JP2000001465A - Production of diphenylmethane diisocyanate and/or polymethylene polyphenylene polyisocyanate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for minimizing zinc content in an isocyanate mixture. SOLUTION: This method is to treat diphenylmethane diisocyanate and/or polymethylene polyphenylene polyisocyanate containing zinc by an ion-exchange resin, to separate the treated diphenylmethane diisocyanate and/or polymethylene polyphenylene polyisocyanate from the resin, and to produce the diphenylmethane diisocyanate and/or polymethylene polyphenylene polyisocyanate of reduced zinc content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate. More specifically, the present invention relates to a method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate having a low zinc content.

[0002]

BACKGROUND OF THE INVENTION Organic isocyanates are extremely reactive substances and are used in a wide variety of applications, including polyurethane foams, elastomers, adhesives and paints. Most of organic isocyanates are industrially produced by the reaction of the corresponding starting amine compound with phosgene.
For example, diphenylmethane diisocyanate (hereinafter, MD)
I) is to react a polyamine mixture synthesized by a condensation reaction of aniline and formaldehyde in the presence of an acid catalyst with phosgene in the presence of an inert solvent, and appropriately perform post-treatments such as degassing and desolvation. Polymethylene polyphenylene polyisocyanate (hereinafter referred to as poly MDI)
It is generally manufactured by extracting crude MDI containing 4,4'-diphenylmethane diisocyanate as a main component from the resulting crude MDI by a method such as distillation and further purifying the crude MDI.

[0003] In general, isocyanates contain impurities, such as acid components and hydrolyzable chlorine (hereinafter referred to as HC) or metal compounds, in a small amount. Such impurities have a significant adverse effect on the reactivity during the reaction with the active hydrogen compound, and also reduce the physical properties of the reaction product. Therefore, it is very important to reduce the acid content and HC components or metal compounds. is there.

Conventionally, H contained in organic isocyanates
As a method of reducing the C component, a method of repeating rectification, a method of adding a metal compound or the like and performing a heat treatment, and the like have been proposed, and by applying these methods, the amount of the HC component is generally allowed. Range, for example 10 for MDI
The purification operation is performed so as to be about 100 ppm.

However, in the method of repeating rectification (JP-B-53-9750 and JP-B-58-90540), the HC content can be reduced relatively easily, but the HC content is reduced to several tens ppm or less. If the amount is to be reduced, a distillation facility having a very high number of distillation stages is required, and the rectification operation needs to be repeated many times. Therefore, the cost is high and it is not industrially preferable. The organic isocyanate is
Due to overheating, when the temperature exceeds a certain temperature range, resinification and gas generation occur rapidly, so that industrially very careful temperature control is required.

On the other hand, HC by the addition treatment of metal compounds
As a reduction method, a treatment method using a zinc compound is known, and a heat treatment method using zinc oxide (Japanese Patent Publication No. Sho 41
No. 21611), a method of heat treatment using zinc acetate (Japanese Patent Publication No. 42-17887), or a method of heat treatment using zinc saturated fatty acid (JP-A-54-44613).
No.) are known. After heat treatment with these zinc compounds, thin-film distillation removes reaction residues containing zinc components as high-boiling components. For example, in the description of JP-B-42-17887, when zinc acetate is used, the acid content is 10 pp.
m, HC components are reduced to 10 to 30 ppm.

A method for treating HC by adding a zinc compound is as follows.
Since the treatment can be performed at a very low temperature as compared with the method of repeating rectification, there is an advantage that isocyanate is less deteriorated and operation is safe. However, at the same time, this method also has a problem that, depending on the amount of the zinc compound added, a reaction residue containing several hundred to several thousand ppm of zinc is generated.

The reaction residue treated with this zinc compound includes:
It contains several percent to tens of percent of MDI, but was conventionally discarded or mixed into poly-MDI. When the reaction residue is discarded, it is apparently not preferable in terms of cost.

On the other hand, when the residual liquid treated with the zinc compound is mixed in the poly-MDI, the zinc content in the poly-MDI naturally increases. Since the activity of isocyanate in the reaction with the hydroxy compound is affected by the content of zinc, when the poly-MDI having a high content of zinc is used as a starting material of the polyurethane polyadduct, its effect must be considered. No. A requirement for the production of polyurethanes is that the zinc content in the isocyanate mixture be as low as possible.

[0010] As described above, HC in isocyanate
Although the method of treating a component by adding a zinc compound is a useful method, there is a problem in treating a reaction residue containing a zinc component, and a method for solving this problem has been demanded.

[0011]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, by treating with an ion exchange resin, particularly a cation exchange resin, diphenylmethane diisocyanate and / or polymethylene polyphenylene. The inventors have found that the zinc content in the polyisocyanate can be reduced, and have completed the invention.

That is, the present invention relates to (1) treating diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate containing zinc as a raw material to be treated with an ion exchange resin, and treating the treated diphenylmethane diisocyanate and / or polymethylene. This is a method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate in which zinc content has been reduced by separating polyphenylene polyisocyanate from an ion exchange resin. (2) Diphenylmethane diisocyanate containing zinc content as a raw material to be treated; And / or treating polymethylene polyphenylene polyisocyanate with an ion exchange resin, and treating the treated diphenylmethane diisocyanate and / or polymethylene polyphenylene. By separating the polyisocyanate from the ion-exchange resin, isocyanate 1 zinc content
This is a method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate having a reduced zinc content, which is reduced to a weight range of 0.1 to 100 mg per kg, and (3) treating with an ion exchange resin for 20 to 150. ℃ temperature, 0.05-10MPa
(1) The method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate with reduced zinc content according to (1) or (2), wherein (4) polymethylene polyphenylene polyisocyanate is performed. From diphenylmethane diisocyanate produced by an operation such as separation and purification and containing a hydrolyzable chlorine component and an acid component, and treated by adding a zinc compound, and the resulting treatment liquid is evaporated or distilled to obtain a purified diphenylmethane diisocyanate fraction. And the residue containing zinc is separated, and the residue containing the separated zinc is used as a raw material to be treated, according to the above (1), (2) or (3).

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
In the present invention, “diphenylmethane diisocyanate (hereinafter, referred to as MDI)” is represented by the formula (1)

Embedded image (Wherein n represents an integer of 0 or more), and represents a compound of n = 0, and also includes by-products and impurities which are usually mixed.

In the present invention, "polymethylene polyphenylene polyisocyanate (hereinafter referred to as poly MDI)"
The term “is” means a mixture of n = 0 or more including n = 0 in the formula (1), and also includes by-products and impurities which are usually mixed.

The "raw material" in the present invention is a material containing zinc in the above-mentioned MDI and / or poly-MDI.

The "acid content" in the present invention is a general term for the acid-causing substances contained in the isocyanate, and the amount is defined in Japanese Industrial Standards JIS-K1603 (Testing method for polymethylene polyphenyl polyisocyanate). It is a value obtained by the method of measuring the “acidity” obtained, and is a value converted into the amount of hydrogen chloride.

In the present invention, "hydrolyzable chlorine (H
"C)" is a generic term for substances contained in isocyanate and generating hydrochloric acid by hydrolysis, and the amount of the substance is defined as "hydrolyzable chlorine" defined in Japanese Industrial Standards JIS-K1556 (test method for tolylene diisocyanate). "It is a value obtained by a measuring method and converted into a chlorine amount.

"Zinc content" in the present invention is a value determined by an atomic absorption method.

The method for treating HC by adding a zinc compound according to the present invention comprises a process comprising a main component comprising 4,4'-diphenylmethane diisocyanate (hereinafter referred to as 4,4'-MDI) and a hydrolyzable chlorine (HC) component and an acid component. The method is performed by adding a zinc compound to the contained crude MDI and subjecting it to a heat treatment.

The crude MDI is reacted with phosgene in a generally known manner, for example, by reacting a polyamine mixture synthesized by a condensation reaction of aniline and formaldehyde in the presence of an acid catalyst with phosgene in the presence of an inert solvent. A post-treatment such as gas and solvent removal is performed to obtain poly-MDI, from which 4,4′-MDI is taken out as a main component by a method such as distillation and then purified if necessary. .

As the zinc compound, one or more compounds selected from the group consisting of zinc oxide, zinc acetate, and saturated fatty acid zinc can be used, and it is particularly preferable to use saturated fatty acid zinc. As the saturated fatty acid zinc, for example,
Zinc laurate, zinc octylate, zinc stearate,
Although zinc palmitate and the like can be mentioned, it is more preferable to use zinc stearate which is inexpensive for industrial use because it is economically advantageous.

The amount of zinc saturated fatty acid added depends on the amount of HC contained.
The amount is from 1 to 10 moles, preferably from 1 to 5 moles, based on the chlorine amount of the compound. When the range of the addition amount when zinc stearate is used as the saturated fatty acid zinc is shown, for example, the HC content is 5%.
When zinc stearate is added to 0 ppm crude MDI and treated, if the atomic weight of chlorine is 35.45 and the molecular weight of zinc stearate is 632.34, the amount of addition is about 8
In the range of 92-8919 ppm, preferably about 892-4
It is in the range of 459 ppm (all on a weight basis).

The temperature of the heat treatment after the addition of the saturated fatty acid zinc is in the range of 50 ° C. to 220 ° C., preferably 60 ° C. to 150 ° C. The time of the heat treatment varies depending on the amount of the HC component contained in the crude MDI, the amount of the added saturated fatty acid zinc, and the temperature of the heat treatment, and cannot be said unconditionally, but is generally in a range of 10 minutes to 8 hours. is there.

The method of adding the saturated fatty acid zinc and heat-treating can be appropriately applied to a general method for this kind of chemical operation, and is not particularly limited. The method can be either a batch system or a continuous system.

In the present invention, MDI and / or poly-MDI containing zinc as a raw material to be treated is treated with an ion-exchange resin, and the treated MDI and / or poly-MD is treated.
Separating I from the ion exchange resin reduces the zinc content.

According to the method of the present invention, as a raw material to be processed, a zinc-containing treatment liquid (A) obtained by adding a zinc compound to the crude MDI according to the above-mentioned method and subjecting it to heat treatment, and a treatment liquid (A) obtained by evaporation from the treatment liquid (A). , 4′-MDI-containing residue after removal of zinc (B), treatment liquid (A) and any mixture of poly-MDI (C), or residue (B) and mixture of any poly-MDI (D) ), Can be performed for both.

The ion exchange resin used in the method of the present invention is a commonly used ion exchange resin, but is preferably a cation exchange resin. Usually, cation exchange resins have many salt types such as alkali metals and alkaline earth metals,
H-type regenerated with a mineral acid such as hydrochloric acid can also be used. For example, a cation exchange resin having a weakly acidic macroporous type and having an iminodiacetate group capable of forming a chelate as an exchange group (trade name Levatit TP207: manufactured by Bayer)
May be regenerated with a mineral acid such as hydrochloric acid.

The ion exchange resin used in the present invention must be used in a dry state. This is necessary to prevent the reaction between water contained in the ion exchange resin and isocyanate in the raw material to be treated.

The method of treating with the ion exchange resin of the present invention may be a method of treating the raw material to be treated as it is or, if necessary, dissolving it in an inert organic solvent and treating it as a solution. The inert organic solvent may be any solvent that does not react with the raw material to be processed and is stable in the processing temperature range and does not hinder the processing reaction.For example, hexane, octane, cyclohexane, toluene, xylene, chlorobenzene, dichlorobenzene, etc. Preferred are aromatic compounds, more preferably chlorinated aromatic compounds such as o-dichlorobenzene.

The concentration of the raw material to be treated when it is dissolved in an inert organic solvent and treated in a solution is not particularly limited, and can be easily determined by a preliminary test.

The treatment method using the ion exchange resin of the present invention is as follows.
Either a continuous system or a batch system can be used. In the case of the continuous type, the treatment is continuously performed by passing the solution at such a speed that the raw material to be treated and the ion exchange resin are sufficiently contacted and zinc is adsorbed. In the case of a batch type, a method in which an ion-exchange resin is added to a raw material to be treated, and the mixture is vigorously stirred so that the mixture is in good contact with the ion-exchange resin, and then the ion-exchange resin is separated by filtration under pressure or under reduced pressure. Perform processing.

The processing conditions of the continuous type and the batch type are as follows: the amount of the ion exchange resin to be used, the processing time, the pressure and the temperature, the type of the raw material to be processed and the content of zinc contained therein, the ion exchange resin to be used. It depends on the nature and activity, and whether the raw material to be treated is undiluted or diluted with an organic solvent. As specific processing conditions, the processing temperature is 20 to 150 ° C., preferably 20 to 80 ° C., and the processing pressure is 0.05 to 10 MPa, preferably 0.1 to 1 MPa.
MPa, and the contact time is usually 0.5 to 200 minutes, preferably 0.5 to 100 minutes. The amount of the ion exchange resin to be used is 0.1 to 1 kg of undiluted raw material to be treated.
It is 1 to 300 g, preferably 0.5 to 200 g. Optimum values of the above-mentioned parameters may be within the ranges described, and can be easily determined by appropriate preliminary tests.

The zinc-reduced MDI and / or poly-MDI produced according to the present invention contains less zinc and impurities than the liquid to be treated, so that poly-MDI
In the general production process, a polyamine mixture synthesized by the condensation reaction of aniline and formaldehyde in the presence of an acid catalyst was reacted with phosgene in the presence of an inert solvent. It can be recovered in any poly-MDI production process system.

The zinc-reduced MDI and / or poly-MDI produced according to the present invention can be treated with an ion-exchange resin in the absence of an organic solvent. When the reaction is carried out in the presence of a solvent, an appropriate poly-M
It can be suitably used directly for industrial purposes by mixing with DI.

The MDI and / or poly-MDI treated according to the process of the invention can be used as starting material, for example, in the production of polyurethane polyadducts.

[0036]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which by no means limit the present invention. Unless otherwise specified, “parts”, “%”, and “ppm” in the examples represent “parts by weight”, “% by weight”, and “ppm by weight”, respectively.

Synthesis Example 1 A polyamine mixture obtained by condensing aniline and formalin in the presence of hydrochloric acid and performing purification such as neutralization and dehydration is reacted with phosgene in o-dichlorobenzene to remove gas, remove solvent and the like. Of poly MDI containing 64% by weight of MDI
I got This poly MDI was evaporated using a thin film evaporator at a temperature of 195 to 215 ° C. under a reduced pressure of 300 to 400 Pa to obtain a crude MDI at a weight of 48% based on the poly MDI. The crude MDI has an acid content of 15 ppm and HC of 34 pp
m. 600 parts of the crude MDI and 0.72 parts of zinc stearate (corresponding to 2.0 times the amount of HC) are charged into a 1-liter four-necked flask equipped with a stirrer and a nitrogen gas inlet tube, and stirred. While heating at 90 ° C. for 4 hours. The zinc content of this reaction solution (raw material X) was 124 mgZ
n / kg. The raw material X is evaporated using a thin film evaporator at a temperature of 179 to 190 ° C. under reduced pressure of 100 to 200 Pa, and 431 parts of a low boiling fraction (MDI) and a residue containing a zinc compound (raw material Y) 169 Got a part. The zinc content of the obtained residue was 440 mg Zn / kg. Raw material Y5
0 parts and 50 parts of poly-MDI containing no zinc were mixed to obtain a raw material Z having a zinc content of 220 mg Zn / kg.

Example 1 190 parts of the raw material X obtained in Synthesis Example 1 and Levatit TP207 which is a weakly acidic macroporous cation exchange resin
(Available from Bayer, H-shaped with hydrochloric acid and dried at 70 ° C. under reduced pressure) 10 parts were charged into a four-necked flask equipped with a stirrer and a nitrogen gas inlet tube, and stirred at 50 ° C. for 2 hours.
Time processed. Then, the cation exchange resin was filtered off under reduced pressure and filtered off. The zinc content in the filtrate is 70 m
gZn / kg.

Example 2 190 parts of the raw material Z obtained in Synthesis Example 1 and Levatit TP207 which is a weakly acidic macroporous cation exchange resin
(Bayer, H-type with hydrochloric acid, dried at 70 ° C. under reduced pressure) 20 parts were charged into a four-necked flask equipped with a stirrer and a nitrogen gas inlet tube, and stirred at 65 ° C. for 2 hours.
Time processed. Then, the cation exchange resin was filtered off under reduced pressure and filtered off. The zinc content in the filtrate is 80m
gZn / kg.

Example 3 A solution was prepared by dissolving 20 parts of the starting material Z obtained in Synthesis Example 1 in 80 parts of o-dichlorobenzene. 100 parts of this o-dichlorobenzene solution was added to Levatit TP207 (Ba)
Yer, H-type with hydrochloric acid, dried at 70 ° C. under reduced pressure) and treated with stirring at 25 ° C. for 2 hours. Next, the cation exchange resin was separated by filtration under reduced pressure. A solution having a zinc content of 7 mg / kg (35 mg Zn / kg / kg of poly MDI) was obtained.

Example 4 A solution was prepared by dissolving 20 parts of the raw material Y obtained in Synthesis Example 1 in 80 parts of o-dichlorobenzene. 100 parts of this o-dichlorobenzene solution was added to Levatit TP207 (Ba)
Yer, H-type with hydrochloric acid and dried at 70 ° C. under reduced pressure) and treated at 65 ° C. for 3 hours with stirring. Next, the cation exchange resin was separated by filtration under reduced pressure. 11 mg / kg zinc content (1 kg poly MDI
Solution having a concentration of 55 mg Zn / kg).

Example 5 A solution was prepared by dissolving 20 parts of the raw material Z obtained in Synthesis Example 1 in 80 parts of o-dichlorobenzene. 2000 ml of this o-dichlorobenzene solution was added to Levatit TP207.
A glass column packed with 157 ml (made by Bayer, H-type with hydrochloric acid and dried at 70 ° C. under reduced pressure)
Pump at a pump speed of 157 ml per hour (temperature 25
° C), and a sample was collected using 157 ml per hour as one fraction. After 10 hours, the fraction obtained had a zinc content of 4 mg Zn / kg (20 mg Zn / kg per kg of poly-MDI).

Comparative Example 1 The same procedure as in Example 2 was carried out except that the processing temperature was 230 ° C. The treatment liquid after 2 hours was resinified while generating gas.

[0044]

The MDI and / or poly-MDI treated by the method of the present invention can be used in the production of polyurethane polyadducts without deteriorating the performance of the conventional MDI and / or poly-MDI. Can be used as a substance. Surprisingly, treatment with the above-mentioned ion exchange resin makes it possible to significantly reduce the zinc content in MDI and / or poly-MDI.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Naoki Sato 30 Asamuta-cho, Omuta-shi, Fukuoka Mitsui Chemicals, Inc. F-term (reference) 4H006 AA02 AD11 AD17 AD30 AD32 BA72 BC51 BC52 BE90

Claims (4)

[Claims] 1. A method for treating a zinc-containing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate as a raw material to be treated with an ion exchange resin, and treating the treated diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate with an ion exchange resin. A method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate in which zinc content has been reduced by separation from zinc. 2. A diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate containing zinc as a raw material to be treated is treated with an ion exchange resin, and the treated diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate is treated with an ion exchange resin. A method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate having a reduced zinc content, wherein the zinc content is reduced to a weight range of 0.1 to 100 mg per kg of isocyanate by separating from zinc. 3. The treatment with an ion exchange resin is carried out at 20 to 150.
The method for producing diphenylmethane diisocyanate and / or polymethylene polyphenylene polyisocyanate having reduced zinc content according to claim 1 or 2, wherein the method is carried out at a temperature of ℃ and a pressure of 0.05 to 10 MPa. 4. A process in which a zinc compound is added to diphenylmethane diisocyanate, which is produced from polymethylene polyphenylene polyisocyanate by an operation such as separation and purification and contains a hydrolyzable chlorine component and an acid component, and is treated. 2. A method for separating a purified diphenylmethane diisocyanate fraction and a residue containing zinc by evaporation or distillation, and using the separated residue containing zinc as a raw material to be treated.
A method according to claim 2 or claim 3.