JP2000281793A - Water-absorbent material - Google Patents

Abstract

(57) Abstract: Provided is a water-absorbing material having sufficient water-absorbing ability and biodegradability, in particular, a highly water-absorbing water-absorbing material. The present invention relates to a water-absorbing material comprising a resin obtained by reacting an anhydrous polyacidic amino acid with a protein and then hydrolyzing a reaction product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-absorbent material comprising a resin obtained by reacting an anhydrous polyacidic amino acid with a protein and then hydrolyzing a reaction product. More specifically, the present invention relates to a water-absorbing resin and a water-absorbing material which has biodegradability and can be used as a water-absorbing resin and a molded article having water-absorbing and water-retaining properties. It can be used as a water-absorbing resin such as a soil conditioner, an anti-condensation agent and a water retention agent for agriculture and horticulture.

[0002]

2. Description of the Related Art Conventionally, water-absorbing resins such as polyacrylate partially crosslinked products, starch acrylic acid copolymer hydrolysates, polyethylene oxide partially crosslinked products, and vinyl alcohol-acrylic acid copolymers have water absorbing properties. High molecular compounds are known. However, although these high molecular compounds are excellent in water absorbing ability, the materials cannot be easily decomposed into low molecules, which is a problem in consideration of environmental conservation after disposal. Further, the partially crosslinked product of polyethylene oxide has a small water absorbing ability itself and is not practical.

[0003] As a high molecular substance having both water absorption and biodegradability, natural resins such as polysaccharides and polyamino acid resins are known.

As natural resins such as polysaccharides, hyaluronic acid and polysaccharides produced by microorganisms belonging to the family Alcaligenes are known to have high water absorption (Japanese Patent Application Laid-Open No. 4-200389). Although it has a sufficient function, it is difficult to obtain it inexpensively and in large quantities by the current production method. Further, as an inexpensive water-absorbing resin using cellulose or starch as a raw material, a water-absorbing resin obtained by mixing a polysaccharide with an amino acid and drying by heating is known (JP-A-8-89796). Insufficient water absorption capacity.

As for the polyamino acid resin, a water-absorbing resin obtained by hydrolyzing a partially crosslinked product of polyaspartic acid with a polyamine (JP-A-7-309943,
JP-A-9-169840), a water-absorbing resin in which the polyamine compound is an amino acid such as lysine, ornithine, cystine and cystamine (JP-A-7-224163), and a crosslinking agent such as a diepoxy compound such as ethylene glycol glycidyl ether. Water absorbent resin (Polym.Mate
r.Sci.Eng., 79, 232, 1998), although these partially crosslinked products are easily decomposable, but in order to obtain sufficient water absorption properties, it is necessary to increase the molecular weight of polyaspartic acid. Is essential.

Further, polyaspartic acid (Japanese Patent Application Laid-Open No. 9-2)
02825), polyglutamic acid (JP-A-6-3223)
58), polylysine (JP-A-8-175901), and a mixed solution of polyglutamic acid and polylysine (J. Appl.
Olym. Sci., 58, 807, 1995) is known in which a cross-linked polyamino acid is obtained by irradiating γ-radiation.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a water-absorbing material having a sufficient water-absorbing ability and biodegradability, in particular, a high water-absorbing material.

[0008]

Means for Solving the Problems Accordingly, the present inventors have:
In light of the existence of various disadvantages in the prior art as described above, as a result of intensive studies, after reacting the protein with an anhydrous polyacidic amino acid, a water-absorbing material obtained by hydrolyzing the reaction product, The present invention has been completed by finding that it has a high degree of water absorption and biodegradability.

That is, [I] The present invention provides a water-absorbing material comprising a resin obtained by reacting an anhydrous polyacidic amino acid with a protein and then hydrolyzing a reaction product. [II] The present invention provides the above-mentioned [I], wherein the anhydrous polyacidic amino acid is a polysuccinimide.
[III] The present invention provides the water-absorbent material according to the above [I] or [II], wherein the water-absorbency of physiological saline is 10 g / g or more. is there.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Examples of the anhydrous polyacid amino acid used in the present invention include polysuccinimides, and copolymers and derivatives thereof. Of these, polysuccinimide is preferred.

[0011] The molecular weight of the anhydrous polyacid amino acid is preferably 3,000 or more, more preferably 5,000 or more, in terms of weight average molecular weight. If the weight average molecular weight is 3,000 or more, after reacting with the protein, the polymer obtained by hydrolyzing the reaction product becomes insoluble in water, and the water-absorbing material intended for the present invention can be obtained. Become.

The method for producing the anhydrous polyacid amino acid is not particularly limited. For example, (a) a method of producing D / L-aspartic acid by heat dehydration-condensation,
(B) a method of producing D / L-aspartic acid by heat dehydration condensation in the presence of a catalyst such as phosphoric acid, and (c) a method of preparing D / L-aspartic acid in a suitable solvent in the presence of a catalyst such as phosphoric acid. A method of producing by heat dehydration condensation,
(D) a method in which ammonia is reacted with maleic anhydride, fumaric acid, malic acid or the like by heating to produce maleimide or maleamic acid, and (e) a method in which maleic anhydride, fumaric acid, malic acid, or the like is reacted with ammonia to produce a maleimide. Or a method of producing maleamic acid and producing it in the presence of a catalyst such as phosphoric acid.

These reactions are shown below for L-aspartic acid.

[0014]

Embedded image

The type of the protein used in the present invention is not particularly limited as long as it has two or more amino groups as side chains which react with the anhydrous polyacid amino acid, and the origin of the protein is not particularly limited. . However, it is not limited to the origin of the protein. Examples of proteins include (a) proteins isolated and recovered from cultures such as bacteria, yeast, filamentous fungi, and animal cells; (b) proteins recovered from plant tissues such as soybean, wheat, and papaya; ) Proteins recovered from animal tissues such as milk, pancreas, liver, hair and bone. Among these proteins, those which can be easily recovered and purified, and which are easily available are preferable. Proteins satisfying such conditions include, for example, glutenin, oryzin, zein,
Casein, glue, gelatin, soybean protein recovered from soybean, and the like are preferable. Among them, proteins mainly containing globulin recovered from soybean are most preferable because they can be easily recovered and purified and are inexpensive.

[0016] These proteins may be in any form. For example, it may be in the form of solid or powder. A solution in which a protein such as a solid is dissolved in a solvent in advance is convenient because it is convenient for handling and becomes a uniform mixture.

The ratio of protein to anhydrous polyacid amino acid is based on 100 parts by weight of anhydrous polyacid amino acid.
It is preferably in the range of 0.1 to 1,000 parts by weight. If the amount is less than 0.1 part by weight, a gel is not formed, and the water-absorbing material containing a crosslinked product of a polyacidic amino acid and / or a polyacidic amino acid salt and a protein becomes water-soluble, and a crosslinked product having a water absorbing function is obtained. Not be. . Also,
If it exceeds 000 parts by weight, it will be difficult to obtain sufficient water absorption performance.

When reacting a protein with an anhydrous polyacidic amino acid, a crosslinking agent may be optionally used. The crosslinking agent to be used is not particularly limited, and examples thereof include a polyhydric alcohol and a polyamine crosslinking agent. Of these, a polyamine crosslinking agent is preferable. Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, triethanolamine, polyoxypropylene, and oxyethyleneoxypropylene block copolymer. Pentaerythrol and sorbitol. Examples of the polyamine crosslinking agent include chain aliphatic polyamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexamethylenediamine, and polyetherpolyamine, mensendiamine, isophoronediamine, bis (4- Cycloaliphatic polyamines such as aminocyclohexyl) methane 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxanepyrro [5,5] undecane, m-xylenediamine, p-xylenediamine And polyamides obtained from dimer acid and aliphatic polyamine, and basic amino acids such as lysine. These may be used alone or in combination of two or more.

The amount of the crosslinking agent used is 0.005 to 20% by weight, preferably 0.005 to 20% by weight, based on 100 parts by weight of the polyacidic amino acid and / or the polyacidic amino acid salt.
It is 5% by weight, more preferably 0.01 to 1% by weight.
If the amount is less than 0.005% by weight, no crosslinking effect is exhibited, and even if the amount exceeds 20% by weight, the effect corresponding to the amount of the crosslinking agent cannot be obtained, and the water absorption capacity may be significantly reduced. . A disulfide bond can also be introduced as a method for crosslinking an anhydrous polyacid amino acid and a protein. A method for crosslinking an anhydrous polyacid amino acid and a protein by a disulfide bond is disclosed in US Pat. No. 4,556,689.
, And various exemplified methods can be used as they are. To illustrate,
(A) The amino group in the protein is converted to a mercapto group using a known crosslinking agent such as 3-mercaptopropylimide hydrochloride, methyl 4-mercaptobutylimide hydrochloride, 2-iminothiolactone, or N-acetylhomocysteinethiolactone. (B) a maleimide group capable of reacting with a mercapto group using a cross-linking agent at an amino group in a protein, by reacting the amino group with an anhydrous polyacid amino acid having a thiol group introduced using cysteine or the like; And a method of introducing a functional group such as a thiol group by reacting with an anhydrous polyacid amino acid.

Further, the crosslinked product of the polyacid amino acid salt and the protein may be further crosslinked by swelling in water and irradiating it with radiation. As radiation, α rays, β rays, γ
Examples include a beam, an electron beam, a neutron beam, an X-ray, and a valence electron beam. The γ-ray absorption amount is preferably from 1 to 500 KGy, and crosslinking proceeds usually at room temperature under normal pressure. It is more preferable to use an inert gas such as nitrogen or argon.

The method for producing a water-absorbing material of the present invention comprises reacting an anhydrous polyacidic amino acid with a protein in the presence of a crosslinking agent, and then hydrolyzing the reaction product in a pH-adjusted aqueous solution. Is obtained by

When reacting an anhydrous polyacidic amino acid with a protein, it is desirable to mix both uniformly and sufficiently. The mixing method is not particularly limited. For example, 1) a method of mixing both in a solid state, 2) a method of mixing both in a solution state or a suspension state, 3) a state in which either one is in a solution state or a suspension state Various methods can be adopted, such as a method of adding the other to this and mixing.
Among these mixing methods, the method 2) is preferable.

In the above mixing method, a solvent is used if necessary. As the solvent to be used, it is most preferable to use water because anhydrous polyacidic amino acids and proteins need to be easily dissolved or suspended.

The mixing is achieved by mixing the aqueous solution or suspension of the anhydrous polyacidic amino acid with the aqueous solution or suspension of the protein. The concentration of the aqueous solution or suspension of anhydrous polyacidic amino acid and protein is 0.1% by weight
Preferably it is in the range of ５０50% by weight. When the concentration of the aqueous solution or the aqueous suspension is less than 0.1% by weight, the amount of the aqueous solution or the aqueous suspension increases, and heating must be performed for a long time to remove water.
Manufacturing efficiency decreases. On the other hand, when the concentration exceeds 50% by weight, it is not preferable because it becomes difficult to sufficiently uniformly suspend the suspension in the aqueous solution or suspension.

The water-absorbing material according to the present invention can be obtained by heating an anhydrous polyacidic amino acid and a protein to cause a reaction and hydrolyzing a reaction product. The heating temperature is preferably in the range of 10C to 200C, and more preferably in the range of 20C to 180C. If the heating temperature does not reach 10 ° C,
This is not preferable because the above reaction hardly proceeds. Also,
If the heating temperature exceeds 200 ° C., it is not preferable because coloring occurs. The heating time is not particularly limited, and may be appropriately set according to the type and combination of the anhydrous polyacid amino acid, protein, and solvent, the heating temperature, the desired physical properties of the water-absorbing material, and the like. Specifically, for example, when the heating temperature is 120 ° C., the heating time is:
The time may be from 1 minute to 5 hours.

In the hydrolysis reaction, an aqueous alkali solution is added dropwise to the solid reaction product, or the product is added to an aqueous alkali solution at 0 to 100 ° C., preferably 20 to 50 ° C.
The reaction is carried out for 0.5 to 24 hours. The alkali used in the aqueous alkali solution is not particularly limited, and examples thereof include hydroxides or carbonates such as alkali metal compounds and / or alkaline earth metal compounds.
LiOH, NaOH, KOH, Mg (OH) _{2 ,} Ca (O
_{H) 2, Li 2 CO 3} , Na 2 CO 3, K 2 CO 3, MgCO 3,
CaCO ₃ is mentioned. As the alkaline aqueous solution, sodium hydroxide or potassium hydroxide of 0.1 to 40
It is common to use a weight percent aqueous solution. The amount of the alkali to be added is 0.2 to 1 mol of the imide ring group of the reaction product.
It is preferable to use ２．０2.0 mol.

After completion of the reaction, the reaction product is poured into a large amount of methanol, ethanol, acetone, or the like, and isolated by precipitating a high molecular compound or by evaporating ion-exchanged water to dryness to obtain the desired product. obtain.

The water-absorbing material of the present invention is excellent in both water absorption and biodegradability.

The water absorption performance is determined by the method of testing the water absorption of a highly water-absorbent resin specified in Japanese Industrial Standards (JIS K-722).
It can be measured by a test of the amount of water absorption by the tea-back method according to 3). When evaluated by the tea-back method, the water-absorbing material according to the present invention has a water-absorbing capacity of 20 times or more with ion-exchanged water and 5 times or more with physiological saline (0.9% by weight physiological saline).

Further, since the water-absorbing material according to the present invention has biodegradability that can be decomposed by bacteria and microorganisms in the soil, it is decomposed only by burying in the soil. For this reason, disposal is simple and excellent in safety, and does not cause environmental health problems such as environmental pollution. Therefore, the water-absorbing material is applicable to all uses of conventionally known water-absorbing resins. For example, the hygiene field such as sanitary goods such as diapers and sanitary goods, the medical field such as cataplasm,
Civil engineering and construction fields as waste mud gelling agents, food fields,
It can be used in a wide variety of fields such as the industrial field, the soil modifying agent, and the agricultural and horticultural field as a water retention agent.

[0031]

The present invention will be described more specifically with reference to the following examples. In addition, various properties of the water-absorbing material were measured by the following methods. Water absorption capacity: In the examples, the water absorption capacity of the water absorbent material is
The test was carried out based on the method for testing the water absorption of a superabsorbent resin described in JIS K-7223. That is, 0.20 g of dry resin (1.0% for 0.9% sodium chloride)
0 g) was placed in a 255-mesh nylon-shear tea bag (200 mm × 100 mm) and immersed in 1000 ml of ion-exchanged water or 0.9% aqueous sodium chloride to swell the resin for a certain period of time. It was pulled up and drained for 10 minutes, and the weight was measured.
The measurement was performed using the weight obtained when the same operation was performed using only the tea bag as a blank. The water absorption ratio W (g / g) is
The mass a (g) of the sample, the tea bag containing the sample is immersed for a predetermined time, the mass b (g) after draining, the tea bag not containing the sample is immersed for a predetermined time, and the average value of the mass after draining It was calculated from c (g) according to the following equation.

[0032]

(Equation 1)

(B) Biodegradation rate: The biodegradability test was performed using the modified M
Performed according to the ITI test. That is, 200m of basal culture
To l, a water-absorbing material as a test substance was added to 100 ppm, and activated sludge was added to 30 ppm. Then, the basal culture was incubated for 2 hours in the dark.
The culture was maintained at 5 ° C. and shaken for 28 days. During the above period, the amount of oxygen consumed by the activated sludge was measured periodically to obtain a biochemical oxygen demand (BOD) curve. The biodegradation rate (%) is the biochemical oxygen demand A (mg) of the test substance (polymer composition) obtained from the BOD curve.
From the blank obtained from the BOD curve, that is, the oxygen demand B (mg) of the basal culture solution, and the total oxygen demand (TOD) C (mg) required when the test substance is completely oxidized,

[0034]

(Equation 2)

Calculated according to:

REFERENCE EXAMPLE 1 100 g of L-aspartic acid and 50% of 85% phosphoric acid were placed in a 1 L metal separable flask.
g at a reaction temperature of 180 ° C. and a reduced pressure of 600 Pa.
The reaction was carried out for 3.5 hours with stirring. After completion of the reaction, 400 ml of DMF was added to the flask to uniformly dissolve the reaction product. The resulting solution was dropped into 1.5 L of ion-exchanged water to reprecipitate the formed resin, and then the slurry was pulverized by a mixer and filtered under reduced pressure. After filtration, washing was performed until the pH of the ion-exchanged water became neutral.
And dried with hot air for 24 hours to obtain 72.5 g of a white powder. As a result of measuring the obtained resin by GPC, the weight average molecular weight was 125,000.

Reference Example 2 As in Reference Example 1, 100 g of L-aspartic acid was reacted at a bath temperature of 260 ° C. under a nitrogen atmosphere with stirring for 6 hours. After the completion of the reaction, 68.3 g of a white powder was obtained by the same operation as in Reference Example 1. As a result of measuring the obtained resin by GPC, the weight average molecular weight was 9,
000.

REFERENCE EXAMPLE 3 25 g of maleimide and 25 mg of hydroquinone were placed in a 1 L eggplant-shaped flask, and 0.25 g of sodium hydroxide was added. Reaction temperature 100 ° C
For 3 hours under reduced pressure. 25 g of the product obtained in Reference Example 3 was washed several times with water and methanol,
23. Drying at 0 ° C. for 2 hours, yellow-white polysuccinimide
7 g were obtained. As a result of measuring the obtained polysuccinimide by GPC, the weight average molecular weight was 20,000.

Example 1 10 g of the polysuccinimide obtained in Reference Example 1 was suspended in 50 g of ion-exchanged water, and 1 g of soybean protein (made by Fuji Oil) was suspended in 10 g of ion-exchanged water. Was added. The mixture obtained after the addition was heated at 120 ° C. for 70 minutes using a dryer to obtain 10.5 g of a dried product. A solution obtained by dissolving 4.2 g of sodium hydroxide in 100 g of ion-exchanged water was added to the dried product, and the mixture was stirred at room temperature for 3 hours to hydrolyze to obtain a viscous liquid. 600 ml of methanol was added to this solution, and the resulting precipitate was filtered under reduced pressure, washed with methanol, and heated at 60 ° C. for 1 hour.
After drying under reduced pressure for 2 hours, 8.4 g of a white powdery resin was obtained.
Table 1 shows the water absorption capacity and biodegradation rate of the obtained water absorbent material.
It described in.

Example 2 16.6 g of a white powdery resin was obtained in the same manner as in Example 1 except that soy protein was changed to 10.0 g. Table 1 shows the water absorption capacity and the biodegradation rate of the obtained water-absorbing material.

Example 3 9.8 g of a resin in the form of a white powder was obtained in the same manner as in Example 1 except that the innumerable polyamino acids obtained in Reference Example 2 were used. Table 1 shows the water absorption capacity and the biodegradation rate of the obtained water-absorbing material.

Example 4 9.5 g of a resin in the form of a white powder was obtained in the same manner as in Example 1 except that the innumerable polyamino acids obtained in Reference Example 3 were used instead of the innumerable polyamino acids. Table 1 shows the water absorption capacity and the biodegradation rate of the obtained water-absorbing material.

Comparative Example 1 8.4 g of a white powdery resin was obtained in the same manner as in Example 1 except that the soybean protein was changed to 0.005 g. Table 1 shows the water absorption capacity and the biodegradation rate of the obtained water-absorbing material.

[0044]

[Table 1]

[0045]

The water-absorbing material of the present invention has high water absorption and is biodegradable, so that it is decomposed only by burying it in the soil by bacteria and microorganisms in the soil, and the disposal is easy. It has excellent safety and does not cause environmental health problems such as environmental pollution. Therefore, it can be used in various fields such as sanitary fields such as sanitary articles such as diapers and sanitary articles, medical fields, civil engineering and construction fields, food fields, industrial fields, and agricultural and horticultural fields.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 101/14 ZAB C08L 101/14 ZAB (72) Inventor Yoshiki Hasegawa 3 Higashi Mikuni, Yodogawa-ku, Osaka, Osaka -2-15- 308 F term (reference) 2B022 AA05 BA11 BA24 BB10 DA19 4J001 DA01 DB09 DB10 DC07 EA36 FA03 GE11 JA20 4J002 CL02X CM04W GD03 4J031 AA04 AA57 AB06 AC07 AD01 AE19 AF01 AF07 AF17 CD05 4J043 PA02 SA01 Q06 XA03 XA12 XA19 YB02 YB08 YB14 YB31 ZA04 ZB60

Claims (3)

[Claims] 1. A water-absorbing material comprising a resin obtained by reacting an anhydrous polyacidic amino acid with a protein and then hydrolyzing a reaction product. 2. The water-absorbing material according to claim 1, wherein the anhydrous polyacidic amino acid is polysuccinimide. 3. The water-absorbing material according to claim 1, wherein the water-absorbing power of physiological saline is 10 g / g or more.