JP5977997B2 - Agricultural multi-film manufacturing method - Google Patents

Description

  The present invention relates to a multifunctional biodegradable composite material and a method for producing the same. More specifically, it can be used as, for example, a multi-film for agriculture (Mulch Film), and is a multifunctional biodegradable composite material for controlling soil temperature, pest control, weed control, moisture retention, environmental protection, labor saving, and the production thereof. Regarding the method.

  In recent years, mass production, mass consumption and mass disposal of synthetic resins have become major social problems. The discarded synthetic resin is incinerated or landfilled, causing global warming and soil contamination. Therefore, biodegradable resins that take these problems into account have been developed and put into practical use. However, polylactic acid represented by biodegradable resins has a long shape collapse period of 3 to 5 years, and is incinerated. Often processed. In addition, non-degradable multi-films consisting of polyethylene films, etc., which are currently mainstream, require labor such as peeling off the film when harvesting crops, and this problem can be solved in Japan, where the number of agricultural workers is decreasing and the population is aging. Is an urgent issue.

  As a related prior art, Patent Document 1 proposes a biodegradable material composition in which a pulverized material of vegetable raw material mainly composed of rice husks and a degradable substance containing a binder are mixed. In addition, Patent Document 2 proposes a material containing a biodegradable organic polymer compound and a basic substance as a biodegradable composite material in consideration of the safety of ecosystems, particularly soil and water quality. ing. This composite material is a composite material that uses lacia belonging to polylactic acid as a biodegradable organic polymer compound and aluminum hydroxide as an additive, such as soil caused by carboxylic acid generated during the decomposition process of the composite material. The decrease in pH is neutralized with the aluminum hydroxide to suppress the decrease in pH of the soil and the like, and the pH can be appropriately maintained.

JP 2000-229311 A JP 2004-182772 A

  In order to eliminate the need for labor such as stripping multi-films at the time of harvesting of crops and after harvesting, it is necessary to match the time of harvesting using a tractor at the time of harvesting or the time of plowing the field with a cultivator after manual harvesting. What is necessary is just to collapse a shape of a film. In addition, depending on the type of crop, there are a short type and a long type from when the multi-film is laid until the crop is harvested. Therefore, if a multi-film whose shape is collapsed can be laid in accordance with the period until the crop is harvested, labor such as peeling off the multi-film at the time of harvesting the crop or after harvesting becomes unnecessary.

  The present invention has been made in order to solve the above-mentioned problems, and the object thereof is to promote the shape collapse of a biodegradable molded article such as a biodegradable film, and to arbitrarily change the shape collapse speed. Another object of the present invention is to provide a multifunctional biodegradable composite material that can be used, and a method for producing the same.

  The multifunctional biodegradable composite material according to the present invention for solving the above problems is a one or more powders containing a biodegradable polymer compound and calcium oxide, calcium hydroxide and calcium carbonate. And at least one of the powders contains 90% by mass or more of the calcium oxide.

  According to the present invention, at least one of the one or more powders containing calcium oxide, calcium hydroxide, and calcium carbonate contains 90% by mass or more of calcium oxide. 90% by mass or more of calcium oxide contained in the powder contained in the material becomes calcium hydroxide with heat generation when it comes into contact with moisture, and a physical crack is formed in a molded article such as a film made of a biodegradable composite material. And induce shape collapse more easily. Moreover, hydrolysis of a biodegradable polymer compound can be accelerated by the basic catalytic effect of calcium hydroxide. As a result, even biodegradable polymer compounds such as polylactic acid with a long degradation period can be rapidly degraded. For example, a multifilm made from this biodegradable composite material pulls the multifilm when harvesting crops. Eliminates the need for labor such as peeling, which can contribute to significant labor savings.

  In addition, when an acid such as carboxylic acid is generated by decomposition of the biodegradable polymer compound, the pH in the soil decreases and shifts to the acidic side. Such pH can be raised back to neutrality by calcium hydroxide produced upon contact with the water. Moreover, even if such an acid does not occur, neutralization of soil acidified with acid rain or the like can be realized.

  The multifunctional biodegradable composite material according to the present invention further contains one or more selected from pepper powder, neem powder, natural product-derived powder and soil modifier.

  According to this invention, since it further contains one or more selected from chili powder, neem powder, natural product-derived powder and soil modifier, the functionality of the multifunctional biodegradable composite material is further enhanced. Can do.

  The manufacturing method of the multifunctional biodegradable composite material which concerns on this invention for solving the said subject is a process which prepares the high molecular compound which has biodegradability, and contains calcium oxide, calcium hydroxide, and calcium carbonate. A step of calcining at least one of the seeds or two or more powders to prepare a powder containing 90% by mass or more of the calcium oxide, the polymer compound and the one or more powders; And kneading.

  According to this invention, a powder containing 90% by mass or more of the calcium oxide is prepared by firing at least one of the one or more powders containing calcium oxide, calcium hydroxide and calcium carbonate. And since such powder is knead | mixed with a biodegradable polymer compound, the obtained multifunctional biodegradable composite material contains the powder containing 90 mass% or more of calcium oxide. When the calcium oxide comes into contact with moisture, it generates heat and becomes calcium hydroxide, causing physical cracks in molded articles such as films made of biodegradable composite materials, and more easily inducing shape collapse. . Hydrolysis of a biodegradable polymer compound can be accelerated by the same basic catalytic effect as described above.

  In the method for producing a multifunctional biodegradable composite material according to the present invention, a plurality of polymorphs in which the mixing ratio of the powder having a calcium oxide content of 90% by mass or more and the powder having the other calcium oxide content is changed The functional biodegradable composite material is kneaded to produce two or more multifunctional biodegradable composite materials having different degradation rates.

  According to the present invention, two or more types of multifunctional biodegradable composite materials having different degradation rates can be arbitrarily controlled and manufactured. Therefore, depending on the type of the crop, the period from when the multifilm is laid to when the crop is harvested The multifunctional biodegradable composite material produced in this invention can be used as a raw material for multi-films that biodegrade in accordance with the period until crops are harvested even if there are short or long types .

  According to the multifunctional biodegradable composite material and the method for producing the same according to the present invention, 90% by mass or more of calcium oxide contained in the powder contained in the biodegradable composite material is heated with heat due to contact with moisture. It becomes calcium oxide and causes physical cracks in a molded article such as a film made of a biodegradable composite material, and induces shape collapse more easily. Hydrolysis of the biodegradable polymer compound can be accelerated by the basic catalytic effect of calcium hydroxide. As a result, even biodegradable polymer compounds such as polylactic acid with a long degradation period can be rapidly degraded. For example, a multifilm made from this biodegradable composite material pulls the multifilm when harvesting crops. Eliminates the need for labor such as peeling, which can contribute to significant labor savings.

  In addition, when an acid such as carboxylic acid is generated by decomposition of the biodegradable polymer compound, the pH in the soil decreases and shifts to the acidic side. Such pH can be raised back to neutrality by calcium hydroxide produced upon contact with the water. Moreover, even if such an acid does not occur, neutralization of soil acidified with acid rain or the like can be realized.

The example of the multifunctional biodegradable composite material which concerns on this invention is shown, (A) is a biodegradable composite material containing a single powder, (B) is a biodegradable composite containing two types of powder. Material. It is a graph which shows the degradability evaluation result after the hydrolysis test of the biodegradable composite material of Experimental Examples 1-3, (A) is a graph which shows a time-dependent change of a weight loss rate, (B) is an intrinsic viscosity reduction | decrease. It is a graph which shows a time-dependent change of a rate. It is a graph which shows the degradability evaluation result after the hydrolysis test of the biodegradable composite material of Experimental example 1-3, (A) is a graph which shows a time-dependent change of pH, (B) is a time-dependent change of TOC. It is a graph to show. It is an electron micrograph of the film surface after the hydrolysis test of the biodegradable composite materials of Experimental Examples 1 to 3 (0 day, 30 days, 90 days). It is a graph which shows the degradability evaluation result after the hydrolysis test of the biodegradable polymer compound of Comparative Experimental Examples 1-3, (A) is a graph which shows a time-dependent change of a weight loss rate, (B) is an intrinsic | native. It is a graph which shows a time-dependent change of a viscosity decreasing rate. It is a graph which shows the degradability evaluation result after the hydrolysis test of the biodegradable high molecular compound of Comparative Experimental Examples 1-3, (A) is a graph which shows a time-dependent change of pH, (B) is the aging of TOC. It is a graph which shows a change. It is a graph which shows the degradability evaluation result after the soil embedding test of the biodegradable composite material of Experimental Examples 1-3, (A) is a graph which shows a time-dependent change of a weight loss rate, (B) is time-dependent pH. It is a graph which shows a change. It is an electron micrograph of the film surface after the soil embedding test of the biodegradable composite material of Experimental Examples 1-3 and Comparative Experimental Examples 4 and 6 (30 days). It is an electron micrograph of the film surface after the soil embedding test of the biodegradable composite material of Experimental Examples 1-3 and Comparative Experimental Examples 4-6 (60 days). It is an electron micrograph of the film surface after the soil embedding test of the biodegradable composite material of Experimental Examples 1-3 and Comparative Experimental Examples 4 and 6 (90 days).

  Hereinafter, the multifunctional biodegradable composite material and the manufacturing method thereof according to the present invention will be described in detail. The present invention is not limited to the following embodiments and experimental examples.

  The multifunctional biodegradable composite material 1 according to the present invention includes, as shown in FIG. 1, for example, one or two kinds containing a biodegradable polymer compound 11 and calcium oxide, calcium hydroxide and calcium carbonate. The above powder 12 is contained. And at least 1 sort (s) of the powder 12 contains 90 mass% or more of calcium oxide.

  Hereinafter, each component will be described in detail.

[Polymer compound]
The polymer compound is not particularly limited as long as it has biodegradability. For example, in addition to polylactic acid, polybutylene succinate, polybutylene succinate adipate used in the following experimental examples, various biodegradable polymers described in Patent Documents 1 and 2, for example, cellulose, starch, Polysaccharide derivatives such as dextran and chitin; peptides such as collagen, casein, fibrin and gelatin; polyamino acids; polyvinyl alcohol; polyamides such as nylon 4 and nylon 2-nylon 6 copolymers; polyglycolic acid, polylactic acid and polysuccinic acid ester , Polyesters such as polyoxalic acid ester, polyhydroxybutyric acid, butylene polydiglycolate, polycaprolactone, polydioxanone; These biodegradable polymer compounds may be used alone or in combination of two or more.

  Each of the biodegradable polymer compounds described above has a different biodegradation performance and a different shape collapse rate (elapsed time until the shape after being molded starts to collapse, also referred to as a shape collapse period). For example, polylactic acid has a shape collapse period of 3 to 5 years and is known as a delayed biodegradable polymer compound. On the other hand, polybutylene succinate adipate and polybutylene succinate have a shape collapse period of about one year and are known as fast-acting biodegradable polymer compounds. In the present invention, various biodegradable polymer compounds having different shape collapse rates can be blended with a powder described later, and the biodegradable polymer can be obtained by the basic catalytic effect of the powder. The biodegradation period of the compound can be accelerated.

[Powder]
The powder 12 is one or more powders containing calcium oxide, calcium hydroxide, and calcium carbonate. And at least 1 sort (s) of the powder 12 contains 90 mass% or more of calcium oxide. In addition, “at least” means that a plurality of types of powders having different calcium oxide contents may be contained, and as shown in FIG. 1 (A), the calcium oxide content is 90% by mass. The same kind of powder 12 as described above may be included, or as shown in FIG. 1B, two or more kinds of powders 12a and 12b having different calcium oxide contents may be included. The at least one of them (12a or 12b) may contain 90% by mass or more of calcium oxide.

  For example, when the powder 12 containing 90% by mass or more of calcium oxide comes into contact with moisture in the soil, the calcium oxide becomes calcium hydroxide with heat generation. Therefore, when such a powder 12 is contained in the biodegradable composite material 1, a biodegradable molded product such as a multi-film made of the biodegradable composite material 1 has an exothermic reaction to calcium hydroxide. A physical crack as a factor is generated, and shape collapse is induced. In addition, calcium hydroxide generated with an exothermic reaction can accelerate hydrolysis of a biodegradable polymer compound due to its basic catalytic effect. As a result, even a biodegradable polymer compound such as polylactic acid having a long decomposition period can be rapidly decomposed.

  Even if the content of calcium oxide is less than 90% by mass, an exothermic reaction takes place upon contact with water and cracks similar to the above are generated to induce shape collapse. However, the degree of the effect is 90% by mass or more. It is insufficient. The powder having a calcium oxide content of 90% by mass or more is more likely to generate heat locally after contact with moisture in the soil than the powder having a calcium oxide content of less than 90% by mass. Therefore, it is better to arbitrarily adjust the blending amount of the powder having a calcium oxide content of 90% by mass or more than when a large amount of the powder having a calcium oxide content of less than 90% by mass is mixed to generate heat. The heat generation is concentrated to cause physical cracks and the like, and the shape can be easily collapsed.

  The particle size of the powder is not particularly limited, but a particle size suitable for the intended use is used. For example, when the biodegradable composite material 1 is used for film applications such as an agricultural multi-film, it is preferable to use a material having a small particle size that does not inhibit the function of the film in consideration of the thickness of the film. For example, in the experimental examples to be described later, those having an average particle diameter of 11 μm are used, but in this example, powders having an average particle diameter of 5 μm or more and 30 μm or less can be used. In addition, when the thickness of a film is about 20 micrometers, for example, about 10 micrometers (for example, about 2 micrometers or more and about 12 micrometers or less) similar to an experiment example are preferable.

  The means for obtaining such powder is not particularly limited, and can be obtained by various methods. For example, a commercially available calcium oxide powder may be obtained and adjusted so that the calcium oxide content is 90% by mass or more. Alternatively, calcium carbonate is obtained and the calcium carbonate is baked and oxidized. The calcium content may be adjusted to 90% by mass or more, or calcium hydroxide is obtained, and the calcium hydroxide content is 90% by mass or more by dehydrating the calcium hydroxide. It may be used as follows. Calcium carbonate may be industrially produced or derived from natural products. As calcium carbonate derived from natural products, shells such as scallops may be used as a calcium carbonate raw material.

  Calcium oxide can be obtained by decarboxylation by baking calcium carbonate at a temperature of 600 ° C. to 700 ° C. or higher. In particular, the content of calcium oxide can be easily increased to 90% by mass or more by performing a plurality of firings in two or more stages such as firing and refiring. Calcium oxide can be obtained by dehydration by heating calcium hydroxide at a temperature of 400 ° C. or higher.

[Control of shape collapse period]
The blending ratio A ([polymer compound: powder]) of the biodegradable polymer compound 11 and the powder 12 is preferably in the range of 99: 1 to 50:50 by mass ratio. By blending within this range, shape collapse of a biodegradable molded product made of a biodegradable composite material can be promoted. In addition, what is necessary is just to raise the compounding ratio A of the powder 12 in order to advance a shape collapse period. Moreover, what is necessary is just to lower the compounding ratio A of the powder 12 in order to delay a shape collapse period. Thus, the multifunctional biodegradable composite material according to the present invention can control the shape collapse period of the produced biodegradable molded article by adjusting the blending ratio A of the powder 12 contained therein. .

  In addition, as a control of the shape collapse period of the biodegradable molded product, a powder having a calcium oxide content of 90% by mass or more (for example, reference numeral 12a in FIG. 1B) and other powders having a calcium oxide content ( For example, the shape collapse period can be controlled by changing the blending ratio B with the reference numeral 12b) in FIG. Specifically, as shown in FIG. 1B, a powder 12a having a calcium oxide content of 90% by mass or more and a powder 12b having a calcium oxide content of less than 90% by mass are mixed at a predetermined blending ratio B. Can be blended. Since the biodegradable composite material 1 obtained in this way can make the shape collapse period slower than that having a calcium oxide content of 90% by mass or more, a plurality of types of biodegradable composite materials having different shape collapse periods can be used. Can be manufactured. For example, a multi-film produced using biodegradable composite materials having different shape collapse periods has a special advantage that it can be arbitrarily applied depending on the crops having different harvest times. In other words, depending on the type of crop, there are some types that have a short period or a long type from the laying of the multi-film to the harvesting of the crops. The shape can be collapsed according to the period.

[Lineup of biodegradable composite materials with different shape collapse periods]
By changing the blending amount of the powder, it is possible to line up biodegradable composite materials 1 having different shape collapse periods. Specifically, as shown in FIG. 1B, a plurality of raw materials in which the blending ratio of the powder 12a having a calcium oxide content of 90% by mass or more and the powder 12b having the other calcium oxide content is changed. By preparing the degradable composite material, two or more multifunctional biodegradable composite materials having different shape collapse periods can be produced. Depending on the type of crop, these biodegradable composite material lineups can be used for crops to be harvested even if there are short or long types of crops after the laying of the multi-film. The multifunctional biodegradable composite material produced in the present invention can be applied as a raw material for a multi-film that biodegrades in accordance with the period.

  The above lineup is possible without using calcium oxide having a content of less than 90% by mass. For example, it is possible to produce two or more multifunctional biodegradable composite materials having different shape collapse periods by blending a single amount of calcium oxide having a content of 90% by mass or more in an arbitrary amount. it can. Further, both use calcium oxide powder having a content of 90% by mass or more, one having a low content, for example, 92% by mass of a single type of calcium oxide powder, and the other having a high content, for example, 98% by mass. It is also possible to produce two or more multifunctional biodegradable composite materials having different shape collapse periods by blending the single calcium oxide powder in any amount.

[Soil neutralization]
The multifunctional biodegradable composite material 1 according to the present invention can neutralize soil. Among the biodegradable polymer compounds contained in the biodegradable composite material 1, when an acid such as carboxylic acid is generated due to decomposition, the pH in the soil may decrease and shift to the acidic side. However, in the present invention, calcium hydroxide produced by contacting calcium oxide contained in the biodegradable composite material 1 with moisture in the soil can raise the lowered pH and return to neutrality. Moreover, even if such an acid does not occur, neutralization of soil acidified with acid rain or the like can be realized.

[Other additives]
The multifunctional biodegradable composite material 1 may optionally contain other additives. Examples of the additive include chili powder, neem powder, natural product-derived powder, soil modifier, and the like, and these additives can contain one kind or two or more kinds.

  Since chili contains 0.1 to 1% by mass of capsaicin, which is a repellent component of pests, by adding chili powder to the biodegradable composite material, for example, multi-film repellent effect produced with the biodegradable composite material 1 Can be granted. In particular, the repellent effect can be imparted to the soil after the multi-film has collapsed.

  Since neem powder also contains azadirachtin, which is a repellent component of pests, by adding neem powder to the biodegradable composite material, it is possible to impart a repellent effect to, for example, a multi-film made of the biodegradable composite material 1. . In particular, the repellent effect can be imparted to the soil after the multi-film has collapsed. Azadirachtin contained in this neem powder has remarkable toxicity to insects (LD50 = 15 μg / g), but is almost harmless to mammals (LD50 = 3,540 μg / g).

  Moreover, you may add the lubricant for increasing the mold release property with a shaping | molding die. Examples of such lubricants include stearamide. Various plasticizers may be added.

  These additives can be added in an amount corresponding to the type and effect within a range that does not impair the function of the biodegradable composite material 1, and further enhance the functionality of the multifunctional biodegradable composite material 1. Can do.

[Production method]
The multifunctional biodegradable composite material 1 is prepared by preparing a polymer compound 11 having biodegradability, and at least one powder out of one or two or more powders containing calcium oxide, calcium hydroxide, and calcium carbonate The powder 12 containing 90% by mass or more of the calcium oxide is prepared by calcining, and the polymer compound 11 and one or more kinds of powders 12 are kneaded. The kneading is preferably performed until the biodegradable polymer compound 11 and the powder 12 are sufficiently dispersed. The kneading means is not particularly limited, but in the present application, a heating kneader used in an experimental example described later is employed.

  The kneaded biodegradable composite material 1 may be used as it is or may be used after being pelletized. For example, the pelletized biodegradable composite material 1 is then molded into a predetermined molded shape to form a biodegradable molded product. For example, when producing a multi-film for agriculture, the biodegradable composite material 1 can be formed into a film having a predetermined thickness using, for example, a roll-shaped hot press machine. In addition, when using the multifunctional biodegradable composite material 1 according to the present invention, when molding into agricultural materials and civil engineering materials such as binding bands for agriculture and horticulture, seedling pots, vegetation nets, soil sheets, It can be molded using a mold or the like for producing the molded product. Moreover, when shape | molding into materials, such as various packaging and a container, it can shape | mold using the type | mold etc. for producing the molded article. It can also be used as a medical material.

  As described above, according to the multifunctional biodegradable composite material 1 according to the present invention, at least one powder out of one or more powders containing calcium oxide, calcium hydroxide, and calcium carbonate is included. Since the calcium oxide contains 90% by mass or more, the calcium oxide becomes calcium hydroxide with heat generation when it comes into contact with moisture, and a physical crack is formed in a molded product such as a film made of a biodegradable composite material. And induce shape collapse more easily. Further, hydrolysis of the biodegradable polymer compound 11 can be accelerated by the basic catalytic effect when changing from calcium oxide to calcium hydroxide. As a result, even a biodegradable polymer compound 11 such as polylactic acid having a long degradation period can be quickly degraded. For example, a multifilm produced from this biodegradable composite material can be Eliminates the need for labor such as peeling, which can contribute to significant labor savings.

  In addition, when an acid such as carboxylic acid is generated by decomposition of the biodegradable polymer compound, the pH in the soil decreases and shifts to the acidic side. Such pH can be raised back to neutrality by calcium hydroxide produced upon contact with the water. Moreover, even if such an acid does not occur, neutralization of soil acidified with acid rain or the like can be realized.

  Hereinafter, the present invention will be described in more detail with reference to the following experimental examples. The scope of the present invention is not limited to the contents of the following experimental examples.

[Experiment 1]
As a biodegradable polymer compound, 100 parts by mass (30 g) of poly-L-lactic acid (PLLA, trade name: Terramac TE-2000, manufactured by Unitika Ltd.) was prepared. As a powder, a powder having a calcium oxide content of 98.4% by mass, a calcium hydroxide content of 0.7% by mass, and a calcium carbonate content of 0.9% by mass (average particle diameter 11 μm, laser diffraction / 10 parts by mass (3 g) of a particle size distribution analyzer, LA-920, manufactured by HORIBA, Ltd. was measured. This powder is obtained by baking (900 ° C.) calcium carbonate derived from scallop shells.

  These raw materials were put into a heat kneader and kneaded. As a kneader, an IMC-196A type kneader manufactured by Imoto Seisakusho was used, and a laboratory apparatus having a blade outer diameter of 70 mm, a blade length of 14 mm, and a capacity of 64 mL was used. The apparatus can be adjusted up to 300 rpm and can be adjusted from room temperature to 250 ° C.

  A sample for hydrolysis test and a sample for soil embedding test were prepared from the obtained kneaded material by a hot press method. The hydrolysis test sample was formed into a strip shape with a width of 6 mm, a length of 100 mm, and a thickness of 0.1 mm, and the soil embedding test sample was formed into a rectangular shape with a width of 20 mm, a length of 20 mm, and a thickness of 0.1 mm. Molded. Thus, the test sample of Experimental Example 1 was produced.

[Experiment 2]
A test sample of Experimental Example 2 was prepared in the same manner as Experimental Example 1, except that polybutylene succinate adipate (PBSA, trade name: Bionore, Showa Denko KK ) was used as the biodegradable polymer compound. did.

[Experiment 3]
The test sample of Experimental Example 3 was prepared in the same manner as Experimental Example 1, except that polybutylene succinate (PBS, trade name: GS Pla AD92W, manufactured by Mitsubishi Chemical Corporation ) was used as the biodegradable polymer compound. Produced.

[Experimental Examples 4 to 6]
Test samples of Experimental Examples 4 to 6 were prepared in the same manner as in Experimental Examples 1 to 3, except that the amount of powder was 15 parts by mass.

[Comparative Experimental Examples 1 to 3]
Test samples of Comparative Experimental Examples 1 to 3 were prepared in the same manner as in Experimental Examples 1 to 3, except that no powder was added.

[Comparative Experimental Examples 4 to 6]
As a powder, a powder having a calcium oxide content of 2.4% by mass, a calcium hydroxide content of 76.6% by mass, and a calcium carbonate content of 21.0% by mass (average particle diameter of 11 μm, laser diffraction / The average particle diameter was measured by a scattering type particle size distribution analyzer, LA-920, manufactured by HORIBA, Ltd.). Produced.

[Hydrolysis test and soil burying test]
In order to investigate hydrolyzability in vitro, 15 mL of ion-exchanged water was used for each of the samples of Experimental Examples 1 to 6 and Comparative Experimental Examples 1 to 6 (Experimental Examples 1 to 6 were pH 6.7, Comparative Experimental Examples 1 to 6). 3 was immersed in pH 7.3) and subjected to a hydrolysis test at 40 ° C. in a constant temperature shaking water bath. The test period was evaluated for degradability after 10 days, 20 days, 30 days, 60 days, and 90 days. Degradability evaluation was performed by changing the weight of the film, thermal analysis of the film, measuring the intrinsic viscosity of the film, changing the pH of the medium, and measuring the TOC of the medium.

  In the soil burying test, samples of Experimental Examples 1 to 3 and Comparative Experimental Examples 1 to 6 were placed in a black jar filled with about 20 g of fertile black soil, and embedded in black soil, and a pF meter (DIK) which is a soil moisture meter. -8343, manufactured by Daiki Rika Kogyo Co., Ltd.), the pF value was moistened to be in the range of 1.7 to 2.3, and the control was performed indoors and at room temperature. The range of the pF value usually indicates a moisture amount suitable for agricultural products. Moreover, when the moisture content of the soil was measured using a simple soil moisture meter (DM-18, manufactured by Takemura Electric Co., Ltd.), the moisture content was 45% by mass. The test period was evaluated for degradability after 10 days, 20 days, 30 days, 60 days, and 90 days. Degradability evaluation was performed by changing the weight of the film, thermal analysis of the film, measuring the intrinsic viscosity of the film, and changing the pH of the soil.

  Thermal analysis is performed by thermogravimetry (TG-DTA2000S type differential thermothermal weight simultaneous measurement device, manufactured by Bruker AXS) and differential scanning calorimetry (DSC3200S type differential scanning calorimetry, manufactured by Bruker AXS). went. The pH was measured using a glass electrode type hydrogen ion concentration meter (GST-5421C, manufactured by Toa Denpa Kogyo Co., Ltd.) and a pH meter (HM-30V, manufactured by Toa Denpa Kogyo Co., Ltd.). TOC (Total Organic Carbon) measurement was performed under high purity air by TOC-V CPH / CPN (manufactured by Shimadzu Corporation, 680 ° C. combustion catalytic oxidation method, NPOC (nonvolatile organic carbon) method). The surface form of the test sample was observed by scanning electron microscope observation (JSM-5610LV type low vacuum scanning electron microscope, manufactured by JEOL Ltd.).

  The intrinsic viscosity was measured by dissolving 100 mg of the kneaded product obtained by heating and kneading in 20 mL of chloroform to prepare a 0.5 g / dL sample solution, and removing components insoluble in chloroform by suction filtration. This sample solution was placed in a U-121 type Ubbelohde viscometer (manufactured by Kusano Chemical Instruments Co., Ltd.) and left in a water bath maintained at 25 ± 0.01 ° C. for 30 minutes. Thereafter, the time taken for the sample solution to fall within the capillary of the viscometer is measured, and the intrinsic viscosity is calculated by the formula of [(Test Sample Drop Time) / (Pure Solvent Drop Time) -1] / [Sample Concentration]. Asked. The measurement was performed until the error of the drop time continued within ± 0.5 seconds three times or more.

  The composition of the calcium powder was determined by analyzing a TG curve of thermogravimetric analysis. In the TG curve of calcium powder, mass phenomena are observed at around 400 ° C and around 600 ° C. It was confirmed that dehydration of calcium hydroxide occurred near 400 ° C, and decarboxylation of calcium carbonate occurred near 600 ° C. Therefore, dehydration and decarboxylation occurred in the powder in which the mass reduction in two steps occurred at around 400 ° C. and around 600 ° C., and the contents of calcium hydroxide and calcium carbonate were calculated from the reduction amounts.

[result]
(Hydrolysis test results)
2 and 3 are graphs showing the evaluation results of the degradability after the hydrolysis test of the biodegradable composite materials of Experimental Examples 1 to 3, and FIG. 2 (A) is a graph showing the change over time in the weight loss rate. 2 (B) is a graph showing the change with time of the intrinsic viscosity reduction rate, FIG. 3 (A) is a graph showing the change with time of pH, and FIG. 3 (B) is a graph showing the change with time of TOC. is there. On the other hand, FIG.5 and FIG.6 is a graph which shows the degradability evaluation result after the hydrolysis test of the biodegradable polymer compound of Comparative Experimental Examples 1-3, FIG.5 (A) shows the time-dependent change of a weight loss rate. 5 (B) is a graph showing the change with time of the intrinsic viscosity reduction rate, FIG. 6 (A) is a graph showing the change with time of pH, and FIG. 6 (B) is the change with time of TOC. It is a graph which shows. The results of FIGS. 2, 3, 5, and 6 are also shown in Table 1.

  In the biodegradable composite materials of Experimental Examples 1 to 3, from the results of hydrolysis tests of films in which each biodegradable polymer compound and powder were combined, all films were brittle from the beginning. A few films were prominent and difficult to recover. The weight loss rate was not as dramatic as the 10th day, but tended to decrease little by little. Although the pH decreased as a whole, the tendency was moderate as compared with the hydrolysis test of the biodegradable polymer compounds of Comparative Experimental Examples 1 to 3. Intrinsic viscosity decreased until the 60th day, and in particular, Experimental Example 1 significantly decreased. The TOC rose dramatically on the 10th day and has remained almost unchanged since then.

  FIG. 4 is an electron micrograph of the film surface after the hydrolysis test (0 days, 30 days, 90 days) of the biodegradable composite materials (a), (b), and (c) of Experimental Examples 1 to 3. As shown in FIG. 4, the surface before the hydrolysis test of Experiment Examples 1 to 3 was smooth (0 day), but the surface after the hydrolysis test for 30 days was rough, and surface degradation was confirmed. In addition, vacancies that were thought to have had calcium oxide and cracks around them were confirmed. When the hydrolysis test progressed to the 90th day, the expansion of the pores was noticeable. Calcium oxide not only acts chemically as a base, but also the pores created by the dissolution of calcium oxide into calcium hydroxide and elution increase the surface area of the sample. It is thought that the decomposition of is promoted.

  As shown in FIG. 5 (A), the weight loss rate of the test samples of Comparative Experimental Examples 1 to 3 was about 2% at the maximum even after 60 days, but as shown in FIG. 2 (A). Moreover, the weight loss rate of Experimental Examples 1 to 3 was 20% or more even after only 10 days had elapsed. The same tendency can be understood from the results of the intrinsic viscosity measurement, and the test samples of Experimental Examples 1 to 3 have a lower intrinsic viscosity than the test samples of Comparative Experimental Examples 1 to 3, as shown in FIG. In addition, the TOC of the media has greatly increased.

  Next, Table 2 shows the results of the hydrolysis test of the test samples of Experimental Examples 4 to 6 in which the blending amount of the powder was 15 parts by mass. In the biodegradable composite materials of Experimental Examples 4 to 6, the hydrolysis test result of the film in which each biodegradable polymer compound and the powder are combined has the same tendency as that in which 10 parts by mass of the powder is blended. Indicated. Specifically, every film was brittle from the beginning. Moreover, the numerical value of each result is rising from the case of 10 mass parts, and the tendency for the density | concentration of TOC to be especially high was seen. Thus, it was confirmed that the action of calcium oxide is increased by increasing the powder content.

(Soil embedding test results)
FIG. 7 is a graph showing the degradability evaluation results after the soil burying test of the biodegradable composite materials of Experimental Examples 1 to 3, (A) is a graph showing the change over time in the weight loss rate, (B) Is a graph showing changes in pH over time. The results of FIG. 7 are shown in Table 3. 8 is an electron micrograph of the film surface after the soil embedding test (30 days) of the biodegradable composite materials of Experimental Examples 1 to 3 and Comparative Experimental Examples 4 and 6, and FIG. FIG. 10 is an electron micrograph of the film surface after the soil burying test (60 days) of the biodegradable composite materials of -3 and Comparative Experimental Examples 4-6. FIG. 10 shows Experimental Examples 1-3 and Comparative Experimental Examples 4, 6 It is an electron micrograph of the film surface after the soil embedding test of the biodegradable composite material of (90 days).

  In particular, from the electron micrographs of FIGS. 8 to 10, it was possible to confirm the shape collapse property of the film over time. On the surface of the photo, the original calcium oxide was present, and the calcium oxide reacted with the moisture in the soil to form calcium hydroxide with heat generation, and the pores that seemed to have eluted in the soil Many (holes) were observed, and microbial implantation and growth were observed.

1 Multifunctional biodegradable composite material (biodegradable film)
11 Biodegradable Polymer Compound 12, 12a, 12b Powder a Result of Experimental Example 1 in FIGS. 8 to 10 b Result of Experimental Example 2 in FIGS. 8 to 10 c Experimental Example 3 in FIGS. 8 to 10 Results a ′ Results of Comparative Experiment Example 4 in FIGS. 8 and 9 b ′ Results of Comparative Experiment Example 5 in FIGS. 8 to 10 c ′ Results of Comparative Experiment Example 6 in FIGS. 8 and 9

Claims (2)

Agriculture that can collapse the shape of the agricultural multi-film according to the period from the laying of the agricultural multi-film according to the type of the crop to the harvest of the crop, and neutralize the soil A method for producing a multi-film for use,
Preparing a biodegradable polymer compound selected from polylactic acid, polybutylene succinate and polybutylene succinate adipate;
About the powder which prepares the 1 type (s) or 2 or more types of powder containing a calcium oxide, a calcium hydroxide, and a calcium carbonate , bakes at least 1 type of powder among this powder , and contains the said calcium oxide 90 mass% or more The blending ratio (mass ratio) of the polymer compound and the powder containing 90% by mass or more of the calcium oxide is 99: 1 to 50: Adjusting and preparing within a range of 50 ;
Method for producing agricultural multi-film, which comprises organic and the step of kneading the said one or more powder prepared as prepared above polymer compound. The manufacturing method of the agricultural multifilm of Claim 1 with which the said powder contains the other powder containing less than 90 mass% of calcium oxide .

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