JP2007091952A - Method for regenerating polymeric material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of efficiently regenerating a water-soluble polymeric material such as alginic acid. <P>SOLUTION: A molded product of a polymeric material, such as water-soluble polysaccharides comprising alginic acid and its derivative, is dissolved in water, and the obtained aqueous solution is dehydrated to obtain a regenerated material. Here, energy and material loss can be reduced by adjusting the concentration and the viscosity of the aqueous solution to 10-30% and 10-1,000 mPa s, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a method for regenerating a polymer material having improved environmental load characteristics in production, regeneration and disposal, and further having improved heat resistance.

  In recent years, from the viewpoint of protecting the natural environment, biodegradable resins that decompose in the natural environment and molded articles thereof have been demanded. For example, biodegradable resins such as aliphatic polyesters have been actively researched. Although this resin does not decompose under normal usage environment, it is expected to be a promising material to solve environmental problems in the future because it is decomposed into water and carbon dioxide by microorganisms in a high temperature and high humidity compost environment. ing.

  Recently, development of making biodegradable polymers derived from bio-degradable polymers using polylactic acid, which is a typical biodegradable resin, or natural polysaccharides such as starch, is also in progress. However, these resins grow on land. Since it is collected and manufactured from the raw materials to be produced, it has the disadvantage of consuming resources for cultivating food and the like.

  On the other hand, since seaweed grows in water, it is advantageous in that it does not consume land resources to cope with future food problems. Alginate, which is a component in this seaweed, has the feature of being water-soluble, and it is promising as a resin material with reduced environmental impact in the future. Attempts have also been made to make biodegradable polymers using this alginic acid. (See Patent Document 1).

  This biodegradable polymer is characterized by being easily biodegradable in soil as compared with plastic made only from petroleum by mixing plant resources, especially algal acid of seaweeds, etc. with plastic made from petroleum. However, alginic acid has the disadvantage that the bond is broken even with slight heating and the molecular weight is lowered. When such a material is used as a molding material, alginic acid is exposed to a high temperature of 140 ° C. or more at the molding stage, and it is difficult for alginic acid to maintain its durability as a molding material during use. Is required.

Furthermore, the current plastic materials have transportation problems and disposal problems after use, which contribute to future resource depletion, reduced transport capacity due to bulkiness, depletion of final disposal sites, and the like. In order to solve this problem, materials that can be easily handled by anyone after use, transportation costs, materials that suppress energy, recycling materials and recycling technology to minimize the waste of resources and reuse are required. ing.
JP-A-3-269059

The present invention is a method for filtering and transporting impurities when regenerating using a polymer material such as alginic acid with improved heat resistance, which has reduced environmental burden in manufacturing, reuse, disposal, etc. It is an object of the present invention to provide a method that can efficiently regenerate by reducing energy required for the recycle process and suppressing loss of substances during the regeneration process.

In the present invention, a polymer material having a repeating unit represented by the following chemical formula 1 or a polymer material having a repeating unit represented by the following chemical formula 1 and chemical formula 2 is dissolved in water. Obtaining an aqueous molecular material solution;
A method for regenerating a polymer material comprising a step of removing water from the aqueous solution of the polymer material prepared in the step to obtain a regenerated polymer material.
Chemical formula 1

In the formula, R1 represents at least one group selected from an alkoxy group (—OR) and a carbamoyl group (—CONR2). R represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituted alkyl group. In the compound represented by the above chemical formula 1, hydrogen and hydroxyl group bonded to the same carbon of the sugar ring may be isomers whose positions are exchanged.

Chemical formula 2

In the chemical formula 2, R2 is a carboxyl group (—COOH), a salt of a carboxyl group (—COOM), a formyl group (—CHO), a carbonyl group (—COR), and an alkoxycarbonyl group (—COOR). Represents at least one group selected from: R represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a substituted alkyl group, and M represents a monovalent metal ion. In the compound represented by the chemical formula 2, hydrogen and hydroxyl group bonded to the same carbon of the sugar ring may be isomers whose positions are exchanged.

  In the method for regenerating a polymer material, the concentration of the aqueous polymer material solution is preferably 10% to 30%, and the viscosity is preferably 10 mPa · s to 1000 mPa · s.

In all the basic inventions, the substituent R1 of the polymer material having the repeating unit represented by the chemical formula 1 is preferably a carbamoyl group (CONR2). In this case, R of the carbamoyl group represents a hydrogen atom or an alkyl group.

According to the present invention, the use of the polymer material having the above structure has the effect of improving the heat resistance while maintaining the water solubility and enabling the regeneration by water treatment. As a result, it is possible to provide a method that can reduce the energy required for impurity filtration / conveyance during regeneration, and can efficiently regenerate while suppressing loss of material during the regeneration process.

  As described above, the present invention relates to a method for performing efficient regeneration by reducing energy loss for regeneration and material loss when reusing a water-soluble polymer material. Such a polymer material suitable for regeneration, a production method thereof, and a regeneration method will be described in detail.

[Polymer material]
A polymer material suitable for use in this embodiment is a polymer material having a first repeating unit represented by the following chemical formula 1 (first polymer material), or a polymer material represented by the following chemical formula 1. A polymer material (second polymer material) having one repeating unit and a second repeating unit represented by Chemical Formula 2.

Chemical formula 1

In the formula, R1 represents at least one group selected from an alkoxy group (—OR) and a carbamoyl group (—CONR2). R represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituted alkyl group. In the compound represented by the above chemical formula 1, hydrogen and hydroxyl group bonded to the same carbon of the sugar ring may be isomers whose positions are exchanged.

Chemical formula 2

In the formula, R2 is at least selected from a carboxyl group (—COOH), a salt of a carboxyl group (—COOM), a formyl group (—CHO), a carbonyl group (—COR), and an alkoxycarbonyl group (—COOR). 1 represents one group, M represents a monovalent metal ion, and specifically, Na and K are preferable.

(First polymer material)
The first polymer material having the first repeating unit of the present embodiment is a polysaccharide having a repeating unit having an alkoxy group (—OR) or a carbamoyl group (—CONR2) as R1 of the chemical formula 1. Specific examples of the polymer material having such a repeating unit include carboxyl group-containing polysaccharides such as alginic acid, alginate, xanthan gum, gellan gum, and hyaluronic acid, and physiologically acceptable products thereof. Artificial derivatives of these, esters obtained by dehydration condensation with alcohols of any carbon number, and polysaccharides that do not normally contain a carboxyl group, such as carboxymethylcellulose, carboxymethyldextran, and carboxymethylpullulan. Carboxyl such as methylchitin There alkoxylated functional groups such introduced chitin derivatives, or include carbamoylated polysaccharides. The polysaccharide of the present embodiment may contain an alkoxy group and a carbamoyl group at the same time.

  Xanthan gum refers to a substance mainly composed of a polysaccharide obtained from a culture solution of Xanthomonas. Gellan gum refers to a polysaccharide mainly obtained from a culture solution of Pseudomonas.

  More specifically, as the first polymer material that can be used in the present embodiment, alginic acid, sodium alginate, hyaluronic acid, potassium alginate, ammonium alginate, propylene glycol ester alginate, esterified starch, agar, pectin, etc. And alkoxylated products or carbamoylated products thereof. Of these, alginic acid and sodium alginate are most preferable from the viewpoint of easy availability of raw materials of alkoxylated products or carbamoylated products.

(Second polymer material)
The second polymer material of the present embodiment is a polysaccharide having a first repeating unit and a second repeating unit, and an alkoxy group (—OR) or a carbamoyl group ( A first repeating unit having —CONR2), and R2 of Formula 2 includes a carboxyl group (—COOH), a carboxyl group salt (—COOM), a formyl group (—CHO), a carbonyl group (—COR), or an alkoxy group. A polysaccharide having a second repeating unit having a carbonyl group (—COOR).

  In the second polymer material, the content ratio of the first repeating unit and the second repeating unit is appropriately in the range of 80% or more as the ratio of the first repeating unit as a whole. When this ratio is less than 80%, there is a problem that desired heat resistance and water solubility cannot be obtained, and this is not appropriate in the present embodiment. Note that a polymer material having a ratio of 100% corresponds to the first polymer material.

  In addition, in the said 1st and 2nd polymeric material, in addition to each repeating unit, other monosaccharides which do not have a carboxyl group, such as glucosamine, may be incorporated.

(Degree of polymerization)
As the first and second polymer materials of the present embodiment, those having a degree of polymerization of 100 to 650 can be adopted, but considering the workability and the durability of the resin, the degree of polymerization is 500 to 600. Those are preferred. When the degree of polymerization is below the above range, the mechanical properties of the polymer material are insufficient, which is not preferable as a molding material. On the other hand, when the degree of polymerization exceeds the above range, thermal decomposition occurs before the polymer material melts, which makes it difficult to mold and is not practical.

(Formability)
The first and second polymer materials of the present embodiment are water-soluble materials. Such a material can be molded by pouring an aqueous polymer material solution into a mold and dried, or a foam can be molded using a known foaming method such as physical foaming or chemical foaming. In disposal, it is a polymer material that is easily decomposed by microorganisms in a high-temperature and high-humidity composting environment and does not give a load to the environment.

[Method for producing polymer material]
Hereinafter, a method for producing the polymer material will be described.

The first polymer material of the present embodiment can be produced by independently glycosidic bonding a monosaccharide having hydrogen bonded to both ends of the first repeating unit. The second polymer material is a mixture of a monosaccharide having hydrogen bonded to both ends of the first repeating unit and a monosaccharide having hydrogen bonded to both ends of the second repeating unit. These can be produced by glycosidic bonding.
As another method for producing the first and second polymer materials of the present embodiment, at least a part of R2 which is a functional group of the polysaccharide having the second repeating unit is substituted with a hydroxyl group, an ether, an ester, It can be produced by substituting an amide group or an alkyl group having any carbon number. For this substitution reaction, a known reaction such as an amidation reaction, reduction, etherification, alkylation, etc. can be adopted (see, for example, Literature Chemistry; McMurry Organic Chemistry 3rd Edition; p1101).
In this case, if the substitution is complete, a first polymeric material consisting of only the first repeating unit is obtained, while if the substitution does not replace all functional groups, the first repeating unit and A second polymer material comprising the second repeating unit is obtained.

  Hereinafter, as a representative example of the present embodiment, a method for producing a polymer material having an increased heat resistance by using alginic acid containing a carboxyl group as R1 in Chemical Formula 1 and containing an amide group as R2 in Chemical Formula 2 will be described.

  The polymer material can be produced by reacting the starting material, alginic acid, a salt or derivative thereof, and an amine in the presence of a condensing agent and a reaction solvent.

  Alginic acid or a salt thereof or a derivative thereof is alginic acid alone, and the salt indicates an alkali metal salt such as sodium or an alkali metal salt such as calcium. As for the derivative, alginic acid has two hydroxyl groups and one carboxyl group. Alginic acid which is particularly easily substituted is preferred in the present invention. Commercially available alginic acid or a salt thereof or a derivative thereof has a degree of polymerization of about 100 to 650. In consideration of easy processing and high durability of the polymer, those having a polymerization degree of about 500 to 600 are preferable.

  As amines used in the above reaction, primary amines, secondary amines, and tertiary amines having an alkyl group having 1 to 5 carbon atoms can be used. Most preferably, primary amines are used. It is an amine. Specific examples include methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, and methylethylamine.

  The condensing agent used in the above reaction is a water-soluble carbodiimide such as 1-ethyl-3 (dimethylaminopropyl) -carbodiimide or its hydrochloride, or N, N′-dicyclohexylcarbodiimide, N, N′-diisopropylcarbodiimide. An organic solvent-soluble carbodiimide or the like can be used. The most preferred condensing agent is 1-ethyl-3 (dimethylaminopropyl) -carbodiimide when water is used as a solvent, and N, N′-dicyclohexylcarbodiimide is effective when an organic solvent is used as a solvent. .

  Preferred examples of the reaction solvent used in the above reaction include water, THF, dichloromethane and the like. It is preferable to select a condensing agent according to the solubility characteristics of the following condensing agent. The most preferred solvent is water when a water-soluble condensing agent is used, and THF when an organic solvent-soluble condensing agent is used.

Hereinafter, the production method of the present embodiment will be specifically described in detail.
Alginic acid or a salt thereof or a derivative thereof and a reaction solvent are added to a container in which a reaction solvent has been placed in advance, and this is immersed in an ice bath and cooled. Then, the condensing agent was slowly added while stirring with a stirrer. At this time, the temperature is controlled in the range of about 0 ° C to 30 ° C. Preferably, the addition of the condensing agent is performed in the range of 0 to 10 ° C. to prevent heat generation. The mixture is stirred for about 15 minutes and then an aqueous solution of amines is added in small portions. Remove the ice bath and stir for 6 hours while warming to room temperature. At this time, the temperature is preferably maintained at 20 to 30 ° C. Thereafter, the floating solid is taken out, precipitated in an alcohol solvent such as methanol or ethanol, stirred and washed. Depending on the substance, a solvent such as water, acetone or isopropanol may be used. This is an effective means for removing unreacted condensing agents and amines. Thereafter, drying is performed at room temperature to obtain a product.

  For substances in which the carboxyl group of alginic acid is amidated, the water solubility can be improved because the amide group is hydrophilic, and the water treatment time is shortened and the viscosity of the aqueous solution is significantly reduced. There are many advantages such as being simple.

  Whether the polymer material of the present invention is a substance substituted with a target substance can be confirmed by observing the presence of an amide bond by NMR, UV, or the like. Furthermore, regarding the evaluation of the heat resistance of the product, the heat resistance can be evaluated by calculating the thermal decomposition temperature from the thermal decomposition curve using an apparatus such as TG-DTA320 manufactured by Seiko Denshi Kogyo.

  According to the production method of the present invention, in order to increase the heat resistance of the polymer material, a specific functional group or bonding portion of the raw material is substituted with a compound having a specific functional group or bonding portion at the raw material stage. By doing so, a polymer material with improved heat resistance can be produced. Depending on the substance, improvement in water resistance, expression of ease of processing, and the like are realized. Thus, by increasing the heat resistance of the polymer material, the application can be expanded to materials that require heat resistance.

  In addition, according to the present invention, since the water performance can be improved, a material that can be easily recycled can be produced. Regarding the water-soluble performance and the performance of the recycled material, the water-soluble time and the viscosity at the time of water-soluble are measured to verify the ease of handling when dissolved in water. In addition, GPC analysis and pyrolysis curve analysis of the recycled material were performed, and changes in physical properties before and after the regeneration were observed.

[Playback method]
The polymer material of the present embodiment is easily regenerated by, for example, a regeneration method having a step of dissolving a polymer material to be regenerated in water and a step of removing water from the aqueous solution to obtain a regenerated polymer raw material. It is possible.

  Usually, in the regeneration of such a polymer material, the spent polymer material is collected in a factory for reprocessing and dissolved in water to reduce the volume. Thereafter, the aqueous solution is dried to produce a recycled polymer raw material, which is then molded into a required shape and reused in a molding factory. At this time, when the reprocessing plant and the molding plant are separated, the aqueous solution in which the polymer material is dissolved is transported between the two plants by a transporting means such as a truck accommodated in a container such as a tank, or re-treated. It is conveyed by means such as a pipeline between the processing plant and the molding plant. In any case, since processing is performed at a plurality of locations, considering the movement between those locations, it is preferable that the volume of the substance to be transferred is small, and considering that it is transported as an aqueous solution The polymer material to be reprocessed is preferably dissolved and transported at a high concentration. However, when the concentration of the polymer material is increased, the viscosity of the solution also increases. If the viscosity is excessive, handling becomes difficult, and material loss is likely to occur in a pipeline or the like during conveyance.

  In consideration of the above points in the regeneration of the water-soluble polymer material, in the present invention, the concentration of the aqueous polymer material solution is 10% or more and 30% or less, and the viscosity is 10 mPa · s or more and 1000 mPa · s or less. did. As a result, a regenerated product can be obtained with high efficiency and in a short time. In order to obtain a regenerated product with high efficiency and in a short time, the most preferable condition is a concentration of 20%. This makes it possible to process a large amount of water-soluble polymer material in a short time without increasing the viscosity.

  As for the basic physical properties of the polymer material, since there is almost no loss in which molecules are decomposed or reduced by the regeneration process or water, the same physical properties as before the regeneration can be obtained. When the substituent of R1 is mainly a carbamoyl group, it can be easily dissolved in water to obtain a regenerated polymer. Compared with the material before modification, the water-soluble time is short, and the viscosity at the same aqueous solution concentration is reduced. This contributes to the reduction of energy required for impurity filtration / conveyance, etc., and to the loss reduction due to the decrease in viscosity, and ultimately leads to a reduction in the regeneration process time and energy consumption.

  Compared with this, in the conventional petroleum-based materials and plant-based materials, recycled materials are obtained through material recycling that requires high-temperature heat melting and chemical recycling using organic solvents. The impact of the method on the environment is very high. Also, conventional water-soluble materials cannot be regenerated unless heat treatment, solvent treatment, acid-alkali treatment, or the like is used. The material can be easily processed without such treatment. Furthermore, compared with before material modification, the viscosity at the time of water solution is significantly reduced, and the time for water solution can also be shortened.

  Hereinafter, the aqueous solution of the polymer material can be dehydrated and dried to be processed into powder or pellets of the polymer material to be a recycled polymer raw material. For this dehydration drying, any drying means such as heat drying, vacuum drying or vacuum heat drying can be employed.

  The recycled polymer raw material obtained by the above method has thermoplasticity, and can be molded into an arbitrary shape using a normal plastic material molding method such as extrusion molding, injection molding, or blow molding.

[Usage]
The polymer material produced in the present invention can be used as a raw material for medical materials, immobilized culture medium for cell culture, packaging materials for industrial / agricultural / food use (for example, food trays), and any other sheet. It is expected that it can be effectively used for packaging containers (one-way containers), toys, sheets, furniture parts, building materials, automobiles, home appliances, OA equipment members, interior materials, housings, etc.

  Hereinafter, it demonstrates in detail based on an Example. The present invention is not limited to these examples.

Example 1
A 200 mL Erlenmeyer flask was charged with 50 mL of a THF solution, immersed in an ice bath, cooled at about 7-8 ° C., 2.5 g of alginic acid was added thereto, and the mixture was stirred with a stirrer. While stirring, 2.9 g of dicyclohexylcarbodiimide was slowly added. After stirring this mixture for about 15 minutes, 1.2 ml of a 40% aqueous solution of methylamine was added little by little. Further, the ice bath was removed, and the mixture was stirred for 6 hours while warming to room temperature. Thereafter, the floating solid was taken out, precipitated in 200 ml of methanol, and stirred. Thereafter, it was dried at room temperature for about 2 hours to obtain a product.
This product was a substance in which the carboxyl group of alginic acid was substituted with an amide group by about 40%. It was 210.0 degreeC when the thermal decomposition start temperature of this substance was measured. Moreover, the thermal decomposition curve of this substance is shown in FIG. In FIG. 1, curve A is a decomposition curve of amidated alginic acid.

Further, IR and NMR results of the substance thus obtained are shown in FIG. 2, FIG. 3, and FIG.
The viscosity characteristics when this substance is dissolved in water are shown in FIG. 5A, and the water performance when this substance is dissolved in water at an aqueous solution concentration of 1% is shown in Table 1. According to these, the viscosity at the time of water solution is reduced, the time for water solution is short, and the handling is easy.
Moreover, the said substance was immersed in water and the relationship between progress of immersion time (elution time) and the amount of eluted substances (measured by the change of a photorefractive index) was investigated. The resulting graph is shown in FIG. On the other hand, a graph showing the relationship between the elution time of a substance and the molecular weight of the substance is shown in FIG. 6 and 7, the molecular weight of this substance can be determined.

(Comparative Example 1)
It was 187.5 degreeC when the thermal decomposition temperature of the sodium alginate which did not perform any modification process was measured. The pyrolysis curve of this material is shown in FIG. In FIG. 1, curve C is a decomposition curve of sodium alginate.

The viscosity characteristics when this substance is dissolved in water are shown in FIG. 5C, and the water solubility when this substance is dissolved in water at an aqueous solution concentration of 1% is shown in Table 1. According to these, it is understood that the viscosity at the time of water solution is high, and the time for water solution is long.

(Comparative Example 2)
10 g of sodium alginate was placed in a 300 ml three-necked flask, 200 ml of glacial acetic acid was added, and the mixture was heated and stirred at 90 ° C. for 1 hour. After cooling, the product was filtered using a glass filter. The mixture is gradually added to an acetylated mixed acid composed of 40 g of acetic anhydride, 40 g of glacial acetic acid and 1 g of sulfuric acid, which has been cooled to 0 ° C. or lower in advance, with stirring. At this time, care was taken so that the internal temperature would not exceed 25 ° C. by cooling from the outside. After the addition was completed, the mixture was kept at 20 to 25 ° C and stirred for 3 hours. After completion, the product was filtered through a glass filter, washed with ethanol (stirred for 30 minutes) and dried at room temperature. This substance was obtained by acetylating about 50% of the hydroxyl group of sodium alginate.
It was 184.0 degreeC when the thermal decomposition start temperature of this substance was measured.

(Example 2)
The product was obtained in the same manner as in Example 1 except that it was not cooled in an ice bath at about 7-8 ° C.
It was 208.3 degreeC when the thermal decomposition start temperature of this substance was measured.

(Example 3)
10 g of propylene oxide was reacted with 5.0 g of alginic acid, and the carboxyl group portion of alginic acid was esterified under pressure at about 70 ° C. for 3 hours. Then, it dried and grind | pulverized and obtained the product. It was 198.7 degreeC when the thermal decomposition start temperature of this substance was measured. Moreover, the thermal decomposition curve of this substance is shown in FIG. In FIG. 1, curve B is a thermal decomposition curve of esterified alginic acid.

  The viscosity characteristics when this substance is dissolved in water are shown in FIG. 5B, and the water-soluble performance when this substance is dissolved in water at an aqueous solution concentration of 1% is shown in Table 1. According to these, when the concentration is low, the viscosity is low and the water-soluble time is short, but a large amount of regeneration treatment cannot be performed. On the other hand, when the concentration is increased, the viscosity rapidly increases, so that the water-soluble time becomes longer, and it becomes difficult to handle the solution during regeneration.

Example 4
The polymer material obtained in Example 1 was allowed to stand for 1 month at 25 ° C. and a humidity of 50%, and then dissolved in water to form a 20% by weight aqueous solution, which was placed in a flat metal container for 2 days. The regenerated material was obtained by drying by blowing at room temperature. The thermal decomposition starting temperature of this substance was measured and found to be 208.2 ° C. Moreover, the thermal decomposition curve of this substance is shown in FIG.

Moreover, the viscosity characteristic when this substance is dissolved in water is shown in FIG. 5A, and the water solubility when this substance is dissolved in water is shown in Table 1. According to these, the viscosity at the time of water-solubility is reduced, the water-solubility time is short, and a larger amount is easy to handle.
In addition, the relationship between the elution time of this substance and the amount of eluted substance was investigated. The results are also shown in FIG.

(Example 5)
A regenerated product was obtained in the same manner as in Example 4 except that the concentration in water was 10% by weight.
It was 206.4 degreeC when the thermal decomposition start temperature of this substance was measured. Moreover, the thermal decomposition curve of this substance is shown in FIG.

Moreover, the viscosity characteristic when this substance is dissolved in water is shown in FIG. 5A, and the water solubility when this substance is dissolved in water is shown in Table 1. According to these, the viscosity at the time of water-solubility is reduced, the water-solubility time is short, and a larger amount is easy to handle.
In addition, the relationship between the elution time of this substance and the amount of eluted substance was investigated. The results are also shown in FIG.

(Example 6)
A regenerated product was obtained in the same manner as in Example 4 except that the concentration in water was 30% by weight.
It was 207.5 degreeC when the thermal decomposition start temperature of this substance was measured. Moreover, the thermal decomposition curve of this substance is shown in FIG.

Moreover, the viscosity characteristic when this substance is dissolved in water is shown in FIG. 5A, and the water solubility when this substance is dissolved in water is shown in Table 1. According to these, the viscosity at the time of water-solubility is reduced, the water-solubility time is short, and a larger amount is easy to handle.
In addition, the relationship between the elution time of this substance and the amount of eluted substance was investigated. The results are also shown in FIG.

(Example 7)
A product was obtained in the same manner as in Example 1 except that 3.0 ml of a 70% aqueous solution of ethylamine was used instead of the 40% aqueous solution of methylamine used in the reaction. It was 202.9 degreeC when the thermal decomposition start temperature of this substance was measured. Table 1 shows the water-soluble performance when this substance is dissolved in water. According to these, compared with the material alginic acid before the reaction, the viscosity at the time of water solution is reduced, the time for water solution is short, and a larger amount of handling is easy.

(Example 8)
A regenerated product was obtained in the same manner as in Example 7 except that the concentration in water was 10% by weight. It was 205.3 degreeC when the thermal decomposition start temperature of this substance was measured. Table 1 shows the water-soluble performance when this substance is dissolved in water. According to these, compared with the material alginic acid before the reaction, the viscosity at the time of water solution is reduced, the time for water solution is short, and a larger amount of handling is easy.

Example 9
A regenerated product was obtained in the same manner as in Example 7 except that the concentration in water was 30% by weight. It was 200.6 degreeC when the thermal decomposition start temperature of this substance was measured. Table 1 shows the water-soluble performance when this substance is dissolved in water. According to these, compared with the material alginic acid before the reaction, the viscosity at the time of water solution is reduced, the time for water solution is short, and a larger amount of handling is easy.

(Evaluation)
FIG. 6 shows the relationship between the elution time of the substance and the amount of the eluted substance, and the relationship between the elution time and the molecular weight of Example 1 and the substances of Examples 4, 5, and 6 which are regenerated materials of the substance. As is clear from FIG. 7, since there is almost no change in the molecular weight distribution curve before and after the regeneration of the substance of Example 1 (in terms of the weight average molecular weight Mw, a range of 6000 or less), the viscosity is greatly reduced. It can be said that the obtained properties are not caused by degradation due to decomposition of the polymer, and it is considered that there is almost no influence on the characteristics of the material.

  Table 2 summarizes the results of measurement of the types of substituents of the polymer material, the aqueous solution concentration, the reaction conditions, and the thermal decomposition start temperature for the above Examples and Comparative Examples.

  As is apparent from Table 2, in the polymer materials of the examples of the present invention, the thermal decomposition starting temperatures are both higher than 190 ° C., and have heat resistance in a practical range as a molding material. On the other hand, in the polymer material of the comparative example, the thermal decomposition temperature was lower than 190 ° C., and the heat resistance was insufficient as a molding material.

  Further, as is apparent from FIG. 1 showing the thermal decomposition curves of the materials of the examples and comparative examples, in the alginic acid (curve C) which has not been subjected to any substitution treatment, thermal decomposition started at about 100 ° C. It is clear that it does not have sufficient heat resistance. On the other hand, in both polymer materials of amidated alginic acid (curve A) and esterified alginic acid (curve B), the degree of thermal decomposition is lower than alginic acid and heat resistance is improved in this region. It became clear.

Also, the regenerated materials from Example 4 to Example 9 can maintain heat resistance, and this material can be said to be a material that hardly affects the deterioration of characteristics due to changes over time or the regeneration process.

The graph which shows the thermal decomposition curve of the polymeric material obtained by the Example and comparative example of this invention. The IR chart of the substance obtained by the Example of this invention. The NMR chart of the substance obtained by the Example of this invention. The principal part enlarged view of the NMR chart of the substance obtained by the Example of this invention. The comparison figure of the viscosity characteristic of the substance obtained in the Example of this invention, alginate, and alginate. The figure which shows the relationship between the elapsed time which immersed the substance obtained in the Example of this invention in water, and the elution amount of the substance. The figure which shows the relationship between the elution time of a substance, and molecular weight.

Claims (3)

A polymer material having a repeating unit represented by the following chemical formula 1 or a molded body molded by a polymer material having a repeating unit represented by the following chemical formula 1 and chemical formula 2 is dissolved in water to prepare an aqueous polymer material solution. Obtaining a step;
A method for regenerating a polymer material, comprising the step of removing water from the aqueous solution of the polymer material prepared in the step to obtain a regenerated polymer raw material.
Chemical formula 1

In the formula, R1 represents at least one group selected from an alkoxy group (—OR) and a carbamoyl group (—CONR2). R represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituted alkyl group. In the compound represented by the above chemical formula 1, hydrogen and hydroxyl group bonded to the same carbon of the sugar ring may be isomers whose positions are exchanged.

Chemical formula 2

In the chemical formula 2, R2 represents a carboxyl group (—COOH), a carboxyl group salt (—COOM), a formyl group (—CHO), a carbonyl group (—COR), and an alkoxycarbonyl group (—COOR). Represents at least one group selected from: R represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a substituted alkyl group, and M represents a monovalent metal ion. In the compound represented by the chemical formula 2, hydrogen and hydroxyl group bonded to the same carbon of the sugar ring may be isomers whose positions are exchanged.   2. The polymer according to claim 1, wherein the concentration of the aqueous polymer material solution is 10% to 30% and the viscosity is 10 mPa · s to 1000 mPa · s. Material recycling method. The method for regenerating a polymer material according to claim 1, wherein the substituent R1 of the polymer material having a repeating unit represented by the chemical formula 1 is a carbamoyl group (CONR2).
R of the carbamoyl group represents a hydrogen atom or an alkyl group.