JPH09221546A - Biodegradable material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biodegradable material having a high biodegradability by hydrolyzing polyaspartic anhydride having a specified terminal structure. SOLUTION: This material contains polyaspartic acid and/or its salt formed by hydrolyzing polyaspartic anhydride having the number of terminal functional groups satisfying the formula.

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 produced by a production method that does not use a solvent or a catalyst, still have insufficient biodegradability as it is. 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 As a result of diligent studies on the biodegradability of polyaspartic acid, the present inventor has found that the biodegradability is improved when the terminal structure of an anhydrous polyaspartic acid is specified. The present invention has been accomplished, and as a result of detailed analysis of its terminal structure using NMR, the present invention has been achieved.

That is, the gist of the present invention is characterized by containing polyaspartic acid obtained by hydrolyzing polyaspartic anhydride having a terminal functional group satisfying the following formula (1) and / or a salt thereof. It exists in a degradable material and a manufacturing method thereof.

[0006]

(Equation 3)

Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

(Aspartic acid terminal, succinimide terminal, maleimide terminal) Here, aspartic acid terminal structure (I), succinimide terminal structure (II) of polyaspartic anhydride is used.
The maleimide terminal structure (III) refers to the following structural formulas, respectively.

[0009]

Embedded image

The value represented by {(the number of aspartic acid terminals) / (the number of aspartic acid terminals + the number of succinimide terminals + the number of maleimide terminals)} × 100 means the number of aspartic acid terminals, the number of succinimide terminals and the number of succinimide terminals of anhydrous polyaspartic acid. It is the percentage of the number of aspartic acid terminals to the total number of maleimide terminals. In the present invention, this percentage is 50
It is important that this is the case.

In the present invention, this ratio is defined as anhydrous polyas
Per 100 units of monomer units in p- formic acid
It is calculated from the number. In the present invention, the monomer
The number of aspartic acid terminals per 100 units is ¹³C
-Split mainly into two due to stereoregularity in NMR
To one carbonyl carbon at the end of aspartic acid
200 times the sum of the 168.8 ppm signal area
The signal of the total carbonyl carbon at 165-180 ppm
It is obtained by dividing by the sum of the areas.

The number of succinimide terminals per 100 monomer units is 4.2 to 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. Monomer unit 10
The number of maleimide terminals per 0 was 4.2 times 50 times the sum of the signal areas of 7.1 ppm attributed to unsaturated hydrogen at the maleimide terminal which was split into a plurality by ¹ H-NMR due to the effect of stereoregularity. It is determined by dividing by the sum of the signal areas of all methine hydrogens at -5.8 ppm.

For NMR measurement, "G" manufactured by JEOL Ltd.
SX400 NMR spectrometer "was used. Also, 100 mg of anhydrous polyaspartic acid dissolved in 0.5 ml of deuterated dimethyl sulfoxide was used as a sample. ¹³ CN
MR has a resonance frequency of 100.5 MHz and an observation width of 23 kHz.
z, number of points 32 k, flip angle 45 °, pulse interval 15 seconds, number of integrations 4000-10000, temperature 60 ° C., and tetramethylsilane was used as a standard for chemical shift.

¹ H-NMR shows a resonance frequency of 399.8 M.
Hz, observation width 6 kHz, number of points 32 k, flip angle 45 °, pulse interval 15 seconds, number of integration times 32, temperature 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 50 or more, preferably 55 or more, more preferably 60 or more.

[0015]

(Equation 4)

(Polyanhydroaspartic acid anhydride) The polyaspartic acid 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). It can be obtained by reacting a product obtained by reacting ammonia, maleamic acid and / or aspartic acid in the presence of a solvent or without a solvent, in the presence of a catalyst or without 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.

The 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, based on 1 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.

The preferred weight average molecular weight of anhydrous polyaspartic acid is 5,000 to 150,0 according to the GPC method.
00, more preferably 10,000 to 100,000
It is. (Hydrolysis) The hydrolysis of the anhydrous polyaspartic acid in the method of the present invention can be carried out by a conventional method,
As a typical example, J. Am. Chem. So
c. 80,3361 (1958), J. Org.
Chem. 26, 1084 (1961), US
5,221,733, US Pat. No. 5,288,783
And Japanese Patent Application Laid-Open No. 60-203636.

The salt of polyaspartic acid can be obtained by hydrolyzing polyaspartic anhydride. 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 the produced polyaspartic acid and its salt with the specific polyaspartic anhydride as an intermediate.

Other components that may be contained include polymers such as polyolefins, polyesters and polyamides, polymer additives such as plasticizers, colorants and fillers.
The preferred weight average molecular weight of polyaspartic acid is GPC.
According to the method, it is 5,000 to 150,000, and more preferably 10,000 to 100,000. (Biodegradability) The biodegradability of the present invention refers to a biodegradation test method for a new chemical substance (modified MITI (II)
Method), and the decomposition rate is
The value obtained as a percentage based on the measurement of total organic carbon (TOC). Specifically, at the start of the biodegradability test, the total organic carbon content of the organic matter of the sample in the culture solution is measured. Then 2
Since carbon in the sample is partially decomposed and removed as carbon dioxide gas in 8 days, 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.

[0029]

【Example】

1) Measurement of weight average molecular weight "TSKgel""GMHHR-M" manufactured by Tosoh Corporation
+ It is a polystyrene equivalent value obtained by gel permeation chromatography (differential refractometer) using "TSKgel""G2000HHR" column and dimethylformamide to which 10 mM LiBr is added as an eluent.

2) Calculation of {(number of aspartic acid terminals) / (number of aspartic acid terminals + number of succinimide terminals + number of maleimide terminals)} × 100 {(number of aspartic acid terminals) / (number of aspartic acid terminals + number of succinimide terminals +) Maleimide terminal number)} × 10
0 is the percentage of the number of aspartic acid terminals to the total of the number of aspartic acid terminals, the number of succinimide terminals and the number of maleimide terminals of polyaspartic anhydride.

This ratio was calculated from the number of each terminal per 100 monomer units in polyaspartic anhydride, based on the NMR signal area. The number of aspartic acid terminals per 100 monomer units is mainly attributed to one carbonyl carbon at the aspartic acid terminal which is split into two due to the effect of stereoregularity in ¹³ C-NMR.
200 times the sum of the signal areas of 8.8 ppm is 165-
It was determined by dividing by the sum of the signal areas of all carbonyl carbons at 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 attributed to imide hydrogen in 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. The number of maleimide terminals per 100 monomer units was 4 times 50 times the sum of the signal areas of 7.1 ppm attributed to unsaturated hydrogen at the maleimide terminals split into a plurality by ¹ H-NMR due to the effect of stereoregularity. It was determined by dividing by the sum of the signal areas of the total methine hydrogen of .2-5.8 ppm.

For the NMR measurement, "G" manufactured by JEOL Ltd.
SX400 NMR spectrometer "was used. A sample was prepared by dissolving 100 mg of anhydrous polyaspartic acid in 0.5 ml of deuterated dimethyl sulfoxide. ¹³ C-NMR
Has a resonance frequency of 100.5 MHz, an observation width of 23 kHz,
Number of points 32k, flip angle 45 °, pulse interval 15
Second, the number of times of integration was 4000-10000, and the temperature was 60 ° C., and tetramethylsilane was used as the standard for chemical shift.

¹ H-NMR shows a resonance frequency of 399.8 M.
Hz, observation width 6 kHz, number of points 32 k, flip angle 45 °, pulse interval 15 seconds, number of integration times 32, temperature 24 ° C.
And tetramethylsilane was used as a standard for chemical shift. 3) Biodegradability test method The biodegradability was measured according to the biodegradation test method (modified MITI (II) method) of a new chemical substance 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;
00 mg / l, test solution volume; 300 ml, test temperature; 25
Performed at ± 1 ° C., test period; 28 days, standard substance: aniline.

The decomposition rate was calculated as a percentage based on the measurement of the total organic carbon (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 Denki's own BOD meter) was used as the biodegradability test device, and a TOC meter (Shimadzu Corporation) was used as the total organic carbon measuring device.
TOC-5000) was used. <Example 1> In a 200 ml four-necked flask equipped with a condenser, a thermometer, a stirrer and a water separator, 25 g of L-aspartic acid, 1.3 g of 85% phosphoric acid and 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 product was filtered off, and the product was washed 4 times with 100 g of pure water and once with 100 g of methanol. 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 anhydrous polyaspartic acid was 70,000, and the conversion rate to polymer was 9
It was 8.0%.

When the polymer terminal of this anhydrous polyaspartic acid was analyzed by NMR, it was {(aspartic acid terminal) / (aspartic acid terminal + succinimide terminal + maleimide terminal)} × 100 = 89. The above-mentioned 3 g of anhydrous polyaspartic acid and 10 g of water were charged, and an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice-cooling, followed by stirring for 1 hour to carry out hydrolysis. After hydrolysis, the reaction solution was
The resulting mixture was precipitated by pouring the mixture into ml to obtain an aspartic acid copolymer sodium salt.

When the TOC of this sodium salt of aspartic acid copolymer 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 for 5 minutes with a "super mixer" (manufactured by Kawata Co., Ltd.) to disperse the catalyst. The polycondensation reaction is carried out by Kurimoto Iron Works Co., Ltd.
C kneader ”(50φ × 661.5L, L / D = 13.
Using 2), the procedure was as follows.

The heating medium is 260 ° C. and the screw rotation speed is 30.
The speed was set to rpm, and the mixture of L-aspartic acid and phosphoric acid obtained above was supplied to carry out polycondensation so that the discharge rate was 1 kg / hr. 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 this anhydrous polyaspartic acid by NMR,
{(Number of aspartic acid terminals) / (number of aspartic acid terminals + number of succinimide terminals + maleimide terminals)} × 10
It was 0 = 81.

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 to perform 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 this anhydrous polyaspartic acid by NMR, it was {(number of aspartic acid terminal) / (number of aspartic acid terminal + number of succinimide terminal + number of maleimide terminal)} × 100 = 60. The above-mentioned 3 g of anhydrous polyaspartic acid and 10 g of water were charged, and an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice-cooling, followed by stirring for 1 hour to carry out 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> 500 m equipped with a cooler, a thermometer, and a stirrer
200 g of L-aspartic acid was charged into a 1-volume four-necked flask. Then, polycondensation was carried out for 6 hours while heating the system in an oil bath maintained at 260 ° C. under a nitrogen stream. The conversion rate to the obtained polyaspartic anhydride is 9
The weight average molecular weight was 7.0% and 13,000.

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 + number of maleimide terminal)} × 100 = 37. The above-mentioned 3 g of anhydrous polyaspartic acid and 10 g of water were charged, and an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice-cooling, followed by stirring for 1 hour to carry out 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> 500 m equipped with a cooler, a thermometer, and a stirrer
200 g of L-aspartic acid was charged into a 1-volume four-necked flask. Then, the pressure inside the system was reduced to 1330 Pa, and 2
Polycondensation was carried out for 5 hours while heating with an oil bath maintained at 30 ° C. The conversion of the product to anhydrous polyaspartic acid was 90.0%.
Repeated washing and filtration were performed to remove unreacted monomers.
The weight average molecular weight of the obtained anhydrous polyaspartic acid was 2
0000.

As a result of analyzing the polymer terminal of this anhydrous polyaspartic acid by NMR, it was {(the number of aspartic acid terminals) / (the number of aspartic acid terminals + the number of succinimide terminals + the number of maleimide terminals)} × 100 = 47. The above-mentioned 3 g of anhydrous polyaspartic acid and 10 g of water were charged, and an aqueous solution in which 1.4 g of sodium hydroxide was dissolved in 20 g of water was added under ice-cooling, followed by stirring for 1 hour to carry out 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%.

[0048]

The biodegradable material of the present invention has a TOC of at least 60% by a conventionally known easy production method, and is of extremely high industrial value.

Claims (2)

[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 method for producing a biodegradable material, which comprises hydrolyzing polyaspartic anhydride having a terminal functional group satisfying the following formula (1). [Equation 2]