JP4973832B2 - Continuous production method of polymethylene polyphenyl polyamine - Google Patents

Abstract

Disclosed is a process for continuous production of a polymethylene polyphenyl polyamine which can produce a polymethylene polyphenyl polyamine continuously by reacting aniline and formaldehyde in the presence of a hydrochloric acid catalyst. The process comprises: (A) a first condensation step in which aniline in an amount of 80-95% by mass relative to the total amount to be charged and a portion of the total amount of formaldehyde to be charged are reacted with each other in the presence of a hydrochloric acid catalyst under such conditions where the hydrogen chloride/aniline ratio (by mole) is 0.99 or less; (B) a second condensation step in which the reaction solution yielded in the first condensation step is mixed with the remainder of formaldehyde to react them with each other; and (C) an isomerization step in which the reaction solution yielded in the second condensation step is mixed with aniline in an amount of 5-20% by mass relative to the total amount to be charged to cause an isomerization reaction between them. According to the process, it becomes possible to produce a polymethylene polyphenyl polyamine which has a reduced N-methyl substance content to the similar level to that in a batch-wise process and contains methylene diphenyl diamine in an amount similar to that in a batch-wide process.

Description

  The present invention relates to a continuous production method of polymethylene polyphenyl polyamine.

Polymethylene polyphenyl polyamine is obtained by condensation of aniline and formaldehyde in the presence of a mineral acid catalyst, and is used as a raw material for diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate used for synthetic leather, adhesives, heat insulating materials, etc. ing.
As a production method of this polymethylene polyphenyl polyamine, a batch method and a continuous method are known.
The batch reaction requires a complicated operation and has a problem that the equipment cost increases. On the other hand, the continuous reaction is simple in operation and has low equipment costs, but has a drawback that the content of methylenediphenyldiamine in the obtained polymethylenepolyphenylpolyamine is lowered.

In order to improve the shortcomings of this continuous reaction, a method of efficiently mixing aniline hydrochloride and formalin by a special mixing method while maintaining a high Reynolds number has been devised (see Patent Documents 1 and 2). .
However, in this method, although the content of methylenediphenyldiamine can be increased, it is difficult to reduce impurities containing N-methyl compounds by-produced by the condensation reaction to the same extent as in the batch reaction. Diphenylmethane diisocyanate and polymethylene polyphenyl polyisocyanate obtained from polymethylene polyphenyl polyamine containing a large amount of N-methyl compound generally have the problem that the acidity and the amount of hydrolyzable chlorine are high and the hue is also deteriorated. Have.

In addition, a method has been devised in which a continuous reaction is performed using a multi-stage tank reactor in which the temperature is kept constant to increase the amino group content of polyamine (see Patent Document 3).
However, with this method, it is extremely difficult to maintain the tank temperature at each stage constant, and not only the operation for maintaining the temperature is complicated, but also the above-described reduction of N-methyl isomers is not possible. It is enough.

As a method for reducing the N-methyl compound in the continuous reaction, a method in which the reaction is carried out in a state where aniline / formaldehyde (molar ratio) is initially increased by dividingly adding formaldehyde (see Patent Document 4), or three stages The temperature of each stage in the above multi-stage tank reaction is controlled within a predetermined range, the molar ratio of water to aniline in each tank is controlled, and the reaction is carried out by dividing and charging formaldehyde into three or more stages. A method (see Patent Document 5) has been devised.
However, in the method of Patent Document 4, the N-methyl isomer in the obtained polyamine is relatively high at 0.6%, and it is difficult to say that the effect of reducing the N-methyl isomer is sufficient. On the other hand, in the method of Patent Document 5, although the N-methyl isomer can be reduced to 0.18% or less, not only the temperature needs to be kept constant in each stage of the reaction vessel, but also the molar ratio of water to aniline. There is a problem that the operation becomes extremely complicated.

Furthermore, a method of reducing the N-methyl form in polymethylene polyphenyl polyamine by a semi-continuous method of circulating the reaction mixture using a circulation circuit has been devised (see Patent Document 6).
In this method, the N-methyl isomer can be reduced to a very small amount of less than 0.1%, but the conventional production equipment cannot be used as it is, so that there is a problem that the equipment cost increases and the operation becomes complicated.
In batch-type reactions, aniline is divided and charged to carry out the reaction to increase the 4,4′-methylenediphenyldiamine content (see Patent Document 7). However, aniline is divided in continuous reactions. The method to do is not known conventionally.

US Pat. No. 3,954,867 Japanese Patent Publication No.41-9536 Japanese Patent Publication No.49-39991 Published German Patent No. 238042 Japanese Patent No. 2825604 Japanese translation of PCT publication No. 2002-502838 Japanese Patent Publication No. 4-17943

  The present invention has been made in view of the above circumstances, and it is possible to reduce the N-methyl body content to the same level as that of the batch type by a relatively simple method and to reduce the amount of methylene in the same level as that of the batch type. An object of the present invention is to provide a continuous production method of polymethylene polyphenyl polyamine containing diphenyldiamine.

  As a result of intensive investigations to achieve the above object, the inventors of the present invention have developed a method for continuously producing polymethylene polyphenyl polyamine, which is a predetermined amount of the total amount of aniline and one of the total amount of formaldehyde. After reacting with hydrogen chloride / aniline (molar ratio) below a predetermined amount, mixing and reacting with the remaining amount of formaldehyde, and then mixing and reacting with the remaining amount of aniline. Thus, the inventors have found that the N-methyl content in the obtained product can be reduced to the same level as that of the batch system, and that the methylenediphenyldiamine content can be as high as that of the batch system, thereby completing the present invention.

That is, the present invention
1. A method for continuously producing polymethylene polyphenyl polyamine by reacting aniline and formaldehyde in the presence of a hydrochloric acid catalyst to continuously produce polymethylene polyphenyl polyamine, comprising (A) 80 to 80 of the total charge of aniline A first condensation step in which 95% by mass and a part of the total amount of formaldehyde are reacted in the presence of the hydrochloric acid catalyst at a hydrogen chloride / aniline (molar ratio) of 0.99 or less, (B) this first A second condensation step in which the reaction solution obtained in the condensation step and the residual amount of the formaldehyde are mixed and reacted; and (C) the reaction solution obtained in the second condensation step and the total charge of the aniline. of a mixture of 5 to 20 wt% with isomerization step of isomerization reaction, the, the reaction of (a) the first condensation step and (B) a second condensation step, at both 20 to 50 ° C. Continuous production process of polymethylene polyphenyl polyamine, wherein the cormorants,
2. (B) In the second condensation step, the continuous production method of one polymethylene polyphenyl polyamine, wherein the remaining amount of formaldehyde is divided into a plurality of arbitrary amounts and mixed,
3. In the (C) isomerization step, the reaction solution obtained in the (B) second condensation step is heated to 50 to 80 ° C. and held at this temperature for a predetermined time. A continuous production method of 1 or 2 polymethylene polyphenyl polyamine, which is mixed with 5 to 20% by mass of the charged amount and further heated to a temperature higher than the holding temperature ;
4). In the (C) isomerization step, a mixed solution obtained by mixing the reaction solution obtained in the (B) second condensation step and 5 to 20% by mass of the total charged amount of the aniline is heated to 50 to 80 ° C. and, this after a temperature was maintained for a predetermined time, and et a continuous production method of 1 or 2 polymethylene polyphenyl polyamines is heated to a temperature higher than the holding temperature,
5. (A) 80 to 95% by mass of the total charge of the aniline and a part of the total charge of the formaldehyde are introduced into the first reactor, and hydrogen chloride / aniline (molar ratio) is added in the presence of the hydrochloric acid catalyst. A first condensation step in which the reaction is carried out at 20 to 50 ° C. at a temperature of 0.99 or less, (B) the reaction liquid obtained in the first condensation step and the residual amount of the formaldehyde are introduced into a second reactor and 20 A second condensation step of reacting at -50 ° C, and (C1) introducing the reaction liquid obtained in the second condensation step into a cage and heating to 50-80 ° C, and holding at this temperature for a predetermined time, In the isomerization step of mixing this heated and held reaction liquid and 5 to 20% by mass of the total charged amount of the aniline and heating to 90 ° C. or more to effect isomerization, or (C2) in the second condensation step 5 to 20 of the total amount of the reaction solution obtained and the aniline And an isomerization step in which the mixture is heated to 50 to 80 ° C. and held at this temperature for a predetermined time, and then heated to 90 ° C. or higher to cause an isomerization reaction. continuous production method 1 of the polymethylene polyphenyl polyamines you,
6). Wherein (B) in a second condensation step, continuous production method of the polymethylene polyphenyl polyamines of 5 Ru used collectively the total amount of residual amounts of the formaldehyde,
7). Either continuous production method of the polymethylene polyphenyl polyamines according to claim 3-6 that holds at 50-70 ° C. 1 to 30 minutes,
8). Wherein (A) in a first condensation step, hydrogen chloride / aniline (mole ratio), 0.90 to 0.98 der Ru 1-7 either continuous production method of the polymethylene polyphenyl polyamine,
9. The continuous production method of the polymethylene polyphenyl polyamine according to any one of 1 to 8 , wherein the molar ratio of the total amount of aniline / the total amount of formaldehyde is 1.5 to 4 ,
10. Wherein (A) in a first condensation step, continuous production method of the total charge of 1-9 Ru by reacting 20 to 60 wt% or polymethylene polyphenyl polyamines of the formaldehyde,
11. In the (A) first condensation step, a continuous production method of 10 polymethylene polyphenyl polyamines in which 50 % by mass of the total amount of formaldehyde is reacted is provided.

According to the continuous production method of polymethylene polyphenyl polyamine of the present invention, N-methyl in the obtained polymethylene polyphenyl polyamine can be obtained by a relatively simple method of using both aniline divided charge and formaldehyde divided charge. The body content can be reduced to the same level as in the batch system, and the methylenediphenyldiamine content in the resulting polymethylene polyphenyl polyamine can also be set to the same level as in the batch system.
Since the production method of the present invention does not require the use of a multistage tank reactor or a circulation circuit unlike the conventional method, it is advantageous in terms of equipment cost and manufacturing cost.
Thus, it can be said that the continuous production method of the polymethylene polyphenyl polyamine of the present invention has extremely high utility value as an industrial production method.

Hereinafter, the present invention will be described in more detail.
In the continuous production method of polymethylene polyphenyl polyamine according to the present invention, when aniline and formaldehyde are reacted in the presence of a hydrochloric acid catalyst to continuously produce polymethylene polyphenyl polyamine, (A) the whole preparation of aniline A first condensation step in which 80 to 95% by mass of the amount and a part of the total amount of formaldehyde are reacted in the presence of a hydrochloric acid catalyst at a hydrogen chloride / aniline (molar ratio) of 0.99 or less, (B) No. The second condensation step in which the reaction solution obtained in the first condensation step and the remaining amount of formaldehyde are mixed and reacted, and (C) the reaction solution obtained in the second condensation step, and the total charged amount of aniline is 5 It comprises an isomerization step in which -20% by mass is mixed and subjected to an isomerization reaction.

(A) A 1st condensation process is demonstrated.
In this step, 80 to 95% by mass of the total charge of aniline and a part of the total charge of formaldehyde are used, and the condensation reaction is performed with hydrogen chloride / aniline (molar ratio) being 0.99 or less.
Here, when hydrogen chloride / aniline (molar ratio) exceeds 0.99, there is a high possibility that the content of the N-methyl compound in the obtained polymethylene polyphenyl polyamine will increase. In consideration of further reducing the amount of N-methyl compound, the hydrogen chloride / aniline (molar ratio) is preferably 0.98 or less, more preferably 0.96 or less. The lower limit is usually about 0.3, but in this case as well, for the same reason, 0.5 or more is preferable, 0.7 or more is more preferable, and 0.9 or more is even more preferable.

The amount of aniline charged may be an amount that satisfies the above hydrogen chloride / aniline (molar ratio). In the present invention, the amount of aniline charged is 80 to 95% by mass, preferably 85 to 95% by mass, More preferably, it is 88-93 mass%. If the charge amount is less than 80% by mass, the content of methylenediphenyldiamine is likely to decrease, and if it exceeds 95% by mass, the content of the N-methyl compound is likely to increase.
The formaldehyde charge is not particularly limited as long as it is a part of the total charge, but in order to reduce the N-methyl body content more effectively, 20 to 60% by mass of the total charge is preferable, and 30 -60 mass% is more preferable, and 50 mass% is still more preferable.
The amount of hydrochloric acid catalyst used is set in a range in which hydrogen chloride / aniline (molar ratio) satisfies the above range depending on the amount of aniline charged. About 0.3 to 3.0 times the molar amount.

In this step, aniline is usually used as an aqueous solution of aniline hydrochloride, and is prepared so as to satisfy the hydrogen chloride / aniline (molar ratio) in the state of the aqueous solution of hydrochloride. Of course, aniline and hydrochloric acid can be used separately.
Formaldehyde is generally used as an aqueous solution (formalin) having a concentration of 20 to 38% by mass.
The condensation reaction in this step is preferably performed at 20 to 50 ° C., more preferably 30 to 40 ° C. from the viewpoint of maintaining the liquidity of the reaction solution and reducing the N-methyl body content. . That is, if the reaction temperature is too low, the reaction solution becomes viscous and the fluidity may be lowered, resulting in a deterioration in operability. On the other hand, if the temperature is too high, the N-methyl body content may be increased. is there.
In addition, since heat_generation | fever by reaction heat arises after mixing aniline, hydrochloric acid, and formaldehyde, it is preferable to perform the condensation reaction of this process so that the said temperature range may be maintained under cooling. In this case, the cooling method is not particularly limited, and may be appropriately selected from known methods such as a method of flowing a coolant such as cooling water through a jacket attached so as to cover the periphery of the reactor.
Moreover, although there is no restriction | limiting in particular in reaction time, Usually, it is about 3 to 15 minutes, Preferably it is about 5 to 10 minutes.

  In this step, the mixing method of each raw material is arbitrary, and aniline (hydrochloric acid aqueous solution) and formaldehyde (aqueous solution) may be put into a reactor, and they may be mixed in the reactor. After mixing in the mixer, it may be put into the reactor. At that time, formaldehyde (aqueous solution) may be added to aniline (hydrochloride aqueous solution) or vice versa. In addition, there is no restriction | limiting in particular in a reactor and a mixer, It selects suitably from conventionally used reactors, such as a tank type, a tube type, and a tower type, a mixer provided with the well-known stirring means, etc. Can be used.

(B) A 2nd condensation process is demonstrated.
In this step, the reaction solution obtained in the first condensation step (A) described above and the remaining amount of formaldehyde are mixed to further perform a condensation reaction.
When mixing the remaining amount of formaldehyde, all of the remaining amount may be mixed at once, and this may be divided and mixed in an arbitrary amount, preferably evenly. When divided and mixed, (A) the reaction solution obtained in the first condensation step and each of the divided formaldehyde may be mixed one after another in the same reactor, but the same number as the divided number of formaldehyde Using the reactor, in or before the first reactor, (A) the reaction solution obtained in the first condensation step and the first divided formaldehyde are mixed and reacted. It is preferable to use a method of repeating the operation of introducing into a reactor and mixing and reacting with the second divided formaldehyde by the number of divisions of formaldehyde.
As the number of divisions increases, the quality of the obtained polymethylene polyphenyl polyamine improves, but the use of the latter of the above-described methods requires complicated operations such as the need to use the same number of reactors as the number of divisions. It becomes inferior in economic efficiency. Therefore, it is preferable that the remaining amount of formaldehyde is used in a lump or divided into a few about 2-3. Formaldehyde is generally used in an aqueous solution (formalin) as in the (A) first condensation step.

The condensation reaction in this step is also preferably performed at 20 to 50 ° C, and more preferably at 30 to 40 ° C for the same reason as described above. Also in this case, since heat is generated by reaction heat, it is preferable to maintain the above temperature range under cooling by the cooling means described above.
Moreover, although there is no restriction | limiting in particular in reaction time, Usually, it is about 3 to 15 minutes, Preferably it is about 5 to 10 minutes.
Also in this step, the method of mixing the reaction solution and the remaining amount of formaldehyde is arbitrary, and the reaction solution and formaldehyde (aqueous solution) may be charged into the reactor and mixed in them. They may be mixed in a mixer and then charged into the reactor. At this time, formaldehyde (aqueous solution) may be added to the reaction solution or vice versa, but in this step, a method of adding formaldehyde (aqueous solution) to the reaction solution that is continuously supplied and mixing them is suitable. . In this case, there is no particular limitation on the reactor and the mixer.

(C) The isomerization step will be described.
In this step, the reaction solution obtained in the second condensation step (B) and the remaining amount of aniline, that is, 5 to 20% by mass of the total charged amount of aniline, are mixed to carry out the isomerization reaction.
The temperature of the isomerization reaction is usually 70 to 130 ° C., but is preferably 90 ° C. or higher, more preferably 95 ° C. or higher in order to allow the reaction to proceed smoothly.
Although there is no restriction | limiting in particular in reaction time, Generally it is about 20 to 120 minutes, Preferably it is 25 to 90 minutes, More preferably, it is 30 to 60 minutes.
The method of mixing the reaction solution with the remaining amount of aniline is arbitrary, and the reaction solution and aniline may be mixed before the isomerization reactor and charged into the reactor, or the reaction solution and aniline may be mixed. It may be put into the chemical reactor and mixed therein. At that time, a method of adding and mixing aniline into the continuously supplied reaction solution is suitable. As the reactor, the various reactors described above can be used. However, since the isomerization reaction is performed at a relatively high temperature, it is preferable to use a column type reactor.

In this step, before starting the isomerization reaction, only the reaction solution obtained in the above-mentioned (B) second condensation step, or the mixture of the reaction solution and the remaining amount of aniline, 50 to 80 It is possible to carry out the isomerization reaction at a temperature higher than this holding temperature after heating to 50 ° C., preferably 50 to 70 ° C., more preferably 60 to 70 ° C. and holding at this temperature for a predetermined time. By performing such a holding step, the content of methylenediphenyldiamine in the obtained polymethylene polyphenyl polyamine can be increased.
Under the present circumstances, although holding time is arbitrary, in order to raise a methylene diphenyldiamine content more, 1 to 40 minutes are preferable, 5 to 30 minutes are more preferable, and 15 to 25 minutes are still more preferable.

  For example, (B) the reactor used in the second condensation step (final stage) may be used as the retainer, and the reaction solution alone or the residual amount of aniline may be added thereto. Well, using another cage different from that, (B) introducing the reaction solution obtained in the second condensation step alone, or introducing the reaction solution and aniline Also good. In addition, the form of the cage is arbitrary, and the same reactors as those described above can be used, but a tank type is preferable.

By passing through the series of steps described above, an aqueous solution of polymethylene polyphenyl polyamine hydrochloride containing unreacted aniline is obtained. Furthermore, pure polymethylene polyphenyl polyamine can be obtained by neutralization, washing and aniline removal according to conventional methods.
The obtained polymethylene polyphenyl polyamine has the same N-methyl content and methylene diphenyldiamine content as those obtained by the batch method, and the quality is good.
This polymethylene polyphenyl polyamine can be derived into polymethylene polyphenyl polyisocyanate by reacting with phosgene according to a conventional method. The resulting polymethylene polyphenyl polyisocyanate has low acidity, hydrolyzable chlorine content, and good color number.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 shows a continuous production apparatus 1A used in the continuous production method of polymethylene polyphenyl polyamine according to the first embodiment of the present invention.
The continuous production apparatus 1A includes a first mixer 10, a first reactor 11, a second mixer 12, a second reactor 13, a retainer 14, and an isomerization reactor 15. These are configured to be connected in series by a liquid supply tube 16 for a reaction liquid or the like.
The formalin 2A corresponding to 50% by mass of the total formaldehyde and the aniline hydrochloride aqueous solution 3A containing 80 to 95% by mass of the total charged amount of aniline supplied to the apparatus 1A are first supplied into the first mixer 10. And mixed here. The first mixer 10 is configured by arranging a stirring device (not shown) such as a mixer in the liquid feeding tube 16. Moreover, the supply amount of formalin 2A and aniline hydrochloride 3A can be set to an appropriate speed (kg / h).

The formalin 2A and the aniline hydrochloride aqueous solution 3A mixed inside the first mixer 10 are introduced into a tank-type first reactor 11 where a condensation reaction is performed ((A) first condensation step). . At this time, cooling water is passed through a jacket (not shown) provided so as to cover the periphery of the first reactor 11, cooled to about 35 ° C., and the reaction is performed for about 10 minutes. The hydrogen chloride / aniline (molar ratio) is 0.99 or less.
To the reaction liquid discharged from the first reactor 11, formalin 4 corresponding to the remaining formaldehyde (50% by mass) is added all at once, and then introduced into the second mixer 12, in which these are After being mixed, the mixture is introduced into the second reactor 13, and the condensation reaction is further performed for about 10 minutes under cooling at about 35 ° C. ((B) second condensation step). The second mixer 12 and the second reactor 13 have the same configuration as the first mixer 10 and the first reactor 11, respectively.

The reaction liquid discharged from the second reactor 13 is further introduced into a tank-type holder 14 where it is heated to about 65 ° C. and held in that state for about 20 minutes. The remaining aniline 5 is further added all at once to the reaction liquid discharged from the cage 14, and after these are introduced into the tower-type isomerization reactor 15, it is heated to 90 ° C. or more and subjected to an isomerization reaction. ((C) isomerization step). The supply amount (flow rate) of the reaction liquid in each step is set to an appropriate speed (kg / h) according to the supply amount of the raw material.
Through the above series of steps, a polymethylene polyphenyl polyamine containing unreacted aniline is obtained, and a pure polymethylene polyphenyl polyamine is obtained through further post-treatment by a conventional method.

[Second Embodiment]
FIG. 2 shows a plurality of second mixers in which the (B) second condensation step of the continuous production apparatus 1B used in the continuous production method of polymethylene polyphenyl polyamine according to the second embodiment of the present invention is performed. 12A-C and also a plurality of second reactors 13A-C are shown. In addition, since the other structure of the continuous production apparatus 1B of this embodiment is the same as that of 1st Embodiment, those illustration and description are abbreviate | omitted.
In the present embodiment, the second mixer 12A, the second reactor 13A, the second mixer 12B, the second reactor 13B, the third mixer 12C, and the second reactor 13C are arranged in series in this order. They are connected by the liquid feeding tube 16 described above.
(B) The remaining formaldehyde used in the second condensation step is divided into three formalins 4A to C equal in number to the second reactors 12A to 12C, each of which is divided into the second mixers 12A and 12B and Before 12C, it is added to each of the reaction liquids conveyed in the liquid feeding tube 16. Subsequently, after being mixed in each of the second mixers 12A to 12C, it is introduced into each of the second reactors 13A to 13C, and further a condensation reaction is performed in a state cooled to about 35 ° C.
In addition, all formaldehyde (formalin) used in this embodiment is equally divided into four parts, a part of (A) is used in the first condensation step, and a part of each of the remaining formalins 4A to C is It introduce | transduces into 2nd reactor 13A-C, respectively. The specific configurations of the second mixers 12A to 12C and the second reactors 13A to 13C are the same as those in the first embodiment.

The reaction solution discharged from the second reactor 13C is further introduced into a tank-type holder 14 and heated and held, and then the remaining aniline 5 is added to the reaction solution discharged from the holder 14 in a lump. And introduced into the isomerization reactor 15 to carry out the isomerization reaction ((C) isomerization step, see FIG. 1).
The heating and holding conditions and the isomerization reaction conditions are the same as those in the first embodiment.

In each of the embodiments described above, the first and second mixers 10 and 12 (A to C) are used, but these are not used, and the raw materials and reaction liquids are directly used in the first and second reactions. It may be introduced into the vessel. Moreover, as each mixer 10 and 12 (A-C), what provided the mixer in the liquid feeding tube 16 was used, However, It is not restricted to this, Conventionally well-known various mixing means can be used suitably. .
Moreover, although the reaction liquid after (B) 2nd condensation process was heat-held using the holder | retainer 14, you may heat-hold in a 2nd reactor without using a holder | retainer, and heat-hold The isomerization reaction may be carried out by directly introducing the reaction solution and the remaining aniline into the isomerization reactor without performing the step.

Furthermore, although the remaining aniline 5 was added and mixed with the reaction solution before the isomerization reactor 15, it can be added and mixed before the cage or added and mixed in the cage.
Moreover, although the tank-type thing was used as each reactor 11 and 13 (A-C) and the tower-type thing was used as the isomerization reactor 15, other types of reactors as already stated should be used. You can also.
In addition, specific conditions such as the number of divisions of formaldehyde (number of second reactors) and the amount of division, and the temperature and time of the condensation reaction, retention, and isomerization reaction may be appropriately changed as long as the present invention can be implemented. it can.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.
In addition, below, the methylene diphenyldiamine content rate and the N-methyl body content rate were measured with the following method.
[1] Methylenediphenyldiamine content rate Measured by gel permeation chromatography. The measuring apparatus and conditions are as follows.
Device: CCP & 8020 (manufactured by Tosoh Corporation)
Detector: RI (differential refractive index detector)
Column: G3000HXL, G2500HXL, G2000HXL (all manufactured by Tosoh Corporation)
Solvent: tetrahydrofuran (THF)
Measurement temperature: 40 ° C
Sample: Used after diluting to 0.5% by mass with THF [2] Content of N-methyl compound Measured by gas chromatography. The measuring apparatus and conditions are as follows.
Apparatus: HP 6890 (manufactured by Hewlett Packard)
Detector: FID (hydrogen flame ionization detector)
Column: Ultra ALLOY 17 (manufactured by Frontier Laboratories)
Sample: Diluted to 5% by mass with dichloroethane

[Example 1]
Polymethylene polyphenyl polyamine was obtained using the continuous production apparatus 1A shown in FIG. At this time, the charged molar ratio was aniline / formaldehyde / HCl = 2.3 / 1.0 / 1.95.
Specifically, 37% formalin 2A in an amount corresponding to 50% by mass of the total formaldehyde is supplied at 0.393 kg / h (HCHO: 0.145 kg / h, water: 0.248 kg / h). An amount of aniline hydrochloride aqueous solution 3A corresponding to 87.8% by mass of the charged amount (2.05 times the molar amount with respect to the total formaldehyde, hydrogen chloride / aniline (molar ratio): about 0.95) is 4.988 kg / h (aniline: 1.848 kg / h, HCl: 0.689 kg / h, water: 2.451 kg / h) and mixed in the first mixer 10. Thereafter, the mixed solution was introduced into the first reactor 11 and allowed to react for 10 minutes while maintaining 35 ° C. by flowing cooling water at 10 ° C. through a jacket covering the first reactor 11 ((A ) First condensation step). The first mixer 10 is provided with a static mixer (model number 140-616, manufactured by Nippon Flow Control Co., Ltd.) in the liquid feeding tube 16 so that the calculated flow rate with the elements ignored is about 10 cm / sec. Set.

To the reaction solution obtained by this reaction, the remaining formalin 4 is added at a rate of 0.393 kg / h before the second mixer 12, and then these are mixed in the second mixer 12. It was introduced into the second reactor 13. The configuration of the second mixer 12 was the same as that of the first mixer 10. In this second reactor 13, the reaction was carried out for 10 minutes while maintaining the temperature at 35 ° C. in the same manner as described above ((B) second condensation step), and then the resulting reaction solution was Furthermore, it introduce | transduced into the holder | retainer 14, and hold | maintained at 65 degreeC and residence time 20 minutes. To this reaction liquid, the remaining aniline 5 (0.25 molar amount relative to the total formaldehyde) is introduced at 0.226 kg / h before the isomerization reactor 15 at 95 ° C. and a residence time of 30 minutes. It was made to react ((C) isomerization process). The flow rate of the condensate after the isomerization step was 6.0 kg / h.
6 kg of the condensate obtained in 1 hour was neutralized with excess caustic soda and washed with water to obtain a crude polymethylene polyphenyl polyamine containing unreacted aniline. Further, the crude polymethylene polyphenyl polyamine was subjected to steam distillation to remove aniline to obtain 1.76 kg of pure polymethylene polyphenyl polyamine. This polymethylene polyphenyl polyamine had a methylenediphenyldiamine content of 73.0% by mass and an N-methyl compound content of 0.33% by mass.

[Comparative Example 1]
A 10 L flask was charged with 53 mass% aniline hydrochloride aqueous solution (5.214 kg) (aniline: 2.074 kg, HCl: 0.689 kg, water: 2.452 kg) and stirred at 50-55 ° C. for 45 minutes. Then, 0.786 kg of 37% formalin was added dropwise. Thereafter, the temperature of the reaction solution was raised to 95 ° C. and stirred at this temperature for 30 minutes to obtain a condensation solution. The molar ratio charged was aniline / formaldehyde / HCl = 2.3 / 1.0 / 1.95.
The obtained condensate was purified in the same manner as in Example 1 to obtain 1.74 kg of pure polymethylene polyphenyl polyamine. This polymethylene polyphenyl polyamine had a methylenediphenyldiamine content of 71.7% by mass and an N-methyl compound content of 0.38% by mass.

[Comparative Example 2]
3 includes a first mixer 10, a first reactor 11, a retainer 14, and an isomerization reactor 15, which are connected in series by a liquid feeding tube 16 for a reaction solution or the like. A polymethylene polyphenyl polyamine was obtained using the constructed general continuous production apparatus 1C. At this time, the charged molar ratio was aniline / formaldehyde / HCl = 2.3 / 1.0 / 1.95.
Specifically, 37% formalin 2B is supplied at a total amount of 0.786 kg / h (HCHO: 0.291 kg / h, water: 0.495 kg / h), and an aniline hydrochloride aqueous solution is supplied to 5.214 kg / h (aniline). : 2.074 kg / h, HCl: 0.689 kg / h, water: 2.451 kg / h), and the mixture is mixed in the first mixer 10, and then this mixture is introduced into the first reactor 11. Then, these were reacted in a residence time of 10 minutes while maintaining 35 ° C. in the same manner as in Example 1.
The reaction solution obtained by this reaction is further introduced into the cage 14 and held at 65 ° C. and a residence time of 20 minutes, and then introduced into the isomerization reactor 15 and reacted at 95 ° C. and a residence time of 30 minutes. I let you. The flow rate of the condensate after the isomerization reaction was 6.0 kg / h.
6 kg of the condensed liquid obtained in 1 hour was purified in the same manner as in Example 1 to obtain 1.68 kg of pure polymethylene polyphenyl polyamine. This polymethylene polyphenyl polyamine had a methylenediphenyldiamine content of 71.2% by mass and an N-methyl compound content of 0.57% by mass.

[Comparative Example 3]
The aniline was divided and 4.988 kg / h (aniline: 1.848 kg / h, HCl: 0.689 kg / h, water: 2) containing 2.05-fold molar amount of aniline with respect to formaldehyde first. .451 kg / h), and then the remaining 0.25-fold molar amount of aniline was supplied at 0.226 kg / h before the cage 14 in the same manner as in Example 1 as in Comparative Example 2. Thus, 1.73 kg of polymethylene polyphenyl polyamine was obtained. At this time, the charged molar ratio was aniline / formaldehyde / HCl = 2.3 / 1.0 / 1.95. This polymethylene polyphenyl polyamine had a methylenediphenyldiamine content of 72.2% by mass and an N-methyl compound content of 0.41% by mass.

[Comparative Example 4]
All aniline was initially fed as an aniline hydrochloride aqueous solution at 5.214 kg / h (aniline: 2.074 kg / h, HCl: 0.689 kg / h, water: 2.451 kg / h) (ie, residual aniline 5 Except for the above, the polymethylene polyphenyl polyamine 1.74 kg was obtained in the same manner as in Example 1 (the charged molar ratio was aniline / formaldehyde / HCl = 2.3 / 1.0 / 1.95). This polymethylene polyphenyl polyamine had a methylenediphenyldiamine content of 72.0% by mass and an N-methyl compound content of 0.43% by mass.

[Comparative Example 5]
Using the continuous production apparatus 1B shown in FIG. 2, all aniline is first converted into an aniline hydrochloride aqueous solution at 5.214 kg / h (aniline: 2.074 kg / h, HCl: 0.689 kg / h, water: 2. 451 kg / h) (that is, the remaining aniline 5 is not used), and formalin is equally divided into four parts and charged at 0.1965 kg / h in front of each mixer 10, 12A-C, 1.76 kg of polymethylene polyphenylpolyamine was obtained in the same manner as in Example 1 except that the reaction was performed at 35 ° C. for 10 minutes in the reactors 11, 13A to C. At this time, the charged molar ratio was aniline / formaldehyde / HCl = 2.3 / 1.0 / 1.95. This polymethylene polyphenyl polyamine had a methylenediphenyldiamine content of 72.3% by mass and an N-methyl content of 0.41% by mass.
A summary of Example 1 and Comparative Examples 1-5 is shown in Table 1.

  As shown in Table 1, the polymethylene polyphenyl polyamine obtained by the method of Example 1 using both aniline splitting and formaldehyde splitting is a general continuous formula (Comparative Example 2), a continuous formula in which only aniline is split. (Comparative Example 3) It can be seen that the methylenediphenyldiamine content is higher and the N-methyl content is lower than the continuous type (Comparative Examples 4 and 5) in which only formalin is divided. Moreover, even if it compares with the polymethylene polyphenyl polyamine obtained by the batch type (comparative example 1), it turns out that quality is favorable.

[Example 2, Comparative Examples 6 to 10]
The polymethylene polyphenyl polyamine obtained in Example 1 (Example 2) and Comparative Examples 1 to 5 (Comparative Examples 6 to 10) was made into a 6% by mass solution of monochlorobenzene, and then this solution was subjected to normal pressure. Then, cold reaction was carried out at 40 ° C. for 1 hour while adding liquefied phosgene dropwise. Subsequently, the temperature was raised to 95 ° C. and a hot reaction was carried out for 2 hours. Then, nitrogen was bubbled at 120 ° C. to remove excess phosgene, and monochlorobenzene was further removed at 170 ° C. under normal pressure. Thereafter, the mixture was heated at 215 ° C. for 30 minutes under a reduced pressure of 30 kPa to obtain crude polymethylene polyphenyl polyisocyanate. The crude polymethylene polyphenyl polyisocyanate was measured and evaluated for NCO content, acidity, hydrolyzable chlorine, and color number. The results are shown in Table 2.
The NCO content and acidity were measured according to JIS K1603 method, hydrolyzable chlorine was measured according to JIS K1556 method, and the color number was evaluated as the Hazen unit color number when diluted 100-fold with methyl ethyl ketone (MEK).

  As shown in Table 2, the polymethylene polyphenyl polyisocyanate using the polymethylene polyphenyl polyamine obtained in Example 1 as a raw material has low acidity, hydrolyzable chlorine, color number, and good quality. I understand.

It is a schematic block diagram of the continuous production apparatus used for the continuous production method of the polymethylene polyphenyl polyamine which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the part which performs the 2nd condensation process of the continuous production apparatus used for the continuous production method of the polymethylene polyphenyl polyamine which concerns on 2nd Embodiment of this invention. It is a schematic block diagram of the general continuous production apparatus used by the comparative example 2.

Explanation of symbols

1A, B Polymethylene polyphenyl polyamine continuous production equipment 2A formalin (part of formaldehyde)
3A Aniline hydrochloride aqueous solution (80 to 95% by mass of the total charged amount of aniline)
4 Formalin (residual amount of formaldehyde)
5 Aniline (5-20% by mass of the total charge of aniline)
11 First reactor (first condensation step)
13 Second reactor (second condensation step)
14 Cage 15 Isomerization reactor (isomerization process)

Claims (11)

A process for continuously producing polymethylene polyphenyl polyamines by continuously reacting aniline with formaldehyde in the presence of a hydrochloric acid catalyst to produce polymethylene polyphenyl polyamines,
(A) Reaction of 80 to 95% by mass of the total charge of the aniline and a part of the total charge of formaldehyde in the presence of the hydrochloric acid catalyst with hydrogen chloride / aniline (molar ratio) of 0.99 or less. A first condensation step,
(B) a second condensation step in which the reaction solution obtained in the first condensation step and the residual amount of formaldehyde are mixed and reacted; and (C) a reaction solution obtained in the second condensation step; An isomerization step in which 5 to 20% by mass of the total charged amount of aniline is mixed and subjected to an isomerization reaction;
Equipped with a,
A continuous production method of polymethylene polyphenyl polyamine, wherein the reactions of (A) the first condensation step and (B) the second condensation step are both carried out at 20 to 50 ° C.   The continuous production method of polymethylene polyphenyl polyamine according to claim 1, wherein, in the (B) second condensation step, the remaining amount of the formaldehyde is divided into a plurality of arbitrary amounts and mixed. In the (C) isomerization step, the reaction solution obtained in the (B) second condensation step is heated to 50 to 80 ° C. and held at this temperature for a predetermined time. The continuous production method of polymethylene polyphenyl polyamine according to claim 1 or 2 , wherein 5 to 20% by mass of the charged amount is mixed and further heated to a temperature higher than the holding temperature . In the (C) isomerization step, a mixed solution obtained by mixing the reaction solution obtained in the (B) second condensation step and 5 to 20% by mass of the total charged amount of the aniline is heated to 50 to 80 ° C. and, this after holding for a predetermined time at a temperature, and et to claim 1 or 2 continuous production method of the polymethylene polyphenyl polyamines according to a temperature higher than the holding temperature. (A) 80 to 95% by mass of the total charge of the aniline and a part of the total charge of the formaldehyde are introduced into the first reactor, and hydrogen chloride / aniline (molar ratio) is added in the presence of the hydrochloric acid catalyst. A first condensation step in which the reaction is performed at 20 to 50 ° C. with 0.99 or less,
(B) a second condensation step in which the reaction solution obtained in the first condensation step and the remaining amount of formaldehyde are introduced into a second reactor and reacted at 20 to 50 ° C., and
(C1) The reaction solution obtained in the second condensation step is introduced into a cage and heated to 50 to 80 ° C. and held at this temperature for a predetermined time, and then the heated and held reaction solution and all of the aniline are mixed. An isomerization step in which 5 to 20% by mass of the charged amount is mixed and heated to 90 ° C. or more to cause an isomerization reaction, or
(C2) The reaction solution obtained in the second condensation step and 5 to 20% by mass of the total charged amount of aniline were introduced into a cage and heated to 50 to 80 ° C. and held at this temperature for a predetermined time. Then, an isomerization step in which these are heated to 90 ° C. or higher to cause an isomerization reaction,
Continuous production process of polymethylene polyphenyl polyamines according to claim 1, wherein you comprising: a. (B) the second at 2 condensation step, continuous production method of the polymethylene polyphenyl polyamines according to claim 5, wherein the Ru used collectively the total amount of residual amount of the formaldehyde. That holds at 50-70 ° C. 1 to 30 minutes according to claim 3-6 continuous production method of the polymethylene polyphenyl polyamines according to any one of. Wherein (A) in a first condensation step, hydrogen chloride / aniline (mole ratio), continuous polymethylene polyphenyl polyamines according to any one of 0.90 to 0.98 Der Ru claim 1-7 Production method. The continuous production method of polymethylene polyphenyl polyamine according to any one of claims 1 to 8 , wherein a molar ratio of the total amount of aniline to the total amount of formaldehyde is 1.5 to 4 . Wherein (A) in a first condensation step, continuous production method of the polymethylene polyphenyl polyamines according to any one of claims 1 to 9 Ru by reacting 20 to 60% by weight of the total charged amount of the formaldehyde. The continuous production method of polymethylene polyphenyl polyamine according to claim 10 , wherein 50 mass% of the total amount of formaldehyde is reacted in the (A) first condensation step.

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