JPH09302088A - Production of polysuccinimide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-mol. -wt. polysuccinimide by subjecting a powdery polymer feedstock contg. specified amts. of a catalyst and a polymn. accelerator to solid-state polymn. under stirring. SOLUTION: 100 pts.wt. powdery polymer feedstock (e.g. L-aspartic acid), 0.1-30 pts.wt., pref. 0.5-25 pts.wt., catalyst (e.g. a phosphoric or phosphorous compd.), and 0.1-100 pts.wt., pref. 0.5-50 pts.wt., polymn. accelerator comprising an aprotic polar solvent (e.g. sulfolane) are fed into a mixer and mixed at room temp. for a certain time. The resultant mixture is subjected to solid-state polymn. by kneading it with a horizontal stirring apparatus under a reduced pressure at about 100-300 deg.C, pref. 150-250 deg.C, for 0.5-240min, pref. 1-180min. The resultant polymer is washed with water and then with methanol and dried under a reduced pressure, thus giving a high-mol. -wt. polysuccinimide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing polysuccinimide. More specifically, it relates to a method for producing a high molecular weight polysuccinimide with high efficiency.

[0002]

2. Description of the Related Art Conventionally, as an industrial synthetic method for polysuccinimide, thermal polymerization in the absence of a catalyst has been described in US Pat. No. 5,11.
6,513, 5,219,986, 5,315,010 or JP-A-6-
No. 206937 and the like, and as a method of polymerizing by using a catalyst, European Patent No. 644,257 discloses aspartic acid, an acid catalyst, a polyfunctional monomer and / or a processing aid.
A method of reacting is disclosed.

However, the non-catalyst production method requires a low conversion rate or requires a long processing time at a high temperature, and in addition, the obtained polysuccinimide has a relatively low molecular weight, so that it is a polymer. Is insufficient to exert the performance as. Further, even in the method using a catalyst, it is necessary to use a large amount of the catalyst, and therefore the operation of removing the catalyst from the mixture after polymerization is difficult.

[0004]

Polysuccinimide is hydrolyzed to form the corresponding polyamino acids and is used for fertilizers, scale inhibitors, detergents, humectants, pigments and mineral dispersants, and for boilers and cooling towers. It is useful as a water additive. In addition, polyamino acid is a biodegradable material, and has been attracting attention as an alternative material in applications where polyacrylic acid or the like has been conventionally used. Therefore, the appearance of a method for easily obtaining a high molecular weight polysuccinimide at a high conversion rate is desired.

Therefore, an object of the present invention is to provide a method for producing a high molecular weight polysuccinimide easily and at a high conversion rate.

[0006]

[Means for Solving the Problems] The present inventors focused on a method of polymerizing aspartic acid powder in the presence of a catalyst while maintaining a substantially solid phase state, and reduced the amount of the catalyst at this time. As a result of diligent studies on a method in which the polymerization is favorably carried out, it was found that a high molecular weight polysuccinimide can be produced in a high yield in a short time by using a polymerization accelerator together with a small amount of the catalyst, and the present invention It came to completion.

That is, the gist of the present invention is to provide a method for producing a powdery polysuccinimide by polymerizing a polymer raw material powder with stirring while maintaining a substantially solid state.
A method for producing a polysuccinimide is characterized in that 0.1 to 30 parts by weight of a catalyst and 0.1 to 100 parts by weight of a polymerization accelerator are present in a raw material powder with respect to 100 parts by weight of a polymer raw material. The method of the present invention is described in detail below.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, polysuccinimide includes not only aspartic acid homopolymer but also copolymer. (Polymer raw material) In the method of the present invention, it is desirable to use a monomer mainly containing aspartic acid as a polymer raw material. As aspartic acid, L-, D
Both-and DL-aspartic acid can be used. In addition to aspartic acid, it is also possible to use other copolymerizable monomers within a range not exceeding 50 mol%. There is no particular limitation on the copolymerizable monomer,
For example, aspartate, glutamic acid and salts thereof,
In addition to amino acids such as alanine, leucine and lysine, glycolic acid, lactic acid, hydroxycarboxylic acids such as 3-hydroxyacetic acid, amino groups such as 2-hydroxyethanol and compounds having two or more functional groups capable of reacting with carboxylic acids, etc. Is mentioned. Further, compounds having one functional group capable of reacting with an amino group such as maleic acid and aniline and a carboxylic acid can also be used for the purpose of adjusting the molecular weight.

(Catalyst) Examples of the polycondensation reaction catalyst that can be used in the method of the present invention include acid catalysts.
Mineral acids such as hydrochloric acid, sulfuric acid, anhydrous sulfuric acid, phosphoric acids such as phosphoric acid, polyphosphoric acid, metaphosphoric acid, condensed phosphoric acid and anhydrous phosphoric acid, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, etc. Phosphite triesters, phosphite diesters such as diphenyl phosphite, phosphite monoesters, phosphites, and phosphites such as phosphites, p-toluenesulfonic acid, trichloroacetic acid, Organic acids such as trifluoroacetic acid, methanesulfonic acid and trifluoromethanesulfonic acid are preferred. Among these, phosphoric acid compounds and phosphorous acid compounds are particularly preferable in that a high-yield polymer having a high molecular weight can be easily obtained.
Among the phosphite compounds, phosphite triesters are preferable from the viewpoints of the molecular weight of the produced polymer and the reaction time, and of these, triphenyl phosphite is more preferable. The amount of catalyst used is 100
It is usually used in an amount of 0.1 to 30 parts by weight, preferably 0.5 to 25 parts by weight, based on parts by weight. When the amount of the catalyst used is less than 0.1 part by weight, the effect of improving the speed of the polycondensation reaction is small. On the other hand, if it exceeds 30 parts by weight, the reaction product is solidified during the polymerization, and a large load is applied to stirring, which is not preferable.

(Polymerization accelerator) The polymerization accelerator that can be used in the method of the present invention is one that dissolves polysuccinimide and accelerates the polymerization reaction. Specifically, a solvent and the like capable of dissolving polysuccinimide at room temperature, preferably 5 wt / wt% or more, more preferably 10 wt / wt% or more, can be mentioned. Suitable specific examples include aprotic polar solvents such as N, N-dimethylformamide, N-methyl-2-pyrrolidone and sulfolane. Among these, sulfolane is particularly preferable in that a high molecular weight polysuccinimide can be obtained. The amount of the polymerization accelerator used is usually 0.1 with respect to 100 parts by weight of the polymer raw material.
To 100 parts by weight, preferably 0.5 to 50 parts by weight. When the amount of the polymerization accelerator used is less than 0.1 part by weight, the effect of improving the speed of the polycondensation reaction is small.
Further, if it exceeds 100 parts by weight, the process for removing the polymerization accelerator becomes complicated, which is not preferable from an industrial viewpoint.

(Dispersion Method of Catalyst and Polymerization Accelerator) When carrying out the polycondensation reaction in the present invention, it is preferable that the polymer raw material and the catalyst and the polymerization accelerator are in a homogeneous state. Here, the homogeneous state is a state in which the mixture of the polymer raw material, the catalyst and the polymerization accelerator is apparently uniform in particle size,
It means a state in which the catalyst and the polymerization accelerator do not include aggregates partially mixed in the polymer raw material. If the polycondensation reaction is carried out without mixing in a homogeneous state, problems such as partial melting and solidification, decrease in molecular weight, and increase in the amount of residual polymer raw material after the reaction are not preferable.

The order of mixing the polymer raw material, the catalyst and the polymerization accelerator is not particularly limited. For example, even if the catalyst is added to the mixture of the polymer raw material and the polymerization accelerator, the polymer raw material, the catalyst and the polymerization accelerator are mixed. You can mix all three at once,
The mixing method is not particularly limited, and may be added all at once, added in small amounts, or mixed using a spraying means. The mixing equipment at this time is preferably a stirrer, a kneader or a kneader, and is not particularly limited as long as it is generally used. Specifically, a mill, a Henschel mixer, a blender, a kneader, etc. are used, and specific examples of large equipment include "Super Mixer" manufactured by Kawata Co., Ltd., "SV-Mixer" manufactured by Shinko Pantech Co., Ltd., "Conical dryer", Okawara Seisakusho Co., Ltd. "MZ-Processor", Nara Machinery Co., Ltd. "Paddle dryer", Kurimoto Iron Works Co., Ltd. "SC"
A "processor", a "pressure kneader", etc. are mentioned.

(Polycondensation Reaction) In the polycondensation reaction in the present invention, preferably, the mixture is heated to 100 to 3 usually.
In the range of 00 ° C, preferably 150 to 250 ° C, the average residence time is 0.5 to 600 minutes, preferably 0.5 to 24.
The reaction is preferably carried out in the solid phase while stirring or kneading for 0 minute, more preferably 1 to 180 minutes. The reaction may be carried out at normal pressure, but it is preferably carried out under reduced pressure from the viewpoint of shortening the reaction time.

When the reaction temperature is less than 100 ° C. and the average residence time is less than 0.5 minutes, the reaction does not proceed easily, which is not preferable. Further, if the reaction is carried out at a reaction temperature of higher than 350 ° C. and an average residence time of longer than 600 minutes, decomposition products are generated and the reaction time becomes long, which is not economically preferable. In addition, in the case of normal pressure, this polymerization reaction is desirably carried out in an inert atmosphere, and as the inert gas used,
There is no particular limitation such as nitrogen and argon. In the polymerization of the present invention, the polymer raw material is supplied in the form of powder, while the polymer produced after the polymerization is also recovered in the form of powder. During the course of the polymerization, a sticky zone may be generated in some cases depending on the case, but as a whole, the polymerization is carried out while substantially maintaining the solid state.

Examples of the polymerization apparatus used in the present invention include a reactor or a stirring tank equipped with a batch or continuous vertical or horizontal stirring apparatus, a kneader, and the like. In particular, a horizontal stirring device equipped with a biaxial stirring blade is preferable, and a commercially available kneader can be used. Specifically, Sumitomo Heavy Industries Co., Ltd. “Vyvolak”, Mitsubishi Heavy Industries Ltd. “SCR”, Japan Steel Works Ltd. “TE
"X", "TEM" manufactured by Toshiba Machine Co., Ltd., "FCM" manufactured by Kobe Steel, Ltd., and "KR" manufactured by Kurimoto Iron Works Co., Ltd.
"C kneader" and the like. Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

[0016]

Example The polysuccinimide obtained by the present invention was analyzed by the following measuring method. 1) Weight average molecular weight Tosoh Corporation “TSKgel” “GMHHR-M”
+ Polystyrene conversion value obtained by gel permeation chromatography (differential refractometer) using “TSKgel” “G2000HHR” column and dimethylformamide added with 10 mM LiBr as an eluent. 2) Conversion rate to polymer The residual rate of aspartic acid in the reaction product was measured by liquid chromatography, and the conversion rate was calculated by the following formula.

[0017]

## EQU00001 ## Conversion (%) = 100-Residual rate of aspartic acid in reaction product

(Example 1) L-aspartic acid powder 40
g, 4% of 85% phosphoric acid and 4 g of sulfolane were charged in a mixer (Oster blender) and mixed at room temperature for 15 minutes to obtain a mixture. Then, the mixture obtained above was charged into a 100 mL eggplant-shaped flask and mounted on a rotary evaporator, and then the temperature of the oil bath was set to 180 ° C. under reduced pressure.
For 3 hours. After completion of the reaction, 4 with 100 g of pure water
It was washed twice and further washed with 100 g of methanol. Then, the product was dried under reduced pressure at 100 ° C. for 12 hours to obtain 28.9 g of a yellowish white powder. The weight average molecular weight of this polysuccinimide is 42,000, and the conversion rate to polymer is 9
It was 9.9% or more.

(Example 2) N-methyl-2 was used as sulfolane.
-By the same operation as in Example 1 except that 4 g of pyrrolidone was changed, 27.6 g of yellowish white powder was obtained. The obtained polysuccinimide had a weight average molecular weight of 31,000 and a conversion rate to a polymer of 99.9% or more.

(Example 3) The same operation as in Example 1 was carried out except that the amount of 85% phosphoric acid was changed to 2 g.
7.9 g were obtained. The obtained polysuccinimide has a weight average molecular weight of 30,000 and a conversion rate to a polymer of 99.2.
%Met. (Example 4) 4% of triphenyl phosphite was added to 85% phosphoric acid.
The same operation as in Example 1 was performed except that the procedure was changed to, to obtain 27.6 g of yellowish white powder. The obtained polysuccinimide had a weight average molecular weight of 43,000 and a conversion rate to a polymer of 99.9% or more.

(Example 5) L-aspartic acid 100
g, 85% phosphoric acid 10 g and sulfolane 50 g were charged in a mixer (Oster blender) and mixed at room temperature for 15 minutes to obtain a mixture. Next, the mixture obtained above was charged into a four-neck decomposition flask equipped with a cooler, a thermometer, a nitrogen introduction tube and a stirrer, and polycondensation was started under a nitrogen stream while heating with a mantle heater. Internal temperature is 165 ° C
Since water began to evaporate near this point, the reaction started at this point,
The temperature was raised to 200 ° C. for 30 minutes, and the mixture was further stirred at the same temperature for 3 hours. After the reaction was completed, the product was washed with 100 g of pure water four times and further with 100 g of methanol. Then, the product was dried under reduced pressure at 100 ° C. for 12 hours to obtain 25.4 g of a yellowish white powder. The weight average molecular weight of this polysuccinimide was 34,000, and the conversion rate into a polymer was 99.9.
% Or more.

Comparative Example 1 A light brown powder was obtained in the same manner as in Example 1 except that sulfolane was removed. The weight average molecular weight of the obtained polysuccinimide is 1500.
0, the conversion rate to polymer was 85.1%. (Comparative Example 2) 100 g of L-aspartic acid alone was charged into a four-neck decomposition flask equipped with a cooler, a thermometer, a nitrogen introducing tube and a stirrer, while heating with a mantle heater.
Polycondensation was started under a nitrogen stream. Since water began to be distilled off at an internal temperature of about 200 ° C., the reaction was started at this point, and the mixture was stirred at the same temperature for 7 hours to obtain 85.0 g of pale pink powder.
The weight average molecular weight of this polysuccinimide is 700
0, the conversion rate to polymer was 41.0%.

[0023]

According to the production method of the present invention, a high molecular weight polysuccinimide can be produced extremely efficiently without the need for a special reaction apparatus or a special process.

Claims (8)

[Claims] 1. A method for producing a polysuccinimide in powder form by polymerizing under stirring a polymer raw material powder while substantially maintaining a solid state, wherein the catalyst is 0.1 to 0.1 parts by weight with respect to 100 parts by weight of the polymer raw material. A method for producing a polysuccinimide, characterized in that 30 parts by weight and 0.1 to 100 parts by weight of a polymerization accelerator are present in a raw material powder. 2. The method for producing polysuccinimide according to claim 1, wherein the content of the catalyst is 0.5 to 25 parts by weight with respect to 100 parts by weight of the polymer raw material. 3. The polymer raw material 1 having a content of the polymerization accelerator is
The method for producing polysuccinimide according to claim 1, wherein the amount is 0.5 to 50 parts by weight with respect to 00 parts by weight. 4. The method for producing polysuccinimide according to claim 1, wherein the catalyst is a phosphoric acid compound and / or a phosphorous acid compound. 5. The method according to claim 4, wherein the phosphite compound is a phosphite ester. 6. The method for producing polysuccinimide according to claim 1, wherein the polymerization accelerator is an aprotic polar solvent. 7. The method for producing polysuccinimide according to claim 1, wherein the polymer raw material is a monomer mainly containing aspartic acid. 8. The method for producing polysuccinimide according to claim 1, wherein the polymerization is carried out using a horizontal stirring device equipped with a biaxial stirring blade.