JP2000239379A - Production of polysuccinimide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain polysuccinimide having high weight-average molecular weight and a specific molecular weight distribution by solid phase polymerization of a pulverized mixture of polysuccinimide and an acid catalyst. SOLUTION: This polysuccinimide is obtained by solid phase polymerization of a pulverized mixture of polysuccinimide and an acid catalyst pref. in an inert gas atmosphere at 120-350 deg.C; wherein the particle size distribution of the pulverized mixture is pref. such that the volume-average diameter is 1-500 μm. The polysuccinimide thus obtained pref. satisfies the following relationships simultaneously: 3×103<=Mw1<=2×105, 8×104<=Mw<=1×106, and Mw1<Mw2 (Mw1 is the weight-average molecular weight of the polysuccinimide before solid phase polymerization; Mw2 is the weight-average molecular weight of the polysuccinimide after solid phase polymerization), and furthermore, it is preferable that the molecular weight distribution of the polysuccinimide before solid phase polymerization satisfy the relationship: 1<=Mw1/Mn1<=4 (Mn1 is the number-average molecular weight of the polysuccinimide before solid phase polymerization).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing polysuccinimide. Further, the present invention relates to a method for producing polysuccinimide in which aspartic acid is polymerized using an acidic catalyst.

[0002]

BACKGROUND OF THE INVENTION Polysuccinimide is a suitable precursor or intermediate in the production of polyamino acid derivatives such as polyaspartic acid. Polyamino acid derivatives such as polysuccinimide and polyaspartic acid are known to have biodegradability and are useful as environmentally compatible polymers. Further, crosslinked polyaspartate, which is a derivative of polysuccinimide, is a very useful polymer having water absorption as well as biodegradability.

Techniques for producing polysuccinimides and polyamino acids by reacting amino acids in the presence of an acidic catalyst include the following techniques.

[0004] P. The method of Neri et al. (Journa
l of Medicinal Chemistry,
1973, Vol. 16, No. 8) Neri et al. Report the result of heating and polymerizing a reaction mixture obtained by reacting aspartic acid and phosphoric acid in a thin layer. By this method, in a vacuum system, the degree of polymerization n = 1100 to 1600 (molecular weight 10.7 to
(Equivalent to 150,000). However, in the normal pressure system, although the heating is performed as a thin layer as described above, the degree of polymerization n
= 380 to 900 (corresponding to a molecular weight of 3.7 to 87,000), and the molecular weight is lower than that of a polymerization operation in a vacuum system.

[0005] The method of heating as a thin layer carried out by Neri et al. Is, specifically, 100 g of aspartic acid.
And 50 g of phosphoric acid, and heating the paste-like reaction mixture on a Teflon-coated tray having an area of 1000 cm ² .

A reaction method requiring such a large apparatus area as compared with the reaction mixture throughput makes it extremely difficult to design the apparatus when performing continuous and large-scale production.
There is no disclosure about the molecular weight distribution of the obtained polysuccinimide.

US Pat. No. 5,142,062 As a first step, a mixture of aspartic acid and phosphoric acid is reacted at a temperature of 100 to 250 ° C. and a pressure of less than 1 bar, containing a polysuccinimide having a molecular weight of 10,000 to 100,000. A solid reaction mixture is prepared, and as a second step, the solid reaction mixture obtained in the first step is pulverized to a particle size of 0.001 to 2 mm, and further, under conditions selected from the temperature and pressure range of the first step. A technique for producing a high-molecular-weight polysuccinimide having a molecular weight of 100,000 to 200,000 by performing polycondensation is disclosed. However, there is no disclosure about the particle size distribution of the solid reaction mixture obtained in the first step.

In this technique, a high-molecular-weight polysuccinimide can be obtained in the same manner as described above, but all require a reaction operation in a vacuum system. In all of the reaction examples disclosed in the examples, a vacuum-based reaction operation is performed. In particular, in a solid-state polymerization operation, an operation under a high vacuum (1 mbar) is required. There is no disclosure about the molecular weight distribution of the obtained polysuccinimide.

JP-A-7-216084 (US Pat. No. 5,457,176) discloses a method for producing an amino acid polymer by heating a mixture of an amino acid and an acidic catalyst. Column 4 (33 ~
It is one of the objectives of this technology to produce an amino acid polymer having a maximum weight average molecular weight of 60,000 or less.
It is clear that it is one.

Example 3 contains 800 g of aspartic acid.
(6.01 mol), a reaction mixture of a wet sticky white powder obtained by mixing 200 g of 85% orthophosphoric acid (1.73 mol of phosphoric acid) was heated in a stainless steel pan and heated as a layer. ing. Example 3 discloses that the reaction mixture of the wet sticky powder was transformed into a solid mass with a hard outer and sticky center by heating at 240 ° C. for 1 hour. For solid masses,
After crushing using a mortar and pestle, further 240 ° C, 6 hours,
By heating, a polysuccinimide having Mw of 155,000 was obtained. Here, there is no disclosure about the particle size after grinding.

The maximum value of the weight average molecular weight of the polysuccinimide disclosed in the Examples is a low molecular weight polymer of 24,000, which is consistent with the purpose of producing an amino acid polymer having a molecular weight of 60,000 or less.

JP-A-8-231710 (US Pat. No. 5,688,903) This technique uses 0.005 to 0.005 amino acids per amino acid molecule.
It is characterized in that a fine powdery raw material (a mixture of an amino acid and a catalyst) in which 0.25 mol of a catalyst is uniformly dispersed is produced, and a polycondensation operation is performed. In Examples, a vacuum system, and a reaction example in a normal pressure system are disclosed, and a reaction in which a raw material obtained by uniformly mixing aspartic acid and phosphoric acid is pulverized by a pulverizer into a fine powdery raw material is described. It has been implemented.

When the amount of phosphoric acid, phosphorus pentoxide or polyphosphoric acid used is within the above range and the reaction is carried out using fine powdery raw materials, problems such as the formation of a foam phase in the polymerization process and the formation of aggregates after the polymerization are solved. Solved. However, when the viscosity index value obtained by evaluating polysuccinimide as a dimethylformamide solution was converted into a molecular weight, Example 4 was about 19,000, Example 8 was about 28,000, and the obtained polysuccinimide had a molecular weight of about 28,000. It is limited to those having a low molecular weight of less than 30,000, which is not sufficient as a method for producing a high molecular weight polysuccinimide. There is no disclosure about the molecular weight distribution of the obtained polysuccinimide.

In the above prior arts, in the polymerization of aspartic acid using an acidic catalyst, a vacuum system and / or a normal pressure system reaction is carried out.

However, conditions for obtaining a high-molecular-weight polysuccinimide having a weight-average molecular weight of 80,000 or more have been substantially limited to only a solid-state polymerization operation performed in a vacuum system.

On the other hand, in the normal-pressure solid-phase polymerization operation,
The method for obtaining a polysuccinimide having a weight-average molecular weight of 30,000 or more is limited to the above-described reaction method requiring a very large apparatus area, and when a continuous and large-scale production is to be performed, Equipment design is difficult.

In the prior art, there is no disclosure regarding a method for producing a high molecular weight polysuccinimide having a weight average molecular weight of 80,000 or more and having a limited molecular weight distribution.

[0018]

One of the problems to be solved by the present invention is to provide a polysuccinimide having a high weight average molecular weight by solid phase polymerization.

One of the problems to be solved by the present invention is as follows.
An object of the present invention is to provide a polysuccinimide having a high weight average molecular weight and a limited molecular weight distribution by solid phase polymerization.

One of the problems to be solved by the present invention is as follows.
An object of the present invention is to provide a technique for solid-state polymerization of polysuccinimide by a simpler apparatus.

One of the problems to be solved by the present invention is as follows.
An object of the present invention is to provide a technique for solid-state polymerization of polysuccinimide which is suitable for continuous and mass production without requiring an expensive and complicated vacuum-type solid-state polymerization apparatus.

[0022]

Means for Solving the Problems In view of the above-mentioned problems of the prior art, the present inventors have conducted intensive studies on a method for producing a high-molecular-weight polysuccinimide, and have found that a mixture comprising a polysuccinimide and an acidic catalyst is obtained. It has been found that a high-molecular-weight polysuccinimide having a weight-average molecular weight of 80,000 or more can be produced by solid-phase polymerization of a powder obtained by pulverizing into a fine powder, and the present invention has been completed.

The present invention is specified by the following items [1] to [19]. In addition, the solid-phase polymerization method of polysuccinimide is an expression having a meaning including the method of producing polysuccinimide.

[1] A method for solid-state polymerization of polysuccinimide, which comprises solid-phase polymerization of a powder obtained by pulverizing a mixture containing polysuccinimide and an acidic catalyst.

[2] The method for solid-state polymerization of polysuccinimide according to [1], wherein the powder has a particle size distribution having a volume average diameter of 1 to 500 μm.

[3] The method for solid-state polymerization of polysuccinimide according to [1] or [2], wherein the solid-state polymerization is performed in an inert gas atmosphere.

[4] The method for solid-state polymerization of polysuccinimide according to any one of [1] to [3], wherein the solid-state polymerization is performed at 120 to 350 ° C.

[5] When the weight average molecular weight of the polysuccinimide before the solid phase polymerization is Mw1 and the weight average molecular weight of the polysuccinimide after the solid phase polymerization is Mw2, the weight average molecular weights Mw1 and Mw2 are: , Formula (1)
The method for solid-state polymerization of polysuccinimide according to any one of [1] to [4], which simultaneously satisfies the following expressions (3) to (3). 3 × 10 ³ ≦ Mw1 ≦ 2 × 10 ⁵ (1) 8 × 10 ⁴ ≦ Mw2 ≦ 1 × 10 ⁶ (2) Mw1 <Mw2 (3).

[6] When the weight average molecular weight of the polysuccinimide before solid phase polymerization is Mw1 and the number average molecular weight is Mn1, the molecular weight distribution Mw1 / Mn1 of the polysuccinimide before solid phase polymerization is represented by the following equation (4). [5] The method for solid-state polymerization of polysuccinimide according to [5]. 1 ≦ Mw1 / Mn1 ≦ 4 (4).

[7] When the weight average molecular weight of the polysuccinimide after the solid phase polymerization is Mw2 and the number average molecular weight is Mn2, the molecular weight distribution M of the polysuccinimide after the solid phase polymerization is M
The solid-state polymerization method of polysuccinimide according to [5] or [6], wherein w2 / Mn2 satisfies Expression (5). 1 ≦ Mw2 / Mn2 ≦ 4 (5).

[8] The weight average molecular weight of the polysuccinimide before solid phase polymerization is Mw1, the number average molecular weight is Mn1, and the weight average molecular weight of the polysuccinimide after solid phase polymerization is M
w2, the number average molecular weight Mn2, the molecular weight distribution Mw1 / Mn1 of the polysuccinimide before solid phase polymerization and the molecular weight distribution Mw2 / M of the polysuccinimide after solid phase polymerization
The solid-state polymerization method for polysuccinimide according to any one of [5] to [7], wherein n2 satisfies Expression (6). 1 ≦ Mw1 / Mn1 ≦ Mw2 / Mn2 ≦ 4 (6).

[9] In step 1 (a step of producing a solid reaction mixture), aspartic acid and an acidic catalyst are mixed,
A step of producing a solid reaction mixture containing a polysuccinimide having a weight average molecular weight Mw1 represented by Formula (1) and obtained by heating at 40 to 350 ° C., Step 2
(Pulverizing step), a step of pulverizing and / or classifying the solid reaction mixture obtained in Step 1 (solid reaction mixture producing step) to produce a fine powdery reaction mixture, Step 3 (solid phase polymerization step) A method for producing a polysuccinimide by the solid-state polymerization method according to any one of [1] to [8]. .

[10] In the step 1 (the step of producing a solid reaction mixture), aspartic acid and an acidic catalyst are mixed under a pressure of 0.1 MPa or more and 50 MPa or less,
[9] characterized by a step of producing a solid reaction mixture containing a polysuccinimide having a weight average molecular weight Mw1 represented by Formula (1) obtained by heating at 40 to 350 ° C. The method for producing a polysuccinimide described in 1 above.

[11] In the step 1 (the step of producing a solid reaction mixture), aspartic acid and an acidic catalyst are mixed under a pressure of not less than 0.00001 MPa and less than 0.1 MPa. The process according to [9] or [10], which is a step of producing a solid reaction mixture containing a polysuccinimide having a weight average molecular weight Mw1 represented by Formula (1) and obtained by heating. A method for producing a polysuccinimide.

[12] In the step 3 (solid phase polymerization step), the fine powdery reaction mixture obtained in the step 2 (pulverization step) is heated to 120 to 350 ° C. in an inert gas having a pressure of 0.1 MPa or more and 50 MPa or less. By performing solid state polymerization at
The method for producing a polysuccinimide according to any one of [9] to [11], which is a step of producing a polysuccinimide having a weight average molecular weight Mw2 represented by Formula (2).

[13] In the step 3 (solid-state polymerization step), the fine powdery reaction mixture obtained in the step 2 (pulverization step) is mixed with 0.1.
A step of producing a polysuccinimide having a weight average molecular weight Mw2 represented by Formula (2) by performing solid-state polymerization at 120 to 350 ° C under a pressure of 00001 MPa or more and less than 0.1 MPa. The method for producing a polysuccinimide according to any one of [9] to [12].

[14] The method according to any one of [1] to [13], wherein the amount of the acidic catalyst used is in the range of 0.01 to 1.0 mol per mol of aspartic acid as a raw material. A method for producing a polysuccinimide.

[15] The method for producing polysuccinimide according to [14], wherein the acidic catalyst contains a phosphorus oxyacid.

[16] The phosphorus oxyacid is orthophosphoric acid,
The method for producing polysuccinimide according to [15], wherein the method is at least one selected from the group consisting of pyrophosphoric acid, polyphosphoric acid, and phosphorus pentoxide.

[17] A polysuccinimide obtained by the production method according to any one of [1] to [16].

[18] Polyaspartic acid (salt) obtained by hydrolyzing the polysuccinimide obtained in [17].

[19] A water-absorbing polymer obtained by performing an operation including a crosslinking reaction and a hydrolysis reaction on the polysuccinimide obtained in [17].

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

[Aspartic acid] The aspartic acid used in the present invention may be any of L-form, D-form and DL-form.

[Acid Catalyst] The acidic catalyst used in the present invention is not particularly limited, but for example, phosphoric acid is preferred. Specific examples of the phosphorus oxygen acids include, for example, orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, and
Phosphorus pentoxide and the like, and it is preferable to use at least one selected from the group consisting of these.

The acidic catalyst may be diluted with a solvent (a polar solvent such as water or alcohol), but is usually preferably at least 10% by weight, more preferably at least 50% by weight.
It is particularly preferred to use an acidic catalyst concentration of at least 70% by weight, most preferably at least 85% by weight. If the concentration of the acidic catalyst is too low, generally the amount of solvent that must be removed during the course of the polymerization operation increases, resulting in additional energy use. Conversely, even if the acidic catalyst concentration is too high,
In general, the effect is not largely changed, but costs related to the acidic catalyst (energy required for concentration of the acidic catalyst, etc.) are increased.

The amount of the acidic catalyst used is preferably 0.001 to 1.5 mol, more preferably 0.01 to 1.0 mol, and further preferably 0.1 to 1 mol per mol of aspartic acid as a raw material. ~ 0.9, particularly preferably 0.4 ~
It is in the range of 0.8 mol. If the amount of the acidic catalyst is too small, the weight average molecular weight of the resulting polysuccinimide usually becomes small. Conversely, the use of excess acid catalyst is generally uneconomical.

[Polysuccinimide] The structure of the polysuccinimide obtained according to the method of the present invention may be a linear structure or a branched structure.

[Inert gas] The inert gas used in the present invention is not particularly limited. A gas that does not adversely affect the reaction is preferable. Specifically, for example, nitrogen, carbon dioxide, argon, or the like is used. The inert gas is 1
Different kinds of gases may be used, or plural kinds of gases may be mixed and used.

Since the inert gas can also be used as a heat transfer medium, it is easy to efficiently and uniformly heat the reaction mixture even when continuous and large-scale production is carried out, and the quality (for example, weight average molecular weight) Etc.) can be produced.

It is preferable that the inert gas is usually reused after a regeneration treatment. The regeneration treatment is generally performed to reduce the concentration of moisture and / or impurities (such as reaction by-products) contained in the inert gas.

As a specific operation, usually, at least one operation selected from an adsorption operation, an absorption operation, a cooling operation, a heating operation, a dust collection operation and the like is performed to reduce the concentration of moisture and / or impurities. Is preferred. Here, in the adsorption operation, zeolites, hydrophilic cross-linked resins (for example, ion-exchange resins, etc.) and the like can be used as the adsorbent.

When an inert gas is used, if the water concentration in the inert gas is high, the weight average molecular weight of the resulting polysuccinimide may usually be low. Conversely, when the water concentration is 0%, there is no effect on the polymer, but in general, it is necessary to consider that the cost related to the inert gas regeneration treatment does not become excessive.

As another criterion for the water concentration, the dew point of the inert gas can be used. In the present invention, the dew point of the inert gas is preferably −20 ° C. or lower, more preferably −30 ° C. or lower, still more preferably −40 ° C. or lower, particularly preferably −50 ° C. or lower, and most preferably
It is preferably −60 ° C. or lower.

If the impurity concentration is high,
Coloring or modification of the polysuccinimide may occur. Conversely, when the impurity concentration is 0%, there is no effect on the polymer, but in general, it is necessary to consider that the cost related to the inert gas regeneration treatment does not become excessive.

[Step of Producing Solid Reaction Mixture] Mixing of Aspartic Acid and Acid Catalyst In the step of producing a solid reaction mixture, the mixing operation of aspartic acid and the acidic catalyst can be carried out directly or by mixing the solvent (water, alcohol, etc.). (Polar solvent).

The temperature at which the mixing operation is performed is preferably 5 to
350 ° C, more preferably 20 to 250 ° C, further preferably 40 to 200 ° C, particularly preferably 60 to 1
50 ° C, most preferably in the range of 80 to 120 ° C. If the temperature is too low, the viscosity is usually high when the concentration of the acidic catalyst is high, and it takes time to obtain a good mixed state. Conversely, if the temperature is too high, the polymerization starts in a heterogeneous state before the acidic catalyst and aspartic acid are sufficiently mixed, and a heterogeneous solid mixture is formed. It causes the formation of acid imide.

The pressure at which the mixing operation is performed is appropriately selected.
At a temperature at which the mixing operation is performed, the pressure is set so that the mixing operation can be performed efficiently. The pressure is preferably between 0.00001 and 5
The pressure is 0 MPa, more preferably 0.0001 to 5 MPa, and still more preferably 0.001 to 0.5 MPa. If the pressure is too low, sufficient mixing may be difficult in the mixing process. If the pressure is too high, a device with high pressure resistance is usually required, and it is difficult to design the device for mass production.

The time for performing the mixing operation is not particularly limited, but is preferably 1 second to 20 hours, more preferably
5 seconds to 8 hours, more preferably 10 seconds to 3 hours, particularly preferably 30 seconds to 2 hours, and most preferably 1 minute to
60 minutes. By setting the mixing operation time to an appropriate time, a mixture having good uniformity can be obtained, and coloring and denaturation can be prevented.

The mixing operation is preferably carried out under the condition where the oxygen concentration in the system is reduced or under the condition where the oxygen concentration is 0%, and is preferably carried out in the above-mentioned inert gas.

In the mixing operation, the reaction of aspartic acid starts simultaneously with the mixing with the acidic catalyst, and water derived from aspartic acid may be generated in the system. It is also preferable to perform the operation of mixing the acidic catalyst and aspartic acid more efficiently by using the generated water.

Production of Solid Reaction Mixture In the solid reaction mixture production step, the raw material mixture mainly composed of aspartic acid and acidic catalyst obtained by the above-mentioned method is further heated to produce a solid reaction mixture.
The raw material mixture shows various properties such as liquid, slurry, and paste, depending on reaction conditions such as the amount of the acidic catalyst and the heating temperature, and then changes to a solid.

The heating of the raw material mixture is preferably carried out at 40 to
It is carried out at 350 ° C, more preferably at 80 to 300 ° C, and still more preferably at 100 to 200 ° C. If the temperature is too low, usually the time required to produce the solid reaction mixture is lengthened, requiring large equipment. If the temperature is too high, the resulting solid reaction mixture is usually colored, denatured,
Or, decomposition occurs.

In the present invention, the pressure is not particularly limited. At the heating temperature, the pressure is set so that the moisture in the system can be efficiently reduced. The pressure is preferably from 0.000001 to
50 MPa, more preferably 0.0001 to 5 MPa,
More preferably, it is 0.001 to 0.5 MPa. When the pressure is too low, in the process of producing a solid-state reaction mixture, volumetric efficiency may decrease due to remarkable foaming when water evaporates. If the pressure is too high,
A high pressure reactor is required, and when mass production is performed, the design of the apparatus becomes difficult.

The time for heating the raw material mixture is not particularly limited, but is preferably 1 second to 20 hours, more preferably 10 seconds to 8 hours, and more preferably 1 minute to 1 hour.
5 hours, particularly preferably 10 minutes to 3 hours, most preferably 30 minutes to 2 hours. By setting the heating time to an appropriate time, a solid reaction mixture free from significant coloring and denaturation can be obtained.

In order to prevent the reaction product from being colored or denatured, the heating is usually carried out under the condition where the oxygen concentration in the system is reduced or under the condition where the oxygen concentration is 0%. It is preferable to carry out in the above-mentioned inert gas.

The preparation of the solid reaction mixture can be carried out continuously,
Any of batch operations may be used. The apparatus for producing the solid reaction mixture is not particularly limited. Any device can be used as long as it can perform the mixing operation and the heating operation of the raw materials as described above. Further, the mixing process of the raw materials and the heating process may be performed separately in two or more devices. Specifically, any device such as a stirring tank, a dryer with a crushing / crushing mechanism, a dryer with a planetary motion stirring device, a stirring dryer, a single-shaft or twin-shaft kneader can be used.

The apparatus and method used in the solid-state reaction mixture process of the present invention are described in “Revised Sixth Edition Chemical Engineering Handbook” (editor: Japan Society for Chemical Engineering, published by Maruzen Co., Ltd., 1999). "14 Humidity control, water cooling, drying"
(Pp. 735-788), “7 Stirring” (421-454)
Page 6) and “6 Heat transfer / evaporation” (pages 343 to 420).

Weight Average Molecular Weight of Polysuccinimide Contained in Solid Reaction Mixture In the solid reaction mixture production process, the weight average molecular weight (Mw
1) produces a solid reaction mixture containing a polysuccinimide having a weight average molecular weight represented by the above formulas (1) to (3). If the weight average molecular weight is too low, the operation in the post-process may be usually difficult. Specifically, in the solid-state polymerization step, the solid reaction mixture may cause melting and fusing. Conversely, if the weight average molecular weight is too high, a very long residence time is usually required in an apparatus for producing a solid reaction mixture, which may cause a side reaction.

In the present invention, the weight average molecular weight of the polysuccinimide contained in the solid reaction mixture is preferably in the range of the formula (7), more preferably in the range of the formula (8), particularly preferably in the range of the formula (8). (9) The operation is most preferably performed so as to fall within the range of Expression (10). 3.0 × 10 ³ ≦ Mw1 ≦ 1.5 × 10 ⁵ (7) 1.0 × 10 ⁴ ≦ Mw1 ≦ 1.0 × 10 ⁵ (8) 1.5 × 10 ⁴ ≦ Mw1 ≦ 8.0 × 10 ⁴ (9) 2.0 × 10 ⁴ ≦ Mw1 ≦ 6.0 × 10 ⁴ (10).

In the present invention, the weight average molecular weight of the polysuccinimide before solid phase polymerization is Mw1 and the number average molecular weight is Mn1 according to the preferred production method described above. In some cases, a solid reaction mixture containing polysuccinimide having a molecular weight distribution Mw1 / Mn1 of the polysuccinimide before the solid-phase polymerization satisfying the above-mentioned formula (4) can be obtained. Molecular weight distribution Mw1 /
Mn1 is closer to Mw1 / Mn1 = 1 for quality and / or
Or a derivative with good performance (for example, a water-absorbing polymer)
Can be manufactured.

In the present invention, the upper limit of the molecular weight distribution Mw1 / Mn1 is preferably 3.0 or less, more preferably 2.
A solid reaction mixture containing a polysuccinimide having a value of 5 or less, more preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.8 or less is produced.

[Pulverizing Step] In the pulverizing step, preferably,
The fine reaction mixture is produced by pulverizing and / or classifying the solid reaction mixture obtained in the solid reaction mixture production step.

As a method for grasping and / or adjusting the particle size of the fine powdery reaction mixture, for example, there is a measuring method using a standard sieve. A standard sieve can be used, for example, with a mechanical shaker and sieved dry or wet to determine the particle size distribution and to define the maximum and / or minimum particle diameter.

As another method for determining the particle size of the fine reaction mixture, there is a measuring method by a laser diffraction / scattering method. In this method, usually, the fine powdered reaction mixture is dispersed in a poor solvent for the components contained in the fine powdered reaction mixture, and the particle size distribution can be measured by a laser diffraction / scattering method. As a specific apparatus, for example, a particle size analyzer (model; 9320-X100) manufactured by Leeds & Northrup Co., Ltd. may be mentioned. In addition, this apparatus can measure the volume average diameter defined by Expression (11) using the particle volume Vi and the particle diameter di as the particle size distribution. Volume average diameter = Σ (Vi × di) / Σ (Vi) (11) Further, as another particle size distribution, assuming that the particles are spherical, the number average diameter defined by Expression (12) is measured. You can also. Number average diameter = (Σ (Vi) / di ² ) / (Σ (Vi) / di ³ ) (12).

In the present invention, the volume average diameter is preferably 1 to 500 μm, more preferably 5 to 300 μm.
m, more preferably from 10 to 200 μm, particularly preferably from 30 to 100 μm.

In the present invention, as another condition, the number average diameter is preferably 0.01 to 500 μm, more preferably 0.1 to 200 μm, and further preferably
A finely divided reaction mixture is produced which is in the range from 0.5 to 100 μm, particularly preferably from 1 to 50 μm.

When the volume average diameter and / or the number average diameter are
If it is too small, it usually becomes difficult to handle fine powder. On the contrary, when the volume average diameter and / or the number average diameter are too large, the weight average molecular weight of the polysuccinimide obtained after the solid phase polymerization step usually becomes low.

Further, assuming that the volume of the whole powder is 100%,
10 calculated when the cumulative curve of the powder volume is obtained
%, 50%, and 90% diameter can also be used as one of the parameters for evaluating the particle size distribution. In the present invention, the smaller the particle size distribution, the better. The 50% diameter is changed to 10
The value divided by the% diameter is usually preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1.5 or less. Further, the 90% diameter is reduced to the 50%
The value divided by the diameter is usually preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1.5 or less.

If the particle size distribution is excessively large, the quality (eg, weight average molecular weight, molecular weight distribution, etc.) may possibly be non-uniform.

In the present invention, the operation method and / or apparatus is not particularly limited as long as a fine powdery reaction mixture having a volume average diameter and / or a number average diameter in the above range can be obtained.
In the present invention, a pulverizing operation and / or a classification operation are preferably performed in order to produce a fine powdery reaction mixture.

The pulverization can be carried out, for example, by a continuous or batch operation using a dry and / or wet pulverizer. The classification is performed by a continuous or batch operation using, for example, a dry and / or wet classification device. Further, an apparatus having both a pulverizing mechanism and a classification mechanism may be used.

When the volume average diameter and / or the number average diameter of the fine powdery reaction mixture is smaller than the above range, the granulation operation of the self-propelled granulation system and / or the forced granulation system is performed to perform the above-mentioned granulation operation. It can also be adjusted to be inside.

[Solid State Polymerization Step] The solid state polymerization step can be performed by a continuous type and / or a batch type operation.

In the solid phase polymerization step of the present invention, the fine powdery reaction mixture produced in the pulverizing step is subjected to solid state polymerization at 120 to 350 ° C. to obtain the following equations (1), (2) and ( There is no particular limitation as long as a polysuccinimide having a weight average molecular weight Mw2 that simultaneously satisfies 3) is produced.

By subjecting the finely powdered reaction mixture obtained by the preferred production method of the present invention to solid phase polymerization, it is possible to produce a polysuccinimide having a high weight average molecular weight and a limited molecular weight distribution. it can.

Operation of Solid Phase Polymerization Step In the solid phase polymerization step, the finely powdered reaction mixture obtained in the pulverization step is heated to perform solid phase polymerization.

The solid-phase polymerization operation is usually carried out under a condition where the oxygen concentration in the system is reduced or under a condition where the oxygen concentration is 0% in order to prevent coloring and denaturation of the product. Preferably, it is carried out in the above-mentioned inert gas.

The solid-phase polymerization operation of the present invention is preferably carried out by continuously supplying an inert gas to the reaction system. The inert gas is used in contact with the solid low-molecular-weight polymer mixture in a countercurrent or cocurrent method. Heating can also be performed by using an inert gas as a heating medium and directly contacting the reactants.

The temperature at which the solid phase polymerization is carried out is preferably 12
0 to 350 ° C, more preferably 140 to 320 ° C, still more preferably 160 to 300 ° C, particularly preferably
170-280 ° C, most preferably 180-260 ° C
And If the temperature is too low, the weight average molecular weight of the resulting polysuccinimide usually becomes low. Conversely, if the temperature is too high, the polymer will usually be colored or denatured and possibly decomposed.

The solid phase polymerization is carried out in the above-mentioned inert gas. In the present invention, the pressure may be any of a vacuum system, a normal pressure system, and a pressure system. The pressure is preferably 0.0
0000 to 50 MPa, more preferably 0.000
01 to 10 MPa, more preferably 0.0001 to
5 MPa. If the pressure is too high, a high pressure reactor is required. On the other hand, if the pressure is too low, it becomes difficult to design a device that can handle high vacuum.

The reaction time depends on the reaction conditions such as temperature and pressure,
In general, the higher the temperature, the shorter the reaction time, although it depends on the equipment conditions. The reaction time is preferably 1 second to 20
Time, more preferably 1 minute to 12 hours, more preferably 10 minutes to 8 hours, particularly preferably 30 minutes to 5 hours. If the reaction time is too short, the polysuccinimide may not usually have a sufficiently high molecular weight. Conversely, if the reaction time is too long, the coloring and denaturation of the polysuccinimide usually become remarkable with time.

1) Vacuum-based solid-phase polymerization operation When performing solid-phase polymerization in a vacuum system, the pressure in the reaction system substantially increases the solid-state polymerization reaction, and the desired weight average molecular weight,
There is no particular limitation as long as a polysuccinimide having a molecular weight distribution can be obtained.

In the vacuum solid phase polymerization, the pressure of the reaction system is
It is set in consideration of the polymerization time, the weight average molecular weight reached by solid phase polymerization, and the like. More specifically, a pressure of less than 0.1 MPa is selected within the above-mentioned pressure range.

2) Normal-pressure solid-phase polymerization operation In the solid-phase polymerization operation of the present invention, the solid-state polymerization reaction proceeds substantially, and polysuccinic acid having a desired weight average molecular weight and / or molecular weight distribution is obtained. There is no particular limitation as long as the imide is obtained.

In the present invention, the normal-pressure solid-phase polymerization operation is preferably selected from the above-mentioned pressure ranges.
1MPa vicinity (more specifically, 0.01 to 1.0MPa
This is an operation performed under the pressure of a).

In the present invention, the normal-pressure solid-phase polymerization operation is preferably carried out by flowing an inert gas.

The amount of the inert gas used is determined based on the flow rate [Nl / ｛(hour) ·
(G-solid low molecular weight polymer mixture)}], preferably 0.0001 to 100, more preferably
0.001 to 60, more preferably 0.01 to 4
0, particularly preferably 0.05 to 30, most preferably 0.5 to 20. Here, [Nl] is
The volume of the gas in the standard state is [l] (liter). If the flow rate is too low, the weight average molecular weight of the resulting polysuccinimide may usually be low. vice versa,
If the flow rate is too high, it usually becomes difficult to handle the finely divided reaction mixture.

On the other hand, the linear velocity [cm / sec] of the inert gas in the reactor is not particularly limited. The linear velocity of the inert gas is preferably 0.01 to 1000, more preferably 0.05 to 500, and still more preferably 0.1 to 500.
100, particularly preferably in the range of 0.3 to 60, most preferably 0.5 to 30. If the linear velocity is too low,
Usually, the weight average molecular weight of the resulting polysuccinimide may be low. Conversely, if the linear velocity is too high, the operation for handling the finely powdered reaction mixture usually becomes difficult.

3) Solid-phase polymerization operation in pressurized system When solid-phase polymerization is performed in a pressurized system, the pressure in the reaction system substantially increases the solid-state polymerization reaction and the desired weight average molecular weight,
There is no particular limitation as long as a polysuccinimide having a molecular weight distribution can be obtained.

In the pressurized solid phase polymerization, the pressure of the reaction system is
It is determined in consideration of the time required for polymerization and the efficiency of removing water generated by polycondensation.

More specifically, the pressure is selected from the above-mentioned pressure range and is higher than 0.1 MPa.

Reactor The solid phase polymerization step can be carried out by a continuous and / or batch operation. The apparatus used in the solid-state polymerization step is not particularly limited as long as the solid-state polymerization reaction substantially proceeds, and a polysuccinimide having a desired weight average molecular weight and / or molecular weight distribution is obtained. The solid-state polymerization step
An appropriate reaction apparatus may be selected and performed according to reaction conditions (temperature, pressure conditions, etc.) for performing solid-phase polymerization.

For example, when the finely powdered reaction mixture causes sticking or fusing of the particles depending on the amount of the acidic catalyst contained and the reaction conditions, an apparatus having a stirring action or a crushing action on the particles is generally used. Is preferred.

More specifically, for example, a hot air transfer type dryer,
At least one device selected from the group consisting of a material stirring type dryer (fluidized bed dryer, etc.), a material transport and stationary type dryer, a cylindrical dryer, an infrared dryer, a microwave dryer, and a superheated steam dryer. , A continuous or batchwise drying operation can be performed.

The apparatus and method used in the solid-state polymerization process of the present invention are described in “Revised Sixth Edition Chemical Engineering Handbook” (editor: Japan Society for Chemical Engineering, publishing office: Maruzen Co., Ltd., 1
999) "14 Humidity control, water cooling and drying" (735-735)
788), "7 Stirring" (pages 421-454), "6
Heat transfer / evaporation ”(pages 343 to 420).

In the solid phase polymerization step, a continuous type or batch type is carried out using at least one device selected from a fluidized bed reactor, a moving bed reactor, a fixed bed reactor, a stir dryer type reactor and the like. Operation can also be performed.

In the solid phase polymerization step, the fine powdery reaction mixture is
It can be carried out in direct and / or indirect contact with the heating medium.

Weight Average Molecular Weight of Polysuccinimide Produced in Solid-State Polymerization Step In the solid-state polymerization step, the weight-average molecular weight (Mw2) has a weight-average molecular weight represented by the above formulas (1) to (3). Manufacture polysuccinimide. By appropriately selecting the above-mentioned conditions in the solid-state polymerization step, a polysuccinimide having a target weight average molecular weight in the range shown by the above formula can be obtained.

In the present invention, the weight average molecular weight of the polysuccinimide is preferably in the range of the formula (13), more preferably in the range of the formula (14), and particularly preferably in the range of the formula (15). Perform the operation. 9.0 × 10 ⁴ ≦ Mw2 ≦ 1.0 × 10 ⁶ (13) 1.0 × 10 ⁵ ≦ Mw2 ≦ 1.0 × 10 ⁶ (14) 1.1 × 10 ⁵ ≦ Mw2 ≦ 1.0 × 10 ⁶ (15).

In the present invention, the lower limit of Mw2 is not particularly limited, but is preferably 8.0 × 10 ⁴ or more, more preferably 9.0 × 10 ⁴ or more, and still more preferably 1 × 10 ⁴ or more. 0.010 ⁵ or more, particularly preferably 1.1
When the content is at least 10 ⁵ , a derivative having good quality and / or performance (for example, a water-absorbing polymer, a polyaspartate, etc.) can be produced. On the other hand, Mw
The upper limit of 2 is not particularly limited, but is preferably 1.0 × 10 ⁶ or less, more preferably 7.0 × 10 ⁶ or less.
10 ⁵ or less, more preferably 5.0 × 10 ⁵ or less, particularly preferably 3.0 × 10 ⁵ or less, most preferably,
By setting the average molecular weight to 2.0 × 10 ⁵ or less, a solid high molecular weight polymer mixture can be produced without requiring a long reaction time in the solid phase polymerization step.

In the present invention, when the weight average molecular weight of the polysuccinimide after the solid phase polymerization is Mw2 and the number average molecular weight is Mn2, A product can be obtained in which the molecular weight distribution Mw2 / Mn2 of the polysuccinimide after the solid phase polymerization satisfies the formula (5) (Equation 5). The molecular weight distribution Mw2 / Mn2 is Mw2 / Mn2 = 1.
In general, a derivative (e.g., a water-absorbing polymer) having good quality and / or performance can be produced in a direction closer to.

In the present invention, the upper limit of the molecular weight distribution Mw2 / Mn2 is preferably 3.0 or less, more preferably 2.
A polysuccinimide having a value of 5 or less, more preferably 2.2 or less, particularly preferably 2.0 or less, and most preferably 1.8 or less is produced.

In the present invention, preferably, the molecular weight distribution Mw1 / Mn1 of the polysuccinimide before solid-state polymerization is preferably used.
And the molecular weight distribution Mw of polysuccinimide after solid-phase polymerization
2 / Mn2 is to produce a polysuccinimide satisfying the formula (6) (Equation 6). Molecular weight distribution Mw1 /
When Mn1 and / or Mw2 / Mn2 are closer to 1, usually, a derivative (for example, a water-absorbing polymer or the like) having good quality and / or performance can be produced. In the present invention, the upper limit of the molecular weight distribution is preferably 3.0 or less, more preferably 2.5 or less, and further preferably 2.
Polysuccinimides having a value of not more than 2, particularly preferably not more than 2.0, most preferably not more than 1.8 are preferably produced.

[Post-Treatment Step] After the solid phase polymerization, the acidic catalyst contained in the polysuccinimide uses a poor solvent for the polysuccinimide (a polar solvent such as methanol, isopropanol, acetone and water). It may be washed at 5 to 300 ° C. and removed.

After the solid state polymerization, the acidic catalyst contained in the polysuccinimide is dissolved once in a good solvent for the polysuccinimide (dimethylformamide (DMF), dimethylsulfoxide, etc.), and then dissolved in the polysuccinimide. May be reprecipitated with a poor solvent (methanol, isopropanol, acetone, water, etc.), filtered, rinsed with a poor solvent, and washed and removed.

After the solid phase polymerization, polysuccinimide can be hydrolyzed to produce polyaspartic acid (salt). The hydrolysis operation may be performed after removing the acidic catalyst from the polysuccinimide, or may be performed while the acidic catalyst is still contained, and may be performed simultaneously with the neutralization of the acidic catalyst.

The amount of the acidic catalyst contained in the polysuccinimide can be usually evaluated by means such as elemental analysis and X-ray fluorescence analysis.

[0119]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to the following examples.

1) Phosphoric Acid Concentration The weight concentration of phosphoric acid was evaluated as orthophosphoric acid based on the elemental analysis of phosphorus (P) element.

2) Weight Average Molecular Weight Since the reaction mixture produced according to the present invention contains an acidic catalyst, the reaction mixture is packed in a glass column and charged with methanol (3
(0 ° C.) to separate the acidic catalyst, and then a solid polymer was recovered by filtration and vacuum dried. Phosphoric acid content in polymer is 100ppm
After confirming that the molecular weight is less than
(Containing 0.01 mol / liter of lithium bromide) and GPC analysis was performed to evaluate the weight average molecular weight.

3) Particle Size The volume average diameter of the finely powdered reaction mixture was measured by a particle size analyzer (model: 9320-X1 manufactured by Leeds & Northrup).
00).

4) Analysis of Product The polymers obtained in the following examples were analyzed by 1H-NMR,
From 3C-NMR, it was confirmed to be polysuccinimide.

5) Water absorption The water absorption in the examples was measured by the following tea bag method. The measurement of the water absorption by the tea bag method was performed on distilled water and physiological saline.

Dried water-absorbing polymer (particle size: 100 to
0.02 g of a dry-classified product (500 μm) is placed in a non-woven tea bag (80 mm × 50 mm), immersed in an excess of a corresponding solution (saline or distilled water), and the water-absorbing polymer is allowed to stand for 40 minutes. After swelling, the tea bag was pulled up and drained for 10 seconds, and further drained on 24 sheets of tissue paper for 10 seconds, and then the weight of the tea bag containing the swollen resin was measured. From the weight, the value obtained by subtracting the value obtained by subtracting the weight of the water-absorbent resin when dried from the blank weight and the weight of the water-absorbent resin when the same operation was performed only with the tea bag by the weight of the water-absorbent resin, Was evaluated for water absorption weight per unit weight (g / g-water-absorbing resin). The physiological saline is a 0.9% by weight aqueous sodium chloride solution.

[Example 1] L was placed in a 500 ml flask.
13. aspartic acid 30.0 g, 85% by weight phosphoric acid
6 g at 80 to 90 ° C. under normal pressure in a nitrogen atmosphere.
The mixture was stirred for 0 minute and mixed to obtain a liquid reaction mixture.

Next, at a temperature of 160 ° C. and a pressure of 500 to 20
Under mmHg (0.0667-0.0027 MPa),
Heating was performed for 3 hours to obtain a solid reaction mixture. The obtained solid reaction mixture was pulverized using a dry pulverizer and classified to obtain a fine powdery reaction mixture (volume average diameter 64 μm).
m). The weight average molecular weight (Mw1) of this fine powdery reaction mixture was 29,000.

5 g of the finely powdered reaction mixture was
It was charged into a 16-tube reactor (inner diameter: 1 cm) and placed in an air oven. Nitrogen was allowed to flow at a flow rate of 0.5 [Nl / min] with the flow path on the reaction tube outlet side opened at atmospheric pressure. The temperature of the thermostat was raised, and a normal-pressure fixed-bed type solid-phase polymerization operation was performed at 200 ° C. for 8 hours.

After cooling to room temperature, the polymer was recovered. The recovered polymer was packed in a glass column, and heated with warm water (40
C) was continuously circulated to remove the phosphoric acid content to less than 100 ppm, then dried and dissolved in DMF. Weight average molecular weight (Mw2) of the obtained polysuccinimide
Was 102,000.

Example 2 5 g of the fine powdery reaction mixture obtained in Example 1 (weight average molecular weight (Mw1) = 2.
90,000), the reaction temperature of the solid-state polymerization operation was 220 ° C.,
The same operation as in Example 1 was performed except that the reaction time was changed to 2 hours. The weight average molecular weight (Mw2) of the obtained polysuccinimide was 91,000.

Example 3 5 g of the finely powdered reaction mixture obtained in Example 1 (weight average molecular weight (Mw1) = 2.
90,000), the reaction temperature of the solid-state polymerization operation was 270 ° C.,
The same operation as in Example 1 was performed except that the reaction time was 30 minutes.

The weight average molecular weight (Mw2) of the obtained polysuccinimide was 101,000.

Example 4 85% by weight of phosphoric acid was added to 15.8
g, temperature 160 ° C., pressure 10 mmHg (0.001
Example 1 except that heating was performed for 2 hours under 3 MPa).
The same operation as described above was repeated to obtain 35.3 g of a solid reaction mixture.
I got The obtained solid reaction mixture was pulverized using a dry pulverizer and classified to produce a fine powdery reaction mixture (volume average diameter 60 μm). The weight average molecular weight (Mw1) of this fine powdery reaction mixture was 34,000, and the number average molecular weight (Mn1) was 20,000 (Mw1 / Mn1 =
1.7).

7 g of the pulverized reaction mixture was
It was charged into a 16-tube reactor (inner diameter: 1 cm) and placed in an air oven. Nitrogen was allowed to flow at a flow rate of 0.5 [Nl / min] with the flow path on the reaction tube outlet side opened at atmospheric pressure. The temperature of the thermostat was raised, and a normal-pressure fixed-bed type solid-phase polymerization operation was performed at 220 ° C. for 4 hours.

After cooling to room temperature, the polymer was recovered. The collected polymer was packed in a glass column, and was heated with warm water (30
° C) continuously, and after removing the phosphoric acid content to less than 100 ppm, drying and polysuccinimide
4.3 g (98% yield) were obtained. A part of the obtained polysuccinimide was dissolved in DMF. The weight average molecular weight (Mw2) of the polysuccinimide was 116,000, and the number average molecular weight (Mn2) was 68,000. (Mw2 / Mn
2 = 1.7).

Comparative Example 1 The same operation as in Example 1 was performed, and the obtained solid reaction mixture was roughly pulverized to obtain a powdery reaction mixture (volume average diameter: 532 μm). The weight average molecular weight (Mw1) of this powdery reaction mixture was 25,000. Example 1 was prepared using 4.5 g of the powdery reaction mixture.
The same operation was performed. The weight average molecular weight (Mw2) of the obtained polysuccinimide was 65,000, and the number average molecular weight (Mn2) was 25,000 (Mw2 / Mn2 =
2.6).

Comparative Example 2 The same operation as in Example 1 was carried out except that 4.5 g of the powdery reaction mixture obtained in Comparative Example 1 was used and the reaction time of the solid-phase polymerization operation was changed to 20 hours. Was done. The weight average molecular weight (Mw2) of the obtained polysuccinimide was 68,000. The polysuccinimide was more colored than Comparative Example 1.

Example 5 Example of Producing a Water Absorbent Polymer from Polysuccinimide In a flask equipped with a stirrer, 8.0 g of DMF and the polysuccinimide obtained in Example 4 (weight average molecular weight of 11.1 g) were added.
60,000) and 2.0 g (0.021 mol).
A homogeneous polymer solution was obtained.

Under a nitrogen stream, 1.5 g of a crosslinking agent solution [0.53 g of L-lysine monohydrochloride was added to a mixed solution of 0.14 g (0.0035 mol) of sodium hydroxide and 0.8 g of distilled water. 0.0029 mol), and hydrochloric acid was neutralized] at 25 ° C. over 30 seconds. Five minutes after the addition of the crosslinking agent solution, the reaction mass became a gel characteristic of the crosslinked product, and the stirring was stopped. The crosslinked product was allowed to stand at 25 ° C. for 20 hours.

Next, 80 g of distilled water and 80 g of methanol
Was charged into a mixer, and the crosslinked product was cut under stirring. Thereafter, an aqueous solution of sodium hydroxide (concentration of sodium hydroxide: 25% by weight) was added at 25 to 30 ° C.
The mixture was added so as to be maintained at 1.5 to 12, and the crosslinked product was hydrolyzed to give a viscous gel. After hydrolysis, the mixture was neutralized to pH 7 with a 7% hydrochloric acid solution, and the gel was introduced into a large excess of methanol and solidified. Next, the solid was recovered by filtration, washed, and dried to obtain 3.0 g of a crosslinked polyaspartate (yield 97%).

The water absorption of the obtained polymer with respect to distilled water was 660 [g / g-polymer] (after 40 minutes),
The water absorption with respect to physiological saline was 61 [g / g-polymer] (after 40 minutes).

Comparative Example 3 Production Example of Water Absorbent Polymer from Polysuccinimide (1) Polysuccinimide obtained by separating phosphoric acid from the powdery mixture before solid phase polymerization obtained in Comparative Example 1 (weight Average molecular weight 2.
The same operation as in Example 5 was repeated, except that 50,000) was used. Even after 20 hours from the addition of the crosslinking agent solution, the reaction mass did not become a gel characteristic of the crosslinked product. Next, a hydrolysis operation was performed in the same manner as in Example 5, but no water-absorbing polymer was obtained, and a water-soluble polymer was produced.

Comparative Example 4 Production Example of Water Absorbent Polymer from Polysuccinimide (2) Same as Example 5 except that the polysuccinimide (weight average molecular weight: 65,000) obtained in Comparative Example 1 was used. Operation was repeated. Next, a hydrolysis operation was performed in the same manner as in Example 5, but no water-absorbing polymer was obtained, and a water-soluble polymer was produced.

[Comparison and Discussion of Examples 1 to 5 and Comparative Examples 1 to 4] In Comparative Example 1, a powdery reaction mixture having a large volume average diameter, which is an index of the particle size distribution, was used at 200 ° C. for 8 hours.
An ordinary pressure solid phase polymerization operation was performed, but the molecular weight of the resulting polysuccinimide was low. In Comparative Example 2, Comparative Example 1
Using the same powdery reaction mixture as in Example 1 and normal-pressure solid-state polymerization at 200 ° C. for 20 hours, polysuccinimide produced in the same manner had a low molecular weight and marked coloration. In Comparative Example 3, an attempt was made to produce a water-absorbing polymer as a derivative using polysuccinimide (weight average molecular weight: 25,000) separated from the powdery reaction mixture before solid phase polymerization produced in Comparative Example 1. The product was a water-soluble polymer. In Comparative Example 4, an attempt was made to produce a water-absorbing polymer as a derivative using the polysuccinimide (weight-average molecular weight: 65,000) produced in Comparative Example 1, but similarly, the product was a water-soluble polymer. .

In contrast, in Examples 1 to 3, the volume average diameter as an index of the particle size distribution was set within a predetermined range.
By performing solid-phase polymerization using the finely powdered reaction mixture, a polysuccinimide having a high weight-average molecular weight could be produced. Furthermore, in Example 4, the solid-state polymerization was performed using a finely powdered reaction mixture in which the volume average diameter, which is an index of the particle size distribution, was within a predetermined range, thereby having a high weight average molecular weight and a small molecular weight distribution. Polysuccinimide could be produced.

In Example 5, a water-absorbing polymer having excellent water absorption could be produced as a derivative by using polysuccinimide having a high weight average molecular weight and a small molecular weight distribution.

[0147]

According to the present invention, a polysuccinimide having a high weight average molecular weight can be provided by solid phase polymerization. Further, polysuccinimide having a high weight average molecular weight and a limited molecular weight distribution can be provided by solid phase polymerization. Further, a technique for solid-phase polymerization of polysuccinimide with a simpler apparatus can be provided. In addition, it does not require an expensive and complicated vacuum solid-state polymerization apparatus, and is suitable for continuous and large-scale production.
A technique for solid-phase polymerization of polysuccinimide can be provided.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinji Ogawa, 580-32, Takuji, Nagaura-shi, Sodegaura-shi, Chiba Pref. In Chemical Co., Ltd. (72) Inventor Makoto Sukekawa 580-32 Takuji, Nagaura, Sodegaura-shi, Chiba Prefecture Mitsui Chemicals Co., Ltd. Chemical Co., Ltd.

Claims (19)

[Claims] 1. A method for solid-state polymerization of polysuccinimide, comprising solid-phase polymerization of a fine powder of a mixture comprising polysuccinimide and an acidic catalyst. 2. The powder according to claim 1, wherein said powder has a volume average diameter of 1 to 5
2. The semiconductor device according to claim 1, which has a thickness of 00 μm.
2. The method for solid-state polymerization of polysuccinimide described in 1. above. 3. The method for solid-state polymerization of polysuccinimide according to claim 1, wherein the solid-state polymerization is performed in an inert gas atmosphere. 4. The method for solid-state polymerization of polysuccinimide according to claim 1, wherein the solid-state polymerization is performed at 120 to 350 ° C. 5. When the weight average molecular weight of the polysuccinimide before solid phase polymerization is Mw1 and the weight average molecular weight of the polysuccinimide after solid phase polymerization is Mw2, the weight average molecular weight Mw1 and the weight average molecular weight Mw2 are: The method for solid-state polymerization of polysuccinimide according to any one of claims 1 to 4, which satisfies Expressions (1) to (3) at the same time. 3 × 10 ³ ≦ Mw1 ≦ 2 × 10 ⁵ (1) 8 × 10 ⁴ ≦ Mw2 ≦ 1 × 10 ⁶ (2) Mw1 <Mw2 (3) 6. The molecular weight distribution Mw of the polysuccinimide before the solid-state polymerization, where the weight average molecular weight of the polysuccinimide before the solid-state polymerization is Mw1 and the number average molecular weight is Mn1.
The solid-state polymerization method for polysuccinimide according to claim 5, wherein 1 / Mn1 satisfies Expression (4). 1 ≦ Mw1 / Mn1 ≦ 4 (4) 7. When the weight average molecular weight of the polysuccinimide after the solid phase polymerization is defined as Mw2 and the number average molecular weight Mn2, the molecular weight distribution Mw of the polysuccinimide after the solid phase polymerization is determined.
The ratio 2 / Mn2 satisfies Expression (5).
Or the solid-state polymerization method of polysuccinimide according to 6. 1 ≦ Mw2 / Mn2 ≦ 4 (5) 8. The weight average molecular weight of the polysuccinimide before solid phase polymerization is Mw1, the number average molecular weight is Mn1, and the weight average molecular weight of the polysuccinimide after solid phase polymerization is Mw1.
2. When the number average molecular weight is Mn2, the molecular weight distribution Mw1 / Mn1 of the polysuccinimide before the solid phase polymerization and the molecular weight distribution Mw2 / Mn of the polysuccinimide after the solid phase polymerization
2 satisfies Expression (6).
The method for solid-state polymerization of polysuccinimide according to any one of the above. 1 ≦ Mw1 / Mn1 ≦ Mw2 / Mn2 ≦ 4 (6) 9. In step 1 (a step of producing a solid reaction mixture), aspartic acid and an acidic catalyst are mixed, and
A step of producing a solid reaction mixture containing a polysuccinimide having a weight average molecular weight Mw1 represented by Formula (1) and obtained by heating at 350 ° C., 3 × 10 ³ ≦ Mw1 ≦ 2 × 10 ⁵ (1) As step 2 (pulverizing step), the solid reaction mixture obtained in step 1 (solid reaction mixture producing step) is pulverized and / or pulverized.
Or a step of producing a finely powdered reaction mixture by classifying; and a step of producing a polysuccinimide by the solid-phase polymerization method according to claim 1 as step 3 (solid-state polymerization step). A method for producing a polysuccinimide characterized by comprising: 10. Step 1 (Step of producing a solid-state reaction mixture)
Is mixed with aspartic acid and an acidic catalyst under a pressure of 0.1 MPa or more and 50 MPa or less,
10. A process for producing a solid reaction mixture containing a polysuccinimide having a weight average molecular weight Mw1 represented by Formula (1) and obtained by heating at 0 ° C. A method for producing a polysuccinimide. 11. Step 1 (a step of producing a solid reaction mixture)
Is obtained by mixing aspartic acid and an acidic catalyst under a pressure of 0.00001 MPa or more and less than 0.1 MPa and heating at 40 to 350 ° C.
The method for producing a polysuccinimide according to claim 9 or 10, wherein the step is a step of producing a solid reaction mixture containing a polysuccinimide having a weight average molecular weight Mw1 represented by: 12. Step 3 (solid phase polymerization step)
(Pulverizing step), the finely pulverized reaction mixture is subjected to a pressure of 0.
A step of producing a polysuccinimide having a weight average molecular weight Mw2 represented by Formula (2) by performing solid phase polymerization at 120 to 350 ° C. in an inert gas of 1 MPa or more and 50 MPa or less. A method for producing a polysuccinimide according to any one of claims 9 to 11. 8 × 10 ⁴ ≦ Mw2 ≦ 1 × 10 ⁶ (2) 13. Step 3 (solid-state polymerization step)
(Pulverizing step), the fine powdery reaction mixture
A step of producing a polysuccinimide having a weight average molecular weight Mw2 represented by Formula (2) by performing solid phase polymerization at 120 to 350 ° C under a pressure of 001 MPa or more and less than 0.1 MPa. A method for producing a polysuccinimide according to any one of claims 9 to 12, wherein: 8 × 10 ⁴ ≦ Mw2 ≦ 1 × 10 ⁶ (2) 14. The polysuccinic acid according to claim 1, wherein the amount of the acidic catalyst used is in the range of 0.01 to 1.0 mol per mol of aspartic acid as a raw material. Method for producing imide. 15. The method for producing polysuccinimide according to claim 14, wherein the acidic catalyst contains phosphorus oxyacid. 16. The polysuccinimide according to claim 15, wherein the phosphorus oxyacid is at least one selected from the group consisting of orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, and phosphorus pentoxide. Production method. 17. A polysuccinimide obtained by the production method according to claim 1. Description: 18. A polyaspartic acid (salt) obtained by hydrolyzing the polysuccinimide obtained in claim 17. 19. A water-absorbing polymer obtained by performing an operation including a crosslinking reaction and a hydrolysis reaction on the polysuccinimide obtained in claim 17.