JP2567810B2 - Biodegradable polymer material - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is a polymer material which can be used as a raw material for the production of films, sheet fibers and other moldings, which is thermally stable, biodegradable and harmful when incinerated. It relates to a material that does not release a substance.

[0002]

BACKGROUND OF THE INVENTION Today, a very wide variety of products are constructed wholly or at least partially using synthetic polymers, which are known to have different chemical constitutions. Many of these various synthetic polymers are highly resistant to chemical and microbial degradation, reflecting the chemical resistance typically required of products.

However, since these products are produced and used in large quantities, a large number of those discarded after use are scattered into the environment, and in connection with this, various products are The excellent stability of the synthetic polymers that make it up causes problems. That is,
In many cases, products that have been mixed in soil or water remain semi-permanently without being decomposed, and are contaminating soil, rivers and even the ocean extensively. Under such circumstances, although attempts have been made to develop biodegradable polymer materials that are decomposed into harmless substances in the environment, a very wide variety of polymer materials have been used and newly synthesized. In contrast, the development of such polymeric materials has been attempted only to a very limited extent.
Therefore, there is a need for such new polymeric materials.

Further, among the polymer materials conventionally used, there are those which generate toxic gas upon incineration and those which generate high heat and damage the incinerator, and a polymer material free from such a fear is developed. It is also required to do.

On the other hand, konjac flour (fine powder) whose main component is konjac mannan, which is a type of glucomannan
Can be converted into a polymer that is difficult to dissolve in water when treated with alkali. This polymer is thermally stable and has various excellent properties such as spontaneous decomposition and disappearance in the environment, so if it can be easily molded into a specific shape, Should have high utility as a characteristic polymer for the manufacture of articles of
However, although this polymer is thermally stable,
Since it is poorly soluble in both water and organic solvents, it is extremely difficult to mold and cannot be used as a polymer material for molding articles.

[0006]

The present invention has very high thermal stability in the above situation, but is easy to be molded into a specific form, is biodegradable, and is incinerated. It is an object of the present invention to provide a new biodegradable polymer material having a characteristic that it does not generate a toxic gas during treatment. The present invention also aims to provide a method for producing such a polymeric material.

[0007]

That is, the polymer material of the present invention is a biodegradable polymer material obtained by acetylating konjak powder, which is insoluble in water and soluble in organic solvents. Here, “soluble” is particularly preferably at room temperature (herein, 25 ° C.).
It means that 2 g or more can be dissolved in 100 mL of chloroform.

The biodegradable polymer material of the present invention is an aqueous solution of konjak flour (preferably refined flour), and after insoluble matter is removed, glacial acetic acid or a water-miscible organic solvent is added to cause precipitation. The precipitate is separated, suspended in glacial acetic acid, added with acetic anhydride and a Lewis acid such as zinc chloride, and heated to acetylate to generate the product. The reaction solution is added to water to precipitate. It can be obtained as a thing.

Prior to finding the above production method, the present inventor tried various acetylation of konjak flour by using konjak flour as it was, suspending it in glacial acetic acid and treating it with acetic anhydride and zinc chloride. However, it did not react and acetylation was impossible. That is, acetylation of konjak powder became possible only by once making konjak powder into an aqueous solution and precipitating the mixture, and then performing the reaction using the precipitate, as shown in the above-mentioned production method. When the konjak powder is used as an aqueous solution, it is usually preferable to use 50 to 200 parts by weight of water per 1 part by weight of konjak powder.

The biodegradable polymeric material of the present invention is insoluble in water but well soluble in chloroform. Therefore,
It can be dissolved in an appropriate organic solvent and formed into a desired specific form such as a film, sheet or fiber. Further, as will be shown later, the molded product obtained by this has a characteristic that the thermal stability is very high. That is, the change in elastic modulus with temperature is small, the coefficient of thermal expansion is very small, and there is almost no change in weight even at high temperatures, and the change in length is very small. Therefore, by utilizing this characteristic, it can be used for various applications in the form of, for example, a film or a fiber.

Further, unlike most synthetic resins, it is biodegradable and has the characteristic that it decomposes and disappears in the environment (for example, in soil). Therefore, the polymer material of the present invention is highly useful in that it does not pollute the environment. In addition, the film, sheet,
Since fibers, etc. consist essentially of carbon, hydrogen and oxygen, there is no danger of producing toxic gas as long as they are completely burned during incineration, and like wood, etc.
There is also an advantage that the incinerator is not damaged because it does not generate extremely high temperature unlike many synthetic resins when incinerated.

[0012]

【Example】

[Example 1] Production of polymer material of the present invention 1 g of konjak flour (fine powder: konjak mannan content 76% by weight) was dissolved in 150 mL of water, and the solution was centrifuged to remove insoluble matter. Add to mL with stirring (precipitate occurs). Separate the precipitate, add 10 mL of glacial acetic acid to suspend it, and stir 60 mL of acetic anhydride while stirring.
And 0.2 g of zinc chloride were added, and the mixture was heated with stirring at 70 ° C for 1 hour,
The precipitate is dissolved. When this solution is added to water with stirring, a new precipitate is formed. The precipitate is collected, washed with alcohol and water, and then dried to obtain 1.3 g of a target polymer material.

Example 2 Production of Polymer Material of the Present Invention To 1 kg of konjak flour (fine powder: konjak mannan content 76% by weight), about 200 L of water was added and dissolved with stirring. 200 L of ethanol was added to this and stirred to form a precipitate. The precipitate is collected by filtration and dried. Then, 20 L of glacial acetic acid was added to the solution to immerse it, and the precipitate was collected by filtering again. Acetic anhydride and zinc chloride were added to this precipitate in the same ratio as in Example 1, and the mixture was heated and stirred at 70 ° C. for 1 hour to dissolve the precipitate. When this solution is added to water with stirring, a new precipitate is formed. The precipitate is collected, washed with ethanol and water, and then dried to obtain a target polymer material.

[Properties of Polymer Material of the Present Invention] Example 1
The polymer material obtained in (1) is insoluble in water, but dissolves well in an organic solvent such as chloroform (dissolves 5 g or more in 100 mL of chloroform). Therefore, the polymer material can be formed into a film, a sheet, a fiber or the like via a solution form with an organic solvent such as chloroform.

When the polymer material obtained in Example 1 was buried in ordinary soil, it was decomposed by microorganisms in the soil and completely decomposed and disappeared in about 3 months in summer.

1 g of the polymer material obtained in Example 1 was dissolved in 20 mL of chloroform, poured thinly on a glass plate and dried to obtain a film having a thickness of 75 μm. about this,
The elastic modulus was measured between 25 ° C and about 200 ° C. As shown in FIG. 1, the change in elastic modulus in this temperature range was only small. The coefficient of thermal expansion is 3.2 x 1
It was ^0-8 , which was very small. Regarding the weight change during high temperature heating, as shown in Fig. 2, the weight decreased slightly at about 400 ° C, but thereafter it remained unchanged even if the temperature was increased to about 600 ° C. Furthermore, 4mm width x 75μ
When the temperature is changed from room temperature to 400 ° C with a 0.1 g weight suspended on a 20 mm long test piece, the change in the length of the test piece is about 100 μm as shown in Fig. 3. And was very small.

[Brief description of drawings]

FIG. 1 is a graph showing a change in elastic modulus of a test piece manufactured from the polymer material of Example 1 with heating. The brackets on the vertical axis indicate the range to which polymers generally belong.

FIG. 2 is a graph showing the weight change with heating of the test piece manufactured from the polymer material of Example 1.

FIG. 3 is a graph showing a change in length of a test piece manufactured from the polymer material of Example 1 with heating.

Claims (3)

(57) [Claims] 1. A biodegradable polymer material obtained by acetylating konjak flour, which is insoluble in water and soluble in organic solvents. 2. Glacial acetic acid or a water-miscible organic solvent is added to an aqueous solution of konjak flour, and the mixture is stirred, and the resulting precipitate is collected and suspended in glacial acetic acid, which is then heated with acetic anhydride and Lewis acid. A method for acetylating konjak flour, which comprises treatment with konjak flour. 3. Glacial acetic acid or a water-miscible organic solvent is added to an aqueous solution of konjak flour and stirred, and the resulting precipitate is collected and suspended in glacial acetic acid, which is then heated under heating to acetic anhydride and Lewis acid. The method for producing a biodegradable polymer material according to claim 1, which comprises treating the reaction solution with water and adding the reaction solution to water to obtain a precipitate.