JPH09316197A - Biodegradable material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable material which has a high biodegradability and is useful for a fertilizer, a scale inhibitor, a builder, a humectant, a dispersant, etc., by hydrolyzing polyaspatic anhydride having specific terminal groups. SOLUTION: This biodegradable material is prepd. by hydrolyzing polyaspartic anhydride having the number of terminal functional groups satisfying the formula and contains polyaspartic acid and/or its salt. The decomposition ratio of this material based on the measurement of the amt. of total org. carbon in a biodegradability test [the modified MITI (II) method] is 60% or higher. Polyaspartic anhydride is obtd. e.g. by reacting the reaction product of maleic acid and ammonia with maleamic acid and/or aspartic acid in the absence or presence of a solvent and in the absence or presence of a catalyst.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a biodegradable material containing polyaspartic acid and / or a salt thereof, which exhibits high biodegradability and is useful as a fertilizer, scale inhibitor, builder, humectant, dispersant, and the like. It is about.

[0002]

2. Description of the Related Art Polyaspartic acid has attracted attention as a substitute for polyacrylic acid because of its biodegradability. However, homopolymers of polyaspartic acid, particularly polyaspartic acid obtained by a production method that does not use a solvent or a catalyst, are still insufficient in biodegradability as they are. Regarding the biodegradability of polyaspartic acid, JP-A-7-3010 has a correlation with the ratio of the total amount of CH groups to the total amount of NH groups in the succinimide portion of polyaspartic anhydride which is a precursor of polyaspartic acid. However, as a result of intensive studies conducted by the present inventors, this method does not necessarily depend on the ratio of the total amount of CH groups to the total amount of NH groups in the succinimide portion of polyaspartic anhydride. It turned out that biodegradability was not obtained.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a biodegradable material containing polyaspartic acid and / or a salt thereof having good biodegradability. An easy manufacturing method is provided. The term “good biodegradability” refers to a substance which shows a decomposition of 60% or more in total organic carbon (TOC) described later.

[0004]

Means for Solving the Problems The present inventor has proposed a method for obtaining polyaspartic acid excellent in biodegradability,
As a result of diligent study, focusing on the terminal structure of anhydrous polyaspartic acid used as a raw material and examining the relationship between this structure and biodegradability, we selected a specific terminal structure and obtained it by hydrolysis. The present inventors have found that the obtained polymer has particularly good biodegradability, and arrived at the present invention. That is, the gist of the present invention is to provide a biodegradable material characterized in that it contains polyaspartic acid obtained by hydrolyzing polyaspartic anhydride having a functional number at the terminal satisfying the following formula (1) and / or a salt thereof. And its manufacturing method.

[0005]

(Equation 3)

Hereinafter, the present invention will be described in detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION

(Aspartic acid terminal, succinimide terminal) where
The aspartic acid terminal structure (I) and succinimide terminal structure (II) of anhydrous polyaspartic acid have the following structural formulas, respectively.

[0008]

Embedded image

The value represented by {(number of aspartic acid terminals) / (number of aspartic acid terminals + number of succinimide terminals)} × 100 means aspartic acid relative to the sum of the number of aspartic acid terminals of anhydrous polyaspartic acid and the number of succinimide terminals. It is a percentage of the number of terminals. In the present invention, it is important that this percentage is 60 or more. This ratio in the present invention is calculated from the number of each terminal per 100 monomer units in polyaspartic anhydride.

In the present invention, 100 monomer units are used.
The number of aspartic acid terminals ¹³Stereo by C-NMR
Asparagi mainly split into two due to the influence of regularity
168. Assigned to one carbonyl carbon at the acid terminal
200 times the sum of the signal areas of 8 ppm is 165-18
Divide by the sum of the signal areas of all carbonyl carbons at 0 ppm
It was obtained by doing.

The number of succinimide terminals per 100 monomer units is 4.2-5.8 pp based on the signal area of 11.6 ppm attributed to imide hydrogen in ¹ H-NMR.
It is obtained by dividing by the sum of the signal areas of all methine hydrogens in m and multiplying by 100. A “GS × 400 NMR spectrometer” manufactured by JEOL Ltd. was used for NMR measurement. Also, 100 mg of anhydrous polyaspartic acid dissolved in 0.5 ml of deuterated dimethyl sulfoxide was used as a sample.

¹³ C-NMR shows a resonance frequency of 100.5M.
Hz, observation width 23 kHz, number of points 32 k, flip angle 45 °, pulse interval 15 seconds, integration number 4000-10
000 at a temperature of 60 ° C., and tetramethylsilane was used as a standard for chemical shift. ¹ H-NMR has a resonance frequency of 3
99.8MHz, observation width 6kHz, number of points 32k,
Flip angle 45 °, pulse interval 15 seconds, integration number 32,
It was measured at a temperature of 24 ° C., and tetramethylsilane was used as a standard for chemical shift. The polyaspartic acid anhydride used in the present invention has a ratio of the number of terminal functional groups thereof in the following general formula (2) of 60 or more, preferably 65 or more, more preferably 70 or more.

[0013]

(Equation 4)

(Polyanhydroaspartic anhydride) The polyaspartic anhydride used in the present invention is not particularly limited in its production method as long as it satisfies the condition of the above general formula (1). For example, maleic acid is used as a reaction monomer. Product obtained by reacting ammonia, maleamic acid and / or
Or aspartic acid in the presence or absence of a solvent,
It can be obtained by reacting in the presence or absence of a catalyst.

The product obtained by reacting maleic acid with ammonia is obtained by reacting maleic acid with ammonia, for example,
DE 3,626,672, US 4,839,4
A product obtained by the reaction according to the method described in US Pat. No. 61, US Pat. No. 5,286,810. Specifically, it may contain products such as maleic acid, maleic acid diammonium salt, ammonia, fumaric acid, aspartic acid, asparagine, iminodisuccinic acid, maleamic acid and the like.

The maleic acid used in the above reaction includes its anhydrides, partial and complete esters. Ammonia is used as a gas or solution. When used as a solution,
A method of dissolving in water to make an ammonium hydroxide aqueous solution,
For example, a method of dissolving in alcohol such as methanol or ethanol, or another appropriate organic solvent is used. Maleamic acid can be obtained by heating a mono- or di-ammonium maleate salt.

Aspartic acid may be D-form, L-form or a mixture thereof. Further, other than these components, other copolymerizable monomers may be used within a range not exceeding 50% by weight of all monomers. The copolymerizable monomer is not particularly limited, but for example, a) aspartate, b)
Glutamic acid and its salts, c) amino acids other than a) and b) such as alanine, leucine and lysine, d) hydroxycarboxylic acids such as glycolic acid, lactic acid and 3-hydroxyacetic acid, e) 2-hydroxyethanol and malein. acid,
A compound having one or more functional groups capable of reacting with an amino group such as 6-aminocaproic acid and aniline and a carboxylic acid may be included.

The presence or absence of the reaction solvent is not particularly limited. When a solvent is used, examples of usable solvents include hydrocarbon solvents, halogenated hydrocarbon solvents, ether solvents,
Examples of the solvent include a solvent having a boiling point of 100 ° C. or more, which is selected from the group consisting of an ester solvent and an aprotic polar solvent, and particularly preferably have a boiling point of 130 ° C. or more. These solvents may be used alone or in combination. Specifically, as the hydrocarbon-based solvent, xylene and diethylbenzene (each of the above two kinds may be composed of a mixture of two or more kinds of isomers, even if the two kinds are composed solely of their ortho, meta or para isomers) ), Toluene, amylbenzene, cumene, mesitylene, tetralin, halogenated hydrocarbon solvents such as chlorotoluene and dichlorobenzene (each of the above two is composed solely of its ortho, meta or para isomer) Or a mixture of two or more isomers), 1,4-dichlorobutane, chlorobenzene, ether solvents such as dichloroethyl ether, butyl ether, diisoamyl ether, anisole, and ester solvents As a solvent, n-amyl acetate,
Isoamyl acetate, methyl isoamyl acetate, cyclohexyl acetate, benzyl acetate, n-butyl propionate, isoamyl propionate, isoamyl butyrate, n-butyl butyrate, aprotic polar solvents such as N, N-dimethylformamide, N, N -Dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, tetramethylurea acid, dimethylsulfoxide, sulfolane and hexamethylphosphoramide. Among these, diethylbenzene, mesitylene, cumene, chlorotoluene, 1,4-
Dichlorobutane, diisoamyl ether, n-butyl butyrate, 1,3-dimethyl-2-imidazolidinone, and sulfolane are preferable in that they have an appropriate boiling point, and mesitylene, cumene, chlorotoluene, 1,3 −
Dimethyl-2-imidazolidinone and sulfolane are particularly preferred.

The solvent is 1 per 100 parts by weight of the monomer.
It can be used in a proportion of up to 5000 parts by weight, preferably 5 to 4000 parts by weight, more preferably 10 to 3000 parts by weight. The presence or absence of a catalyst is not particularly limited, but it is preferable to use a catalyst because the percentage of the number of terminals of aspartic acid is easily increased and, as a result, the effect of improving biodegradability becomes remarkable. When using a catalyst, an acid catalyst is preferable, and examples of the acid catalyst include inorganic acid catalysts such as sulfuric acid, sulfuric anhydride, phosphoric acid, polyphosphoric acid, metaphosphoric acid, condensed phosphoric acid, and anhydrous phosphoric acid, and p-toluenesulfonic acid. , Organic acid catalysts such as trichloroacetic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid. Among these, phosphoric acid catalysts are preferably used because the polymer can be easily obtained in high yield.

A suitable amount of these acid catalysts used is in the range of 0.002 to 0.5 mol, preferably 0.02 to 0.3 mol, per mol of the monomer. The reaction conditions are not particularly limited, but the reaction temperature is usually 100 to 30.
The temperature is 0 ° C, preferably 130 to 280 ° C. If the polycondensation temperature is less than 100 ° C, the reaction is difficult to proceed, and if it exceeds 300 ° C, decomposition products may be produced. However, in order to increase the percentage of the number of aspartic acid terminals, it is preferable to carry out at the lowest temperature possible.

The pressure during the reaction is not particularly limited and may be normal pressure,
Either reduced pressure or increased pressure may be used, but normal pressure or reduced pressure is preferred. The reaction time is 1 second to 100 hours, preferably 1
It is 0 second to 50 hours, most preferably 20 seconds to 10 hours. Further, the substantial end point of the reaction is a point at which the generation of water by-produced during the reaction has ceased.

An amine or the like may coexist during the polycondensation reaction for the purpose of controlling the molecular weight. The post-treatment step can be appropriately selected according to the use of the polymer. For example, it can be carried out by a conventional method such as a method of removing the solvent by centrifugation or a method of washing with water or a low boiling point solvent after centrifugation. Examples of these polycondensation reactions are described in JP-B-48-2038, US Pat. No. 4,839,461.
Specification, US 5,057,597 Specification, US 5,
219,986 specification, EP578,449 specification, etc. are mentioned. In order to efficiently obtain the polyaspartic acid anhydride specified in the present invention, it is usually desirable to carry out the polymerization reaction at a relatively low temperature in a short time using a catalyst. still,
The preferred weight average molecular weight of anhydrous polyaspartic acid is G
It is 5,000 to 150,000 by the PC method, and more preferably 10,000 to 100,000.

(Hydrolysis) The hydrolysis of polyaspartic anhydride in the method of the present invention can be carried out by a conventional method. Am. Che
m. Soc. 80, 3361 (1958), J. Or
g. Chem. 26, 1084 (1961), US5
No. 221,733, US Pat. No. 5,288,783, JP-A-60-203636 and the like. The salt of polyaspartic acid is obtained by hydrolyzing anhydrous polyaspartic acid. Examples of the salt of polyaspartic acid include alkali metal salts and alkaline earth metal salts. Preferred are alkali metal salts, and more preferred are sodium and potassium salts.

(Biodegradable Material) As described above, the biodegradable material of the present invention contains polyaspartic acid and a salt thereof which are produced by using the specific polyaspartic anhydride as an intermediate. Other components that may be included include polymers such as polyolefins, polyesters, and polyamides, and polymer additives such as plasticizers, colorants, and fillers. The preferred weight average molecular weight of the polyaspartic acid is G
It is 2,000 to 150,000 according to the PC method, and more preferably 5,000 to 100,000.

(Biodegradability) The biodegradability of the present invention is the biodegradation test method (modified MIT) of a new chemical substance shown in the Chemical Substances Control Law.
I (II) method) is a measurement method based on
The decomposition rate is a value obtained as a percentage based on the measurement of the total organic carbon content (TOC). Specifically, at the start of the biodegradability test, the total organic carbon content of the organic matter in the sample in the culture solution is measured. Thereafter, the carbon in the sample is partially decomposed and removed as carbon dioxide gas for 28 days, so that the amount of organic carbon decreases. The reduced total organic carbon amount was determined by measuring the total organic carbon remaining in the culture solution after 28 days, and the reduced total organic carbon amount was divided by the total organic carbon amount at the start of the test to calculate the decomposition rate as a percentage. It is. Good biodegradability in the present invention means the above TO
C refers to a substance showing 60% or more of decomposition. Less than,
The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0026]

【Example】

1) Measurement of weight average molecular weight Tosoh Corporation “TSKgel” “GMHHR-M”
+ Polystyrene conversion value obtained by gel permeation chromatography (differential refractometer) using dimethylformamide with 10 mM LiBr added as an eluent, using a “TSKgel” “G2000HHR” column.

2) {(number of aspartic acid terminals) / (number of aspartic acid terminals + number of succinimide terminals)} × 100
The calculation of {(number of aspartic acid terminals) / (number of aspartic acid terminals + number of succinimide terminals)} × 100 is the percentage of the number of aspartic acid terminals to the total number of aspartic acid terminals and the number of succinimide terminals of anhydrous polyaspartic acid. . This ratio was calculated from the number of each terminal per 100 monomer units in the polyaspartic anhydride based on the NMR signal area.

The number of aspartic acid terminals per 100 monomer units is a signal at 168.8 ppm assigned to one carbonyl carbon at the aspartic acid terminal which is mainly split into two due to the effect of stereoregularity in ¹³ C-NMR. It was determined by dividing 200 times the sum of the areas by the sum of the signal areas of all carbonyl carbons at 165-180 ppm.

The number of succinimide terminals per 100 monomer units is 4.2-5.8 pp based on the signal area of 11.6 ppm assigned to imide hydrogen by ¹ H-NMR.
It was determined by dividing by the sum of the signal areas of all methine hydrogens in m and multiplying by 100. A “GS × 400 NMR spectrometer” manufactured by JEOL Ltd. was used for NMR measurement. A sample was prepared by dissolving 100 mg of anhydrous polyaspartic acid in 0.5 ml of deuterated dimethyl sulfoxide.

¹³ C-NMR shows a resonance frequency of 100.5 M
Hz, observation width 23 kHz, number of points 32 k, flip angle 45 °, pulse interval 15 seconds, integration number 4000-10
000 at a temperature of 60 ° C., and tetramethylsilane was used as a standard for chemical shift. ¹ H-NMR has a resonance frequency of 3
99.8MHz, observation width 6kHz, number of points 32k,
Flip angle 45 °, pulse interval 15 seconds, integration number 32,
It was measured at a temperature of 24 ° C., and tetramethylsilane was used as a standard for chemical shift.

3) Biodegradability test method The biodegradability was measured in accordance with the biodegradability test method (modified MITI (II) method) of new chemical substances shown in the Chemical Substances Control Law. Activated sludge purchased from the Chemical Inspection Association was used as the microorganism (activated sludge) used in this test. The test conditions are, specifically, activated sludge concentration: 30 mg / l, sample concentration: 10
0 mg / l, test solution amount; 300 ml, test temperature; 25 ±
1 ° C., test period; 28 days, standard substance: performed with aniline.

The decomposition rate was obtained as a percentage based on the measurement of the total organic carbon content (TOC). Specifically, at the start of the biodegradability test, the total organic carbon content of the organic matter in the sample in the culture solution is measured. Thereafter, the carbon in the sample is partially decomposed and removed as carbon dioxide gas for 28 days, so that the amount of organic carbon decreases. The reduced total organic carbon amount was obtained by measuring the total organic carbon remaining in the culture medium after 28 days, and the reduced total organic carbon amount was divided by the total organic carbon amount at the start of the test to calculate the decomposition rate as a percentage. A closed system oxygen consumption measuring device (Okura Electric's self-recording BOD meter) was used as a biodegradability test device, and a TOC meter (TOC manufactured by Shimadzu Corporation) was used as a total organic carbon measuring device.
-5000).

Example 1 In a 200 ml four-necked flask equipped with a condenser, a thermometer, a stirrer and a water separator, L
25 g of aspartic acid, 1.3 g of 85% phosphoric acid, 56 g of mesitylene and 24 g of sulfolane were charged. Then, polycondensation was carried out under normal pressure and under reflux of mesitylene (162 ° C.) for 4.5 hours. Water generated during the reaction was distilled out of the system together with a part of mesitylene. After completion of the reaction, the mixture was filtered off, and the product was washed four times with 100 g of pure water and 100 g of methanol.
Was washed once. Next, this was dried under reduced pressure at 80 ° C. for 24 hours to obtain a yellow-white powder. The weight average molecular weight of this polyaspartic anhydride was 70,000, and the conversion to a polymer was 98.0%.

When the polymer terminal of this anhydrous polyaspartic acid was analyzed by NMR, {(aspartic acid terminal) / (aspartic acid terminal + succinimide terminal)}
× 100 = 94. 3 g of anhydrous polyaspartic acid and 10 g of water were charged, an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice cooling, and then the mixture was stirred for 1 hour for hydrolysis. After the hydrolysis, the reaction solution was poured into 300 ml of methanol to cause precipitation, thereby obtaining an aspartic acid copolymer sodium salt. T of this sodium salt of aspartic acid copolymer
When the OC was measured, the decomposition rate was 90%.

<Example 2> Under a nitrogen gas atmosphere, 5.0 kg of L-aspartic acid and 500 g of 85% phosphoric acid were mixed with a "super mixer" (manufactured by Kawata Co., Ltd.) for 5 minutes to disperse the catalyst. It was The polycondensation reaction is performed by "KRC Kneader" (50φ x 661.5L, L manufactured by Kurimoto Steel Works Co., Ltd.)
/D=13.2) was used as follows. The heating medium was set to 260 ° C., the screw rotation speed was set to 30 rpm, and the mixture of L-aspartic acid and phosphoric acid obtained above was supplied so that the discharge rate was 1 kg / hr, and polycondensation was performed. The obtained polyaspartic anhydride had a weight average molecular weight of 17,000 and a conversion to a polymer of 99.9% or more.

As a result of analyzing the functional group at the polymer terminal of the anhydrous polyaspartic acid by NMR, it was {(number of terminal of aspartic acid) / (number of terminal of aspartic acid + number of terminal of succinimide)} × 100 = 96. 3 g of anhydrous polyaspartic acid and 10 g of water were charged, an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice cooling, and then the mixture was stirred for 1 hour for hydrolysis. After the hydrolysis, the reaction solution was poured into 300 ml of methanol to cause precipitation, thereby obtaining an aspartic acid copolymer sodium salt. When the TOC of this sodium salt of aspartic acid copolymer was measured, the decomposition rate was 75%.

Example 3 200 g of L-aspartic acid was placed in a 500 ml four-necked flask equipped with a condenser, a thermometer and a stirrer. Then, in the system, 1330 Pa
Polycondensation was carried out for 3 hours while reducing the pressure to 2, and heating with an oil bath maintained at 230 ° C. Since the conversion rate of the product to polyaspartic anhydride was 82.3%, the product was washed and filtered 5 times with a large excess of water to remove unreacted monomers. The weight average molecular weight of the obtained anhydrous polyaspartic acid was 15,700.

As a result of analyzing the polymer terminal of the anhydrous polyaspartic acid by NMR, it was {(number of aspartic acid terminal) / (number of aspartic acid terminal + number of succinimide terminal)} × 100 = 64. 3 g of anhydrous polyaspartic acid and 10 g of water were charged, an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice cooling, and then the mixture was stirred for 1 hour for hydrolysis. After the hydrolysis, the reaction solution was poured into 300 ml of methanol to cause precipitation, thereby obtaining an aspartic acid copolymer sodium salt. When the TOC of this sodium salt of aspartic acid copolymer was measured, the decomposition rate was 70%.

<Comparative Example 1> 200 g of L-aspartic acid was placed in a 500 ml four-necked flask equipped with a condenser, a thermometer and a stirrer. Then, inside the system under a nitrogen stream,
The polycondensation was performed for 6 hours while heating with an oil bath maintained at 260 ° C. The conversion rate to the obtained anhydrous polyaspartic acid was 97.0%, and the weight average molecular weight was 13,000. As a result of analyzing the polymer terminal of this anhydrous polyaspartic acid by NMR, {(number of aspartic acid terminal) / (number of aspartic acid terminal + number of succinimide terminal)} × 10
It was 0 = 41.

The above-mentioned 3 g of polyaspartic anhydride and 10 g of water were charged, and 1.4 g of sodium hydroxide was added under ice-cooling.
Was dissolved in 20 g of water, and then the mixture was stirred for 1 hour for hydrolysis. After the hydrolysis, the reaction solution was poured into 300 ml of methanol to cause precipitation, thereby obtaining an aspartic acid copolymer sodium salt. When the TOC of this sodium salt of aspartic acid copolymer was measured, the decomposition rate was 46%.

Comparative Example 2 200 g of L-aspartic acid was charged in a 500 ml four-necked flask equipped with a condenser, a thermometer and a stirrer. Then, in the system, 1330 Pa
Polycondensation was carried out for 5 hours while reducing the pressure to 2, and heating with an oil bath maintained at 230 ° C. Since the conversion rate of the product to anhydrous polyaspartic acid was 90.0%, the product was repeatedly washed and filtered 5 times with a large excess of water to remove unreacted monomers. The weight average molecular weight of the obtained anhydrous polyaspartic acid was 20,000.

As a result of analyzing the polymer terminal of this anhydrous polyaspartic acid by NMR, {(number of aspartic acid terminal) / (number of aspartic acid terminal + number of succinimide terminal)} × 100 = 50. 3 g of anhydrous polyaspartic acid and 10 g of water were charged, an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice cooling, and then the mixture was stirred for 1 hour for hydrolysis. After the hydrolysis, the reaction solution was poured into 300 ml of methanol to cause precipitation, thereby obtaining an aspartic acid copolymer sodium salt. When the TOC of this sodium salt of aspartic acid copolymer was measured, the decomposition rate was 45%.

[0043]

According to the present invention, polyaspartic acid anhydride having a specific terminal structure is selected as a raw material, and this hydrolyzate is used as a biodegradable material. Therefore, the TOC is always 60% or more and high biodegradability is maintained. It is shown.

Claims (3)

[Claims] 1. A biodegradable material comprising a polyaspartic acid obtained by hydrolyzing polyaspartic anhydride and / or a salt thereof, wherein the number of functional groups at the terminal satisfies the following formula (1). [Equation 1] 2. A biodegradability test method (modified MITI (II)
Method, the decomposition rate is 60 based on the measurement of total organic carbon content.
% Or more, biodegradable material according to claim 1. 3. A method for producing a biodegradable material, which comprises hydrolyzing polyaspartic anhydride having a terminal functional group satisfying the following formula (1). [Equation 2]