Biodegradation evaluation case and method for evaluating biodegradation of biodegradable resin molded article using biodegradation evaluation case

Abstract

To provide technology that is applicable to a field test for biodegradation of a biodegradable resin molded article comprising a biodegradable resin and that enables simple and precise evaluation of biodegradation conditions.SOLUTION: A biodegradation evaluation case 1, with an evaluation body T based on a biodegradable resin molded article RT containing a biodegradable resin accommodated therein, is buried in soil G inhabited by microorganisms to biodegrade the evaluation body T and evaluate the biodegradation conditions. The case is configured in a box shape with an upper surface 3, a bottom surface 5, and a side surface 4, where the upper surface 3, the bottom surface 5, and the side surface 4 form an internal space S. The evaluation body T, together with the soil G, is housed in the internal space S. A plurality of openings 3h and 5h are formed in the upper surface 3 and the bottom surface 5, respectively, and the size of each opening 5h in the bottom surface 5 is equal to or larger than the size of each opening 3h in the upper surface 3.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a biodegradation evaluation case and a method for evaluating the biodegradation of a biodegradable resin molded article using the biodegradation evaluation case.

Background Art

[0002] A biodegradable resin molded article formed by including a biodegradable resin that can be biodegraded by microorganisms is, like a non-biodegradable resin, incinerated or landfilled at a final disposal site. However, due to the implementation of the Plastic Resources Recycling Law, incineration has become limited. Therefore, in the future, biodegradation treatment by soil burial under certain conditions is expected to progress. In facilities where biodegradation treatment is carried out, the burial of the biodegradable resin molded article in the soil and biodegradation are repeated. That is, when the biodegradable resin molded article is buried in the soil and biodegradation is completed, the next biodegradable resin molded article to be the subject of biodegradation treatment is buried in the soil where biodegradation has been completed and is subjected to biodegradation.

[0003] In order to efficiently biodegrade a biodegradable resin molded article, it is important to embed the biodegradable resin molded article to be subjected to biodegradation treatment at an appropriate timing so that the amount of the biodegradable resin molded article embedded in the soil becomes appropriate. Since the state of the embedded biodegradable resin molded article cannot be visually observed, after embedding the biodegradable resin molded article once and starting the biodegradation treatment, the timing for embedding the next biodegradable resin molded article may be determined by the worker's feeling, for example, one year later. However, if the determined timing is too short and the next biodegradable resin molded article to be subjected to biodegradation treatment is embedded before the biodegradation of the already embedded biodegradable resin molded article is completed, too many biodegradable resin molded articles may be embedded in the soil and become saturated, and the rate at which the biodegradable resin molded article is biodegraded may decrease. On the other hand, if the determined timing is too long, a wasteful period will occur during which no biodegradation treatment of the biodegradable resin molded article is performed between the completion of the biodegradation of the already embedded biodegradable resin molded article and the embedding of the next biodegradable resin molded article to be subjected to biodegradation treatment. Therefore, when determining the timing for embedding the biodegradable resin molded article based on the worker's feeling, the biodegradation of the biodegradable resin molded article may not be performed efficiently.

[0004] Thus, in order to embed the next biodegradable resin molded article to be subjected to biodegradation treatment at an appropriate timing, it is important to evaluate the biodegradation status of the already embedded biodegradable resin molded article and determine whether the biodegradation has ended or, if not, when it is likely to end. However, it is not easy to evaluate the biodegradation status. As a standard test for biodegradation, there is, for example, JIS K 6955, etc., but this is for evaluating the biodegradability of biodegradable resins under certain soil conditions and cannot be applied to the evaluation of the biodegradation status in the soil environment where biodegradation actually occurs. Also, in the above-mentioned standard tests, in order to measure the amount of gas generated as a result of biodegradation, etc., it is necessary to conduct the test in a dedicated container and use dedicated measuring equipment. Therefore, even if the soil in which biodegradation actually occurs is used for the above-mentioned standard tests, the biodegradation environment is different and it is difficult to perform the evaluation simply.

[0005] In order to evaluate the state of biodegradation in soil where biodegradation actually occurs, a field test may be conducted. In general, a field test is conducted by placing a biodegradable resin molded object that is actually to be subjected to biodegradation treatment in a resin net, burying it in soil where biodegradation treatment is actually to be performed, digging it out after a certain period of time has passed and biodegradation has progressed, washing it to wash away the soil, drying it, visually observing the remaining biodegradable resin molded object, and measuring its weight. The resin net used here is flexible and can easily change its overall shape, so that the mesh openings of the net may become larger during the above-mentioned work, and the biodegradable resin molded object that has become finer due to biodegradation may fall off. In this case, the exact weight of the remaining biodegradable resin molded object cannot be measured. Therefore, it is difficult to evaluate the state of biodegradation with high accuracy.

[0006] Patent Document 1 discloses a method for evaluating the activity of a microbial group by placing a thin film of a biodegradable polymeric material in a place where the microbial group to be evaluated grows, and measuring the change in the thin film caused by microbial decomposition. The thin film of the polymeric material contains a colorant, and the activity state of the microbial group is evaluated based on the change in color caused by the colorant falling off when the film thickness decreases due to microbial decomposition. In Patent Document 1, the type and shape of the polymer material are limited, so it is difficult to apply the method when the biodegradable resin molded product to be actually subjected to the biodegradation treatment is different in type and shape from those to be subjected to the evaluation method described in Patent Document 1. In addition, since the evaluation is performed by measuring the change in color, there is a possibility that the measurement results may have errors. Therefore, it is difficult to evaluate the state of biodegradation with high accuracy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2004-344056 A Summary of the Invention

Problems to be Solved by the Invention

[0008] The problem to be solved by the present invention is applicable to the field test of biodegradation of a biodegradable resin molded article formed including a biodegradable resin, and it can evaluate the biodegradation situation simply and with high accuracy. The present invention provides a biodegradation evaluation case and a method for evaluating the biodegradation of a biodegradable resin molded article using the biodegradation evaluation case.

Means for Solving the Problems

[0009] In order to solve the above problems, the present invention adopts the following means. That is, the present invention is a biodegradation evaluation case in which an evaluation body based on a biodegradable resin molded article formed including a biodegradable resin is buried in soil where microorganisms inhabit in a state of being accommodated, and the evaluation body is biodegraded to evaluate the biodegradation state. The biodegradation evaluation case has an upper surface, a bottom surface, and side surfaces, and is box-shaped so that an internal space is formed by the upper surface, the bottom surface, and the side surfaces. The evaluation body is accommodated in the internal space together with the soil. A plurality of openings are formed in the upper surface and the bottom surface respectively, and the size of the opening in the bottom surface is equal to or larger than the size of the opening in the upper surface. According to the above configuration, the biodegradation evaluation case has a box shape with a top surface, a bottom surface, and side surfaces, and an internal space is formed by the top surface, the bottom surface, and the side surfaces. A plurality of openings (mesh openings in the case where the top and bottom surfaces are nets) are formed in the top and bottom surfaces, respectively. In such a biodegradation evaluation case, when a biodegradable resin molded product-based evaluation body is buried in the soil in a state of being accommodated in the internal space together with the soil, components such as moisture flow through the openings formed in the top and bottom surfaces, so that the environment in the internal space can be made the same as the surrounding soil in which it is buried. Further, since the biodegradation evaluation case is formed in a box shape so as to have a certain volume, regardless of the shape of the biodegradable resin molded product that is actually the object to be treated, the biodegradable resin molded product itself or, for example, a part thereof cut can be accommodated as an evaluation body. Therefore, for example, by burying the soil in which the biodegradable resin molded product that is actually the basis of the evaluation body is buried and biodegraded together with the evaluation body in the internal space and then burying it in the soil, a field test of biodegradation can be carried out on the biodegradable resin molded product and the soil that are actually the objects of biodegradation treatment. In addition, the biodegradation evaluation case has a certain rigidity by forming a box shape, and the overall shape is not easily changed, and the shapes of the openings on the upper and lower surfaces are also not easily changed. Therefore, during the operation on the biodegradation evaluation case, the dropping of the evaluation object is suppressed. As a result, since the weight of the remaining evaluation object can be accurately measured, the biodegradation situation can be accurately evaluated. Further, for example, before burying the biodegradation evaluation case in the soil, it is also possible to sieve the soil through the opening formed on the upper surface and accommodate the soil in the internal space. Since the size of the opening on the bottom surface (the mesh opening when the bottom surface is a net) is equal to or larger than the size of the opening on the upper surface (the mesh opening when the upper surface is a net), solid substances such as small stones mixed in the soil that can pass through the opening on the upper surface can be discharged from the opening on the bottom surface. Therefore, when removing the soil in the internal space through the opening on the bottom surface after digging out and recovering the biodegradation evaluation case, it is possible to suppress the above-mentioned solid substances from remaining in the internal space together with the remaining evaluation object. In this state, by taking out all the contents in the internal space and measuring the weight, it is possible to measure a more accurate weight of the remaining evaluation object with the influence of the weight of the soil reduced. Therefore, the accuracy of the evaluation of the biodegradation situation is further improved. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are necessary. Therefore, the evaluation can be easily performed. In this way, it is possible to provide a biodegradation evaluation case that is applicable to the field test of the biodegradation of a biodegradable resin molded product formed by including a biodegradable resin, and can evaluate the biodegradation situation simply and with high accuracy.

[0010] Furthermore, the present invention is a method for evaluating the biodegradation state of the biodegradable resin molded article using the biodegradation evaluation case as described above. The method includes: placing the evaluation body based on the actual biodegradable resin molded article to be processed and the soil in which the biodegradable resin molded article is actually buried and biodegraded in the internal space, then burying the biodegradation evaluation case in the soil; after biodegradation progresses, digging out and recovering the biodegradation evaluation case, shaking and washing the biodegradation evaluation case, removing the soil in the internal space through the opening on the bottom surface, and measuring the weight of the evaluation body remaining in the internal space. The soil is characterized in that it is accommodated in the internal space while sifting the soil through the opening on the upper surface. A method for evaluating the biodegradation of a biodegradable resin molded article is provided. According to the above configuration, using the actual biodegradable resin molded article to be processed itself, or for example, a part thereof that has been cut, as the evaluation body, together with the soil in which the biodegradable resin molded article is actually buried and biodegraded, the biodegradation evaluation case is buried in the soil with the internal space containing these, and after biodegradation progresses, the biodegradation evaluation case is dug out and recovered, and the weight of the evaluation body remaining in the internal space is measured. Thus, a field test of biodegradation can be carried out on the actual biodegradable resin molded article and soil that are the targets of biodegradation treatment. Also, after digging out and recovering the biodegradation evaluation case, the biodegradation evaluation case is shaken and washed to remove the soil in the internal space through the opening on the bottom surface, and only the evaluation object that remains undegraded is left inside the biodegradation evaluation case. In this case, the biodegradation evaluation case forms a box shape, has a certain rigidity, is not easily deformed in its overall shape, and the shape of the openings on the upper and bottom surfaces is not easily changed either. Therefore, during the above series of operations, the dropping off of the evaluation object is suppressed. As a result, since the weight of the remaining evaluation object can be accurately measured, the biodegradation situation can be accurately evaluated. Furthermore, since the size of the opening on the bottom surface is equal to or larger than the size of the opening on the upper surface, solid objects such as small stones mixed in the soil that can pass through the opening on the upper surface can be discharged from the opening on the bottom surface. Therefore, when accommodating soil in the internal space before burying the biodegradation evaluation case in the soil, by sieving the soil through the opening formed on the upper surface, when removing the soil in the internal space through the opening on the bottom surface after digging out and recovering the biodegradation evaluation case, it is possible to suppress the above-mentioned solid objects from remaining in the internal space together with the remaining evaluation object. In this state, by taking out all the things in the internal space and measuring the weight, it is possible to measure a more accurate weight of the remaining evaluation object with the influence of the weight of the soil reduced. Therefore, the accuracy of the evaluation of the biodegradation situation is further improved. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are needed either. In particular, as described above, when removing the soil in the internal space, since it is possible to suppress solid objects other than the evaluation object from remaining in the internal space, there is no particular need to sort the remaining evaluation object and the solid objects with tweezers or the like. Therefore, the evaluation can be carried out simply. In this way, it is possible to provide a method for evaluating the biodegradation of a biodegradable resin molded article that is applicable to the field test of the biodegradation of a biodegradable resin molded article formed by including a biodegradable resin, and can evaluate the biodegradation situation simply and with high accuracy.

[0011] In one aspect of the present invention, after removing the soil in the internal space, a separation sheet having a plurality of openings smaller than the size of the opening in the bottom surface is provided so as to cover the inside of the upper surface. The biodegradation evaluation case is watered from the bottom surface in a state where it is turned upside down, and the evaluation body remaining in the internal space is dropped onto the separation sheet and collected. When removing the separation sheet together with the collected evaluation bodies and measuring the weight of the remaining evaluation bodies, the weight of the evaluation bodies collected together with the separation sheet is measured, and the weight of the separation sheet is subtracted to measure the weight of the remaining evaluation bodies. According to the configuration as described above, after digging out and recovering the biodegradation evaluation case and removing the soil in the internal space, a separation sheet having a plurality of openings formed therein is provided so as to cover the inside of the upper surface. By watering from the bottom surface in a state where the biodegradation evaluation case is turned upside down, the evaluation bodies remaining in the internal space can be dropped onto the separation sheet and collected. At this time, in the biodegradation evaluation case, evaluation bodies larger than the size of the opening in the bottom surface should remain. However, since the openings in the separation sheet are smaller than the size of the opening in the bottom surface, even if the above-described operation is performed, the evaluation bodies remaining in the biodegradation evaluation case are suppressed from falling off through the openings in the separation sheet. In this way, the evaluation bodies remaining in the biodegradation evaluation case can be efficiently taken out from the biodegradation evaluation case. Thereafter, by measuring the weight of the evaluation bodies collected together with the separation sheet and subtracting the weight of the separation sheet, the weight of the remaining evaluation bodies can be accurately measured. Based on the weight of the evaluation bodies measured in this way, the biodegradation situation can be evaluated simply and with high accuracy. In addition, the evaluation bodies collected on the separation sheet can be directly used for visual observation, microscopic observation, microscope observation, etc., and the biodegradation situation can be qualitatively grasped. Thereby, for example, when biodegradation is slow, it can be used to clarify the cause.

[0012] Further, the present invention provides a biodegradation evaluation case in which an evaluation body based on a biodegradable resin molded article formed by including a biodegradable resin is buried in soil where microorganisms inhabit, the evaluation body is biodegradated, and the state of biodegradation is evaluated. The biodegradation evaluation case includes a first case and a second case. Each of the first case and the second case has an upper surface, a bottom surface, and side surfaces, and is box-shaped such that an internal space is formed by the upper surface, the bottom surface, and the side surfaces. The second case is formed larger than the first case. The evaluation body is accommodated in the internal space of the first case together with the soil, and the first case is accommodated in the second case together with the soil. A plurality of openings are formed in each of the upper surface and the bottom surface of each of the first case and the second case. The size of the opening in the bottom surface of the first case is larger than the size of the opening in the bottom surface of the second case. In each of the first case and the second case, the size of the opening in the bottom surface is equal to or larger than the size of the opening in the upper surface. The size of the opening in the upper surface of the first case is larger than the size of the opening in the upper surface of the second case. According to the above configuration, the biodegradation evaluation case includes a first case and a second case. Each of the first case and the second case has an upper surface, a bottom surface, and side surfaces, and is box-shaped such that an internal space is formed by the upper surface, the bottom surface, and the side surfaces. A plurality of openings (mesh holes in the case where the upper surface and the bottom surface are meshes) are formed in the upper surface and the bottom surface, respectively. In such a biodegradation evaluation case, an evaluation body based on a biodegradable resin molded article is accommodated together with soil in the internal space of the first case, and with the first case accommodated in the second case, when the biodegradation evaluation case is buried in the soil, components such as moisture flow through the openings formed in the upper surface and the bottom surface of each of the first case and the second case, so that the environment of the internal space can be made the same as the surrounding soil in which it is buried. Further, since the biodegradation evaluation case is formed in a box shape so as to have a certain volume, regardless of the shape of the biodegradable resin molded article that is actually the object to be treated, the biodegradable resin molded article itself or, for example, a part thereof cut can be accommodated as the evaluation body. Therefore, for example, together with the evaluation body, the soil in which the biodegradable resin molded article that is actually the basis of the evaluation body is buried and biodegraded is accommodated in the internal space of the first case, and with the first case accommodated in the internal space of the second case together with the soil, by burying it in the soil, a field test of biodegradation can be carried out on the biodegradable resin molded article and the soil that are actually the objects of biodegradation treatment. Also, after excavating and recovering the biodegradation evaluation case, the biodegradation evaluation case can be shaken, washed, etc., to remove the soil in the internal space through the openings in the bottom surfaces of the first case and the second case, for example, and only the evaluation body that remains without being biodegraded can be left inside the biodegradation evaluation case. In this case, the first case and the second case of the biodegradation evaluation case form a box shape, have a certain rigidity, are not easily deformed in the overall shape, and the shapes of the openings on the upper surface and the bottom surface are not easily changed either. Therefore, the dropping of the evaluation body during the above series of operations is suppressed. As a result, since the weight of the remaining evaluation body can be accurately measured, the biodegradation situation can be accurately evaluated. Further, for example, before burying the biodegradation evaluation case in the soil, the soil can be sieved through the opening formed on the upper surface of the second case so that the soil can be accommodated in the internal spaces of the first case and the second case. In this case, even if solid substances such as stones are mixed into the internal space, they are smaller in size than the openings formed on the upper surfaces of the second case. Here, according to the above configuration, the size of the opening on the bottom surface of the first case (the mesh opening when the bottom surface is a net) is equal to or larger than the size of the opening on the upper surface of the first case (the mesh opening when the upper surface is a net), and the size of the opening on the upper surface of the first case is larger than the size of the opening on the upper surface of the second case (the mesh opening when the upper surface is a net). Therefore, the size of the opening on the bottom surface of the first case is larger than the size of the opening on the upper surface of the second case. Also, the size of the opening on the bottom surface of the second case (the mesh opening when the bottom surface is a net) is also equal to or larger than the size of the opening on the upper surface of the second case. For this reason, the solid substances that have passed through the opening on the upper surface of the second case can easily pass through the openings on the bottom surfaces of the first case and the second case. Therefore, after excavating and recovering the biodegradation evaluation case, by shaking, washing, etc., the biodegradation evaluation case and removing the soil in the internal space through the openings in the bottom surfaces of the first case and the second case, the solid substances that have entered the internal space can be easily discharged to the outside through the openings on the bottom surface. In this way, since the solid substances in the soil are prevented from remaining in the internal space together with the remaining evaluation body, a more accurate weight of the remaining evaluation body with the influence of the weight of the soil reduced can be measured.Therefore, the accuracy of evaluating the biodegradation situation is further improved. In particular, since the size of the opening on the upper surface of the first case is larger than that of the opening on the upper surface of the second case, when the first case is accommodated in the internal space of the second case, if the soil is sieved through the opening formed on the upper surface of the second case, the soil passing through the opening on the upper surface of the second case fills the internal space of the second case while easily passing through the opening on the upper surface of the first case and entering the internal space of the first case. In this way, the soil can be easily and simply accommodated in the internal spaces of the first case and the second case respectively. Also, the size of the opening on the bottom surface of the first case is larger than that of the opening on the bottom surface of the second case. For this reason, after the biodegradation evaluation case is dug out and recovered and the soil in the internal space is removed, the remaining evaluation objects are separated into an evaluation object larger than the size of the opening on the bottom surface of the first case and an evaluation object larger than the size of the opening on the bottom surface of the second case and smaller than the size of the opening on the bottom surface of the first case. Based on this, the weight of the evaluation object larger than the size of the opening on the bottom surface of the first case and the weight of the evaluation object larger than the size of the opening on the bottom surface of the second case can be measured respectively. In such a case, even if the weight of the evaluation object larger than the size of the opening on the bottom surface of the second case is constant, if the weight of the evaluation object larger than the size of the opening on the bottom surface of the first case is large, it can be determined that the biodegradation is not progressing as a whole. Therefore, as described above, by measuring the weight according to the size of the evaluation object, the biodegradation situation can be evaluated more precisely. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are needed. Therefore, the evaluation can be carried out simply. In this way, a biodegradation evaluation case can be provided that is applicable to the field test of the biodegradation of a biodegradable resin molded product formed by including a biodegradable resin and can evaluate the biodegradation situation simply and with high accuracy.

[0013] Furthermore, the present invention is a method for evaluating the biodegradation state of the biodegradable resin molded article using the biodegradation evaluation case as described above, which includes: using the evaluation body based on the actual biodegradable resin molded article to be processed and the soil in which the biodegradable resin molded article is actually buried and biodegraded, accommodating them in the internal space of the first case, and then accommodating the first case together with the soil in the internal space of the second case. After that, the biodegradation evaluation case is buried in the soil. After biodegradation progresses, the biodegradation evaluation case is dug out and recovered, shaken and washed, and the soil in the internal spaces of the first case and the second case is removed through the openings on the bottom surfaces of the first case and the second case respectively. Then, the weight of the evaluation body remaining in the internal spaces of the first case and the second case is measured. The soil is sieved through the opening on the upper surface of the second case in a state where the first case is accommodated in the internal space of the second case, so as to be accommodated in the internal spaces of the first case and the second case. The present invention provides a method for evaluating the biodegradation of a biodegradable resin molded article characterized by the above. According to the above configuration, the biodegradable resin molded article itself that is actually the object to be processed, or a part thereof cut, for example, is used as the evaluation body. Together with this, the soil in which the biodegradable resin molded article is actually buried and biodegraded is accommodated in the internal space of the first case, and the first case is accommodated in the internal space of the second case together with the soil. In this state, the biodegradation evaluation case is buried in the soil. After biodegradation progresses, the biodegradation evaluation case is dug out and recovered, and the weight of the evaluation body remaining in the internal spaces of the first case and the second case is measured. Thus, a field test of biodegradation can be carried out on the actual biodegradable resin molded article and soil that are the objects of biodegradation treatment. Also, after digging out and collecting the biodegradation evaluation case, the biodegradation evaluation case is shaken and washed, and the soil in the internal space is removed through the openings on the bottom surfaces of each of the first case and the second case, leaving only the evaluation body that has not been biodegraded inside the biodegradation evaluation case. In this case, the first case and the second case of the biodegradation evaluation case are box-shaped, have a certain rigidity, are not easily deformed in overall shape, and the shapes of the openings on the upper and bottom surfaces are not easily changed either. Therefore, during the above series of operations, the evaluation body is prevented from falling off. As a result, the weight of the remaining evaluation body can be accurately measured, and the biodegradation situation can be accurately evaluated. Further, when accommodating soil in the internal space of the first case before burying the biodegradation evaluation case in the soil, with the first case accommodated in the internal space of the second case, by sieving the soil through the opening formed on the upper surface of the second case, when removing the soil in the internal space through the openings on the bottom surfaces of each of the first case and the second case after digging out and collecting the biodegradation evaluation case, it is suppressed that solids other than the evaluation body remain in the internal space together with the remaining evaluation body. In this state, by taking out all the contents in the internal space and measuring the weight, a more accurate weight of the remaining evaluation body with the influence of the weight of the soil reduced can be measured. Therefore, the accuracy of the evaluation of the biodegradation situation is further improved. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are needed. In particular, as described above, when removing the soil in the internal space, since it is suppressed that solids other than the evaluation body remain in the internal space, there is no particular need to sort the remaining evaluation body and the solids with tweezers or the like. Therefore, the evaluation can be easily performed. In this way, a method for evaluating the biodegradation of a biodegradable resin molded article, which is applicable to the field test of the biodegradation of a biodegradable resin molded article formed by including a biodegradable resin and can evaluate the biodegradation situation simply and with high accuracy, can be provided.

[0014] In one aspect of the present invention, after removing the soil in the internal spaces of the first case and the second case, the first case is taken out from the internal space of the second case, and in each of the first case and the second case, a separation sheet having a plurality of openings smaller than the size of the opening of the bottom surface is provided so as to cover the inner side of the upper surface. Then, water is sprayed from the bottom surface with each of the first case and the second case turned upside down, so that the evaluation bodies remaining in the internal space fall onto the separation sheet and are collected. When measuring the weight of the remaining evaluation bodies, the weight of the evaluation bodies collected together with the separation sheet is measured for each of the separation sheets removed from the first case and the second case, and the weight of the separation sheet is subtracted to measure the weight of the remaining evaluation bodies. According to the above configuration, after the biodegradation evaluation case is dug out and recovered and the soil in the internal spaces of the first case and the second case is removed, the first case is taken out from the internal space of the second case, and in each of the first case and the second case, a separation sheet having a plurality of openings is provided so as to cover the inner side of the upper surface. By spraying water from the bottom surface with each of the first case and the second case turned upside down, the evaluation bodies remaining in the internal spaces of the first case and the second case can be individually dropped onto the separation sheet and collected. At this time, in each of the first case and the second case, there should be evaluation bodies larger than the size of the opening of the bottom surface remaining, but since the openings of the separation sheet are smaller than the size of the opening of the bottom surface in each of the first case and the second case, even if the above operations are performed, the evaluation bodies remaining in each of the first case and the second case are suppressed from falling off through the openings of the separation sheet. In this way, the evaluation bodies remaining in each of the first case and the second case can be efficiently taken out from each of the first case and the second case. Thereafter, for each of the separation sheets removed from the first case and the second case, the weight of the evaluation bodies collected together with the separation sheet is measured, and by subtracting the weight of the separation sheet, the weight of the remaining evaluation bodies can be accurately measured for each of the first case and the second case. Based on the weight of the evaluation bodies measured in this way, the biodegradation situation can be evaluated simply and with high accuracy. In addition, the evaluation bodies collected on the separation sheet can be directly used for visual observation, microscopic observation, microscope observation, etc., and the biodegradation situation can be qualitatively grasped. Thereby, for example, when biodegradation is slow, it can be used to clarify the cause.

[0015] In another aspect of the present invention, when embedding the biodegradation evaluation case, the biodegradable resin molded article to be actually processed is embedded in the soil for biodegradation, and at the same time, the evaluation body and the soil are accommodated in the internal space of the first case, and each of the plurality of biodegradation evaluation cases is embedded in the soil in a state where the first case is accommodated in the internal space of the second case together with the soil. When digging out and recovering the biodegradation evaluation case, each of the plurality of biodegradation evaluation cases is recovered at a time point when different embedding times have elapsed, and when measuring the weight of the remaining evaluation bodies, the weight of the remaining evaluation bodies is measured for each of the plurality of biodegradation evaluation cases. Then, from the relationship between the embedding time and the weight of the remaining evaluation bodies for each of the plurality of biodegradation evaluation cases, the mode of progress of biodegradation is estimated. According to the above configuration, a plurality of biodegradation evaluation cases are prepared, and in each of these cases, the biodegradable resin molded article itself that is actually the object to be processed, or for example, a part thereof that has been cut, etc. is used as an evaluation body, and it is housed together with soil, and at the same time as actually burying the biodegradable resin molded article to be decomposed in the soil, it is buried. By doing so, the biodegradation status of the evaluation body housed in each of the plurality of biodegradation evaluation cases can be made the same as the biodegradation status of the biodegradable resin molded article that is actually the object to be processed. Therefore, after the biodegradation progresses, the biodegradation evaluation case is dug out and recovered, and by observing the evaluation body remaining in the internal space, it is possible to easily estimate the current biodegradation status of the biodegradable resin molded article that is actually the object to be processed. Here, each of the plurality of biodegradation evaluation cases is recovered at different times after different burial times have elapsed, such as 1 month, 2 months, 3 months, etc. after burial, and the weight of the evaluation body remaining in the internal space of each biodegradation evaluation case is measured. From the relationship between the burial time and the weight of the remaining evaluation body for each of the plurality of biodegradation evaluation cases, it is possible to estimate the mode of progress of biodegradation, such as at what rate the biodegradable resin molded article that is actually the object to be processed is being biodegraded, or what tendency of biodegradation it shows, etc. Thereby, it is possible to determine whether the biodegradation of the biodegradable resin molded article that is actually the object to be processed has ended, and if it has not ended, it is possible to estimate when the biodegradation is likely to end. Also, since the additional embeddable amount at that time can be estimated from the difference between the weight of the embedded evaluation body and the weight of the remaining evaluation body, it is possible to embed the biodegradable resin molded article in an additional amount. Therefore, for example, in a facility where biodegradation treatment is carried out, before the biodegradation of the already buried biodegradable resin molded article is completed, by excessively burying the next biodegradable resin molded article to be subjected to biodegradation treatment, a state where too many biodegradable resin molded articles are buried in the soil and saturated is achieved, and the rate at which the biodegradable resin molded article is biodegraded is reduced, which is suppressed. Also, immediately after the time when it is considered that the biodegradation of the already buried biodegradable resin molded article has ended, the next biodegradable resin molded article to be subjected to biodegradation treatment can be buried, so that a waste period during which the biodegradation treatment of the biodegradable resin molded article is not carried out occurs between the end of biodegradation and the burial of the next biodegradable resin molded article, which is suppressed. In this way, the biodegradation of the biodegradable resin molded article can be carried out efficiently.

Effect of the Invention

[0016] According to the present invention, it is applicable to the field test of the biodegradation of a biodegradable resin molded article formed by including a biodegradable resin, and a biodegradation evaluation case capable of evaluating the biodegradation situation simply and with high accuracy, and a method for evaluating the biodegradation of a biodegradable resin molded article using the biodegradation evaluation case can be provided.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. (First Embodiment) A perspective view of the biodegradation evaluation case according to the first embodiment of the present invention is shown in FIG. 1. FIG. 2 is a longitudinal sectional view of the biodegradation evaluation case shown in FIG. 1. FIG. 3 is a perspective view when the upper surface is opened in the biodegradation evaluation case shown in FIG. 1. Waste formed including a biodegradable resin is buried in soil where microorganisms inhabit, for example, in a facility for biodegradably treating waste, and is subjected to biodegradation. The biodegradation evaluation case 1 of the present embodiment contains, in its internal space S, a biodegradable resin molded product (evaluation body based thereon) formed including a biodegradable resin, which is a treatment target to be actually biodegradated as such waste, and is buried in the soil where the waste is biodegradated, for example, in a facility for biodegradably treating waste, to biodegrade the evaluation body and observe the situation, thereby determining whether the biodegradation of the waste is completed, and if not, to what extent the biodegradation has progressed, etc.

[0019] In this embodiment, the biodegradation evaluation case 1 has a cubic shape. The biodegradation evaluation case 1 may have other shapes such as a rectangular parallelepiped, a prism with a polygon other than a quadrilateral as the bottom surface, or a cylinder. The biodegradation evaluation case 1 includes a frame 2, an upper surface 3, a plurality of side surfaces 4, a bottom surface 5, and a hinge 6.

[0020] The frame 2 includes a bottom frame 2a, side frames 2b, an upper frame 2c, and a lid frame 2d. The bottom frame 2a, side frames 2b, upper frame 2c, and lid frame 2d are all long metallic members. The bottom frame 2a is provided so as to extend in the horizontal direction. In this embodiment, four bottom frames 2a are provided. The four bottom frames 2a are joined at their ends so as to be orthogonal to each other, thereby forming a rectangular shape as a whole for the bottom frame 2a. The side frames 2b are joined to the joints of the two bottom frames 2a so as to extend upward from each of the rectangular corners of the bottom frame 2. The upper frame 2c is joined so as to connect the upper ends of the two side frames 2b. In this way, a cubic frame is formed by the bottom frame 2a, side frames 2b, and upper frame 2c. The lid frame 2d will be described later.

[0021] The bottom surface 5 is formed in a planar shape so as to have a quadrilateral shape. The bottom surface 5 is provided at the lowest position of the biodegradation evaluation case 1 so as to extend within a horizontal plane. Each side of the bottom surface 5 is joined to each of the four bottom frames 2a. In this way, the bottom surface 5 is provided so as to cover the space surrounded by the bottom frame 2a. The bottom surface 5 is made of metal. More preferably, the bottom surface 5 is desirably formed of stainless steel with high corrosion resistance. The bottom surface 5 has a plurality of openings 5h. Each of the plurality of openings 5h has substantially the same size. In the present embodiment, the bottom surface 5 is a metal net. That is, in the present embodiment, the openings 5h of the bottom surface 5 are the mesh of the net, and the size of the openings 5h is the mesh opening, that is, the dimension of the gap portion of the mesh.

[0022] Each of the plurality of side surfaces 4 is formed in a planar shape so as to have a quadrilateral shape. Each side surface 4 rises upward from the end side of the bottom surface 5 and is provided so as to extend in a vertical plane. Among the side edges of each side surface 4, the lowermost end side is joined to the bottom frame 2a. Among the side edges of each side surface 4, the side edge extending in the vertical direction is joined to the side frame 2b. Among the side edges of each side surface 4, the uppermost end side is joined to the upper frame 2c. In this way, the side surface 4 is provided so as to cover the space surrounded by the bottom frame 2a, the side frame 2b, and the upper frame 2c. The side surface 4 can be formed of, for example, a metal or resin plate material. In the present embodiment, unlike the bottom surface 5, the side surface 4 is configured not to have an opening, but as will be described later as a modification, it may be configured to have an opening.

[0023] Similar to the side surface 4, four lid frames 2d are provided in the present embodiment. The four lid frames 2d are joined at their ends so as to be orthogonal to each other, thereby forming a rectangular shape as a whole of the lid frames 2d. The upper surface 3 is formed in a planar shape so as to have a quadrilateral shape. The upper surface 3 is provided at the uppermost position of the biodegradation evaluation case 1 so as to extend in a horizontal plane. Each side edge of the upper surface 3 is joined to each of the four lid frames 2d. In this way, the upper surface 3 is provided so as to cover the space surrounded by the lid frames 2d. The upper surface 3 is made of metal. More preferably, the upper surface 3 is desirably formed of stainless steel with high corrosion resistance. The upper surface 3 has a plurality of openings 3h. Each of the plurality of openings 3h has substantially the same size. It is desirable that the upper surface 3 has an opening ratio, which is the ratio of the total area of the openings 3h to the area of the upper surface 3, as large as possible. In the present embodiment, the upper surface 3 is a metal mesh. That is, in the present embodiment, the openings 3h of the upper surface 3 are the mesh openings, and the size of the openings 3h is the mesh size, that is, the dimension of the gap portion of the mesh. The upper surface 3 can also be formed of punching metal with a large opening ratio.

[0024] In the present embodiment, the openings 3h and 5h of the bottom surface 5 and the upper surface 3 are formed so that the size (mesh size) BH of the openings 5h of the bottom surface 5 is equal to or greater than the size (mesh size) TH of the openings 3h of the upper surface 3. The size BH of the openings 5h of the bottom surface 5 is preferably 2 mm or more and 5 mm or less. More preferably, the size BH of the openings 5h of the bottom surface 5 is 2 mm.

[0025] The upper surface 3 covers the upper part of the space surrounded by the plurality of side surfaces 4, and each of the lid frame portions 2d is provided along the upper frame 2c. With such a configuration, the biodegradation evaluation case 1 has a box shape so that an internal space S surrounded by the upper surface 3, the side surfaces 4, and the bottom surface 5 is formed. On one side 3a of the upper surface 3, the side surface 4 constituting the side is joined by a hinge 6. Thereby, the upper surface 3 can be rotated with respect to the side surface 4 about the side 3a provided with the hinge 6, so that the biodegradation evaluation case 1 is provided to be openable and closable. That is, in the biodegradation evaluation case 1, the upper surface 3 functions as a lid for closing the internal space S.

[0026] Note that the structure of the biodegradation evaluation case 1 may be any structure as long as the upper surface 3 is configured to be openable and closable as a lid for closing the internal space S as described above. For example, a hinge 6 may not be provided between the upper surface 3 and the side surface 4, and the upper surface 3 may be configured to be completely separable from the side surface 4. Alternatively, a rail or the like may be provided at the upper end of the side surface 4, and the upper surface 3 may be configured to slide horizontally along the rail. In addition, in the case of biodegradation evaluation case 1, when performing biodegradation treatment as described later, it is necessary to have a certain rigidity so that its shape can be maintained even at the end of the biodegradation treatment. In this regard, in the above, while forming the upper surface 3 and the bottom surface 5 with a net, this is joined to the rigid frame 2 so that the biodegradation evaluation case 1 has rigidity as a whole. Alternatively, for example, when the upper surface 3 and the bottom surface 5 are formed of a material such as punching metal that has rigidity by itself, the frame 2 may not be provided and the bottom surface 5 may be directly joined to the side surface 4.

[0027] Next, a method for evaluating the biodegradability of a biodegradable resin molded article using the biodegradation evaluation case 1 as described above will be described. FIG. 4 is a flowchart of the method for evaluating the biodegradability of a biodegradable resin molded article. The method for evaluating the biodegradability of a biodegradable resin molded article includes a step S1 of embedding a biodegradation evaluation case, a step S2 of recovering the biodegradation evaluation case after biodegradation has progressed, a step S3 of removing the soil in the internal space of the biodegradation evaluation case, a step S4 of providing a separation sheet so as to cover the inside of the upper surface, a step S5 of dropping and collecting the remaining evaluation bodies onto the separation sheet, a step S6 of removing the separation sheet together with the collected evaluation bodies, a step S7 of measuring the weight of the remaining evaluation bodies, and a step S8 of estimating the mode of biodegradation.

[0028] FIG. 5 is a plan view of a state in which a hole is dug in the soil and a biodegradation evaluation case is installed. FIG. 6 is a longitudinal sectional view of FIG. 5. First, determine the soil to be evaluated and the biodegradable resin molded article. As already described, in the present embodiment, the biodegradation status of a biodegradable resin molded article formed including a biodegradable resin, which is such a waste to be actually biodegraded, is evaluated. For this purpose, with an evaluation body based on the biodegradable resin molded article accommodated in the internal space S of the biodegradation evaluation case 1, for example, in a facility for biodegrading the waste, it is buried in the soil where the waste is biodegraded to biodegrade the evaluation body and observe the situation. Therefore, the soil to be evaluated is the soil at the location where the waste, which is the biodegradable resin molded article RT to be actually treated, is buried and biodegraded.

[0029] In the step S1 of burying the biodegradation evaluation case, first, a hole Gh is dug in a portion having a soil environment equivalent to the location where the biodegradation treatment of the biodegradable resin molded article is actually performed, such as the location itself where the biodegradation treatment of the biodegradable resin molded article is actually performed or the vicinity of the location. Then, the biodegradation evaluation case 1 is installed in the hole Gh. The hole Gh is dug deeper than the height of the biodegradation evaluation case 1 so that when the biodegradation evaluation case 1 is installed in the hole Gh, the upper surface 3 is located below the ground surface. In order to match the biodegradable resin molded article RT to be actually treated with the soil environment, when the evaluation body is provided in the biodegradation evaluation case 1 as will be described later, it is desirable to adjust the depth of the hole Gh so that the depth of the evaluation body from the ground surface is equivalent to the burial depth of the biodegradable resin molded article RT to be actually treated. In the present embodiment, a plurality of biodegradation evaluation cases 1A to 1C are installed. Therefore, a plurality of holes Gh are provided corresponding to each of the plurality of biodegradation evaluation cases 1A to 1C. In the present embodiment, since three biodegradation evaluation cases 1A to 1C are used, three holes Gh are provided.

[0030] The plurality of biodegradation evaluation cases 1A to 1C are installed in the holes Gh while actually burying the biodegradable resin molded product RT to be treated in the soil for biodegradation. Among these biodegradation evaluation cases 1A to 1C, an evaluation body based on the actual biodegradable resin molded product RT to be treated is accommodated and buried in the soil G where the biodegradable resin molded product RT is actually buried and biodegraded. Then, the progress of biodegradation of the evaluation body among these plurality of biodegradation evaluation cases 1A to 1C becomes substantially equal to the progress of biodegradation of the biodegradable resin molded product RT that is actually the object to be treated. Therefore, by digging out and recovering the plurality of biodegradation evaluation cases 1A to 1C and checking the status of the accommodated evaluation body, it is possible to estimate the progress of biodegradation of the biodegradable resin molded product RT that is actually the object to be treated at the time of recovery. Here, after providing the plurality of biodegradation evaluation cases 1A to 1C as described above, if each of the biodegradation evaluation cases 1A to 1C is recovered at a time point when different burial times have elapsed, it is possible to estimate the progress of biodegradation of the biodegradable resin molded product RT that is actually the object to be treated at different time points when different times have elapsed. For this reason, although the biodegradation evaluation case 1 is described as three in this embodiment, it is desirable to provide as many as possible, more than this.

[0031] Note that the progress of biodegradation of the biodegradable resin molded product varies depending on the season, weather conditions, and soil environment. Therefore, in order to make the progress of biodegradation of the evaluation body in the biodegradation evaluation cases 1A to 1C equal to the progress of biodegradation of the biodegradable resin molded product RT that is actually the object to be treated, as will be described later, it is necessary to accommodate the same soil G as the soil G in which the biodegradable resin molded product RT is actually buried and biodegraded in the biodegradation evaluation cases 1A to 1C. Moreover, as described above, it is essential to bury the biodegradation evaluation case 1 at the same time as burying the biodegradable resin molded product RT that is actually the object to be treated in the soil G for biodegradation and start the evaluation using the biodegradation evaluation case 1. Here, "simultaneously" with actually embedding the biodegradable resin molded article RT to be processed means, for example, the same day as the day when the biodegradable resin molded article RT to be actually processed is embedded. Alternatively, as long as the season, weather conditions, soil environment, etc. do not fluctuate significantly, it can include within several days before and after the day when the biodegradable resin molded article RT to be actually processed is embedded. Of course, the plurality of biodegradation evaluation cases 1A to 1C each accommodate the same evaluation object. "Same" here means that the evaluation object is formed of the same material and has substantially the same volume and weight.

[0032] FIG. 7 is a longitudinal sectional view of a state in which the evaluation object is accommodated in the internal space of the biodegradation evaluation case. Next, the soil G excavated for digging the hole Gh is accommodated in the internal space S of the biodegradation evaluation case 1 through the opening 3h on the upper surface 3 of the biodegradation evaluation case 1, such that the soil G is sieved by the opening 3h. Specifically, the excavated soil G is placed on the upper surface 3, and while gently leveling it with a hand, a scoop, etc., the soil G is passed through the opening 3h. By doing so, the soil G sieved by the sieve can be accommodated in the internal space S without performing the operation of separately providing a sieve and sieving the soil G with the sieve. The soil G is accommodated such that the height from the bottom surface 5 is, for example, 2 to 3 cm. Thereafter, the lid (upper surface 3) of the biodegradation evaluation case 1 is opened, the evaluation object T is placed on the soil G, and the lid (upper surface 3) of the biodegradation evaluation case 1 is closed.

[0033] As described above, the evaluation object T accommodated in the internal space S of the biodegradation evaluation case 1 is based on the biodegradable resin molded article RT that is actually the object to be processed. Biodegradable resin molded articles have different biodegradation periods depending on the material and shape. In addition, biodegradable resins gradually deteriorate due to the influence of moisture and ultraviolet rays. Biodegradable resin molded articles have different deterioration situations depending on the usage environment and usage period until they are discarded. Therefore, this difference in the deterioration situation may also affect the period required for biodegradation. Therefore, by using the biodegradable resin molded article RT itself that is actually the object to be processed, or a part of the biodegradable resin molded article RT, as the evaluation object T based on the biodegradable resin molded article RT, and accommodating this evaluation object T in the internal space S to evaluate the biodegradation situation, it is possible to improve the accuracy of the evaluation. For example, when the evaluation object T is small enough to be accommodated in the internal space S of the biodegradable resin molded article RT that is actually the object to be processed, the biodegradable resin molded article RT itself can be used. Also, when the biodegradable resin molded article RT that is actually the object to be processed is large, fragments, pieces generated by cutting, breaking, or crushing it into a size that can be accommodated in the internal space S can be used as the evaluation object T.

[0034] The biodegradable resin molded article RT and the evaluation body T based on it are formed by including a biodegradable resin. Examples of the biodegradable resin include polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polyethylene terephthalate succinate, polycaprolactone butylene succinate, polytetramethylene adipate terephthalate, polyethylene succinate, polyethylene adipate, polybutylene adipate, polyglycolic acid, polycaprolactone, polyhydroxyalkanoate, polyhydroxybutyric acid, polyhydroxyvaleric acid, polyhydroxybutyric acid-hydroxyvaleric acid copolymer, polyhydroxybutyric acid-hydroxyhexanoic acid copolymer, starch polyester resin, and copolymers with other biodegradable resins, polymer alloys, compounds, etc., but are not limited thereto. Although polylactic acid is hardly decomposed in the soil, polylactic acid may be used as the biodegradable resin to confirm this. Further, the biodegradable resin includes a mixture in which a plurality of the above biodegradable resins are mixed.

[0035] The biodegradable resin molded article RT and the evaluation body T based on it may contain, in addition to the biodegradable resin as described above, other thermoplastic resins, fillers, reinforcing materials, colorants, thickeners, mold release agents, plasticizers, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, lubricants, antiblocking agents, antifogging materials, nucleating agents, fillers, etc. These additives can be contained to the extent that they are compatible with or sufficiently dispersed in the biodegradable resin and do not affect the biodegradation treatment. The biodegradable resin molded article RT and the evaluation body T based on it may be formed only by the biodegradable resin as described above. Examples of the biodegradable resin molded article RT and the evaluation body T based on the same include, but are not limited to, packaging materials, curing films, curing sheets, curing boards, building material bags, reinforcing bar protection caps, single pipe protection caps, single pipe clamp covers, single pipe barricades, display boards, color cones (registered trademark), cone bars, etc. for construction and civil engineering materials, packaging films, bags, trays, bottles, foams for cushioning, fish boxes, etc. for packaging materials, mulching films, tunnel films, greenhouse films, germination sheets, vegetation mats, seedling beds, flower pots, etc. for agricultural materials.

[0036] FIG. 8 is a longitudinal sectional view of the biodegradation evaluation case buried in the soil. After accommodating the evaluation body T in the internal space S, soil G is accommodated in the internal space S so as to cover the evaluation body T from above the evaluation body T and fill the internal space S. The soil G is accommodated in the internal space S of the biodegradation evaluation case 1 through the opening 3h in a state where the upper surface 3 of the biodegradation evaluation case 1 is closed, and the soil G is sieved by the opening 3h. In this way, by accommodating the soil G in the internal space S both before and after the timing of accommodating the evaluation body T in the internal space S, the evaluation body T can be provided at a distance from the upper surface 3 and the bottom surface 5 of the biodegradation evaluation case 1. Further, by placing the evaluation body T at the central portion in a plan view of the internal space S, the evaluation body T can also be provided at a distance from the side surface 4. Thereby, when the biodegradation of the evaluation body T progresses, it is suppressed that the evaluation body T adheres to the upper surface 3, the side surface 4, and the bottom surface 5.

[0037] Also, the entire hole Gh including the space between the biodegradation evaluation case 1 and the inner wall of the hole Gh is filled with the soil G excavated for digging the hole Gh. In this way, in the step S1 of burying the biodegradation evaluation case, the evaluation body T based on the biodegradable resin molded article RT that is actually the object to be processed and the soil G in which the biodegradable resin molded article RT is actually buried and biodegraded are accommodated in the internal space S, and the biodegradation evaluation case 1 is buried in the soil G.

[0038] Next, after biodegradation has progressed, the biodegradation evaluation case is recovered (step S2). As described above, in the present embodiment, while actually embedding the biodegradable resin molded article RT to be processed in the soil G for biodegradation, a plurality of biodegradation evaluation cases 1A to 1C are also embedded in the soil G, and each of the biodegradation evaluation cases 1A to 1C is recovered at a point in time when different embedding times have elapsed. The period from when each of the biodegradation evaluation cases 1A to 1C is embedded until it is recovered may be determined in advance. Also, the timing for recovering the next biodegradation evaluation case 1 may be determined according to the state of biodegradation of the evaluation body T in the biodegradation evaluation case 1 recovered immediately before.

[0039] After recovering the biodegradation evaluation case, the soil in the internal space of the biodegradation evaluation case is removed (step S3). Specifically, for example, by shaking the biodegradation evaluation case 1, the soil G in the internal space S is removed through the opening 5h on the bottom surface 5 of the biodegradation evaluation case 1. Then, the biodegradation evaluation case 1 is immersed in water, or water is sprayed from above, etc., and by washing, the soil G in the internal space S is removed through the opening 5h on the bottom surface 5. As already explained, the size BH of the opening 5h on the bottom surface 5 of the biodegradation evaluation case 1 is greater than or equal to the size TH of the opening 3h on the upper surface 3, and in the internal space S, the soil G is accommodated such that the soil G is sieved by the opening 3h on the upper surface 3. Therefore, since the soil G accommodated in the internal space S has a particle size smaller than the size TH of the opening 3h on the upper surface 3, these soils G are easily discharged to the outside of the biodegradation evaluation case 1 through the opening 5h on the bottom surface 5 having a size greater than or equal to the opening 3h on the upper surface 3.

[0040] Next, a separation sheet is provided so as to cover the inside of the upper surface 3 of the biodegradation evaluation case 1 (step S4). FIG. 9 is a perspective view showing a state in which the soil in the internal space is removed and the separation sheet is provided in the biodegradation evaluation case. After removing the soil in the internal space S of the biodegradation evaluation case 1, open the upper surface 3 (lid), place the separation sheet 7 on the upper end of the side surface 4 so as to cover the internal space S from above, and then close the upper surface 3 (lid) to provide the separation sheet 7 so as to cover the inside of the upper surface 3. The separation sheet 7 is a sheet-like member in which a plurality of openings 7h smaller than the size of the opening 5h of the bottom surface 5 are formed. The separation sheet 7 is, for example, a sheet material made of metal or resin formed in a mesh shape, or a perforated metal. As will be described later, the evaluation body T remaining in the internal space S without being biodegraded is collected on this separation sheet 7 and removed from the biodegradation evaluation case 1. Considering the ease of this operation and the subsequent observation of the evaluation body T, etc., it is preferable to use a resin-made net as the separation sheet 7. In this case, the openings 7h of the separation sheet 7 are the meshes of the net, and the size of the openings 7h is the mesh opening, that is, the dimension of the gap portion of the mesh.

[0041] FIG. 10 is a perspective view of a state in which the biodegradation evaluation case is inverted upside down and water is being sprinkled from the bottom surface. Thereafter, with the biodegradation evaluation case 1 inverted upside down, water is sprinkled from the bottom surface 5 to drop and collect the evaluation body T remaining in the internal space S on the separation sheet 7 (step S5). In order to suppress the shape of the evaluation body T from collapsing, it is preferable to perform the water sprinkling with a weak water pressure using a shower 100 or a watering can. The soil G in the internal space S has already been discharged in step S3. Also, the size of the evaluation body T remaining in the internal space S is larger than the opening 5h of the bottom surface 5. Since the size of the opening 7h of the separation sheet 7 is smaller than the size BH of the opening 5h of the bottom surface 5, in step S5, the evaluation body T remaining in the internal space S is suppressed from falling below the separation sheet 7 through the opening 7h of the separation sheet 7. In this way, only the evaluation body T remaining in the internal space S and larger than the opening 5h of the bottom surface 5 basically remains on the separation sheet 7.

[0042] FIG. 11 is a perspective view of the separation sheet on which the evaluation body is collected. Then, from the biodegradation evaluation case 1, the separation sheet 7 is removed together with the evaluation object T collected on the separation sheet 7 (step S6).

[0043] Furthermore, the weight of the evaluation object T remaining in the internal space S of the biodegradation evaluation case 1 is measured (step S7). Also, visual observation, photographing, microscopic observation, various microscopic observations, etc. of the evaluation object T are appropriately performed. At this time, the weight of the separation sheet 7 is measured in advance, the weight of the collected evaluation object T together with the separation sheet 7 is measured, and the weight of the remaining evaluation object T is measured by subtracting the weight of the separation sheet 7. In step S2, it was explained that each of the plurality of biodegradation evaluation cases 1A to 1C is recovered when different burial times have elapsed. Therefore, step S7 is performed for each of the plurality of biodegradation evaluation cases 1A to 1C at the time when each of the biodegradation evaluation cases 1A to 1C is recovered. That is, the weight of the remaining evaluation object T is measured for each of the plurality of biodegradation evaluation cases 1A to 1C.

[0044] Then, based on the measured weight of the evaluation object T, the mode of progress of biodegradation is estimated (step S8). In the present embodiment, before burying the biodegradation evaluation case 1, the weight of the evaluation object T before biodegradation accommodated in the internal space S is measured in advance, and the weight of the evaluation object T after biodegradation measured in step S7 is divided by the weight of the evaluation object T before biodegradation to calculate the residual rate of the evaluation object T. FIG. 12 is a graph showing an example of the relationship between the burial period of the biodegradable resin molded product and the residual rate of the biodegradable resin. In FIG. 12, after each of the biodegradable resin molded products RT1 and RT2 is buried, the respective residual rates at the time points TM1 (for example, 1 month after burial), TM2 (for example, 2 months after burial), TM3 (for example, 3 months after burial) when different burial times have elapsed are shown.

[0045] The residual rate of the biodegradable resin molded article basically decreases with the passage of time. The object of the present embodiment is to determine whether the biodegradation of the biodegradable resin molded article RT, which is waste actually buried in soil as a treatment target, has been completed. When it has not been completed, the additional embeddable amount at that time is estimated from the difference between the weight of the evaluation body and the weight of the remaining evaluation body, and it is also to estimate when the biodegradation is likely to end and that period. When the biodegradable resin molded article to be treated cannot be left for a long time, a biodegradable resin molded article in an amount corresponding to the additional embeddable amount at the time of performing the biodegradation evaluation is buried.

[0046] If the biodegradable resin molded article RT is such that the rate of biodegradation is substantially constant as in the biodegradable resin molded article RT1 shown in FIG. 12, the biodegradation evaluation cases 1A and 1B are collected at two different time points, for example, time point TM1 and time point TM2, and the residual rate of each evaluation body T is calculated. From the elapsed time from time point TM1 to time point TM2 and the residual rates at these two time points TM1 and TM2, the end time of the biodegradation treatment after embedding the biodegradable resin molded article such that the residual rate approaches, for example, 0 (zero) can be calculated. However, how the biodegradation proceeds varies depending on the type of the biodegradable resin molded article and the like. For example, in the biodegradable resin molded article RT2 of FIG. 12, although the rate of biodegradation is low at the initial stage of the embedding period, the rate increases as time progresses. Also, the progress of biodegradation can vary depending on the season and the soil environment. Therefore, it is basically not easy to estimate the end time of the biodegradation treatment. Therefore, as already described, when it is necessary to calculate the time when the residual rate of the biodegradable resin molded article approaches 0, in Biodegradation Evaluation Case 1, it is preferable to embed as many as possible. If the number of Biodegradation Evaluation Case 1 is small, for example, when the progress rate of biodegradation of the biodegradable resin molded article is slow, it may be assumed that the biodegradation of the actual biodegradable resin molded article RT to be treated has not been completed, but all of the Biodegradation Evaluation Case 1 have been recovered. In order to suppress this and to collect the Biodegradation Evaluation Case 1 and calculate the residual rate with a margin until the biodegradation of the actual biodegradable resin molded article RT to be treated is completed, it is desirable to embed as many Biodegradation Evaluation Case 1 as possible.

[0047] The Biodegradation Evaluation Case 1 as described above is a biodegradation evaluation case 1 in which an evaluation body T based on a biodegradable resin molded article RT formed including a biodegradable resin is embedded in soil G where microorganisms inhabit in a state where the evaluation body T is accommodated, the evaluation body T is biodegraded, and the state of biodegradation is evaluated. It has an upper surface 3, a bottom surface 5, and a side surface 4, and forms a box shape so that an internal space S is formed by the upper surface 3, the bottom surface 5, and the side surface 4. The evaluation body T is accommodated in the internal space S together with the soil G. A plurality of openings 3h and 5h are formed in the upper surface 3 and the bottom surface 5, respectively. The size BH of the opening 5h of the bottom surface 5 is equal to or larger than the size TH of the opening 3h of the upper surface 3. According to the above configuration, the biodegradation evaluation case 1 has an upper surface 3, a bottom surface 5, and side surfaces 4, and is box-shaped such that an internal space S is formed by the upper surface 3, the bottom surface 5, and the side surfaces 4. A plurality of openings 3h, 5h (mesh openings in the case where the upper surface 3 and the bottom surface 5 are meshes) are formed in the upper surface 3 and the bottom surface 5, respectively. In such a biodegradation evaluation case 1, when the evaluation body T based on the biodegradable resin molded article RT is accommodated in the internal space S together with the soil G and the biodegradation evaluation case 1 is buried in the soil G, components such as moisture flow through the openings 3h, 5h formed in the upper surface 3 and the bottom surface 5, so that the environment of the internal space S can be made the same as the surrounding soil G in which it is buried. Further, since the biodegradation evaluation case 1 is formed in a box shape so as to have a certain volume, regardless of the shape of the biodegradable resin molded article RT that is actually the object to be treated, the biodegradable resin molded article RT itself or, for example, a part thereof cut can be accommodated as the evaluation body T. Therefore, for example, by burying the soil G in which the biodegradable resin molded article RT that is actually the basis of the evaluation body T is buried and biodegraded together with the evaluation body T in the internal space S and then burying it in the soil G, a field test of biodegradation can be carried out on the biodegradable resin molded article RT and the soil G that are actually the objects of biodegradation treatment. In addition, the biodegradation evaluation case 1 has a box shape, has a certain rigidity, is less likely to change in its overall shape, and is also less likely to easily change the shapes of the openings 3h and 5h on the upper surface 3 and the bottom surface 5. Therefore, during the operation on the biodegradation evaluation case 1, the dropping of the evaluation object T is suppressed. As a result, since the weight of the remaining evaluation object T can be accurately measured, the biodegradation situation can be accurately evaluated. Further, for example, before burying the biodegradation evaluation case 1 in the soil G, it is also possible to sieve the soil G through the opening 3h formed on the upper surface 3 and accommodate the soil G in the internal space S. Since the size BH of the opening 5h on the bottom surface 5 (the mesh opening when the bottom surface 5 is a net) is equal to or greater than the size TH of the opening 3h on the upper surface 3 (the mesh opening when the upper surface 3 is a net), solid substances such as small stones mixed in the soil that can pass through the opening 3h on the upper surface 3 can be discharged from the opening 5h on the bottom surface 5. Therefore, when removing the soil G in the internal space S through the opening 5h on the bottom surface 5 after digging out and recovering the biodegradation evaluation case 1, it is possible to suppress the above-mentioned solid substances from remaining in the internal space S together with the remaining evaluation object T. In this state, by taking out all the things in the internal space S and measuring the weight, it is possible to measure a more accurate weight of the remaining evaluation object T with the influence of the weight of the soil G reduced. Therefore, the accuracy of the evaluation of the biodegradation situation is further improved. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are needed. Therefore, the evaluation can be carried out simply. In this way, it is possible to provide a biodegradation evaluation case 1 that is applicable to the field test of the biodegradation of the biodegradable resin molded product RT formed by including a biodegradable resin, and can evaluate the biodegradation situation simply and with high accuracy.

[0048] Also, a biodegradability evaluation method for a biodegradable resin molded article RT that evaluates the biodegradation state of the biodegradable resin molded article RT using the above-described biodegradation evaluation case 1 includes: an evaluation body T based on the actual biodegradable resin molded article RT to be processed; and soil G in which the biodegradable resin molded article RT is actually buried and biodegrades. With the evaluation body T and the soil G accommodated in the internal space S, the biodegradation evaluation case 1 is buried in the soil G. After biodegradation progresses, the biodegradation evaluation case 1 is dug out and recovered, shaken, washed, and the soil G in the internal space S is removed through the opening 5h on the bottom surface 5, and the weight of the evaluation body T remaining in the internal space S is measured. The soil G is accommodated in the internal space S while sifting the soil G through the opening 3h on the upper surface 3. According to the above configuration, the biodegradable resin molded article RT itself that is actually the object to be processed, or for example, a part thereof that has been cut, etc., is used as the evaluation body T. Together with this, the soil G in which the biodegradable resin molded article RT is actually buried and biodegrades is accommodated in the internal space S of the biodegradation evaluation case 1. The biodegradation evaluation case 1 is buried in the soil G. After biodegradation progresses, the biodegradation evaluation case 1 is dug out and recovered, and the weight of the evaluation body T remaining in the internal space S is measured, so that a field test of biodegradation can be carried out on the biodegradable resin molded article RT and the soil G that are actually the objects of biodegradation treatment. After digging out and recovering the biodegradation evaluation case 1, the biodegradation evaluation case 1 is shaken and washed to remove the soil G in the internal space S through the opening 5h of the bottom surface 5, and only the evaluation body T that remained without being biodegraded is left inside the biodegradation evaluation case 1. In this case, the biodegradation evaluation case 1 forms a box shape, has a certain rigidity, is not easily deformed in its overall shape, and the shapes of the openings 3h and 5h of the upper surface 3 and the bottom surface 5 are not easily changed either. Therefore, the dropping of the evaluation body T during the above series of operations is suppressed. As a result, since the weight of the remaining evaluation body T can be accurately measured, the biodegradation situation can be accurately evaluated. Furthermore, since the size BH of the opening 5h of the bottom surface 5 is equal to or larger than the size TH of the opening 3h of the upper surface, after digging out and recovering the biodegradation evaluation case 1, by shaking and washing the biodegradation evaluation case 1 and removing the soil G in the internal space S through the opening 5h of the bottom surface 5, the solid matter that has entered the internal space S can be easily discharged to the outside through the opening 5h of the bottom surface 5. Therefore, the accuracy of evaluating the biodegradation situation is further improved. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are needed. In particular, as described above, when removing the soil G in the internal space S, since the solid matter other than the evaluation body T remaining in the internal space S is suppressed, there is no particular need to sort the remaining evaluation body T and the solid matter with tweezers or the like. Therefore, the evaluation can be easily performed. In this way, it is possible to provide a method for evaluating the biodegradation of a biodegradable resin molded article RT that is applicable to the field test of the biodegradation of the biodegradable resin molded article RT formed by including a biodegradable resin and can evaluate the biodegradation situation simply and with high accuracy.

[0049] Also, after removing the soil G in the internal space S, a separation sheet 7 with a plurality of openings 7h smaller than the size of the opening 5h of the bottom surface 5 is provided so as to cover the inside of the upper surface 3. The biodegradation evaluation case 1 is watered from the bottom surface 5 in a state where it is turned upside down, and the evaluation body T remaining in the internal space S is dropped onto the separation sheet 7 and collected. When the separation sheet 7 is removed together with the collected evaluation body T and the weight of the remaining evaluation body T is measured, the weight of the evaluation body T collected together with the separation sheet 7 is measured, and the weight of the separation sheet 7 is subtracted to measure the weight of the remaining evaluation body T. According to the above configuration, after the biodegradation evaluation case 1 is dug out and recovered and the soil G in the internal space S is removed, a separation sheet 7 with a plurality of openings 7h formed is provided so as to cover the inside of the upper surface 3. By watering from the bottom surface 5 in a state where the biodegradation evaluation case 1 is turned upside down, the evaluation body T remaining in the internal space S can be dropped onto the separation sheet 7 and collected. At this time, in the biodegradation evaluation case 1, an evaluation body T larger than the size of the opening 5h of the bottom surface 5 should remain. However, since the opening 7h of the separation sheet 7 is smaller than the size of the opening 5h of the bottom surface 5, even if the above operation is performed, the evaluation body T remaining in the biodegradation evaluation case 1 is suppressed from falling off from the opening 7h of the separation sheet 7. In this way, the evaluation body T remaining in the biodegradation evaluation case 1 can be efficiently taken out from the biodegradation evaluation case 1. Thereafter, by measuring the weight of the evaluation body T collected together with the separation sheet 7 and subtracting the weight of the separation sheet 7, the weight of the remaining evaluation body T can be accurately measured. Based on the weight of the evaluation body T measured in this way, the biodegradation situation can be evaluated simply and with high accuracy. Also, the evaluation body T collected on the separation sheet 7 can be directly used for visual observation, microscopic observation, microsope observation, etc., and the biodegradation situation can be qualitatively grasped. Thereby, for example, when biodegradation is slow, it can be used to clarify the cause.

[0050] In particular, as described above, by taking out the remaining evaluation body T onto the separation sheet 7, visual observation, photographing, microscopic observation, various microscopic observations, etc. can be appropriately performed on the recovered evaluation body T. Since the evaluation body T is in a state of falling and being placed on the separation sheet 7, it is also easy to take out the evaluation body T from the separation sheet 7. Therefore, it is also possible to more accurately measure the weight of the biodegradable substance from the difference between the weight of the residue when the evaluation body T is evaporated to dryness at, for example, 105 °C and the weight when it is ashed at 550 °C. Also, when recovering and observing the evaluation body T as described above, it is not necessary to pick up the evaluation body T with tweezers or the like. From this perspective as well, it is possible to simply evaluate the state of biodegradation.

[0051] Also, when embedding the biodegradation evaluation case 1, while actually embedding the biodegradable resin molded article RT to be treated in the soil G for biodegradation, each of the plurality of biodegradation evaluation cases 1 is embedded in the soil G in a state where the evaluation body T and the soil G are accommodated in the internal space S. When digging out and recovering the biodegradation evaluation case 1, each of the plurality of biodegradation evaluation cases 1 is recovered at a time point when different embedding times have elapsed. When measuring the weight of the remaining evaluation body T, the weight of the remaining evaluation body T is measured for each of the plurality of biodegradation evaluation cases 1. Then, from the relationship between the embedding time and the weight of the remaining evaluation body T for each of the plurality of biodegradation evaluation cases 1, the mode of progress of biodegradation is estimated. According to the above configuration, a plurality of biodegradation evaluation cases 1 are prepared, and in each of them, the biodegradable resin molded article RT itself to be actually processed, or for example, a part thereof such as a cut piece, is used as the evaluation body T, and is accommodated together with the soil G, and the biodegradable resin molded article RT to be actually processed is buried in the soil G where it biodegrades while being buried for the purpose of biodegrading the biodegradable resin molded article RT to be processed. By doing so, the biodegradation status of the evaluation body T accommodated in each of the plurality of biodegradation evaluation cases 1 can be made the same as the biodegradation status of the biodegradable resin molded article RT that is actually the object to be processed. Therefore, after the biodegradation progresses, the biodegradation evaluation case 1 is dug out and recovered, and by observing the evaluation body T remaining in the internal space S, it is possible to easily estimate the current biodegradation status of the biodegradable resin molded article RT that is actually the object to be processed. Here, each of the plurality of biodegradation evaluation cases 1 is recovered at different times, for example, 1 month, 2 months, 3 months, etc. after burial, with a time difference, and the weight of the evaluation body T remaining in the internal space S of each biodegradation evaluation case 1 is measured. From the relationship between the burial time of each of the plurality of biodegradation evaluation cases 1 and the weight of the remaining evaluation body T, it is possible to estimate the mode of biodegradation progress, such as at what rate the biodegradable resin molded article RT that is actually the object to be processed is biodegrading, or what tendency of biodegradation it shows. Thereby, it is possible to determine whether the biodegradation of the biodegradable resin molded article RT that is actually the object to be processed has ended. If it has not ended, it is possible to estimate the additional burial amount at that time from the difference between the weight of the evaluation body T and the weight of the remaining evaluation body, and it is also possible to estimate the time when the biodegradation is likely to end. Therefore, for example, in a facility where biodegradation treatment is performed, before the biodegradation of the already buried biodegradable resin molded article RT is completed, by excessively burying the next biodegradable resin molded article RT to be subjected to biodegradation treatment, a state where too many biodegradable resin molded articles RT are buried in the soil G and saturated is achieved, and the rate at which the biodegradable resin molded article RT is biodegraded is reduced, which is suppressed. Also, immediately after the time when it is considered that the biodegradation of the already buried biodegradable resin molded article RT has ended, the next biodegradable resin molded article RT to be subjected to biodegradation treatment can be buried, so that a waste period during which the biodegradation treatment of the biodegradable resin molded article RT is not performed occurs between the end of biodegradation and the burial of the next biodegradable resin molded article RT, which is suppressed. In this way, the biodegradation of the biodegradable resin molded article RT can be efficiently performed.

[0052] (First Modification Example of the First Embodiment) Next, a first modification example of the biodegradation evaluation case 1 shown as the above embodiment will be described. FIG. 13 is a perspective view of the biodegradation evaluation case according to this modification example. The biodegradation evaluation case 1 in this first modification example includes a gripping portion 8 and a locking mechanism 9. The gripping portion 8 has a horizontal portion 8a and a connecting portion 8b. The horizontal portion 8a is provided so as to extend in the horizontal plane parallel to the upper surface 3. The connecting portion 8b connects the horizontal portion 8a to the upper surface 3. The connecting portion 8b is bent at both ends of the horizontal portion 8a and provided so as to extend downward. The tip of the connecting portion 8b is joined to the upper surface 3. The locking mechanism 9 is provided on the end side of the upper surface 3 opposite to the hinge 6. The locking mechanism 9 is provided so as to be freely switchable between a state where the upper surface 3 and the side surface 4 are fixed and the upper surface 3 cannot be opened when the upper surface 3 is closed, and a state where the upper surface 3 can be opened with respect to the side surface 4.

[0053] According to the configuration as described above, by an operator gripping the gripping portion 8, operations such as transportation, burial, recovery, and cleaning of the biodegradation evaluation case 1 can be easily performed. Also, when embedding the biodegradation evaluation case 1 in the soil G, if the upper end of the gripping portion 8 is projected upward from the surface of the soil G and exposed, this serves as a mark, so that the location where the biodegradation evaluation case 1 is embedded can be easily grasped. Furthermore, as shown in FIG. 10, when watering from the bottom surface 5 with the biodegradation evaluation case 1 turned upside down, the entire biodegradation evaluation case 1 is supported by the gripping portion 8, and a space is provided between the ground and the upper surface 3. Therefore, the water watered from above easily flows downward from the upper surface 3, improving the cleaning efficiency. And by providing the lock mechanism 9, when an operator grips and lifts the gripping portion 8, the upper surface 3 can be fixed to the side surface 4 so that the upper surface 3 does not open.

[0054] Note that the gripping portion 8 is not limited to the above configuration. For example, the gripping portion 8 can be configured to be telescopically extendable such that the upper end is movable relative to the upper surface 3 in the vertical direction. In this way, no matter at what depth the biodegradation evaluation case 1 is embedded in the soil G, the length of the gripping portion 8 can be appropriately adjusted so that its upper end projects upward from the surface of the soil G and is exposed for use as a mark.

[0055] (Second Modification Example of the First Embodiment) In the above-described first embodiment, the side surface 4 of the biodegradation evaluation case 1 has been described as having no opening, but the side surface 4 may also have an opening. For example, the side surface 4 may also be realized by a net formed of metal or resin. If the side surface 4 also has an opening, in addition to the openings 3h and 5h formed in the upper surface 3 and the bottom surface 5, components such as moisture can flow through the opening in the side surface 4, making the environment of the internal space S closer to the surrounding soil G in which it is embedded. In this case, it is desirable that the size of the opening in the side surface 4 be equal to or smaller than the size of the opening 5h in the bottom surface 5. This suppresses the evaluation body T, which is larger than the opening 5h in the bottom surface 5 and should remain without falling off from the opening 5h in the bottom surface 5, from falling off through the opening in the side surface 4.

[0056] (Second Embodiment) Next, the second embodiment will be described. A perspective view of the biodegradation evaluation case according to the second embodiment of the present invention is shown in FIG. 14. FIG. 15 is a longitudinal sectional view of the biodegradation evaluation case shown in FIG. 14. FIG. 16 is a perspective view when the upper surface of the biodegradation evaluation case shown in FIG. 14 is opened. In the second embodiment, two biodegradation evaluation cases 1 of the first embodiment are used by overlapping them doubly, and in other respects, it is common to the first embodiment. Therefore, in the second embodiment, the description of the same parts as those in the first embodiment will be omitted as appropriate. In parts not described as the second embodiment, the same description as that in the first embodiment is possible.

[0057] The biodegradation evaluation case 10 of the present embodiment includes a first case 11A and a second case 11B. From the viewpoints of shape and structure, each of these first case 11A and second case 11B is the same as the biodegradation evaluation case 1 of the first embodiment, so the detailed description will be omitted. The second case 11B has the same size as the biodegradation evaluation case 1 of the first embodiment. The first case 11A has a smaller size than the second case 11B. That is, the second case 11B is formed larger than the first case 11A. The first case 11A is formed to have a size that can be accommodated in the internal space S of the second case 11B. More specifically, when the first case 11A is accommodated in the internal space S of the second case 11B, sufficient spaces are formed between the upper surfaces 3 of the first case 11A and the second case 11B and between the side surfaces 4 of the first case 11A and the second case 11B.

[0058] In the first case 11A, similarly to the biodegradation evaluation case 1 of the first embodiment, the openings 5h and 3h of the bottom surface 5 and the upper surface 3 are formed such that the size BHA of the opening 5h of the bottom surface 5 is equal to or greater than the size THA of the opening 3h of the upper surface 3. Similarly, in the second case 11B, the openings 5h and 3h of the bottom surface 5 and the upper surface 3 are formed such that the size BHB of the opening 5h of the bottom surface 5 is equal to or greater than the size THB of the opening 3h of the upper surface 3. Here, the bottom surface 5 of the first case 11A and the bottom surface 5 of the second case 11B are formed such that the size BHA of the opening 5h in the bottom surface 5 of the first case 11A is larger than the size BHB of the opening 5h in the bottom surface 5 of the second case 11B. Specifically, when the size BHB of the opening 5h in the bottom surface 5 of the second case 11B is, for example, 2 mm as in the biodegradability evaluation case 1 of the first embodiment, it is preferable that the size BHA of the opening 5h in the bottom surface 5 of the first case 11A be about 5 mm. Also, the upper surface 3 of the first case 11A and the upper surface 3 of the second case 11B are formed such that the size THA of the opening 3h in the upper surface 3 of the first case 11A is larger than the size THB of the opening 3h in the upper surface 3 of the second case 11B. However, when punching metal is used for the upper surface 3 of the first case 11A, punching metal is also used for the upper surface 3 of the second case 11B.

[0059] Next, a method for evaluating the biodegradability of a biodegradable resin molded article using the biodegradability evaluation case 10 as described above will be explained. The method for evaluating the biodegradability of the biodegradable resin molded article of the present embodiment also includes, similar to the first embodiment, a step S1 of embedding the biodegradability evaluation case, a step S2 of recovering the biodegradability evaluation case after biodegradation has progressed, a step S3 of removing the soil in the internal space of the biodegradability evaluation case, a step S4 of providing a separation sheet so as to cover the inside of the upper surface, a step S5 of dropping and collecting the remaining evaluation bodies onto the separation sheet, a step S6 of removing the separation sheet together with the collected evaluation bodies, a step S7 of measuring the weight of the remaining evaluation bodies, and a step S8 of estimating the mode of biodegradation.

[0060] FIG. 17 is a plan view of a state in which a hole is dug in the soil and the biodegradability evaluation case is installed. FIG. 18 is a longitudinal sectional view of FIG. 17. First, similar to the first embodiment, the soil to be evaluated and the biodegradable resin molded article are determined. In the step S1 of embedding the biodegradation evaluation case, first, a hole Gh is dug in a part having a soil environment equivalent to the actual biodegradation treatment location, such as the actual location where the biodegradation treatment is performed on the biodegradable resin molded product itself or the vicinity of the location. Then, with the first case 11A housed in the second case 11B, the biodegradation evaluation case 10 is installed in the hole Gh. Also in this embodiment, a plurality of biodegradation evaluation cases 10A to 10C are installed. For this reason, a plurality of holes Gh are provided corresponding to each of the plurality of biodegradation evaluation cases 10A to 10C.

[0061] The plurality of biodegradation evaluation cases 10A to 10C are installed in the holes Gh at the same time as the biodegradable resin molded product RT to be actually treated is buried in the soil for biodegradation. An evaluation body based on the biodegradable resin molded product RT to be actually treated is housed in these biodegradation evaluation cases 10A to 10C and is buried in the soil G where the biodegradable resin molded product RT is actually buried and biodegraded. Then, the progress of biodegradation of the evaluation body in these plurality of biodegradation evaluation cases 10A to 10C is substantially equal to the progress of biodegradation of the biodegradable resin molded product RT to be actually treated. Therefore, by digging out and recovering the plurality of biodegradation evaluation cases 10A to 10C and checking the status of the housed evaluation body, the progress of biodegradation of the biodegradable resin molded product RT to be actually treated at the time of recovery can be estimated.

[0062] FIG. 19 is a longitudinal sectional view of a state in which an evaluation body is housed in the internal space of the biodegradation evaluation case. Next, the soil G excavated to dig the hole Gh is housed in the internal space S of the second case 11B through the opening 3h on the upper surface 3 of the second case 11B with the first case 11A housed in the internal space S of the second case 11B, so as to sieve the soil G through the opening 3h. Specifically, the excavated soil G is placed on the upper surface 3 of the second case 11B, and while gently leveling it with a hand or a scoop, the soil G is passed through the opening 3h. By doing so, the soil G sieved by the sieve can be housed in the internal space S without performing the operation of separately providing a sieve and sieving the soil G with the sieve. As described above, the size THA of the opening 3h on the upper surface 3 of the first case 11A is larger than the size THB of the opening 3h on the upper surface 3 of the second case 11B. Therefore, the soil G that has passed through the opening 3h on the upper surface 3 of the second case 11B can easily pass through the opening 3h on the upper surface 3 of the first case 11A and be accommodated in the internal space S of the first case 11A. After that, open the lids (upper surfaces 3) of the second case 11B and the first case 11A, place the evaluation body T on the soil G, and close the lids (upper surfaces 3) of the first case 11A and the second case 11B.

[0063] Figure 20 is a longitudinal sectional view of the state where the biodegradation evaluation case is buried in the soil. After accommodating the evaluation body T in the internal space S, cover the evaluation body T from above the evaluation body T, and accommodate the soil G in the internal space S so as to fill the internal space S. The soil G is accommodated in the internal spaces S of both the first case 11A and the second case 11B through the opening 3h with the upper surfaces 3 of the first case 11A and the second case 11B closed, screening the soil G by the opening 3h. Also, fill the entire hole Gh, including the space between the biodegradation evaluation case 10 and the inner wall of the hole Gh, with the soil G excavated for digging the hole Gh. In this way, in the step S1 of burying the biodegradation evaluation case, the evaluation body T based on the biodegradable resin molded product RT that is actually the object to be processed and the soil G in which the biodegradable resin molded product RT is actually buried and biodegrades are accommodated in the internal space S of the first case 11A (and the second case 11B), and the biodegradation evaluation case 10 is buried in the soil G with the first case 11A accommodated in the second case 11B.

[0064] Next, recover the biodegradation evaluation case after biodegradation progresses (step S2). Also in this embodiment, while actually burying the biodegradable resin molded product RT that is the object to be processed in the soil G for biodegradation, a plurality of biodegradation evaluation cases 10A to 10C are buried in the soil G, and each of the biodegradation evaluation cases 10A to 10C is recovered at a time point when different burial times have elapsed.

[0065] After collecting the biodegradation evaluation case, remove the soil from the internal space of the biodegradation evaluation case (step S3). As already described, in the internal space S of the first case 11A, the soil G is accommodated in such a manner that the soil G is sieved by the opening 3h of the upper surface 3 of the second case 11B having a size THB smaller than the size THA of the opening 3h of the upper surface 3 of the first case 11A. Therefore, the soil G accommodated in the internal space S of the first case 11A has a particle size smaller than the size THA of the opening 3h of the upper surface 3 of the first case 11A. Here, since the size BHA of the opening 5h of the bottom surface 5 of the first case 11A is equal to or larger than the size THA of the opening 3h of the upper surface 3, these soils G are easily discharged into the internal space S of the second case 11B through the opening 5h of the bottom surface 5 of the first case 11A. Also, in the internal space S of the second case 11B, the soil G is accommodated in such a manner that the soil G is sieved by the opening 3h of the upper surface 3 of the second case 11B. Therefore, the soil G accommodated in the internal space S of the second case 11B has a particle size smaller than the size THB of the opening 3h of the upper surface 3. Here, since the size BHB of the opening 5h of the bottom surface 5 of the second case 11B is equal to or larger than the size THB of the opening 3h of the upper surface 3, these soils G, together with the soil G discharged into the internal space S of the second case 11B through the opening 5h of the bottom surface 5 of the first case 11A, are easily discharged to the outside of the biodegradation evaluation case 10 through the opening 5h of the bottom surface 5 of the second case 11B.

[0066] Here, the size BHA of the opening 5h of the bottom surface 5 of the first case 11A is larger than the size BHB of the opening 5h of the bottom surface 5 of the second case 11B. For this reason, among the evaluation bodies T remaining in the internal space S of the first case 11A without being biodegraded while removing the soil as described above, the fraction smaller than the size BHA of the opening 5h of the bottom surface 5 of the first case 11A is discharged into the internal space S of the second case 11B through the opening 5h of the bottom surface 5 of the first case 11A, and the fraction larger than the size BHA of the opening 5h of the bottom surface 5 of the first case 11A remains in the internal space S of the first case 11A. Also, among the evaluation objects T discharged into the internal space S of the second case 11B, a fraction smaller than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B is discharged to the outside through the opening 5h on the bottom surface 5 of the second case 11B, and a fraction larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B remains in the internal space S of the second case 11B. For example, if the size BHA of the opening 5h on the bottom surface 5 of the first case 11A is 5 mm and the size BHB of the opening 5h on the bottom surface 5 of the second case 11B is 2 mm, after removing the soil and sand, evaluation objects T larger than 5 mm remain in the internal space S of the first case 11A, and evaluation objects T larger than 2 mm and smaller than 5 mm remain in the internal space S of the second case 11B. In this way, the remaining evaluation objects T are separated according to their sizes.

[0067] Next, a separation sheet is provided so as to cover the inside of the upper surface 3 of the biodegradation evaluation case 10 (step S4). FIG. 21 is a perspective view showing a state in which the soil in the internal space of the biodegradation evaluation case is removed and a separation sheet is provided. After removing the soil in the internal spaces S of the first case 11A and the second case 11B, the upper surface 3 (lid) of the second case 11B is opened, and the first case 11A is taken out from the internal space S of the second case 11B. Next, the upper surface 3 (lid) of the first case 11A is also opened. Then, in each of the first case 11A and the second case 11B, after placing the separation sheet 7 on the upper ends of the side surfaces 4 so as to cover the internal space S from above, the upper surface 3 (lid) is closed, thereby providing the separation sheet 7 so as to cover the inside of the upper surface 3. The size of the opening 7h of the separation sheet 7A provided in the first case 11A is smaller than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A. Similarly, the size of the opening 7h of the separation sheet 7B provided in the second case 11B is smaller than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B.

[0068] FIG. 22 is a perspective view showing a state in which the biodegradation evaluation case is inverted upside down and water is being sprinkled from the bottom surface. After that, water is sprinkled from the bottom surface 5 with each of the first case 11A and the second case 11B turned upside down, and the evaluation body T remaining in the internal space S is dropped onto the separation sheet 7 and collected (step S5). The soil G in the internal space S of each of the first case 11A and the second case 11B has already been discharged in step S3. Also, in the first case 11A, although the size of the evaluation body T remaining in the internal space S is larger than the opening 5h of the bottom surface 5, since the size of the opening 7h of the separation sheet 7A is smaller than the size BHA of the opening 5h of the bottom surface 5, in step S5, the evaluation body T remaining in the internal space S is suppressed from falling below the separation sheet 7A through the opening 7h of the separation sheet 7A. Similarly, in the second case 11B, in step S5, the evaluation body T remaining in the internal space S is suppressed from falling below the separation sheet 7B through the opening 7h of the separation sheet 7B. In this way, only the evaluation body T larger than the opening 5h of the bottom surface 5, which remains in the internal space S of the first case 11A, is basically left on the separation sheet 7A. Similarly, only the evaluation body T larger than the opening 5h of the bottom surface 5, which remains in the internal space S of the second case 11B, is basically left on the separation sheet 7B.

[0069] FIG. 23 is a perspective view of the separation sheet on which the evaluation body is collected. Then, from the first case 11A, the separation sheet 7A is removed together with the evaluation body TA collected on the separation sheet 7A. Also, from the second case 11B, the separation sheet 7B is removed together with the evaluation body TB collected on the separation sheet 7B. (Step S6). For example, if the size BHA of the opening 5h of the bottom surface 5 of the first case 11A is 5 mm and the size BHB of the opening 5h of the bottom surface 5 of the second case 11B is 2 mm, after step S6, on the separation sheet 7A, those larger than 5 mm remain as the evaluation body TA, and on the separation sheet 7B, those larger than 2 mm and smaller than 5 mm remain as the evaluation body TB.

[0070] Furthermore, measure the weight of the evaluation object T remaining in the internal space S of the biodegradation evaluation case 10 (step S7). Also, perform visual observation, photography, microscopic observation, various microscopic observations, etc. of the evaluation object T as appropriate. At this time, measure the weights of the separation sheets 7A and 7B in advance, measure the weights of the collected evaluation objects TA and TB together with the separation sheets 7A and 7B, and subtract the weights of the separation sheets 7A and 7B to measure the weights of the remaining evaluation objects TA and TB. Also, in step S2, it was explained that each of the plurality of biodegradation evaluation cases 10A to 10C is recovered at a time point when different burial times have elapsed. Therefore, step S7 is performed for each of the plurality of biodegradation evaluation cases 10A to 10C at the time when each of the biodegradation evaluation cases 10A to 10C is recovered. That is, measure the weights of the remaining evaluation objects TA and TB for each of the plurality of biodegradation evaluation cases 10A to 10C.

[0071] Then, based on the measured weight of the evaluation object T, estimate the mode of progress of biodegradation (step S8). In the present embodiment, before burying the biodegradation evaluation case 10, measure in advance the weight of the evaluation object T before biodegradation accommodated in the internal space S, and divide the weight of the evaluation object T after biodegradation measured in step S7 by the weight of the evaluation object T before biodegradation to calculate the residual rate of the evaluation object T. Similar to that described in the first embodiment with reference to FIG. 12, by burying a plurality of biodegradation evaluation cases 10 and from the relationship between the burial time and the weight of the remaining evaluation object T for each of the plurality of biodegradation evaluation cases 10, it is possible to accurately estimate the mode of progress of biodegradation of the biodegradable resin molded product RT.

[0072] Here, in the present embodiment, it is possible to measure the weight WA of the evaluation body TA that is larger than the size BHA (for example, 5 mm) of the opening 5h on the bottom surface 5 of the first case 11A, and the weight WB of the evaluation body TB that is larger than the size BHB (for example, 2 mm) of the opening 5h on the bottom surface 5 of the second case 11B and smaller than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A. Based on this, by dividing the weight WA by the weight of the evaluation body T before biodegradation, the residual rate RA of the evaluation body TA larger than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A can be calculated. Also, by dividing the sum of the weight WA and the weight WB by the weight of the evaluation body T before biodegradation, the residual rate RB of the evaluation body TB larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B can be calculated.

[0073] Here, for example, when one biodegradation evaluation case 10 is collected and the residual rates RA and RB are calculated, for example, the case where the residual rate RB is 30% and the residual rate RA is 25%, and the case where the residual rate RB is 30% and the residual rate RA is 5% will be exemplified and examined. In both of these cases, in either case, the residual rate RB is 30%, and it is possible to judge that the progress of biodegradation is about the same in the sense that 70% of the evaluation body T has already been biodegraded. However, in the former case, the residual rate RA is 25%, and a large fraction of the evaluation body T remains without being biodegraded. Therefore, it can be judged that in the biodegradable resin molded product RT that is currently buried in the soil G and being biodegraded, the biodegradation treatment has not yet progressed sufficiently, and it is too early to input the next biodegradable resin molded product RT to be treated. On the other hand, in the latter case, the residual rate RA is 5%, and a large fraction of the evaluation body T is in a state where almost none remains. Therefore, it can be judged that in the biodegradable resin molded product RT that is currently buried in the soil G, the biodegradation treatment has progressed sufficiently, and it is possible to input the next biodegradable resin molded product RT to be treated.

[0074] As described above, in this embodiment, when one biodegradation evaluation case 10 is collected, only the collected biodegradation evaluation case 10 is targeted, and the remaining evaluation body T is separated by a plurality of different thresholds (BHA, BHB) regarding the size of the remaining evaluation body T, and a plurality of remaining ratios RA, RB can be calculated as described above. As a result, both the first embodiment and the second embodiment can obtain a remaining ratio corresponding to the above remaining ratio RB. However, in the second embodiment, the above remaining ratio RA can be obtained as a breakdown thereof, so that the biodegradation state can be grasped with higher accuracy.

[0075] The biodegradation evaluation case 10 as described above is a biodegradation evaluation case 10 in which an evaluation body T based on a biodegradable resin molded article RT formed including a biodegradable resin is accommodated, buried in soil G where microorganisms inhabit, the evaluation body T is biodegraded, and the state of biodegradation is evaluated. It includes a first case 11A and a second case 11B. Each of the first case 11A and the second case 11B has an upper surface 3, a bottom surface 5, and a side surface 4, and is box-shaped so that an internal space S is formed by the upper surface 3, the bottom surface 5, and the side surface 4. The second case 11B is formed larger than the first case 11A. The evaluation body T is accommodated in the internal space S of the first case 11A together with the soil G, and the first case 11A is accommodated in the second case 11B together with the soil G. A plurality of openings 3h, 5h are formed in the upper surface 3 and the bottom surface 5 of each of the first case 11A and the second case 11B. The size BHA of the opening 5h on the bottom surface 5 of the first case 11A is larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B. In each of the first case 11A and the second case 11B, the sizes BHA, BHB of the opening 5h on the bottom surface 5 are equal to or larger than the sizes THA, THB of the opening 3h on the upper surface 3. The size THA of the opening 3h on the upper surface 3 of the first case 11A is larger than the size THB of the opening 3h on the upper surface 3 of the second case 11B. According to the above configuration, the biodegradation evaluation case 10 includes a first case 11A and a second case 11B. Each of the first case 11A and the second case 11B has an upper surface 3, a bottom surface 5, and side surfaces 4, and is box-shaped such that an internal space S is formed by the upper surface 3, the bottom surface 5, and the side surfaces 4. A plurality of openings 3h, 5h (mesh openings when the upper surface 3 and the bottom surface 5 are meshes) are formed in the upper surface 3 and the bottom surface 5, respectively. In such a biodegradation evaluation case 10, when an evaluation body T based on a biodegradable resin molded article RT is accommodated in the internal space S of the first case 11A together with soil G, and the first case 11A is accommodated in the second case 11B and the biodegradation evaluation case 10 is buried in the soil G, components such as moisture flow through the openings 3h, 5h formed in the upper surface 3 and the bottom surface 5 of each of the first case 11A and the second case 11B, so that the environment of the internal space S can be made the same as the surrounding soil G in which it is buried. Further, since the biodegradation evaluation case 10 is formed in a box shape so as to have a certain volume, regardless of the shape of the biodegradable resin molded article RT that is actually the object to be treated, the biodegradable resin molded article RT itself or, for example, a part thereof cut can be accommodated as the evaluation body T. Therefore, for example, together with the evaluation body T, the soil G in which the biodegradable resin molded article RT that is actually the basis of the evaluation body T is buried and biodegraded is accommodated in the internal space S of the first case 11A, and the first case 11A is accommodated in the internal space S of the second case 11B together with the soil G, and by burying it in the soil G, a field test of biodegradation can be carried out on the biodegradable resin molded article RT and the soil G that are actually the objects of biodegradation treatment. Also, after digging out and recovering the biodegradation evaluation case 10, the biodegradation evaluation case 10 is shaken, washed, etc., and for example, the soil G in the internal space S is removed through the openings 5h on the bottom surfaces 5 of each of the first case 11A and the second case 11B, and only the evaluation body T that remained without being biodegraded is left inside the biodegradation evaluation case 10. In this case, even if solid matter such as stones is mixed into the internal space S, it is smaller in size than the openings 3h formed on each of the upper surfaces 3 of the second case 11B. Here, according to the above configuration, the size BHA of the opening 5h on the bottom surface 5 of the first case 11A (the mesh opening when the bottom surface 5 is a net) is equal to or greater than the size THA of the opening 3h on the upper surface 3 of the first case 11A (the mesh opening when the upper surface 3 is a net), and the size THA of the opening 3h on the upper surface 3 of the first case 11A is larger than the size THB of the opening 3h on the upper surface 3 of the second case 11B (the mesh opening when the upper surface 3 is a net). Therefore, the size BHA of the opening 5h on the bottom surface 5 of the first case 11A is larger than the size THB of the opening 3h on the upper surface 3 of the second case 11B. Also, the size BHB of the opening 5h on the bottom surface 5 of the second case 11B (the mesh opening when the bottom surface 5 is a net) is also equal to or greater than the size THB of the opening 3h on the upper surface 3 of the second case 11B. For this reason, the solid matter that has passed through the opening 3h on the upper surface 3 of the second case 11B can easily pass through the openings 5h on the bottom surfaces 5 of the first case 11A and the second case 11B. Therefore, after digging out and recovering the biodegradation evaluation case 10, by shaking, washing, etc., the biodegradation evaluation case 10 and removing the soil G in the internal space S through the openings 5h on the bottom surfaces 5 of each of the first case 11A and the second case 11B, the solid matter that has invaded the internal space S is easily discharged to the outside through the openings 5h on the bottom surface 5. In this way, since the solid matter in the soil G is suppressed from remaining in the internal space S together with the remaining evaluation body T, it is possible to measure a more accurate weight of the remaining evaluation body T with the influence of the weight of the soil G reduced. Therefore, the accuracy of the evaluation of the biodegradation situation is further improved.In particular, since the size THA of the opening 3h on the upper surface 3 of the first case 11A is larger than the size THB of the opening 3h on the upper surface 3 of the second case 11B, when the first case 11A is accommodated in the internal space S of the second case 11B and the soil G is sieved through the opening 3h formed on the upper surface 3 of the second case 11B, the soil G that has passed through the opening 3h on the upper surface 3 of the second case 11B fills the internal space S of the second case 11B while easily passing through the opening 3h on the upper surface 3 of the first case 11A and entering the internal space S of the first case 11A. In this way, the soil G can be easily and simply accommodated in the internal spaces S of the first case 11A and the second case 11B respectively. Also, the size BHA of the opening 5h on the bottom surface 5 of the first case 11A is larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B. For this reason, after the biodegradation evaluation case 10 is dug out and recovered and the soil G in the internal space S is removed, the remaining evaluation body T is separated into an evaluation body TA larger than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A and an evaluation body TB larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B and smaller than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A. Based on this, the weight of the evaluation body TA larger than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A and the weight of the evaluation body larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B can be measured respectively. In such a case, even if the weight of the evaluation body larger than the size BHB of the opening 5h on the bottom surface 5 of the second case 11B is constant, if the weight of the evaluation body TA larger than the size BHA of the opening 5h on the bottom surface 5 of the first case 11A is large, it can be determined that the biodegradation has not progressed as a whole. Therefore, as described above, by measuring the weight according to the size of the evaluation body T, the biodegradation situation can be evaluated more precisely. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are needed. Therefore, the evaluation can be carried out simply. In this way, it is possible to provide a biodegradation evaluation case 10 that is applicable to the field test of biodegradation of the biodegradable resin molded article RT formed by including a biodegradable resin, and can evaluate the biodegradation situation simply and with high accuracy.

[0076] Further, a method for evaluating the biodegradation state of the biodegradable resin molded article RT using the biodegradation evaluation case 10 as described above includes an evaluation body T based on the actual biodegradable resin molded article RT to be processed, and soil G in which the biodegradable resin molded article RT is actually buried and biodegraded. The evaluation body T and the soil G are accommodated in the internal space S of the first case 11A, and the first case 11A is accommodated in the internal space S of the second case 11B together with the soil G. The biodegradation evaluation case 10 is buried in the soil G. After the biodegradation progresses, the biodegradation evaluation case 10 is dug out and recovered, the biodegradation evaluation case 10 is shaken and washed, and the soil G in the internal space S of each of the first case 11A and the second case 11B is removed through the opening 5h of the bottom surface 5 of each of the first case 11A and the second case 11B, and the weight of the evaluation body T remaining in the internal space S of each of the first case 11A and the second case 11B is measured. The soil G is accommodated in the internal space S of each of the first case 11A and the second case 11B by sieving the soil G through the opening 3h of the upper surface 3 of the second case 11B in a state where the first case 11A is accommodated in the internal space S of the second case 11B. According to the above configuration, the actual biodegradable resin molded article RT to be processed itself, or a part thereof such as a cut part, is used as the evaluation body T, and together with this, the soil G in which the biodegradable resin molded article RT is actually buried and biodegraded is accommodated in the internal space S of the first case 11A, and the first case 11A is accommodated in the internal space S of the second case 11B. The biodegradation evaluation case 10 is buried in the soil G. After the biodegradation progresses, the biodegradation evaluation case 10 is dug out and recovered, and the weight of the evaluation body T remaining in the internal space S of each of the first case 11A and the second case 11B is measured, so that a field test of biodegradation targeting the actual biodegradable resin molded article RT and the soil G to be subjected to biodegradation treatment can be carried out. Also, after digging out and recovering the biodegradation evaluation case 10, the biodegradation evaluation case 10 is shaken and washed to remove the soil G in the internal space S through the openings 5h in the bottom surfaces 5 of the first case 11A and the second case 11B, and only the evaluation body T that has remained without being biodegraded is left inside the biodegradation evaluation case 10. In this case, the first case 11A and the second case 11B of the biodegradation evaluation case 10 form a box shape, so they have a certain rigidity, the overall shape is not easily changed, and the shapes of the openings 3h and 5h in the upper surface 3 and the bottom surface 5 are also not easily changed. Therefore, the dropping of the evaluation body T during the above series of operations is suppressed. As a result, since the weight of the remaining evaluation body T can be accurately measured, the biodegradation situation can be accurately evaluated. Further, when accommodating the soil G in the internal space S of the first case 11A before embedding the biodegradation evaluation case 10 in the soil G, with the first case 11A accommodated in the internal space S of the second case 11B, the soil G is sieved through the opening 3h formed in the upper surface 3 of the second case 11B. Therefore, after digging out and recovering the biodegradation evaluation case 10, the biodegradation evaluation case 10 is shaken, washed, etc., and the soil G in the internal space S is removed through the openings 5h in the bottom surfaces 5 of the first case 11A and the second case 11B, so that the solid matter that has entered the internal space S is easily discharged to the outside through the openings 5h in the bottom surface 5. In this way, it is possible to suppress the solid matter in the soil G from remaining in the internal space S together with the remaining evaluation body T. Therefore, it is possible to measure a more accurate weight of the remaining evaluation body T with the influence of the weight of the soil G reduced. Therefore, the accuracy of the evaluation of the biodegradation situation is further improved. In the evaluation of the biodegradation situation as described above, basically no special equipment or facilities are required, and no complicated and specialized operations are necessary. In this way, it is possible to provide a method for evaluating the biodegradation of a biodegradable resin molded article RT that contains a biodegradable resin and is applicable to a field test of the biodegradation of the biodegradable resin molded article RT, and can evaluate the biodegradation situation simply and with high accuracy.

[0077] Also, after removing the soil G in the internal space S of each of the first case 11A and the second case 11B, the first case 11A is taken out from the internal space S of the second case 11B, and in each of the first case 11A and the second case 11B, a separation sheet 7 is provided with a plurality of openings 7h smaller than the sizes BHA and BHB of the openings 5h of the bottom surface 5 so as to cover the inside of the upper surface 3. With each of the first case 11A and the second case 11B turned upside down, water is sprinkled from the bottom surface 5, and the evaluation body T remaining in the internal space S is dropped and collected onto the separation sheet 7. From each of the first case 11A and the second case 11B, the separation sheet 7 is removed together with the collected evaluation body T. When measuring the weight of the remaining evaluation body T, for each of the separation sheets 7A and 7B removed from the first case 11A and the second case 11B, the weight of the evaluation bodies TA and TB collected together with the separation sheets 7A and 7B is measured, and the weight of the remaining evaluation bodies TA and TB is measured by subtracting the weight of the separation sheets 7A and 7B. According to the above configuration, after excavating and recovering the biodegradation evaluation case 10 and removing the soil G in the internal spaces S of each of the first case 11A and the second case 11B, the first case 11A is taken out from the internal space S of the second case 11B, and in each of the first case 11A and the second case 11B, a separation sheet 7 having a plurality of openings 7h formed so as to cover the inner side of the upper surface 3 is provided. By spraying water from the bottom surface 5 with each of the first case 11A and the second case 11B turned upside down, the evaluation bodies T remaining in the internal spaces S of each of the first case 11A and the second case 11B can be individually dropped onto the separation sheet 7 and collected. At this time, in each of the first case 11A and the second case 11B, an evaluation body T larger than the sizes BHA and BHB of the openings 5h of the bottom surface 5 should remain. However, since the openings 7h of the separation sheet 7 are smaller than the sizes BHA and BHB of the openings 5h of the bottom surface 5 in each of the first case 11A and the second case 11B, even if the above operations are performed, the evaluation bodies T remaining in each of the first case 11A and the second case 11B are suppressed from falling off through the openings 7h of the separation sheet 7. In this way, the evaluation bodies T remaining in each of the first case 11A and the second case 11B can be efficiently taken out from each of the first case 11A and the second case 11B. Thereafter, for each of the separation sheets 7A and 7B removed from the first case 11A and the second case 11B, the weights of the evaluation bodies TA and TB collected together with the separation sheets 7A and 7B are measured, and by subtracting the weights of the separation sheets 7A and 7B, the weights of the remaining evaluation bodies TA and TB can be accurately measured for each of the first case 11A and the second case 11B. Based on the weight of the evaluation body T measured in this way, the biodegradation situation can be evaluated simply and with high accuracy. In addition, the evaluation body T collected on the separation sheet 7 can be directly used for visual observation, microscopic observation, microscope observation, etc., and the biodegradation situation can be qualitatively grasped. Thereby, for example, when biodegradation is slow, it can be used to clarify the cause.

[0078] When embedding the biodegradation evaluation case 10, while actually embedding the biodegradable resin molded product RT to be treated into the soil G for biodegradation, the evaluation body T and the soil G are accommodated in the internal space S of the first case 11A, and the first case 11A is accommodated in the internal space S of the second case 11B together with the soil G. In this state, each of the plurality of biodegradation evaluation cases 10 is embedded in the soil G. When digging out and recovering the biodegradation evaluation case 10, each of the plurality of biodegradation evaluation cases 10 is recovered at a time point when different embedding times have elapsed, and when measuring the weight of the remaining evaluation body T, the weight of the remaining evaluation body T is measured for each of the plurality of biodegradation evaluation cases 10. Then, from the relationship between the embedding time and the weight of the remaining evaluation body T for each of the plurality of biodegradation evaluation cases 10, the mode of progress of biodegradation is estimated. According to the above configuration, a plurality of biodegradation evaluation cases 10 are prepared, and in each of them, the biodegradable resin molded product RT itself to be actually treated, or for example, a part thereof cut, etc. is used as the evaluation body T, and is accommodated together with the soil G, and at the same time as actually embedding the biodegradable resin molded product RT to be treated into the soil G for biodegradation, it is embedded. By doing so, the biodegradation situation of the evaluation body T accommodated in each of the plurality of biodegradation evaluation cases 10 can be made the same as the biodegradation situation of the biodegradable resin molded product RT to be actually treated. Therefore, after the biodegradation progresses, by digging out and recovering the biodegradation evaluation case 10 and observing the evaluation body T remaining in the internal space S, it is possible to easily estimate the current biodegradation situation of the biodegradable resin molded product RT to be actually treated. Here, each of the plurality of biodegradation evaluation cases 10 is collected at different times after elapse of different burial times, such as 1 month, 2 months, 3 months, etc. after burial, and the weight of the evaluation body T remaining in the internal space S of each biodegradation evaluation case 10 is measured. From the relationship between the burial time and the weight of the remaining evaluation body T for each of the plurality of biodegradation evaluation cases 10, the biodegradation progress mode of the biodegradable resin molded article RT to be actually treated, such as at what speed the biodegradable resin molded article RT is being biodegraded or what tendency of biodegradation it shows, etc., is estimated. Thereby, it can be determined whether the biodegradation of the biodegradable resin molded article RT to be actually treated has ended, and if it has not ended, it is possible to estimate when the biodegradation is likely to end. In addition, since the additional embeddable amount at that time can be estimated from the difference between the weight of the buried evaluation body and the weight of the remaining evaluation body, a biodegradable resin molded article of an embeddable amount can be buried. Therefore, for example, in a facility where biodegradation treatment is performed, before the biodegradation of the already buried biodegradable resin molded article RT is completed, by excessively burying the next biodegradable resin molded article RT to be the object of biodegradation treatment, a state where too many biodegradable resin molded articles RT are buried in the soil G and saturated is reached, and it is possible to suppress the reduction in the rate at which the biodegradable resin molded article RT is biodegraded. Also, since the next biodegradable resin molded article RT to be the object of biodegradation treatment can be buried immediately after the time when the biodegradation of the already buried biodegradable resin molded article RT is considered to have ended, it is possible to suppress the occurrence of a wasteful period during which the biodegradation treatment of the biodegradable resin molded article R is not performed between the end of biodegradation and the burial of the next biodegradable resin molded article RT. In this way, the biodegradation of the biodegradable resin molded article RT can be efficiently performed.

[0079] (Modification of the Second Embodiment) Also in the second embodiment, it can have the same configuration as the first modification example and the second modification example of the first embodiment. For example, either one or both of the first case 11A and the second case 11B may have a gripping portion 8 or a locking mechanism 9 as described in the first modification of the first embodiment. Also, either one or both of the first case 11A and the second case 11B may have a configuration in which the side surface 4 has an opening, as described in the second modification of the first embodiment.

[0080] (Evaluation example) Next, since the biodegradation evaluation of the biodegradation evaluation case 10 of the second embodiment described above was performed, the details will be described. As an example, in the biodegradation evaluation case 10 of the second embodiment, a structure in which an opening is also provided in the side surface 4 was prepared as follows. First, as the first case 11A, a basket made of stainless steel (SUS304) with outer dimensions of width 100 mm × depth 100 mm × height 100 mm and with the upper surface 3 being openable and closable by a hinge was prepared. Each surface of this basket had a wire diameter of 0.8 mm and a wire pitch of 5.5 mm for the wire mesh. Therefore, in the first case 11A, the sizes of all the openings 3h and 5h of the upper surface 3, the bottom surface 5, and the side surface 4, that is, the mesh size, were about 5 mm. Also, as the second case 11B, a basket composed of the side surface 4 and the bottom surface 5 made of stainless steel (SUS304) with outer dimensions of width 150 mm × depth 150 mm × height 150 mm was prepared. This basket had a wire diameter of 0.8 mm and a wire pitch of 5 mm for the wire mesh. For this reason, a plain woven wire mesh made of stainless steel (SUS304) with a wire diameter of 0.47 mm and a mesh of 2.07 mm × 2.07 mm (10 meshes) was internally pasted. Further, the upper surface 3 (lid) was made of the same plain woven wire mesh and was rotatably fixed to the above basket with a wire. Therefore, in the second case 11B, the sizes of all the openings 3h and 5h of the upper surface 3, the bottom surface 5, and the side surface 4, that is, the mesh size, were about 2 mm.

[0081] As the separation sheet 7, a nylon mesh sheet with a wire diameter of 0.25 mm and a mesh opening of 0.7 mm was used. As the separation sheet 7A for the first case 11A, a piece of the above nylon mesh sheet cut out to 150 mm × 150 mm was prepared. The weight was 2.9561 g. As the separation sheet 7B for the second case 11B, a piece of the above nylon mesh sheet cut out to 200 mm × 200 mm was prepared. The weight was 5.1440 g.

[0082] As the evaluation body T, a test piece with a size of 50 mm × 50 mm was cut out from a 60-μm-thick film made of polybutylene succinate adipate compound (Mitsubishi Chemical Corporation) as the raw material. The weight was 0.1654 g. After accommodating the evaluation body T as described above in the first case 11A, the first case 11A was accommodated in the second case 11B. The soil to be evaluated was excavated to a depth of about 200 mm, and the biodegradation evaluation case 10 was placed. Soil G was placed on the upper surface 3 of the second case 11B, and while gently leveling it by hand, soil G was spread to about 20 mm at the bottom of the first case 11A. After placing the evaluation body T, the upper surface 3 was closed, soil G was placed on the upper surface 3, and while gently leveling it by hand, the internal space S of the second case 11B including the internal space S of the first case 11A was filled with soil G. Then, soil G was piled up around the second case 11B, and the biodegradation evaluation case 10 was buried. As a result, the evaluation body T was located at a depth of about 130 mm from the ground.

[0083] After burying the biodegradation evaluation case 10, when 70 days had passed, the biodegradation evaluation case 10 was dug out, and while the first case 11A was still accommodated in the second case 11B, the biodegradation evaluation case 10 was shaken to drop as much soil G as possible. Then, while shaking the biodegradation evaluation case 10 in a bucket filled with water, soil G was removed. When this was repeated three times, although the roots of the plants were partially entangled in the mesh-like part of the biodegradation evaluation case 10, most of the soil G could be removed. Then, the first case 11A was taken out from the second case 11B, separation sheets 7A and 7B were provided for each of them, and they were sprinkled with water in a shower-like water pattern in a state of being turned upside down, and the biodegradable substances were separated and recovered from each of the first case 11A and the second case 11B.

[0084] FIG. 24 is a photograph showing the evaluation bodies remaining in each of the second case and the first case in this embodiment. FIG. 25 is an enlarged photograph showing the evaluation body remaining in the second case shown on the left side of FIG. 24. For both the separation sheets 7A and 7B, no solid matter other than the remaining evaluation body T was found on the separation sheets 7A and 7B, and it was confirmed that the evaluation body T and the soil G could be separated with high accuracy. Since the inside of the first case 11A and the second case 11B was filled with the soil G that passed through the opening 3h on the upper surface 3 of the second case 11B, by shaking the biodegradation evaluation case 10 and swaying it in water, it was confirmed that the soil G could be easily removed from the bottom surface 5 and the side surface 4 having an opening of the same size as the opening 3h on the upper surface 3.

[0085] Next, the evaluation body TA larger than 5 mm in mesh size collected on the separation sheet 7A and the evaluation body TB larger than 2 mm and smaller than 5 mm in mesh size collected on the separation sheet 7B were each dried at 60° C. for 1 hour together with the separation sheets 7A and 7B, and then the weight was measured. The weight of the evaluation body TA larger than 5 mm in mesh size was 0.0475 g, and the weight of the evaluation body TB larger than 2 mm and smaller than 5 mm in mesh size was 0.0006 g. As a result, the residual rate of the fraction larger than 5 mm was 0.0475 / 0.1654×100 = 28.7% and that of the fraction larger than 2 mm was (0.0475 + 0.0006) / 0.1654×100 = 29.1% It was confirmed that the residual rate of the evaluation body T could be obtained based on two types of criteria (mesh size). Also, in the above process, it was confirmed that the operation of pinching the evaluation body T with tweezers was unnecessary, and the biodegradation situation and the degree of biodegradation could be easily evaluated.

[0086] Next, a comparative example will be described in comparison with the above-described embodiment. As a comparative example, as a resin net, a polyethylene drain net for triangular corners (280 mm × 250 mm) was cut to produce a protective resin net in a spread-out shape (closed size: 70 mm × 75 mm). The shape of the mesh was a rhombus and the size was about 1 mm × 4.5 mm. An evaluation body T identical to that of the above embodiment except that the weight was 0.1677 g was sandwiched therein and buried at a position about 130 mm deep, adjacent to the 0.3 m of the above embodiment.

[0087] After 70 days had passed since the resin net was buried, it was dug out. Since the position of the buried resin net was unknown and it was necessary to prevent the resin net from getting caught on the scoop, careful scoop operation was required, which took a considerable amount of time. After recovery, the resin net was shaken to remove as much adhering soil G as possible, the resin net was picked up with two tweezers, and the soil G was removed while gently rocking it in a 500 mL beaker containing 400 mL of water. The roots of the plants entangled in the resin net were removed with tweezers. The resin net showed an increase in mesh opening and damage during the process of excavation from the soil G and washing with water. When it was rocked in water, small pieces of the remaining evaluation body T fell off from the mesh and were confirmed to sink in the water. Also, the soil G adhering to the resin net could not be completely removed only by rocking it in water.

[0088] FIG. 26 is a photograph showing the evaluation body remaining in the comparative example. The shape of the evaluation body T changed due to rocking in water, and it partially aggregated compared to the dug-up state, resulting in a different shape. The mesh of the resin net was a rhombus of about 1 mm × 4.5 mm before being buried, but at the stage when the washing with water was completed, the mesh randomly expanded and damage was also observed. From this, it became unclear whether the recovered evaluation body T satisfied any size criteria. Also, small pieces of the evaluation body T had fallen off from the mesh during burial in the soil G and during washing with water.

[0089] Since the resin net was in a state of being buried together with the evaluation body T for 70 days, its weight changed before and after burial. Therefore, by measuring the weight of the resin net in advance, measuring the weight of the evaluation body T for each recovered resin net, and then subtracting the weight of the resin net, the weight of the remaining evaluation body T cannot be calculated. Therefore, all the evaluation bodies T including the small pieces were taken out from above the resin net using tweezers and weighed. The total weight of the biodegradable substances was 0.0374 g, and the biodegradable substance residual rate was 22.3%, which was lower than that of the example. It is unclear whether the lower value than that of the example is due to the change in the mesh size and shape and the dropout of the evaluation body T, or due to the insufficient extraction by tweezers when measuring the weight of the evaluation body T.

[0090] Summarize the above evaluation from the perspective of the separation and recovery of the remaining evaluation body T. In the example, since the evaluation body T is dug out together with the biodegradation evaluation case 10, compared with the comparative example, there is no need to pay special attention when digging, and it does not require much effort. The removal of the soil in the biodegradation evaluation case 10 is also easy. In addition, the recovery of the evaluation body T to the separation sheet 7 is easy because the biodegradation evaluation case 10 can be inverted and watered. On the other hand, in the comparative example, it is necessary to swing in water while pinching the resin net with tweezers. In this operation, the shapes of the resin net and the evaluation body T are likely to change. In addition, the evaluation body T easily drops off from the resin net. In this evaluation, since the evaluation body T was in a film shape, a series of operations related to the resin net could be carried out. However, in the case where the evaluation body T has a three-dimensional shape, for example, it is necessary to reconsider how to perform various operations using the resin net.

[0091] Next, summarize the above evaluation from the perspectives of observation and photography. In the comparative example, when it was swayed in water, the shape of the resin net changed, and accordingly, the shape of the evaluation body T also changed. Therefore, it was difficult to observe the state of the evaluation body T in the state where the resin net was dug out and recovered as it was. On the other hand, in the example, the evaluation body T is housed in the first case 11A having a certain rigidity, and since the operation during washing is only a vertical inversion, the deformation of the evaluation body T is small, and it is possible to observe the state of the evaluation body T close to the dug-out state.

[0092] Finally, the above evaluation is summarized from the viewpoint of evaluating the biodegradation situation. In the example, the remaining evaluation body T is recovered on the separation sheet 7. Water adheres to this separation sheet 7 by watering, but since the soil G is removed during watering, the possibility of adhesion of the soil G or the like is extremely low. Therefore, after watering, the separation sheet 7 (together with the evaluation body T) is dried, and the weight of the evaluation body T can be accurately calculated by measuring the weight of the separation sheet 7 together with the evaluation body T. Also, in this operation, unlike the comparative example, it is not necessary to pick up the evaluation body T with tweezers, so there is no possibility of the evaluation body T escaping due to the tweezers. Therefore, compared with the comparative example, the example is less laborious and has higher evaluation accuracy. Also, in the example, the size BHA of the opening 5h on the bottom surface 5 of the first case 11A and the size BHB of the opening 5h on the bottom surface 5 of the second case 11B can be set to different sizes. For this reason, compared with the comparative example in which there is only one type of mesh size, information regarding weight and the like can be obtained for each size of the fraction of the remaining evaluation body T. As a result of the above synergistically, it was found that the example can evaluate the biodegradation situation simply and with high accuracy compared with the comparative example.

[0093] Note that the biodegradation evaluation case of the present invention and the method for evaluating the biodegradability of a biodegradable resin molded product using the biodegradation evaluation case are not limited to the above-described embodiments and each modification described with reference to the drawings, and various other modifications can be considered within the technical scope thereof. For example, in the above-described second embodiment, the configuration in which the first case 11A and the second case 11B are double has been described. However, the present invention is not limited to this. A third case larger than the second case 11B may be prepared, and the first case 11A may be housed in the second case 11B, and the second case 11B may be housed in the third case. By doing so, the biodegradation situation can be evaluated with higher accuracy. In addition to this, it is possible to select the configurations exemplified in the above-described embodiments and modified examples, or to appropriately change them to other configurations.

Explanation of reference numerals

[0094] 1, 10 Size of the opening at the bottom surface of the biodegradation evaluation case BH 3 Size of the opening at the bottom surface of the upper surface BHA of the first case 3h Size of the opening BHB at the bottom surface of the upper surface of the second case 4 Size of the opening at the side surface TH of the upper surface 5 Size of the opening at the upper surface of the bottom surface THA of the first case 5h Size of the opening THB at the upper surface of the bottom surface of the second case 7, 7A, 7B Internal space of the separation sheet S 7h Opening RT of the separation sheet Biodegradable resin molded product actually to be processed 11A First case T, TA, TB Evaluation body 11B Second case G Soil

Claims

1. A biodegradation evaluation case in which an evaluation body based on a biodegradable resin molded article formed containing a biodegradable resin is buried in soil where microorganisms inhabit, the evaluation body is biodegraded, and the state of biodegradation is evaluated, comprising: It has an upper surface, a bottom surface, and side surfaces, and forms a box shape such that an internal space is formed by the upper surface, the bottom surface, and the side surfaces; The evaluation body is accommodated in the internal space together with the soil; A plurality of openings are formed in the upper surface and the bottom surface respectively, and the size of the openings in the bottom surface is not less than the size of the openings in the upper surface. A biodegradation evaluation case characterized by this.

2. A method for evaluating the biodegradation state of a biodegradable resin molded article, using the biodegradation evaluation case according to Claim 1, comprising: With the evaluation body based on the biodegradable resin molded article that is actually the object to be treated and the soil in which the biodegradable resin molded article is actually buried and biodegraded accommodated in the internal space, the biodegradation evaluation case is buried in the soil; After biodegradation has progressed, the biodegradation evaluation case is dug out and recovered; The biodegradation evaluation case is shaken and washed, and the soil in the internal space is removed through the openings in the bottom surface; Measuring the weight of the evaluation body remaining in the internal space; Including; The soil is characterized in that it is accommodated in the internal space while sieving the soil through the openings in the upper surface. A method for evaluating the biodegradation of a biodegradable resin molded article.

3. After removing the soil in the internal space, A separation sheet having a plurality of openings smaller than the size of the openings in the bottom surface is provided so as to cover the inside of the upper surface; Water is sprayed from the bottom surface with the biodegradation evaluation case turned upside down, and the evaluation body remaining in the internal space is dropped and collected onto the separation sheet; The separation sheet is removed together with the collected evaluation body; When measuring the weight of the remaining evaluation body, the weight of the evaluation body collected together with the separation sheet is measured, and the weight of the separation sheet is subtracted to measure the weight of the remaining evaluation body. A method for evaluating the biodegradation of a biodegradable resin molded article according to Claim 2.

4. A biodegradation evaluation case for evaluating the state of biodegradation by burying an evaluation body based on a biodegradable resin molded article formed containing a biodegradable resin in soil where microorganisms inhabit, in a state where the evaluation body is accommodated. Comprising a first case and a second case, each of the first case and the second case has an upper surface, a bottom surface, and side surfaces, and forms a box shape such that an internal space is formed by the upper surface, the bottom surface, and the side surfaces. The second case is formed larger than the first case, the evaluation body is accommodated in the internal space of the first case together with the soil, and the first case is accommodated in the second case together with the soil. A plurality of openings are formed in each of the upper surface and the bottom surface of each of the first case and the second case. The size of the opening in the bottom surface of the first case is larger than the size of the opening in the bottom surface of the second case. In each of the first case and the second case, the size of the opening in the bottom surface is equal to or larger than the size of the opening in the upper surface. A biodegradation evaluation case, characterized in that the size of the opening in the upper surface of the first case is larger than the size of the opening in the upper surface of the second case.

5. A method for evaluating the biodegradation state of a biodegradable resin molded article, using the biodegradation evaluation case according to claim 4, the method comprising: Accommodating the evaluation body based on the biodegradable resin molded article to be actually processed and the soil in which the biodegradable resin molded article is actually buried and biodegraded in the internal space of the first case, and burying the biodegradation evaluation case in the soil in a state where the first case is accommodated in the internal space of the second case together with the soil. After biodegradation progresses, digging out and recovering the biodegradation evaluation case. Shaking and washing the biodegradation evaluation case, and removing the soil in the internal spaces of the first case and the second case through the openings in the bottom surfaces of the first case and the second case. Measuring the weight of the evaluation body remaining in the internal spaces of the first case and the second case. Including The biodegradation evaluation method of a biodegradable resin molded article is characterized in that, with the first case accommodated in the internal space of the second case, the soil is sieved through the opening on the upper surface of the second case, and is thereby accommodated in the internal space of each of the first case and the second case.

6. After removing the soil in the internal space of each of the first case and the second case, the first case is taken out from the internal space of the second case, and in each of the first case and the second case, a separation sheet having a plurality of openings smaller than the size of the opening on the bottom surface is provided so as to cover the inner side of the upper surface, water is sprayed from the bottom surface with each of the first case and the second case inverted, and the evaluation bodies remaining in the internal space are dropped and collected onto the separation sheet, the separation sheet is removed together with the collected evaluation bodies from each of the first case and the second case, When measuring the weight of the remaining evaluation bodies, for each of the separation sheets removed from the first case and the second case, the weight of the evaluation bodies collected together with the separation sheet is measured, and the weight of the separation sheet is subtracted to measure the weight of the remaining evaluation bodies. The biodegradation evaluation method of a biodegradable resin molded article according to claim 5 is characterized in that.

7. When embedding the biodegradation evaluation case, while actually embedding the biodegradable resin molded article to be treated in the soil for biodegradation, the evaluation bodies and the soil are accommodated in the internal space of the first case, and each of the plurality of biodegradation evaluation cases is embedded in the soil in a state where the first case is accommodated in the internal space of the second case together with the soil, When excavating and recovering the biodegradation evaluation case, each of the plurality of biodegradation evaluation cases is recovered at a time point when different embedding times have elapsed, When measuring the weight of the remaining evaluation bodies, for each of the plurality of biodegradation evaluation cases, the weight of the remaining evaluation bodies is measured, and then, from the relationship between the embedding time and the weight of the remaining evaluation bodies of each of the plurality of biodegradation evaluation cases, the mode of progress of biodegradation is estimated. The biodegradation evaluation method of a biodegradable resin molded article according to claim 5 is characterized in that.

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