JP2000038447A - Production of succinimide-based polymer and aspartic acid-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a succinimide-based polymer useful for a detergent additive, dispersion stabilizer, scale repeller, moisture-retaining agent, fertilizer or the like by heat-polymerizing an ammonium salt of amino acid in the presence of acid catalyst. SOLUTION: This productions method is conducted by using an ammonium salt of an amino acid essentially comprising an aspartic acid, pref., in the form of aqueous solution and by heat-polymerizing the salt, pref., homogeneously dissolved in the solution in the presence of acid catalyst, pref., at 150 to 220 deg.C, for 0.5 to 8 hrs. under a reduced pressure of 50 to 300 mmHg. The acid catalyst is pref. a phosphoric acid derivative (e.g. orthophosphoric acid) having at least one P-OH bond or a boron derivative (e.g. orthoboric acid) having at least one B-OH bond, and the usage of the acid catalyst is pref. 0.5 to 40 wt.% based on the amino acid. The solution of ammonium aspartate is pref. used in a concentration of 5 to 50 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a succinimide-based polymer and an aspartic acid-based polymer.

[0002]

BACKGROUND OF THE INVENTION Succinimide polymers are hydrolyzed to form the corresponding succinimide polymers, which are detergent additives, dispersion stabilizers, scale inhibitors, humectants,
It is useful as a fertilizer.

Conventionally, various methods have been proposed as methods for obtaining polysuccinimide by thermal polymerization using aspartic acid as a raw material.

[0004] German Patent DE 4429108 A1 discloses a process in which a solution of ammonium aspartate is concentrated under reduced pressure and then heated to polymerize it.

According to this method, when the polymerization temperature is 180 ° C. and the polymerization time is 4 hours, the yield of polysuccinimide is 30%. To increase the polymer yield, the polymerization temperature should be 22
It had to be 0 ° C. In addition, there is a problem that polyaspartic acid obtained by this method has low biodegradability.

[0006] JP-A-8-103796 discloses a method of polymerizing aspartic acid in the presence of an acid catalyst. In this method, acid aspartic acid is used as a raw material.Since aspartic acid is usually produced as a solution, it is necessary to separate and use acid aspartic acid from the solution in advance, which causes high cost. Was.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for efficiently producing a succinimide polymer and a polyaspartic acid polymer having good biodegradability.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a process for producing an aspartic acid, comprising adding an acid catalyst to an ammonium aspartate solution, heating the mixture in the presence of the acid catalyst to evaporate water, and adding ammonia to the solution. This is a method for producing a polysuccinimide-based polymer by removing and recovering the resulting polymer, followed by heating.

In this method, since an acid catalyst is used, the polymerization temperature can be lowered and the polymerization time can be shortened. Therefore, there is an advantage that the polyaspartic acid-based polymer derived from the obtained polysuccinimide-based polymer has high biodegradability. The ammonia released during the polymerization can be recovered and reused as a raw material for L-aspartic acid. In particular, when collected with a suspension of fumaric acid, which is a raw material of L-aspartic acid,
It is suitable for use as a raw material for aspartic acid.

When an acid catalyst is added to a solution of ammonium L-aspartate, a counter ion usually binds to an acid having a high acid strength, so that the effect of the catalyst acid is lost. Sulfuric acid produces ammonium sulfate, which is 2
If the temperature is not higher than 80 ° C., it will not be decomposed and the catalytic activity as an acid will be lost. However, surprisingly, when relatively weak acids such as phosphoric acid and boric acid are used, the decomposition temperature of these ammonium salts is relatively low, and ammonium phosphate decomposes at 190 ° C. to generate free phosphoric acid. It has been found that the catalyst ability as an acid can be maintained. Boric acid can also be used as a catalyst. Further, by adding the acid catalyst to the ammonium aspartate solution, the acid catalyst can be uniformly dissolved and dispersed throughout, so that a high-molecular-weight polysuccinimide can be efficiently produced with a small amount of the acid catalyst.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an amino acid containing aspartic acid as an essential ingredient is used as a raw material. As the aspartic acid, an L-form, a D-form, or a mixture thereof can be used. In addition to aspartic acid, up to 100% by weight, based on the weight of aspartic acid, of one or more other amino acids can be mixed and polymerized. As amino acids copolymerized with aspartic acid, glycine, alanine, asparagine, glutamic acid, lysine, valine, leucine, isoleucine,
Examples include phenylalanine, methionine, histidine, proline, serine, threonine, cysteine and the like.

The ammonium aspartate solution used in the present invention is preferably used at a concentration of 5 to 50%. In particular, it is preferable to use a solution of ammonium L-aspartate obtained by the action of aspartase from fumaric acid and ammonia. Further, this solution can be used by increasing the concentration to 50 to 90% by pre-concentration under reduced pressure.

In the present invention, an acid which can exist as a free acid or an acid which can take a form having an effect as an acid in the presence of ammonium ions at the reaction temperature can be used as the acid catalyst. In particular, a phosphoric acid derivative having at least one P-OH bond or a boron derivative having at least one B-OH bond is used as the acid catalyst. Specifically, as the phosphoric acid derivative, phosphoric acids such as orthophosphoric acid, metaphosphoric acid, and polyphosphoric acid, acidic phosphoric acid esters such as methylphosphoric acid, ethylphosphoric acid, and phenylphosphoric acid, and ammonium salts thereof can be used. it can. Also, as boric acid derivatives, orthoboric acid, metaboric acid, boric acids such as tetraboric acid, ammonium salts thereof, ethyl alcohol,
Boric esters with alkyl alcohols such as methyl alcohol, boric acid complexes with polyhydric alcohols, and the like can be used.

The acid catalyst is used in an amount of 0.5 to 40% by weight, preferably 1 to 30% by weight, and more preferably 2 to 1% by weight, based on the amino acid containing aspartic acid as a raw material.
It is preferable to use it in the range of 5% by weight. If the amount of the acid catalyst is small, the reaction time becomes long, and a high molecular weight polymer cannot be obtained. On the other hand, if the amount of the acid catalyst is large, a large amount of the acid catalyst remains in the polymer, which is unfavorable because it causes a decrease in product quality and an increase in cost.

The acid catalyst may be added directly to the first amino acid ammonium solution containing aspartic acid, or may be added after being concentrated to some extent under reduced pressure. By adding the acid catalyst to the solution, the acid catalyst can be uniformly dispersed and dissolved.

The polymerization temperature is 100 to 250 ° C., preferably 100 to 215 ° C., and more preferably 130 to 210 ° C.
Range is good. If the polymerization temperature is low, the polymerization does not proceed, and if the polymerization temperature is high, a complicated structure that adversely affects biodegradability is formed in the polymer, which is not preferable. The polymerization time is usually 0.5 to 8 hours at a polymerization temperature of about 210 ° C.

During the polymerization, the pressure is reduced to
It is desirable to facilitate removal of water and excess ammonia contained in the amino acid ammonium solution containing aspartic acid as an essential component, and ammonia and water released during polymerization. The degree of reduced pressure during the polymerization is 1 to 500 mmHg, preferably 10 to 400 mmHg, more preferably 50 to 400 mmHg.
The range is 300 mmHg. The degree of decompression is preferably as high as possible, and the efficiency of removing water and ammonia is improved.
The polymerization time can be shortened. However, if the degree of pressure reduction is too high, problems such as a complicated apparatus occur. If the degree of pressure reduction is low, the efficiency of removing water and ammonia is poor, and the polymerization time is prolonged.

Ammonia is liberated when heated and decompressed. This ammonia can be trapped and reused. In particular, when trapped in a suspension of fumaric acid, which is a raw material for L-aspartic acid, ammonia and fumaric acid are added as appropriate to reuse as a reaction raw material for synthesis of L-aspartic acid from fumaric acid and ammonia by aspartase. can do.

Various apparatuses such as a shelf type vacuum dryer, a belt conveyor type dryer, a drum dryer and a vent type screw extruder can be used as the apparatus used for heating and depressurizing. Because of the change, a kneader and a vent-type screw extruder that can knead particularly a highly viscous substance are preferable. Also, when not depressurized, the surface area can be increased by using a belt conveyor type or drum dryer,
It is preferable because water and ammonia can be easily removed.

The polysuccinimide polymerized in the present invention is
For example, by dissolving in an aqueous solution of a basic substance such as an alkali metal hydroxide or an alkaline earth metal hydroxide at 20 to 95 ° C., preferably 40 to 70 ° C., the imide ring is hydrolyzed and opened, A polyaspartate is obtained.
The concentration of the aqueous solution of the basic substance used is 5 to 50% by weight.
Is preferred. Here, as the alkali metal hydroxide,
Examples thereof include sodium hydroxide and potassium hydroxide, and examples of the alkaline earth metal hydroxide include calcium hydroxide, magnesium hydroxide, and strontium hydroxide. Among them, sodium hydroxide is inexpensive and is preferred when used for applications such as detergent additives, dispersion stabilizers, and scale inhibitors. For applications such as fertilizers and plant growth promoters, potassium hydroxide as a fertilizer component is particularly preferred.

In the polyaspartate solution which has been hydrolyzed and ring-opened in this manner, ammonia which cannot be removed during polymerization is present. Thereby, it can be expelled from the solution as free ammonia and recovered. In this case as well, trapping with a fumaric acid suspension is preferable, because it can be reused as a raw material for L-aspartic acid.

The molecular weight of the polyaspartate is determined by gel permeation chromatography (GPC) using, for example, a Shodex OH packed column manufactured by Showa Denko with a standard polyaspartic acid sample of known molecular weight manufactured by Sigma. It can be determined by analysis. According to the method of the present invention, polyaspartic acid having a weight average molecular weight of 2,000 or more can be produced.

The biodegradability of polyaspartic acid can be measured, for example, by the modified MITI test of the OECD Test Guideline. According to the method of the present invention, in a 28-day test using activated sludge from a sewage treatment plant, the biodegradation rate calculated from the biochemical oxygen demand (BOD) was 6%.
Polyaspartic acid having a degradability of 0% or more can be produced.

The succinimide polymer produced according to the present invention forms the corresponding amino acid polymer by hydrolysis, and is used as a detergent additive, dispersion stabilizer, scale inhibitor, humectant, fertilizer, etc. having excellent biodegradability. Can be used.

[0025]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Escherichia coli ATCC11303 strain was inoculated into 10 test tubes containing 3 ml of the medium shown in Table 1, cultured at 37 ° C. for 8 hours, and then placed in 10 Sakaguchi flasks containing 100 ml of the medium having the same composition. Each was inoculated and shaken at 30 ° C. overnight.
Cells were collected from the culture by centrifugation. When the aspartase activity of the cells was measured, 0.05
It was molesL-aspartic acid production / hr / g cells.

Table 1 Medium composition

[0028]

[Table 1]

Sterilized in an autoclave at 121 ° C. for 15 minutes PAS-880 (manufactured by Nitto Boseki) was pH 7.0 with alkali.
70 g of the mixture in the vicinity and 230 g of deionized water were mixed well, and the cells recovered earlier were uniformly dispersed. Ion exchange resin (Amberlite IRA)
-96SB C1 type, manufactured by Organo, average particle size 0.5 mm) 300
ml and 200 pieces of 0.5-inch Teflon spheres, put 1/6 of the bacterial cell dispersion obtained above, dry at 30 ° C. for 1 hour with an evaporator while rotating at 30 ° C. Coated. After performing this operation six times, the Teflon spheres were removed to obtain a bead-like immobilized aspartase.
The activity of this immobilized aspartase was 210 U / ml.

The immobilized aspartase thus prepared was added to a 20% ammonium fumarate solution (pH 8.3) for 4 hours.
After soaking overnight at 10 ° C., the column was filled with 10 ml,
The reactor was insulated by keeping the outside of the column warm with foamed polystyrene humectant. A 20 ° C. substrate solution (200 g per liter) kept in a 20 ° C. constant temperature water bath was added to this column.
Fumaric acid, 200 g of 25% aqueous ammonia, 0.25
g of MgSO ₄ .7H ₂ O and adjusted to pH 3 with ammonia) was passed through a Teflon tube wrapped with a heat insulating material at a rate of 5 ml / hour (SV = 0.5) to carry out a continuous reaction. When the reaction solution was analyzed three hours after the start of the reaction, L-aspartic acid was produced as a reaction product in an amount substantially equal to the consumed fumaric acid, and the reaction conversion rate was 99.77%. Was.

500 ml of an ammonium L-aspartate solution formed by flowing through a column (114.3 g of ammonium L-aspartate, water, L-aspartic acid)
Containing) in a stainless steel vat and add orthophosphoric acid 1
After mixing 1 g, in a vacuum dryer at 210 ° C. for 8 hours,
Heating and decompression were performed. The pressure was reduced by evacuating with a diaphragm vacuum pump, the degree of decompression was adjusted to 150 mmHg, and the exhaust was passed through a suspension containing 60 g of fumaric acid and 60 ml of water to collect ammonia. After 4 hours, all the fumaric acid was dissolved by the ammonia released during the polymerization. The liquid volume was about 500 ml. The amount of polysuccinimide obtained by polymerization was 97 g.

10 g of this polysuccinimide was added to 70 m of water.
The suspension was suspended in 1 l, and a 10 N aqueous solution of sodium hydroxide was added to dissolve the polysuccinimide to adjust the pH to 10. This solution was heated to 90 ° C., and the gas phase was blown with nitrogen to circulate the remaining ammonia in order to drive out the remaining ammonia. Thus, an aqueous solution of sodium polyaspartate was obtained. When this solution was analyzed by HPLC, no peak of aspartic acid was detected, and the polymer yield was almost 100%.

The weight average molecular weight of the sodium polyaspartate was determined using a Shodex OH pack column manufactured by Showa Denko KK and polyaspartic acid (Shig manufactured by Sigma).
ma P3418, Shigma P5387, Shigma P3056, Shigma P6762)
Was determined to be about 7000 by GPC analysis using as a standard substance. This sodium polyaspartate solution was subjected to running water dialysis with a cellophane tube for 16 hours to remove low molecular weight fractions, and then sodium polyaspartate was recovered by freeze-drying. The biodegradability of the dialyzed polyaspartic acid was measured according to the modified MITI test, except that the sludge returned from the municipal sewage treatment plant was used. That is, polyaspaaraginic acid as a test substance was added to 200 ml of a basic culture solution as a composition solution specified in the section of biochemical oxygen demand in JIS K-0102 so as to be 100 ppm, and activated sludge was added. Was added to be 30 ppm. Thereafter, the basal culture was kept at 25 ° C. in the dark and stirred for 2 hours.
Cultured for 8 days. During the culturing period, the amount of oxygen consumed by the activated sludge is periodically measured, and the biochemical oxygen demand (BOD) is measured.
d) The curve was determined.

The biodegradation rate (%) is calculated from the biochemical oxygen demand A (mg) of the test substance obtained from the BOD curve,
The blank obtained from the BOD curve, that is, the oxygen consumption B (mg) of the basal culture solution, and the total oxygen demand (TOD: Theoretical Oxygen) required for complete oxidation of the test substance
Demand) C (mg) and the ratio of the following formula to the theoretical oxygen demand (TOD) of the test substance was calculated according to the following formula.

[0035]

## EQU1 ## The biodegradation rate (%) = {(AB) / C} × 100 Further, the decrease in the total organic carbon content (TOC) in the test solution is expressed by T
It measured using the OC measuring device (TOC-500 made by Shimadzu). The TOC removal rate was calculated according to the following equation.

[0036]

## EQU2 ## TOC removal rate (%) = ｛(C _o −C _BO ) − (C
₂₈ -C _B28 ) / (C _o -C _BO )｝ × 100 where C _o : TOC (mg / l) in the test solution at the start of the test C ₂₈ : TOC (mg / l) in the test solution after 28 days l) C _BO : TOC at the start of the test (blank test solution) without the test substance (blank test solution) C _B28 : TOC (mg) after 28 days of the system without the test substance (blank test solution) / l).

The biodegradation rate after 28 days was 60.3%.

The fumaric acid solution from which ammonia generated during polymerization was collected was concentrated under reduced pressure to 300 ml, and 40 g of fumaric acid, 77.5 g of 25% ammonia, and 0.13 g of M
Add the gSO ₄ · 7H ₂ O, pH8.3,500m
l. This solution was applied to a column packed with immobilized aspartase in the same manner as above at a rate of 5 ml / h (SV = 0.5).
And a continuous reaction was performed. The reaction solution was analyzed 3 hours after the start of the reaction, and as a result, L-aspartic acid was produced in a substantially equimolar amount with fumaric acid consumed as a reaction product, and the reaction conversion was 99.7%. Thus, the collected ammonia could be reused in the next enzymatic reaction with aspartase.

Example 2 In place of the solution in which the enzyme reaction was carried out in the column, D.I. Polymerization was carried out in the same manner as in Example 1 except that 500 ml of an ammonium salt solution of L-aspartic acid (23% aspartic acid, pH 8.3, neutralized with ammonia) was used.

The obtained polysuccinimide was used in Example 1
The weight average molecular weight was determined to be about 7,000 by GPC using sodium polyaspartate as described above. When this solution was analyzed by HPLC, no peak of aspartic acid was detected, and the polymer yield was almost 100%.
Met.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradability test.
The biodegradation rate in 28 days was 60.3%.

As in Example 1, the fumaric acid solution from which ammonia was collected was readjusted, and a continuous reaction was performed with immobilized aspartase. The reaction solution was analyzed three hours after the start of the reaction. As a result, L-aspartic acid was produced in a substantially equimolar amount with fumaric acid consumed as a reaction product, and the conversion was 99.6%. Thus, the collected ammonia could be reused for the next enzymatic reaction with aspartase.

Example 3 Example 1 except that 11 g of boric acid was used as the acid catalyst.
Polymerization was carried out in the same manner as described above. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight average molecular weight measured by GPC was about 70.
00. When this solution was analyzed by HPLC,
No aspartic acid peak was detected, and the polymer yield was almost 100%.

After dialyzing this sodium polyaspartate in the same manner as in Example 1, a biodegradability test was conducted.
The biodegradation rate in 28 days was 61.7%.

As in Example 1, the fumaric acid solution from which ammonia was collected was readjusted, and a continuous reaction was performed with immobilized aspartase. When the reaction solution was analyzed 3 hours after the start of the reaction, L-aspartic acid was produced in an amount substantially equal to the consumed fumaric acid as a reaction product, and the conversion was 99.7%. Thus, the collected ammonia could be reused for the next enzymatic reaction with aspartase.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the polymerization time was changed to 18 hours without using a catalyst. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, aspartic acid remained, and the polymer yield was 82%.
%Met. After the sodium polyaspartate was dialyzed in the same manner as in Example 1, a biodegradability test was performed.
The biodegradation rate in 28 days was 45.5%.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that sulfuric acid was used as the acid catalyst. The obtained polysuccinimide was prepared in Example 1.
The weight average molecular weight was determined to be about 7,000 by GPC using sodium polyaspartate as described above. When this solution was analyzed by HPLC, aspartic acid remained, and the polymer yield was 68%. After the sodium polyaspartate was dialyzed in the same manner as in Example 1, a biodegradability test was performed. The biodegradation rate in 28 days was 41.8%.

Example 4 Polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was changed to 190 ° C. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, no peak of aspartic acid was detected, and the polymer yield was almost 100%.
%Met.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradation test. 2
The biodegradation rate in 8 days was 62.3%.

As in Example 1, the fumaric acid solution from which ammonia was collected was readjusted, and a continuous reaction was carried out using immobilized aspartase. When the reaction solution was analyzed three hours after the start of the reaction, L-aspartic acid was produced in a substantially equimolar amount to fumaric acid consumed as a reaction product, and the conversion was 99.5%. Thus, the collected ammonia could be reused in the next enzymatic reaction using aspartase.

Example 5 Example 4 except that 11 g of boric acid was used as the acid catalyst.
Polymerization was carried out in the same manner as described above. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight average molecular weight measured by GPC was about 70.
00. When this solution was analyzed by HPLC,
No aspartic acid peak was detected, and the polymer yield was almost 100%.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradation test. 2
The biodegradation rate in 8 days was 62.8%.

As in Example 1, the fumaric acid solution from which ammonia was collected was readjusted, and a continuous reaction was performed with immobilized aspartase. When the reaction solution was analyzed three hours after the start of the reaction, L-aspartic acid was produced in a substantially equimolar amount to fumaric acid consumed as a reaction product, and the conversion was 99.5%. Thus, the collected ammonia could be reused for the next enzymatic reaction with aspartase.

Example 6 Polymerization was carried out in the same manner as in Example 4 except that the polymerization temperature was changed to 180 ° C. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, no peak of aspartic acid was detected, and the polymer yield was almost 100%.
%Met.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradation test. 2
The biodegradation rate in 8 days was 63.5%.

As in Example 1, the fumaric acid solution from which ammonia was collected was readjusted, and a continuous reaction was performed with immobilized aspartase. When the reaction solution was analyzed 3 hours after the start of the reaction, L-aspartic acid was produced in an amount substantially equal to the consumed fumaric acid as a reaction product, and the conversion was 99.7%. Thus, the collected ammonia could be reused for the next enzymatic reaction with aspartase.

Example 7 Example 6 was repeated except that 11 g of boric acid was used as the acid catalyst.
Polymerization was carried out in the same manner as described above. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight average molecular weight measured by GPC was about 70.
00. When this solution was analyzed by HPLC,
No aspartic acid peak was detected, and the polymer yield was almost 100%.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradation test. 2
The biodegradation rate in 8 days was 62.8%.

The fumaric acid solution from which ammonia was collected was readjusted in the same manner as in Example 1, and a continuous reaction was carried out using immobilized aspartase. When the reaction solution was analyzed 3 hours after the start of the reaction, L-aspartic acid was produced in an amount substantially equal to the consumed fumaric acid as a reaction product, and the conversion was 99.7%. Thus, the collected ammonia could be reused in the next enzymatic reaction using aspartase.

Example 8 Polymerization was carried out in the same manner as in Example 4 except that the polymerization temperature was 170 ° C. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 53%.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradation test. 2
The biodegradation rate in 8 days was 63.5%.

Example 9 Example 6 except that 11 g of boric acid was used as the acid catalyst.
Polymerization was carried out in the same manner as described above. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight average molecular weight measured by GPC was about 70.
00. When this solution was analyzed by HPLC,
Aspartic acid remains and the polymer yield is 79%
Met.

This sodium polyaspartate was dialyzed in the same manner as in Example 1 and then subjected to a biodegradation test. 2
The biodegradation rate in 8 days was 63.5%.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 4 except that no acid catalyst was used. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 60%.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 4 except that 11 g of sulfuric acid was used as an acid catalyst. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight-average molecular weight measured by PC was about 700.
It was 0. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 60%.

Comparative Example 5 Polymerization was carried out in the same manner as in Example 6 except that no acid catalyst was used. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 35%.

Comparative Example 6 Polymerization was carried out in the same manner as in Comparative Example 5, except that 11 g of sulfuric acid was used as an acid catalyst. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight-average molecular weight measured by PC was about 700.
It was 0. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 48%.

Comparative Example 7 Polymerization was carried out in the same manner as in Example 8 except that no acid catalyst was used. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and the weight average molecular weight measured by GPC was about 7,000. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 25%.

Comparative Example 8 Polymerization was carried out in the same manner as in Comparative Example 7, except that 11 g of sulfuric acid was used as the acid catalyst. The resulting polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1,
The weight-average molecular weight measured by PC was about 700.
It was 0. When this solution was analyzed by HPLC, aspartic acid remained, and the yield of the polymer was 30%.

Comparative Example 9 Polymerization was carried out in the same manner as in Example 1 except that the polymerization temperature was changed to 160 ° C. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1 and analyzed by HPLC. Aspartic acid remained, and the yield of the polymer was 22%.

Comparative Example 10 Polymerization was carried out in the same manner as in Example 3 except that the polymerization temperature was changed to 160 ° C. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1 and analyzed by HPLC. Aspartic acid remained, and the yield of the polymer was 7.5%.

Comparative Example 11 Polymerization was carried out in the same manner as in Comparative Example 1 except that the polymerization temperature was changed to 160 ° C. The obtained polysuccinimide was converted into sodium polyaspartate in the same manner as in Example 1 and analyzed by HPLC. Aspartic acid remained, and the yield of the polymer was 41%.

Comparative Example 12 Polymerization was carried out in the same manner as in Comparative Example 2 except that the polymerization temperature was changed to 160 ° C. The obtained polysuccinimide was converted into sodium polyaspartate in the same manner as in Example 1 and analyzed by HPLC. Aspartic acid remained, and the yield of the polymer was 26%.

Comparative Example 13 Polymerization was carried out in the same manner as in Comparative Example 1 except that the polymerization temperature was changed to 240 ° C. The obtained polysuccinimide was converted into sodium polyaspartate in the same manner as in Example 1 and analyzed by HPLC. Aspartic acid had disappeared, and the yield of the polymer was almost 100%.

After the polyaspartic acid was dialyzed in the same manner as in Example 1, a biodegradability test was conducted. The biodegradation rate in 28 days was 38.6%.

Example 10 Pseudomonas fluorescens NSM-4 strain (FE
RM P-15560) was inoculated into 10 test tubes containing 3 ml of the medium shown in Table 2 below, cultured at 37 ° C. for 8 hours, and then placed in 10 Sakaguchi flasks containing 100 ml of the medium shown in Table 2 each.
This was inoculated one by one, and cultured with shaking at 30 ° C. overnight. Cells were collected from this culture by centrifugation. The activity of the cells to produce aspartase from maleic acid was measured to be 0.03 moles L-aspartic acid / h
r / g cells. Table 2 Medium composition

[0077]

[Table 2]

Sterilization in an autoclave at 121 ° C. for 15 minutes In the same manner as in Example 1, bacteria were sterilized with PAS-880 (manufactured by Nitto Boseki) and an ion exchange resin (Amberlite IRA-96SBCl type manufactured by Organo, average particle size 0.5 mm). The cells were immobilized to obtain immobilized microbes containing maleate isomerase and aspartase. The activity of the immobilized cells to produce L-aspartic acid from ammonium maleate was 120 U / ml. After immersing the prepared immobilized aspartase in a 20% ammonium maleate solution at 4 ° C. overnight,
The reactor was thermally insulated by filling the column with 00 ml and keeping the outside of the column warm with foamed polystyrene. This column was kept at 20 ° C in a constant temperature water bath at 20 ° C.
Substrate solution (200 g of maleic acid in 1 L, 170 g of 2
5% ammonia water, MgSO of 0.25g ₄ · 7H ₂ O,
PH 8. with 1 ml of mercaptoethanol and ammonia.
3) through a Teflon tube wrapped with insulation
A continuous reaction was carried out at a flow rate of 2 ml / hour (SV = 0.2). When the reaction solution was analyzed three hours after the start of the reaction, L-aspartic acid was produced as a reaction product in an approximately equimolar amount to the consumed maleic acid, and the reaction conversion was 99.6%. Was. 200 ml of L-ammonium L-aspartate solution produced by flowing through the column was placed in a stainless steel vat,
After mixing 11 g of orthophosphoric acid, the mixture was placed in a vacuum drier at 210
Heating and decompression were performed at 8 ° C. for 8 hours. The pressure is reduced by evacuating with a diaphragm vacuum pump.
0 mmHg, and exhaust was performed with 24 g of maleic acid and 24 g of water.
The ammonia was collected through a trap containing ml.
Four hours later, the amount of liquid in the trap was about 200 ml due to the ammonia released during the polymerization.

The polysuccinimide obtained by polymerization is 3
It was 8.6 g. The obtained polysuccinimide was converted to sodium polyaspartate in the same manner as in Example 1, and GP
The weight average molecular weight was measured by C to be about 7000
Met. When this solution was analyzed by HPLC, no peak of aspartic acid was detected, and the polymer yield was almost 100%.

The maleic acid solution from which ammonia was collected at the time of polymerization was concentrated under reduced pressure to 150 ml.
g of 25% ammonia water 31g, MgSO ₄ · 7H ₂ O
0.05 g and 0.15 ml of mercaptoethanol were added, and the pH was adjusted to 8.3 and 200 ml with ammonia. This solution was passed through a column filled with fresh immobilized cells at a rate of 2 ml / hour (SV = 0.2) to perform a continuous reaction in the same manner as above. When the reaction solution was analyzed three hours after the start of the reaction, L-aspartic acid was produced in a substantially equimolar amount to the consumed maleic acid as a reaction product, and the reaction conversion was 99.7%. .

Thus, the collected ammonia could be reused in the enzymatic reaction with the following maleate isomerase and aspartase.

Example 11 500 ml of the reaction solution and boric acid 1 in the same column as in Example 1 were used.
1.5g to 1L kneader (Irie Shokai, BENCH KNEADER
PNV-1HS) and heated under reduced pressure at 190 ° C. The pressure was reduced by evacuating with a diaphragm vacuum pump, and the exhaust was circulated through a suspension containing 60 g of fumaric acid and 60 ml of water to collect ammonia. Two hours later, the fumaric acid was completely dissolved by the ammonia released during the polymerization. Further, the liquid volume was about 500 ml. The amount of polysuccinimide obtained by polymerization was 107 g.

10 g of this polysuccinimide was added to 70 m of water.
and a 10N aqueous sodium hydroxide solution was added to dissolve the polysuccinimide to adjust the pH to 10. The solution was heated to 90 ° C., and the gas phase was blown with nitrogen to circulate the remaining ammonia in order to drive out the remaining ammonia. Thus, an aqueous solution of sodium polyaspartate was obtained. The aspartic acid in this solution is replaced with H
When analyzed by PLC, no peak of aspartic acid was detected, and the polymer yield was almost 100%.

The fumaric acid solution from which ammonia was collected during polymerization was concentrated under reduced pressure to 300 ml, and 40 g of fumaric acid, 77.5 g of 25% aqueous ammonia and 0.13 g of MgSO
₄ · 7H ₂ O, by adding, was pH8.3,500ml. This solution was passed through a column packed with immobilized aspartase at a rate of 5 ml / h (SV = 0.5) to carry out a continuous reaction in the same manner as above. When the reaction solution was analyzed three hours after the start of the reaction, L-aspartic acid was produced as a reaction product in an amount substantially equal to the consumed fumaric acid, and the reaction conversion rate was 99.7%. Was. Thus, the collected ammonia could be reused for the next enzymatic reaction with aspartase.

[0085]

According to the present invention, a succinimide-based polymer having excellent biodegradability can be produced by an extremely simple method. Further, an aspartic acid-based polymer having excellent biodegradability can be easily produced from the obtained succinimide-based polymer.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4J043 PA02 QB06 RA34 SA05 SA62 SA66 SB01 UA761 XA03 XB13 YB08 YB14 ZA03 ZB31 ZB41

Claims (6)

[Claims] 1. A method for producing a succinimide-based polymer, comprising subjecting an ammonium salt of an amino acid containing aspartic acid to heat polymerization in the presence of an acid catalyst. 2. An acid catalyst comprising at least one P-OH
A phosphoric acid derivative having a bond or at least one B
The method according to claim 1, wherein a boron derivative having an -OH bond is used. 3. The method according to claim 1, wherein the ammonium salt of aspartic acid is used as an aqueous solution, and the acid catalyst is uniformly dissolved and used. 4. The method according to claim 1, wherein the reaction temperature is 150 to 220 ° C. 5. The method according to claim 1, wherein the amount of the acid catalyst used is 0.5 to 40% by weight based on the amino acid. 6. A method for producing an aspartic acid-based polymer, comprising contacting a succinimide-based polymer obtained according to any one of claims 1 to 5 with a basic substance and hydrolyzing the same.