented. Moreover, the foam excellent in color can be obtained by using the obtained methylene crosslinked polyphenylene polyisocyanate.

According to this invention, the methylene crosslinked polyphenylene polyisocyanate which is excellent in color can be manufactured easily. Moreover, this invention is useful at the point that the fall of the quality by a secondary byproduct can be prevented compared with the conventional method.

Claims (7)

In a method of producing a methylene crosslinked polyphenylene polyisocyanate by reacting a polyamine mixture produced by condensation reaction between aniline and formaldehyde in the presence of an acid catalyst with phosgene in the presence of an inert solvent, (1) After the said phosgenation reaction, after removing the remaining phosgene from the reaction mixture containing the obtained methylene crosslinked polyphenylene polyisocyanate, (2) Salicylic acid, 3-methyl salicylic acid, 4-methyl salicylic acid, 5-methyl salicylic acid, 3-isopropyl salicylic acid, 3,5-di-t-butyl salicylic acid, to the said prepared methylene crosslinked polyphenylene polyisocyanate A hydroxyl group-containing aromatic compound having a carboxyl group at the ortho position selected from -methyl-6-isopropylsalicylic acid, 3-isopropyl-6-methylsalicylic acid, 3,5-diisopropylsalicylic acid and 2-hydroxy-3-phenylbenzoic acid Process for producing methylene crosslinked polyphenylene polyisocyanate, characterized in that the heat treatment by addition. The method of claim 1, An amount of 0.2 to 1 part by weight of the aromatic compound having the hydroxyl group is added to 100 parts by weight of the methylene crosslinked polyphenylene polyisocyanate of the preparation. The method of claim 1, A method for producing methylene crosslinked polyphenylene polyisocyanate, wherein the amount of 0.2 to 0.4 parts by weight of the aromatic compound having the hydroxyl group is added to 100 parts by weight of the prepared methylene crosslinked polyphenylene polyisocyanate. 4. The method according to any one of claims 1 to 3, The said process (1) WHEREIN: The manufacturing method of the methylene crosslinked polyphenylene polyisocyanate which heats at the temperature of 100-180 degreeC, and removes remaining phosgene. 4. The method according to any one of claims 1 to 3, The said process (1) WHEREIN: The manufacturing method of the methylene crosslinked polyphenylene polyisocyanate which heats at the temperature of 100-140 degreeC, and removes remaining phosgene. 4. The method according to any one of claims 1 to 3, The process for producing methylene cross-linked polyphenylene polyisocyanate in the step (2), characterized in that the heat treatment at a temperature in the range of 30 ~ 180 ℃. 4. The method according to any one of claims 1 to 3, The process for producing methylene cross-linked polyphenylene polyisocyanate in the step (2), characterized in that the heat treatment at a temperature in the range of 50 ~ 140 ℃.