JP2022151892A - Resin product biodegradation promoter - Google Patents

Abstract

To provide a resin product biodegradation promoter capable of effectively utilizing plant biomass, capable of using a cellulose nano-fiber easily produced or available, capable of reducing an amount use of a resin and capable of promoting biodegradation of resin products manufactured by blending resins.SOLUTION: A resin product biodegradation promoter containing plant biomass having an average particle size of 1 mm or less and cellulose nanofibers, where a water content of the resin product biodegradation promoter is 0.1% or more and 20% or less, a mass of cellulose nanofibers is 0.1% or more and 50% or less with respect to the mass of the plant biomass.SELECTED DRAWING: Figure 12

Description

TECHNICAL FIELD The present invention relates to a resin product biodegradation accelerator capable of promoting the biodegradability of resin products by blending with resin.

In recent years, petroleum-derived resin waste has become a global warming problem as it generates carbon dioxide when incinerated. There is a problem with the use of resin, and there is a demand for reducing the amount of resin used.

In addition, plant biomass is produced from carbon dioxide in the atmosphere through photosynthesis, and is carbon neutral even if carbon dioxide is emitted during the process of using it. Therefore, it is expected to be an alternative to fossil resources. However, there is a problem that plant biomass is not effectively utilized.

As a method for reducing the amount of resin used and utilizing plant biomass, Patent Document 1 describes a resin molded product in which plant biomass or the like is used as an extender to be blended with resin. There is only a description of using a biodegradable resin, and there is no description of the problem of slow biodegradation of resin moldings.

As for promotion of biodegradability of biodegradable resin, it is described in Patent Document 2 that biodegradability is promoted by adding solvothermally treated cellulose nanofibers to biodegradable resin, but solvothermal The problem is that it is limited to treated cellulose nanofibers and is not easily manufactured or available.

Japanese Patent Application Laid-Open No. 2001-226492 Japanese Patent Application Laid-Open No. 2021-021041

The present invention can effectively utilize plant biomass, can use cellulose nanofibers that can be easily manufactured or obtained, can reduce the amount of resin used, and can biodegrade resin products by blending with resin. To provide a resin product biodegradation accelerator capable of promoting

A resin product biodegradation accelerator containing plant biomass having an average particle size of 1 mm or less and cellulose nanofibers,
The water content of the resin product biodegradation accelerator is 0.1% or more and 20% or less,
The mass of the cellulose nanofibers is 0.1% or more and 50% or less with respect to the mass of the plant biomass,
Biodegradation of resin products manufactured by blending with resin is promoted.

Said plant biomass is a food by-product.

The plant biomass has a water content of 0.1% or more and 20% or less by drying at a surface temperature of 200° C. or less.

A resin product containing a resin product biodegradation accelerator and a resin,
The mass of the resin product biodegradation accelerator is 0.1% or more and 40% or less with respect to the mass of the resin product.

The biodegradability accelerator for resin of the present invention can effectively utilize plant biomass, can reduce the amount of resin used by being blended with resin, and uses cellulose nanofibers that can be easily manufactured or obtained. The biodegradation of the resin product produced by blending the biodegradation accelerator for resin of the present invention is promoted.

It is a photograph of a test piece before a soil embedding test. 2 is a photograph of a test piece of polylactic acid alone (Comparative Example 1) two to twelve weeks after the soil burial test. 2 is a photograph of a test piece with a mass ratio of polylactic acid and cellulose nanofibers of 10:0.1 (Comparative Example 2) two to twelve weeks after the soil burial test. 2 is a photograph of a test piece with a mass ratio of polylactic acid and cellulose nanofibers of 10:1 (Comparative Example 3) 2 to 12 weeks after the soil burial test. 2 is a photograph of a test piece having a mass ratio of polylactic acid, bean curd refuse and cellulose nanofibers of 7:3:0 (Comparative Example 4) two to twelve weeks after the soil burial test. 2 is a photograph of a test piece having a mass ratio of polylactic acid, bean curd refuse and cellulose nanofibers of 7:3:0.1 (Example 1) two to 12 weeks after the soil burial test. 2 is a photograph of a test piece having a mass ratio of polylactic acid, bean curd refuse and cellulose nanofibers of 7:3:1 (Example 2) two to twelve weeks after the soil burial test. 4 is a scanning electron micrograph showing the state of the surface of a polylactic acid-only test piece (Comparative Example 1) four weeks after being buried in soil. 4 is a scanning electron micrograph showing the surface state of a test piece with a mass ratio of polylactic acid and cellulose nanofibers of 10:0.1 (Comparative Example 2) four weeks after being buried in soil. FIG. 4 is a scanning electron micrograph showing the state of the surface of a test piece having a mass ratio of polylactic acid and cellulose nanofibers of 10:1 (Comparative Example 3) four weeks after being buried in soil. FIG. 4 is a scanning electron micrograph showing the state of the surface of a test piece with a mass ratio of polylactic acid, bean curd refuse and cellulose nanofibers of 7:3:0 (Comparative Example 4) four weeks after being buried in soil. 4 is a scanning electron micrograph showing the state of the surface of a test piece having a mass ratio of polylactic acid, bean curd refuse, and cellulose nanofibers of 7:3:0.1 (Example 1) four weeks after being buried in soil. . 4 is a scanning electron micrograph showing the state of the surface of a test piece having a mass ratio of polylactic acid, bean curd refuse and cellulose nanofibers of 7:3:1 (Example 2) four weeks after being buried in soil.

Hereinafter, examples of embodiments of the present invention will be described with reference to the drawings. In addition, the present invention is not limited to the examples of the following forms.

The resin product biodegradation accelerator of the present invention contains plant biomass having an average particle size of 1 mm or less and cellulose nanofibers (hereinafter referred to as "CNF"). By setting the average particle diameter of the plant biomass to 1 mm or less, it becomes easier to uniformly mix the biomass with the resin, and problems with the strength and molding of the finished resin product are less likely to occur. When the particle size of the plant biomass is about 1 mm, it is used as it is or sieved. Plant biomass with a large particle size is pulverized by a common method or sieved after pulverization to an average particle size of 1 mm or less.

The moisture content of the resin product biodegradation accelerator is set to 0.1% or more and 20% or less. If the water content exceeds 20%, the water boils when blended into the resin, and the strength and molding of the finished resin product may be impaired. The mass of the CNF is 0.1% or more and 50% or less with respect to the mass of the pulverized plant biomass. Biodegradation of resin products produced by blending a resin product biodegradation accelerator with resin is accelerated. One example of biodegradation is biodegradation by microorganisms in soil.

The shape of the resin product biodegradation accelerator of the present invention may be any shape as long as it is easy to mix with the resin, and examples thereof include powders, granules, and pellets.

(Plant biomass)
As an example, the plant biomass is food by-products such as bean curd refuse, coffee grounds, tea leaf waste, used tea leaves, barley tea grounds, bean skins, citrus peels, potato skins, beer lees, juice lees, At least one of bran, rice bran, soybean lees, or rapeseed lees is included. Since food by-products are easily decomposed by biodegradable microorganisms, the biodegradation of resin products manufactured by mixing them with resin is promoted.

The plant biomass has a water content of 0.1% or more and 20% or less by drying at a surface temperature of 200° C. or less. Vegetable biomass is converted into food by-products (bean curd refuse, coffee grounds, tea leaf waste, used tea leaves, barley tea grounds, bean skins, citrus peels, potato skins, beer lees, juice lees, wheat bran, rice bran, In the case of soybean lees, rapeseed lees, etc.), since they contain a lot of water, they are dried using, for example, hot air drying. Hot air drying involves drying food by-products by applying hot air to them while stirring them. At this time, the temperature of the hot air is adjusted so that the surface temperature of the food by-products is about 200° C. or less. If the temperature of the food by-products exceeds about 200°C, the food by-products will burn or the components will be denatured, making it difficult to promote the biodegradation of the resin products that are produced by blending with the resin. As an example, the upper limit of the temperature of the hot air is about 400° C., because the hot air loses heat when drying the food by-products. The lower limit of the hot air temperature is not particularly limited, and is set to about 80° C. as an example. If the food by-product has a large average particle size (greater than about 5 mm), the drying efficiency can be increased by pulverizing the food by-product before drying.

The CNF used in the resin product biodegradation accelerator of the present invention refers to finely loosened cellulose constituting wood to a nano level. In general, CNF is powdered, suspended in water, or chemically treated (TEMPO oxidation treatment, CM treatment, etc.), but any state of CNF can be used, and the CNF production method is also There is no particular limitation, and easily manufactured or available cellulose nanofibers can be used.

CNF is added and mixed with plant biomass having a moisture content of 0.1% or more and 20% or less, or added and mixed before or during drying of plant biomass. Since CNF is originally derived from plants and has affinity with plant biomass, it is uniformly mixed in plant biomass.

The resin to which the resin product biodegradation accelerator of the present invention can be added is not particularly limited, and examples thereof include thermoplastic resins, biodegradable resins, and resins obtained by regenerating these resins. Examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, ABS resin, polyvinyl chloride, and polyethylene terephthalate. Examples of biodegradable resins include polylactic acid, polyglycolic acid, polybutylene succinate, polybutylene adipate, polyethylene terephthalate succinate, and polyvinyl alcohol. By using a biodegradable resin as the thermoplastic resin, the resin product containing the resin product biodegradation accelerator of the present invention can be discarded by burying it in the soil without incinerating it.

The biodegradability of the resin containing the resin product biodegradation accelerator of the present invention is promoted. As an example, the mass of the resin product biodegradation accelerator is 0.1% or more and 40% or less with respect to the mass of the resin. The resin product biodegradation accelerator of the present invention can be blended with a thermoplastic resin. Thermoplastic resins containing resin product biodegradation accelerators can be processed into resin products using commonly used methods.

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

(Example and Comparative Example)
Table 1 shows comparative examples and examples used in the biodegradation test, in which a test piece using polylactic acid (hereinafter referred to as "PLA") as a resin was used. The bean curd refuse used in Comparative Example 4 and Examples 1 and 2 was heated to a surface temperature of approximately 80° C. to 130° C. by generating a hot air of about 280° C. to 300° C. while stirring the bean curd refuse. , dried to a moisture content of about 8%. In the example, a resin product biodegradation accelerator was used in which powdered CNF (manufactured by Sugino Machine Co., Ltd., BINFIS-S (registered trademark)) was added to okara with a moisture content of about 8% and mixed. All of the test pieces used in the test were left to stand in a desiccator at room temperature with a humidity of about 20% for two weeks or more and sufficiently dried. The mass of the test piece after the drying treatment was measured and taken as the mass before biodegradation.

(Table 1)

(Soil burying test)
The soil burial test method will be explained. About half of the 18 test samples for each comparative example and each example were buried in a plastic container containing surface soil of a bamboo forest. A plastic container filled with water was placed inside the plastic container in which the test piece was embedded, and the top of the plastic container was covered with a vinyl sheet to prevent moisture from evaporating from the soil. It was placed in a dark place at 30°C.

Three test specimens were collected every two weeks. After removing the soil adhering to the surface of the collected test piece, the surface was wiped with a paper rag impregnated with 70% ethanol solution, and allowed to stand at about 30°C for 1 week to volatilize the ethanol. After that, the state of the test piece was visually confirmed. Thereafter, the test piece from which ethanol was volatilized was allowed to stand in a desiccator at room temperature with a humidity of about 20% for about 2 weeks to 1 month. The mass of the test piece left standing was measured at intervals of time, and the mass at the time when the mass became stable was defined as the mass after biodegradation.

Photographs of each test piece before burying and up to 12 weeks after burying are shown in FIGS. As a result of visually confirming the examples and comparative examples, there was no change in comparative example 1 (only PLA). In Comparative Examples 2 and 3 (PLA+CNF), the coloring caused by thermal denaturation of CNF was slightly decolored, but the surface of the test piece remained smooth. Comparative Example 4 (PLA + bean curd refuse) and Examples 1 and 2 (PLA + bean curd refuse + CNF) caused significant fading from dark brown. After the 4th week of burying, soil and biofilm strongly adhered to the specimens. It was observed that the surface smoothness of the test piece was lost and the test piece was biodegraded. Compared to Comparative Example 4, in which only bean curd refuse was used, in Examples 1 and 2, in which the resin product biodegradation accelerator of the present invention was blended, it was observed that biodegradation of the surface of the test piece was accelerated.

Table 2 summarizes the biodegradable mass in Comparative Examples and Examples. The pre-biodegradation mass and post-biodegradation mass of each test piece were measured, and the biodegradation mass was obtained by subtracting the post-biodegradation mass from the pre-biodegradation mass of each test piece. The biodegradation rate was defined as the ratio of the biodegradation mass to the mass before biodegradation. Table 2 summarizes the biodegradation rate in the soil burial test.

(Table 2)

From Table 2, the following was found. Since Comparative Examples 1, 2 and 3 were hardly biodegraded, it was found that the mere addition of CNF does not promote biodegradation by soil microorganisms. As a result of comparing Comparative Example 4 with Examples 1 and 2, it was found that the addition of CNF to bean curd refuse promoted the biodegradability of the test piece more than the case of bean curd refuse alone. And it turned out that biodegradability of a test piece is accelerated, so that the amount of CNF added to bean curd refuse is large. In Comparative Examples 1 to 3, the reason why the biodegradation rate shows a negative value is that when the test piece was buried in the soil, the test piece absorbed water in the soil and the mass of the test piece increased. Conceivable.

Four weeks after burying in the soil, the surface of the test piece was observed with a scanning electron microscope (manufactured by JEOL Ltd., JCM-6000plus) at a magnification of 1000, and photographs were taken (see FIGS. 8 to 13). ). Compared to the test piece containing only PLA (Comparative Example 1), the test pieces containing only CNF (Comparative Examples 2 and 3) showed slight surface irregularities. The surface of the test piece to which only bean curd refuse was added (Comparative Example 4) was scooped out, but the test pieces to which CNF was added to bean curd refuse (Examples 1 and 2) were scooped out deeper, and the test piece biodegraded. was found to be progressing. Then, when the amount of CNF added is 0.1% (Example 1), when the amount of CNF added is 1.0% (Example 2), the recess is deeper, and the amount of CNF added is It was found that biodegradation is accelerated as the amount increases.

(Microbe bed burying test)
A potato dextrose agar medium with a diameter of 90 mm was spread with C. versicolor mycelium, and about half of the agar medium was homogenized with about 50 ml of water to prepare a cell suspension. Distilled water was added to the prepared bacterial cell suspension to make the water content about 70%, then added to wood flour (beech) sterilized at 121°C for 20 minutes, mixed well, and dried at 30°C in the dark for 2 hours. It was left to stand for a week and cultured. After culturing, it was confirmed that the mycelium had sufficiently spread over the wood flour, and the test pieces of Comparative Examples and Examples were embedded and allowed to stand at 30° C. for 2 weeks.

The mass before biodegradation and the mass after biodegradation of each test piece were measured in the same manner as in the soil burial test, and the biodegradation mass was obtained by subtracting the mass after biodegradation from the mass before biodegradation of each test piece. The biodegradation rate was defined as the ratio of the biodegradation mass to the mass before biodegradation. Table 3 summarizes the biodegradation rate in the soil burial test.

(Table 3)

Similar to the soil burial test, Table 3 shows that Comparative Examples 1, 2, and 3 are hardly biodegraded, and therefore, the addition of CNF does not promote biodegradation by soil microorganisms. As a result of comparing Comparative Example 4 with Examples 1 and 2, it was found that the addition of CNF to bean curd refuse promoted the biodegradability of the test piece more than the case of bean curd refuse alone. And it turned out that biodegradability of a test piece is accelerated, so that the amount of CNF added to bean curd refuse is large.

Claims (4)

A resin product biodegradation accelerator containing plant biomass having an average particle size of 1 mm or less and cellulose nanofibers,
The water content of the resin product biodegradation accelerator is 0.1% or more and 20% or less,
The mass of the cellulose nanofibers is 0.1% or more and 50% or less with respect to the mass of the plant biomass,
Promotes biodegradation of resin products manufactured by blending with resin,
Resin product biodegradation accelerator. wherein the plant biomass is a food by-product;
The resin product biodegradation accelerator according to claim 1 . The plant biomass has a water content of 0.1% or more and 20% or less by drying at a surface temperature of 200 ° C. or less.
The resin product biodegradation accelerator according to claim 1 or 2. A resin product comprising the resin product biodegradation accelerator according to any one of claims 1 to 3 and a resin,
The resin product, wherein the mass of the resin product biodegradation accelerator is 0.1% or more and 40% or less with respect to the mass of the resin product.

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