JP2006160842A - Polyuronic acid molded article and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-insoluble polyuronic acid excellent in safety such as biocompatibility, biodegradability, etc., having uniform structure and excellent in physical properties as a functional material, remarkably effective as various additives imparting hyrophilicity, moisture absorbing and releasing property, moisture controlling property to various functional materials such as food, medical treatment/medicine, a cosmetic, or the like, or an extender, a bulking agent, a filler, etc., and to provide a method for producing a polyglucuronic acid in an easy and safety process. <P>SOLUTION: The invention relates to the water-insoluble polyuronic acid molded article having a polyvalent metal salt of carboxy group. The invention relates to the method for producing the water-insoluble polyuronic acid molded article comprising a process at least selectively oxidizing polysaccharides, and a process insolubilizing the oxidized polysaccharides by adding the polyvalent metal salt to the oxidized polysaccharide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to polyuronic acid having a uniform structure derived from a polysaccharide. The polyuronic acid molded product of the present invention has excellent biodegradability, safety to the living body, and uniformity of structure, and is insolubilized with a polyvalent metal salt. Therefore, it is used alone or mixed with other binders. Therefore, it is very effective for imparting hydrophilicity and moisture absorption / desorption characteristics, moisture controllability, or for use as various additives such as a bulking agent, bulking agent and filler. In addition, since it can be isolated and purified by washing with water, a simple production method can be provided.

  Naturally occurring uronic acids are mainly glucuronic acid, mannuronic acid, and galacturonic acid, and are present as plant structural polysaccharides such as pectin and alginic acid, etc. It also plays a function. The pectin is polyglucuronic acid mainly composed of α-D-galacturonic acid, and alginic acid is polyglucuronic acid composed of β- (1,4) -mannuronic acid and α- (1,4) -L-glucuronic acid. It is. These are used industrially as food additives, thickeners, stabilizers and the like.

  However, the naturally-occurring polyglucuronic acids are mostly heteropolysaccharides, and because of their heterogeneous structure, it is difficult to analyze the chemical structure affecting the function, control the material design, and control the material properties. Taking advantage of the safety, biodegradability, biocompatibility, and physiological functions of polyglucuronic acid, and chemical and physical modification, derivatization, compounding with other materials, etc. It is not preferable as a study raw material for developing a new high-performance material by secondary modification.

On the other hand, glucuronic acid is widely present as a constituent monosaccharide of polysaccharides of plants, animals, and microorganisms. When a foreign substance or drug is administered to an animal, they are directly or after being converted into a derivative and then combined with D-glucuronic acid. It is excreted outside the body in the form. Regarding the in vivo metabolism of glucuronic acid, a sugar nucleotide called uridine diphosphate (UDP) -D-glucuronic acid is widely present in bacteria, plants and animals, and this UDP-D-glucuronic acid is UDP-D-glucuronid. It is known that it is decarbonized by acid decarboxylase and nicotinamide adenine dinucleotide (NAD) to become UDP-D-xylose and CO ₂ and finally decomposed into CO ₂ and water. However, the natural homopolysaccharide having D-glucuronic acid as a constituent monosaccharide has not been confirmed at present. If polyglucuronic acid can be produced efficiently, it can be expected to be used not only for polyglucuronic acid so far but also in new fields.

Attempts have also been made to obtain polyglucuronic acids by oxidizing inexpensive polysaccharides such as starch and cellulose. There are few methods for selectively oxidizing only the primary hydroxyl group at the C6 position of the pyranose ring, and effective oxidation means currently proposed include oxidation with nitrogen dioxide and 2,2,6,6-tetramethyl-1 -Oxidation with an N-oxyl compound catalyst such as piperidine-N-oxyl (TEMPO).
However, in the oxidation method using nitrogen dioxide, if only a few carboxyl groups are introduced or highly oxidized and all the 6-position primary hydroxyl groups are oxidized, the oxidation at the 2- and 3-positions, Side reactions such as a decrease in molecular weight were remarkable, and complete water-soluble polyglucuronic acid could not be obtained.

  On the other hand, in the oxidation of polysaccharides by a TEMPO catalyst, which is an oxidation method that has been attracting attention in recent years, almost all primary hydroxyl groups at the C6 position of polysaccharides can be oxidized with considerably high selectivity (see Non-Patent Document 1). The most common TEMPO oxidation of polysaccharides is an oxidation method using sodium hypochlorite as a cooxidant in the presence of TEMPO and sodium bromide. However, since the oxidation reaction proceeds on the alkali side, Glucuronic acid is usually a sodium salt.

  This sodium salt of polyuronic acid has very high water solubility, and can be dissolved in water at a high concentration even when the molecular weight is tens of thousands, and the viscosity of the high aqueous solution is relatively low. In view of this, a method of using the polyuronic acid aqueous solution by coating or mixing with a solution has been reported. For example, Patent Document 1 reports a method of using an aqueous solution of polyglucuronic acid as a gas barrier coating agent.

However, the water-soluble nature of this polyuronic acid sodium salt is effective for use as an aqueous solution, but it is often disadvantageous in terms of water resistance and moisture resistance. For example, these gas barrier coating films of polyuronic acid can be confirmed to have excellent oxygen barrier properties in a very dry state, but their oxygen barrier properties are greatly reduced at high humidity close to 100%. . Further, for example, when these polyuronic acids are used as various additives, it may be considered that the polyuronic acid flows out in an atmosphere where a large amount of water is present.
Isogai, A.I. Kato, Y. et al. Preparation of polyuronic acid from cellulose by TEMPO-mediated oxidation. cellulose, 5, 153-164 (1998) JP 2001-334600 A

  The subject of the present invention is excellent in safety such as biocompatibility, biodegradability, etc., has a uniform structure and excellent physical properties as a functional material, and further, food, medical / pharmaceutical, cosmetics, various Providing water-insolubilized polyuronic acid that is very effective for imparting hydrophilicity, moisture absorption and desorption characteristics, moisture controllability, and as additives such as bulking agents, bulking agents, and fillers in functional materials There is to do. Another object of the present invention is to provide a production method capable of producing these polyglucuronic acids by a simple and safe method.

  The invention described in claim 1 is a water-insoluble polyuronic acid molded product using polyuronic acid having a polyvalent metal salt of a carboxyl group.

  The invention described in claim 2 is the water-insoluble polyuronic acid molded product according to claim 1, wherein the polyvalent metal is one selected from calcium, copper, zinc, and aluminum.

  The invention described in claim 3 is characterized in that the water-insoluble polyuronic acid molded product is in the form of particles, and the particle size thereof is 20 μm or less. Polyuronic acid molded product.

  The invention according to claim 4 is the water-insoluble polyuronic acid molded product according to claim 1 or 2, characterized in that the shape of the water-insoluble polyuronic acid molded product is fibrous.

  The invention according to claim 5 is the water-insoluble polyuronic acid molded product according to claim 1, wherein the water-insoluble polyuronic acid molded product has a film shape.

  The invention according to claim 6 includes at least an oxidation step of selectively oxidizing a polysaccharide, and adding a polyvalent metal salt to the polysaccharide oxidized in the oxidation step to form a precipitate, thereby forming a molded product. And a method for producing a water-insoluble polyuronic acid molded product characterized by comprising a step of washing the molded product with water.

  The invention according to claim 7 includes at least an oxidation step for selectively oxidizing a polysaccharide, a molding step for molding the polysaccharide oxidized in the oxidation step, and an oxidized polysaccharide molded in the molding step. It is a method for producing a water-insoluble polyuronic acid molded article, which comprises a step of adding a polyvalent metal salt.

  The invention according to claim 8 includes at least an oxidation step of selectively oxidizing a polysaccharide, a molding step of molding the polysaccharide oxidized in the oxidation step, and a step of adding a polyvalent metal salt. In a method for producing a water-soluble polyuronic acid molded article, a water-insoluble polyuronic acid molded article characterized in that a molding step for molding a polysaccharide oxidized in an oxidation step and a step for adding a polyvalent metal salt are performed simultaneously. Is the method.

  The invention according to claim 9 is characterized in that the polysaccharide is one kind selected from starch, cellulose, chitin, and chitosan, or a mixture of two or more kinds. This is a method for producing a water-insoluble polyuronic acid molded article.

  The polyuronic acid molded article of the present invention can be applied to various uses as a functional material such as a biomaterial, food / medicine, cosmetics as well as a general functional material. In particular, since it is water insolubilized with a polyvalent metal salt, imparting hydrophilicity, moisture absorption and desorption characteristics, moisture controllability to various functional materials, or use as various additives such as bulking agents, bulking agents, fillers, etc. In addition, it is very convenient to use as various additives. It can also be easily used as a raw material for composite materials with other polysaccharides.

The present invention is described in detail below.
The polyuronic acid molded product according to the present invention has a structure in which a large number of D-glucuronic acids are α- or β- (1,4) -bonded or D-glucosaminouronic acid is β- (1,4) -bonded. Is clear and uniform and has high hydrophilicity. And it is the polyuronic acid molded product characterized in that its carboxyl group is water-insolubilized with a polyvalent metal salt. Here, the polyuronic acid molded product refers to polyuronic acid having various shapes such as particles, fibers, and films.

  Examples of polyvalent metal salts include calcium, magnesium, aluminum, silica, titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, silver, barium, etc. You can choose. For example, in addition to water insolubilization, a polyvalent metal such as copper, silver, or zinc is selected for the purpose of imparting antibacterial properties. When only water insolubilization is intended, a calcium salt is more preferable in terms of cost, safety, convenience of handling, and the like.

  Here, the content of metal ions contained in the polyglucuronic acid molded product can be examined by various analysis methods, but it is easily examined by elemental analysis of EPMA method and X-ray fluorescence analysis method using an electron beam microanalyzer. be able to.

  Furthermore, the polyuronic acid molded product of the present invention can be prepared by a selective oxidation reaction using a natural polysaccharide as a raw material. For example, D-glucuronic acid is obtained by oxidizing starch having α- (1,4) -D-glucose as a main chain or cellulose which is a homopolymer of β- (1,4) -D-glucose. Polyglucuronic acid possessed by the constituent monosaccharides can be obtained. In addition, polyuronic acid having N-acetylglucosaminouronic acid as a constituent sugar can be obtained by oxidizing chitin, which is a polysaccharide having β- (1,4) -N-acetylglucosamine as a main chain. .

  There are various types of starch, and it is said that it consists of amylose and amylopectin in terms of chemical structure, and the blending ratio depends on the raw material resources, but the raw material for the polyglucuronic acid molded product of the present invention is not particularly limited, It can be obtained from various natural resources. In addition, the origin and type of cellulose and chitin used as raw materials are not particularly limited, but if these highly crystalline cellulose and chitin are used once dissolved and regenerated, side reactions are suppressed and high A completely water-soluble polyuronic acid having a molecular weight is obtained.

In this selective oxidation method, an oxidation method using an N-oxyl compound catalyst is used. However, in order to obtain a polyglucuronic acid molded article having a uniform structure and a high molecular weight, which is a feature of the present invention, a mild method is used. Under such reaction conditions, it is important that a necessary amount of a drug necessary for the progress of a selective reaction is supplied at any time, and oxidation is performed in the shortest possible time. For example, by using an alkali metal bromide and an oxidizing agent in the presence of an N-oxyl compound catalyst and oxidizing at a low temperature of 5 ° C. or lower and an aqueous system while keeping the pH constant in the range of 10 to 11, The inventive polyglucuronic acid molded product is obtained.
Here, as the N-oxyl compound, 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) is used, sodium bromide is used as the alkali metal bromide, and hypoxia is used as the oxidizing agent. Sodium chlorate is particularly preferred.

  In this oxidation method, for example, a raw material is dissolved or uniformly dispersed in water, an aqueous solution in which TEMPO and sodium bromide are dissolved is added, the system is cooled to 5 ° C. or lower, and the pH is adjusted to 10. First, when a small amount of sodium hypochlorite solution is added, the pH temporarily rises, but if the stirring is continued, the pH in the system gradually decreases. The pH is kept constant in the range of 10-11. Furthermore, the sodium hypochlorite solution, which is an oxidant, is added dropwise while adjusting according to the progress of the reaction, thereby suppressing the presence of excess oxidant in the system and acting on side reactions. During the reaction, the temperature in the system is maintained at 5 ° C. or lower. As the reaction proceeds, the system becomes a homogeneous solution. Under these reaction conditions, the amount of sodium hydroxide added substantially corresponds to the amount of carboxyl groups introduced by oxidation, and when the amount of glucose residues in the raw material and the amount added in an equimolar amount are reached, Ethanol is added to quench excess oxidant.

  In this state, an excess amount of ethanol, which is a poor solvent for polyuronic acid, is added to precipitate polyuronic acid, followed by isolation and washing by filtration, or purification by dialysis, etc., so that sodium salt of polyuronic acid is obtained. can get.

Alternatively, an immediately insolubilized polyuronic acid molded product can be obtained by adding an aqueous solution containing a polyvalent metal salt to the reaction solution after the oxidant is deactivated. If the polyuronic acid molded product is insolubilized by this method, it is possible to remove impurities such as salts and chemicals by washing with water and to isolate the polyuronic acid molded product, and to reduce the amount of organic solvent used. it can.
In this case, an example using calcium chloride will be described for the insolubilization treatment with a polyvalent metal salt. First, it is sufficient to contain a sufficient amount to crosslink the carboxyl group of polyuronic acid in advance, theoretically 0.5 times the molar amount of calcium, but the excess metal salt can be easily washed by subsequent water washing. For example, an aqueous calcium chloride solution containing 1 mol or 2 mol of calcium is prepared in consideration of the fact that it can be removed easily and that the replacement of sodium with calcium proceeds very easily. The aqueous calcium chloride solution is added to the reaction solution after the oxidant is deactivated and stirred. Then, the dissolved sodium polyuronic acid salt is replaced with calcium polyuronic acid salt and precipitates. Since this calcium polyuronic acid salt does not dissolve in water, it is possible to remove salts generated by reaction with the reaction reagent, excess calcium chloride, etc. by washing with water. By repeatedly washing and drying, fine particles of calcium polyuronic acid salt are obtained.

It is also possible to carry out a water insolubilization treatment with polyvalent cationic ions after passing through a molding step from the sodium salt of polyuronic acid obtained as described above into fine particles or films. In this case, for example, the sodium polyuronic acid aqueous solution is dried by spray drying or the like to form fine particles. The fine particles are put into an aqueous solution containing a polyvalent metal salt, insolubilized, and subjected to a washing and drying process to prepare polyuronic acid fine particles.
Alternatively, a polyuronic acid sodium salt is coated on a substrate such as a film or a metal plate, and after forming a film, a polyuronic acid film treated with water insolubilization is formed by coating a coating solution containing a polyvalent metal salt. It is also possible to obtain.

Furthermore, it is also possible to simultaneously perform a forming step from a sodium salt of polyuronic acid into fine particles or a film, and a water insolubilization treatment with polyvalent cationic ions. In this case, for example, sodium polyuronic acid and a binder are mixed, and this is spun into a fiber in a coagulation bath of an aqueous solution containing, for example, a polyvalent metal salt to prepare polyuronic acid fibers. In addition, polyuronic acid fine particles may be prepared by contacting a sodium salt of polyuronic acid, a solution containing an additive such as a porosifying agent or a surfactant or an organic solvent, and a solution containing a polyvalent metal salt. it can.
Furthermore, these various polyuronic acid molded products can be used as additives. For example, polyuronic acid fine particles can be mixed with various binders and used as a coating agent.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, the technical scope of this invention is not limited to these embodiment.

1.0 g of water-soluble starch (manufactured by ACROS) was uniformly dispersed in distilled water at a concentration of 5%. To this, an aqueous solution in which 19 mg of TEMPO and 0.25 g of sodium bromide were dissolved was added to prepare a solid content concentration of amylose of about 2 wt%. The reaction system is cooled, and 3.0 g of 11% aqueous sodium hypochlorite solution is added to start the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system decreases, but 0.5N-NaOH aqueous solution is sequentially added to adjust the pH to around 10.8, and 8.0 g of 11% sodium hypochlorite aqueous solution is further added according to the progress of the reaction. It was added dropwise while adjusting. When approaching the amount of alkali added corresponding to 100% of the total number of moles of glucose residues, the rate of alkali addition becomes slow regardless of the dropping of the sodium hypochlorite aqueous solution, and the system is completely removed. Dissolves to a yellow uniform solution. When the amount of alkali added reached 100% (12.34 ml) with respect to the total number of moles of glucose residues, ethanol was added to stop the reaction. The reaction time was 2 hours.
When an aqueous solution in which 1.1 g of calcium chloride was previously dissolved in 10 g of water was added to the system, a white precipitate was formed. This precipitate was repeatedly washed with distilled water to obtain a particulate amylouronate calcium salt.

  10 g of starch was dissolved by heating in 400 g of distilled water and cooled. A solution prepared by dissolving 0.18 g of TEMPO and 2.5 g of sodium bromide in 100 g of distilled water was added to this solution, and 104 g of 11% sodium hypochlorite solution was added dropwise to initiate the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75. Then, when the alkali addition amount corresponding to the mole number of 100% with respect to the total mole number of the primary hydroxyl group at the 6-position was reached, ethanol was added to stop the reaction. The reaction solution was poured into an excess amount of ethanol to reprecipitate the product. Furthermore, after sufficiently washing with a solution of water: acetone = 1: 7, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain 12 g of white powdery polyglucuronic acid sodium salt powder. Dissolve 1.0 g of the polyglucuronic acid sodium salt in 40 ml of distilled water, add 1.1 g of calcium chloride previously dissolved in 10 ml of water while stirring, and add fine particulate calcium amylouronate Got.

  As the regenerated cellulose, Benise manufactured by Asahi Kasei Kogyo Co., Ltd. is used, 10 g of regenerated cellulose is suspended in 400 g of distilled water, a solution of 0.18 g of TEMPO and 2.5 g of sodium bromide is added to 100 g of distilled water, and 5 ° C. or less. Until cooled. Here, 104 g of an aqueous 11% sodium hypochlorite solution was added dropwise to initiate the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75. Then, when the alkali addition amount corresponding to the mole number of 100% with respect to the total mole number of the primary hydroxyl group at the 6-position was reached, ethanol was added to stop the reaction. When an aqueous solution in which 11 g of calcium chloride was previously dissolved in 100 g of water was added to the system, a white precipitate was formed. This precipitate was repeatedly washed with distilled water to obtain a fine particle calcium seuroronate.

Daiichi Seika Kogyo Co., Ltd. Daichitosan 100D (VL) is used as 100% deacetylated chitosan. 10 g of this chitosan is dissolved in 190 g of 10% acetic acid, diluted with 1 L of methanol, and acetic anhydride 12 is stirred. When .68 g was added, it gelled in a few minutes. After standing for 15 hours, 1 L of methanol was further added and stirred with a homogenizer, and 2N-NaOH aqueous solution was added to neutralize to pH 7. This was filtered, washed thoroughly with methanol and deionized water, and then frozen. It was dried to obtain 11.6 g of N-acetylated chitosan. By elemental analysis, the degree of N-acetylation was 95%.
10 g of the N-acetylated chitosan prepared above was suspended in 400 g of distilled water, and a solution prepared by dissolving 0.1 g of TEMPO and 2.0 g of sodium bromide was added to 10 g of distilled water and cooled to 5 ° C. or lower. 84 g of an aqueous 11% sodium hypochlorite solution was added dropwise thereto to initiate the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system was lowered, but a 0.5 N NaOH aqueous solution was sequentially added to adjust the pH to 10.75. Then, when the alkali addition amount corresponding to the mole number of 100% with respect to the total mole number of the primary hydroxyl group at the 6-position was reached, ethanol was added to stop the reaction. When an aqueous solution in which 11 g of calcium chloride was previously dissolved in 100 g of water was added to the system, a white precipitate was formed. This precipitate was repeatedly washed with distilled water to obtain a particulate calcium chitouronic acid salt.

<Comparative Example 1>
Commercially available sodium alginate powder was put into an aqueous solution in which 11 g of calcium chloride was dissolved in 100 ml of water while stirring. After a while, the stirring was stopped, and the precipitated powder was washed with water to obtain a calcium alginate salt.

<Comparative example 2>
1.0 g of water-soluble starch (manufactured by ACROS) was uniformly dispersed in distilled water at a concentration of 5%. An aqueous solution in which 19 mg of TEMPO and 0.25 g of sodium bromide were dissolved was added thereto so that the amylose solid concentration was about 2 wt%. The reaction system was cooled and 3.0 g of 11% aqueous sodium hypochlorite solution was added to initiate the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system decreases, but 0.5N NaOH aqueous solution is added successively to adjust the pH to around 10.8, and 8.0 g of 11% sodium hypochlorite aqueous solution is further added according to the progress of the reaction. It was added dropwise while adjusting. When approaching the amount of alkali added corresponding to 100% of the total number of moles of glucose residues, the rate of alkali addition becomes slow regardless of the dropping of the sodium hypochlorite aqueous solution, and the system is completely removed. Dissolves to a yellow uniform solution. When the amount of alkali added reached 100% (12.34 ml) with respect to the total number of moles of glucose residues, ethanol was added to stop the reaction. The reaction solution was poured into an excess amount of ethanol to reprecipitate the product. Furthermore, after sufficiently washing with a solution of water: acetone = 1: 7, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain a sodium salt of polyglucuronic acid in the form of white powder.

(Evaluation of carboxyl group content)
The amounts of carboxyl groups in Examples 1 to 4 and Comparative Examples 1 and 2 were measured by conductivity titration as follows.
Each test sample is accurately weighed from 0.05 to 0.3 g and dissolved or suspended in 55 g of water. To this, 5 ml of 0.01N-NaCl aqueous solution and 5 ml of 0.1N-HCl aqueous solution are added. This solution was titrated with 0.1N-NaOH aqueous solution, 0.1N-NaOH dropping amount at that time, pH, and conductivity were plotted, and the carboxyl group amount was determined from the graph. The results are shown in Table 1.

(Metal ion content)
The metal ion contents of Examples 1 to 4 and Comparative Examples 1 and 2 were measured by EPMA analysis using an electron beam microanalyzer or elemental analysis by fluorescent X-ray analysis. The results are shown in Table 1.

(Water absorption test)
2 g of calcium amylouronate obtained from Example 1 and calcium alginate obtained from Comparative Example 1 were each placed in a 100 ml beaker and sufficiently moistened. The filter was naturally filtered through a glass filter, and the weight of the calcium amylouronate and calcium alginate was measured in a wet state without drying, and the water absorption rate against absolute dryness was calculated.

  As a result of water absorption measurement, calcium amylouronate can hold 1.4 times its own weight, and calcium alginate, which is generally known for its high water absorption, holds 1.6 times its own weight. The result was almost equivalent to the ability to do.

(Hygroscopic moisture release test)
Calcium amylouronate obtained from Example 1, calcium chitouronate obtained from Example 4, calcium alginate obtained from Comparative Example 1, cellulose, and silica gel were weighed in an amount of 2 g each, and 40 ° C. and 20% RH. Placed in the atmosphere. When each test sample reached an equilibrium state, the test sample was moved under an atmosphere of 40 ° C. and 95% RH, and the weight change with respect to the absolute dry weight was measured.
When each test sample reached an equilibrium state again, the test sample was moved again under an atmosphere of 40 ° C. and 20% RH, and the weight change with respect to the absolute dry weight was measured.

  The test results are shown in FIG. As is apparent from FIG. 1, the polyuronic acid of the present invention exhibited moisture absorption and desorption performance comparable to that of silica gel and calcium alginate, which are conventionally known hygroscopic agents.

  1.0 g of water-soluble starch (manufactured by ACROS) was uniformly dispersed in distilled water at a concentration of 5%. An aqueous solution in which 19 mg of TEMPO and 0.25 g of sodium bromide were dissolved was added thereto to prepare a solid content concentration of amylose of about 2 wt%. The reaction system is cooled, and 3.0 g of 11% aqueous sodium hypochlorite solution is added to start the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system decreases, but 0.5N-NaOH aqueous solution is sequentially added to adjust the pH to around 10.8, and 8.0 g of 11% sodium hypochlorite aqueous solution is further added according to the progress of the reaction. It was added dropwise while adjusting. When approaching the amount of alkali added corresponding to 100% of the total number of moles of glucose residues, the rate of alkali addition becomes slow regardless of the dropping of the sodium hypochlorite aqueous solution, and the system is completely removed. Dissolves to a yellow uniform solution. When the amount of alkali added reached 100% (12.34 ml) with respect to the total number of moles of glucose residues, ethanol was added to stop the reaction. The reaction solution was poured into an excess amount of ethanol to reprecipitate the product. Further, after sufficiently washing with a solution of water: acetone = 1: 7, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain 1.2 g of sodium salt of polyglucuronic acid in the form of white powder. When 1.0 g of the sodium salt of polyglucuronic acid obtained was dissolved in 40 ml of distilled water and 1.4 g of aluminum chloride dissolved in 10 ml of water was added with stirring, a white precipitate was formed. This precipitate was repeatedly washed with distilled water to obtain a particulate aluminum amylouronate.

  1.0 g of water-soluble starch (manufactured by ACROS) was uniformly dispersed in distilled water at a concentration of 5%. An aqueous solution in which 19 mg of TEMPO and 0.25 g of sodium bromide were dissolved was added thereto to prepare a solid content concentration of amylose of about 2 wt%. The reaction system is cooled, and 3.0 g of 11% aqueous sodium hypochlorite solution is added to start the oxidation reaction. The reaction temperature was always kept below 5 ° C. During the reaction, the pH in the system decreases, but 0.5N-NaOH aqueous solution is sequentially added to adjust the pH to around 10.8, and 8.0 g of 11% sodium hypochlorite aqueous solution is further added according to the progress of the reaction. It was added dropwise while adjusting. When approaching the amount of alkali added corresponding to 100% of the total number of moles of glucose residues, the rate of alkali addition becomes slow regardless of the dropping of the sodium hypochlorite aqueous solution, and the system is completely removed. Dissolves to a yellow uniform solution. When the amount of alkali added reached 100% (12.34 g) with respect to the total number of moles of glucose residues, ethanol was added to stop the reaction. The reaction solution was poured into an excess amount of ethanol to reprecipitate the product. Further, after sufficiently washing with a solution of water: acetone = 1: 7, it was dehydrated with acetone and dried under reduced pressure at 40 ° C. to obtain 1.2 g of sodium salt of polyglucuronic acid in the form of white powder. When 1.0 g of the obtained sodium salt of polyglucuronic acid was dissolved in 40 ml of distilled water and the supernatant of a saturated aqueous solution of copper chloride was added with stirring, a light blue precipitate was formed. This precipitate was repeatedly washed with distilled water to obtain fine-grained amylouronate copper salt.

  Amino group-containing polyvinyl alcohol is dissolved in water at a concentration of 12%. In this aqueous solution, sodium celouronate is further dissolved to a concentration of 10%. A mixed solution of amino group-containing polyvinyl alcohol and sodium celouronate was spun in a coagulation bath in which zinc chloride was dissolved to prepare a fiber containing zinc seurouronate.

(Antimicrobial test)
The particulate amylouronate copper salt obtained in Example 6, the zinc seurouronate-containing fiber obtained from Example 7, and the sodium salt of polyglucuronic acid obtained from Comparative Example 2 were heated in a wet state at a temperature. It was placed in an atmosphere of 35 ° C. and humidity 65%. After 3 months, it was confirmed by visual observation that the propagation of miscellaneous bacteria was suppressed in the amylouronate copper salt and zinc seurouronate-containing fibers as compared with the sodium salt of polyglucuronic acid.

  The polyuronic acid molded product of the present invention can be applied to various uses as a functional material such as a biomaterial, food, medical / medicine, cosmetics as well as a general functional material. For example, it can be applied to functional membranes, gas barrier materials, biocompatible materials, etc. by processing them into fibers by spinning, or applying them as aqueous solutions. It can also be easily used as a raw material for composite materials with other polysaccharides.

It is a figure which shows the result of the moisture absorption / desorption test of the polyuronic acid molded article in this invention.

Claims (9)

  A water-insoluble polyuronic acid molded article characterized by using polyuronic acid having a polyvalent metal salt of a carboxyl group.   The water-insoluble polyuronic acid molded product according to claim 1, wherein the polyvalent metal is one selected from calcium, copper, zinc, and aluminum.   The water-insoluble polyuronic acid molded product according to any one of claims 1 and 2, wherein the water-insoluble polyuronic acid molded product has a particle shape and a particle size of 20 µm or less.   The water-insoluble polyuronic acid molded product according to any one of claims 1 and 2, wherein the water-insoluble polyuronic acid molded product has a fibrous shape.   The water-insoluble polyuronic acid molded product according to any one of claims 1 and 2, wherein the water-insoluble polyuronic acid molded product has a film shape.   At least an oxidation step for selectively oxidizing a polysaccharide, a step of forming a precipitate by adding a polyvalent metal salt to the polysaccharide oxidized in the oxidation step to form a molded product, and washing the molded product with water A process for producing a water-insoluble polyuronic acid molded product, comprising the step of:   At least an oxidation step for selectively oxidizing a polysaccharide, a molding step for molding the polysaccharide oxidized in the oxidation step, and a step of adding a polyvalent metal salt to the oxidized polysaccharide molded in the molding step A method for producing a water-insoluble polyuronic acid molded product, comprising:   A method for producing a water-soluble polyuronic acid molded article, comprising at least an oxidation step for selectively oxidizing a polysaccharide, a molding step for molding the polysaccharide oxidized in the oxidation step, and a step for adding a polyvalent metal salt The method for producing a water-insoluble polyuronic acid molded product, comprising simultaneously performing a molding step of molding the polysaccharide oxidized in the oxidation step and a step of adding a polyvalent metal salt.   The method for producing a water-insoluble polyuronic acid molded product according to any one of claims 6 to 8, wherein the polysaccharide is one type selected from starch, cellulose, chitin, and chitosan, or a mixture of two or more types. .

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