JP7798280B2 - Biodegradable resin composition - Google Patents

Description

The present invention relates to a novel biodegradable resin composition.

BACKGROUND ART Various biodegradable plastics have been developed to date in order to reduce the environmental load.
For example, Patent Document 1 describes a bioplastic composite material characterized by containing 1.5 to 7.5 parts by weight of a compatibilizer, 0.5 to 3.0 parts by weight of a plasticizer, and 0.25 to 1.5 parts by weight of a hydrolysis inhibitor per 100 parts by weight of a mixture of polylactic acid and plastic.
Furthermore, Patent Document 2 describes a biodegradable plastic composition containing cassava-derived starch and polycaprolactone and/or polyhydroxybutyric acid as raw materials.

As awareness of hygiene has increased, many plastic products with antibacterial properties have been developed. For example, plastic products carrying metal particles such as silver nanoparticles and plastic products carrying silver ions on their surfaces are widely known (see, for example, Non-Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-125470 JP 2014-125611 A

Kyoto Prefectural Small and Medium Enterprise Technology Center Technical Report No. 46 (2018)

As mentioned above, technology that imparts antibacterial properties using metal microparticles or metal ions is widely known. However, because this technology is intended for antibacterial purposes, it has been thought that it cannot be applied to biodegradable plastics, which are intended to be biodegraded by bacteria.

Therefore, the problem to be solved by this invention is to provide a resin composition that combines antibacterial activity and biodegradability.

The present invention, which solves the above-mentioned problems, is a biodegradable resin composition containing a transition metal belonging to Period 4 or Period 5 and/or an oxide thereof or an ion thereof.
The biodegradable resin composition of the present invention has both antibacterial activity and biodegradability.

In a preferred embodiment of the present invention, the biodegradable resin composition contains 50% by mass or more of plant-derived raw materials.
In a more preferred embodiment, the plant-derived material includes at least bamboo.
According to the present invention, it is possible to provide a novel biodegradable resin composition having improved biodegradability and various properties, in particular, a biodegradable resin composition that has antibacterial properties as a whole but is also biodegradable.

In a preferred embodiment of the present invention, the transition metal is one or more selected from titanium, silver, vanadium, copper, and zinc oxide.
According to the present invention, it is possible to provide a novel biodegradable resin composition that has various effects, preferably antibacterial properties, due to the above transition metals and/or their oxides, yet is biodegradable.

A preferred embodiment of the present invention further comprises polybutylene adipate terephthalate, polybutylene succinate, and/or polylactic acid.

The present invention provides a novel biodegradable resin composition that has antibacterial activity derived from transition metals belonging to the fourth or fifth period and/or their oxides or ions, yet is biodegradable.

Photographs showing the results of Test Example 2. The mandarins inside and outside the container of the Comparative Example on the left are rotten, while the mandarins inside and outside the container of the Example on the right are not rotten. Photograph showing seedling pods used in Test Example 4. 10 is a photograph showing the results of Test Example 4 of seedling pods decomposed by soil bacteria.

In the present invention, the components of the biodegradable resin composition other than the plant-derived raw materials are not particularly limited as long as they are biodegradable polymers that have traditionally been used as components of biodegradable plastics. That is, they may be petroleum-derived biodegradable polymers or biomass-derived biodegradable polymers. They may also be biodegradable polymers produced by chemical synthesis or by microbial production.
Examples of petroleum-derived biodegradable polymers include polyglycolic acid (PGA), polyvinyl alcohol (PVA), polycaprolactone (PCL), polybutylene adipate terephthalate (PBAT), and polybutylene succinate (PBS).
Examples of biodegradable polymers derived from biomass include polylactic acid (PLA), polyhydroxyalkanoic acids (PHAs), and polyamide 4 (PA4).
Examples of biodegradable polymers produced by microorganisms include polyhydroxybutyrate (PHB) and PHBH (copolyesters consisting of R-3-hydroxybutanoic acid (3HB) and R-3-hydroxyhexanoic acid (3HH)).
Two or more of these biodegradable polymers may be used, for example, polybutylene adipate terephthalate, polybutylene succinate, and/or polylactic acid.
These biodegradable polymers may be synthesized or obtained by known methods, or may be commercially available.
The composition of the biodegradable polymer in the biodegradable resin composition can be appropriately determined depending on the desired strength and degree of biodegradability as a plastic.

In a preferred embodiment of the present invention, the biodegradable resin composition contains 1% by mass or more of plant-derived raw materials, more preferably 5% by mass or more, even more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 25% by mass or more, and even more preferably 30% by mass or more of plant-derived raw materials.
According to the present invention, the biodegradability of a biodegradable resin composition can be improved.
The upper limit of the plant-derived raw materials in the biodegradable resin composition can be determined appropriately depending on the desired strength of the plastic, etc., but can be, for example, 50% by mass or less, 45% by mass or less, or 40% by mass or less.

The plant-derived raw material is not particularly limited as long as it is a raw material obtained by collecting a plant and optionally processing it by baking, drying, powdering, fragmenting (chips), granulating, or the like.
In a preferred embodiment of the present invention, the plant-derived raw material is a raw material containing plant fiber.
In a preferred embodiment of the invention, the plant-derived material is bamboo.
In a preferred embodiment of the present invention, the plant-derived raw material is powdered bamboo (bamboo powder).
According to the present invention, it is possible to obtain a biodegradable plastic that has improved biodegradability while still having the properties derived from the transition metals and/or oxides thereof described below, particularly antibacterial properties.
In particular, when the plant-derived raw material is bamboo, a biodegradable plastic can be produced that has improved biodegradability while still retaining the properties derived from the transition metals and/or their oxides described below, particularly antibacterial properties.

The type of bamboo is not particularly limited as long as it is a commonly available type, and examples thereof include, but are not limited to, Madake, Moso Bamboo, Awatake, Metake, Kurotake, and Hotei Bamboo.
Bamboo can be processed using known equipment and methods.

When the biodegradable resin composition of the present invention is applied to the production of products other than bottles, it is preferable to use bamboo as the plant-derived raw material.
When bamboo is used as the plant-derived raw material, the biodegradable resin composition preferably contains 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more of bamboo.
The bamboo content can be adjusted as appropriate depending on the desired product characteristics.

The biodegradable resin composition according to the present invention contains a transition metal belonging to the fourth or fifth period and/or an oxide thereof.
According to the present invention, it is possible to provide a novel biodegradable resin composition having improved biodegradability and various properties.

The transition metals belonging to the fourth period are scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc.
The transition metals belonging to the fifth period are yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, and cadmium.
The oxide of a transition metal belonging to the fourth or fifth period is an oxide of the metal, regardless of the valence of the metal. For example, copper may be copper(I) oxide or copper(II) oxide. The same applies to other transition metals having multiple valences.

In a preferred embodiment of the present invention, the transition metal and/or oxide thereof is a transition metal and/or oxide thereof belonging to Period 4 or Period 5 and to any one of Groups 4, 5, 11, or 12.
In a more preferred embodiment of the present invention, the transition metal is one or more selected from titanium, silver, vanadium, copper, and zinc oxide.
According to the present invention, it is possible to obtain a biodegradable resin composition that has biodegradability while retaining the properties derived from the added metal, particularly antibacterial properties.

The type and amount of the transition metal belonging to the fourth or fifth period and/or its oxide can be determined depending on the desired performance.
Furthermore, the transition metals belonging to the fourth or fifth period and/or their oxides may be, for example, commercially available raw materials that can be added during the production process of the biodegradable resin composition.

It is preferable that the transition metals and/or their oxides belonging to the fourth or fifth period are present in the biodegradable resin composition in the form of fine particles dispersed therein, or that they are present in the biodegradable resin composition in the form of metal ions.

The fine particles used in the present invention are preferably particles with a diameter of ^10-20 nm to ^10-1 nm. Although solid metals or solid metal oxides are poorly water-soluble, they release low concentrations of metal ions in the microenvironment on their surfaces, which is the reason for their antibacterial activity.
By forming the transition metal belonging to Period 4 or Period 5 and/or its oxide into fine particles, the surface area is increased, and it becomes possible to efficiently exert the antibacterial activity of the metal ions released from the surface.

Furthermore, when a transition metal belonging to Period 4 or Period 5 is contained in the biodegradable resin composition in the form of a metal ion, the biodegradable resin composition may contain metal ions eluted by dissolving a solid metal with an acid, or may contain metal ions generated by dissolving an organic acid metal salt or an inorganic acid metal salt and ionizing it.
Alternatively, a solid metal may be dispersed in a biodegradable resin composition, so that the composition contains a low concentration of metal ions released from the microenvironment on the metal surface.

The concentration of the metal ions in the biodegradable resin composition is not particularly limited as long as it is within a concentration range that exhibits antibacterial activity.
For example, the concentration of the metal ions can be preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and even more preferably 6% by mass or more.
The concentration of the metal ions can be preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 8% by mass or less.

More specifically, the concentration of titanium ions in the biodegradable resin composition of the present invention can be preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 0.8% by mass or more, even more preferably 1% by mass or more, even more preferably 1.2% by mass or more, and even more preferably 1.3% by mass or more.
Furthermore, the concentration of titanium ions in the biodegradable resin composition of the present invention can be preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1.6% by mass or less, and even more preferably 1.4% by mass or less.

The concentration of silver ions in the biodegradable resin composition of the present invention can be preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 1.3% by mass or more, and even more preferably 1.5% by mass or more.
The concentration of silver ions in the biodegradable resin composition of the present invention can be preferably 3% by mass or less, more preferably 2.5% by mass or less, even more preferably 2% by mass or less, and even more preferably 1.8% by mass or less.

The concentration of copper ions in the biodegradable resin composition of the present invention can be preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, even more preferably 1.5% by mass or more, and even more preferably 1.7% by mass or more.
The copper ion concentration in the biodegradable resin composition of the present invention can be preferably 3% by mass or less, more preferably 2.5% by mass or less, even more preferably 2% by mass or less, and even more preferably 1.8% by mass or less.

The concentration of vanadium ions in the biodegradable resin composition of the present invention can be preferably 0.05% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.15% by mass or more, and even more preferably 0.2% by mass or more.
The concentration of vanadium ions in the biodegradable resin composition of the present invention can be set to preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.3% by mass or less.

The transition metal belonging to the fourth or fifth period and/or its oxide may be a commercially available metal processed as needed, or a raw material containing the transition metal and/or its oxide may be used.
An example of a raw material containing a transition metal belonging to Period 4 or Period 5 and/or an oxide thereof is an aqueous solution containing a surfactant and in which the transition metal and/or an oxide thereof is dispersed.

When an aqueous solution containing a surfactant and in which the transition metal and/or its oxide belonging to the fourth or fifth period is dispersed is used as a raw material containing the transition metal and/or its oxide, the type of surfactant contained is not particularly limited, and examples include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.
Examples of anionic surfactants that can be used include carboxylic acid-type anionic surfactants (aliphatic monocarboxylic acid salts, polyoxyethylene alkyl ether carboxylates, N-acyl sarcosinates, N-acyl glutamates, etc.), sulfonic acid-type anionic surfactants (dialkyl sulfosuccinates, alkanesulfonates, alpha olefin sulfonates, linear alkylbenzene sulfonates, branched alkylbenzene sulfonates, naphthalene sulfonate-formaldehyde condensates, alkyl naphthalene sulfonates, N-methyl-N-acyltaurates, etc.), sulfate ester-type anionic surfactants (alkyl sulfates, polyoxyethylene alkyl ether sulfates, fat sulfate esters, etc.), and phosphate ester-type anionic surfactants (alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, etc.).

Examples of cationic surfactants include, but are not limited to, alkylamine salt-type cationic surfactants (monoalkylamine salts, dialkylamine salts, trialkylamine salts, etc.) and quaternary ammonium salt-type cationic surfactants (alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkylbenzalkonium chloride, alkyltrimethylammonium bromide, dialkyldimethylammonium bromide, alkyltrimethylammonium iodide, dialkyldimethylammonium iodide, etc.).

Examples of nonionic surfactants include, but are not limited to, ester-type nonionic surfactants (glycerin fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid ester sugars), ether-type nonionic surfactants (polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycols, etc.), ester-ether-type polyethylene glycol surfactants (fatty acid polyethylene glycols, fatty acid polyoxyethylene sorbitan, etc.), and alkanolamide-type nonionic surfactants (fatty acid alkanolamides, etc.).

Examples of amphoteric surfactants include, but are not limited to, carboxybetaine-type amphoteric surfactants (alkylbetaines, fatty acid amidopropyl betaines, etc.), 2-alkylimidazoline-derived amphoteric surfactants (2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaines, etc.), glycine-type amphoteric surfactants (alkyldiethylenetriaminoacetic acid, dialkyldiethylenetriaminoacetic acid, etc.), and amine oxide-type amphoteric surfactants (alkylamine oxide, etc.).

The biodegradable resin composition according to the present invention has various properties.
For example, it has the effects of generating negative ions, antibacterial effects, deodorizing effects, antistatic effects, chemical resistance, anti-rust effects, anti-fungal effects, oxidation suppression effects, promoting plant growth, increasing the amount of mitochondria in the human body, reducing active oxygen, activating NK cells (and thereby improving physical condition), heat retention effects, moisturizing effects, antiviral effects, water repellency effects, reducing substances that cause sick building syndrome such as formaldehyde, reducing electromagnetic waves, and maintaining the freshness of vegetables.

The biodegradable resin composition according to the present invention may contain components other than those described above.
For example, it may contain raw materials other than plant-derived raw materials that are used as biomass plastic raw materials. Examples of biomass plastic raw materials other than plant-derived raw materials include, but are not limited to, seashells.
The biodegradable resin composition according to the present invention may also contain a polymer compound. The polymer compound may be a natural polymer compound or a synthetic polymer compound as long as it does not affect the biodegradability of the biodegradable resin composition according to the present invention, but a natural polymer compound is preferred. An example of a natural polymer compound is starch, but it is not limited to this.

The biodegradable resin composition according to the present invention can be produced using known devices and methods.
For example, the biodegradable resin composition according to the present invention can be produced by mixing the heated biodegradable polymer described above with a raw material containing a transition metal belonging to the fourth or fifth period and/or its oxide or ion, molding the resulting mixture, and cooling it.
When the biodegradable resin composition contains a plant-derived raw material, the plant-derived raw material may be added to the heated biodegradable polymer. In this case, the order of addition of the plant-derived raw material and the raw material containing the transition metal belonging to Period 4 or Period 5 and/or its oxide or ion does not matter, and they may be added simultaneously.

The biodegradable resin composition of the present invention can be used to produce a variety of products.
For example, everyday items (e.g., shampoo bottles and storage containers, diapers, clothing (disposable/recyclable), curtains, plastic bags, straws, cups, disposable tableware, toys, blow-dried products, PET bottles, cases, files, etc.), building materials and furniture (e.g., wall materials, cushioning materials and covers for desks, tables, chairs, etc.), agricultural materials (e.g., weed control sheets and seedling pots, crop transport containers, crop storage containers, resin sheets (for greenhouses), films, fertilizer bags, plantains, shipping wrap films, bags, and boxes, etc.), electrical materials (e.g., light switches and outlets), automotive, electrical, and machinery materials (e.g., seats, seat belts, interior parts of electrical appliances such as air conditioners, refrigerators, and televisions, etc.), packaging containers for pharmaceuticals and food and beverages (e.g., medicine packaging, lunch boxes, etc.), and polystyrene foam can be produced without any particular limitation.

Products using the biodegradable resin composition of the present invention can be produced using known devices and methods.
For example, the biodegradable resin composition of the present invention, which has been previously formed into pellets by the above-mentioned method, can be melted, extruded or molded into a desired shape, and cooled to produce a desired product.
It can also be combined with other materials to produce products such as mirrors, if desired.

<Test Example 1>
Bamboo powder, an antibacterial agent*, polybutylene adipate terephthalate, polybutylene succinate, and polylactic acid were heated and mixed to produce a pellet-shaped biodegradable resin composition.
*The antibacterial agent is a dispersion liquid in which fine particles of titanium, copper, silver, vanadium, and zinc oxide are dispersed in an aqueous surfactant solution, and contains metal ions eluted from the fine particles as well as metal ions generated by separately dissolving these metals.

In the production of the biodegradable resin composition, the concentrations of the metal ions in the composition after production were adjusted to fall within the following numerical ranges.
Titanium: 1.3-1.4%
Silver: 1.5-1.75%
・Copper: 1.7-1.8%
Vanadium: 0.2 to 0.25%
Other atoms: 2 to 2.5%

When the biodegradable resin composition was subjected to a test to confirm its antibacterial activity according to a conventional method, it was confirmed that it exhibited a significant antibacterial activity compared to the control.
When this biodegradable resin composition was buried in soil, it was completely biodegraded after 180 days.

<Test Example 2>
The pellets produced in Test Example 1 were heat-molded to produce a sealed container with a lid. Mandarin oranges were placed inside the sealed container and on the lid, and the container was left at room temperature. As a comparative example, a similar test was carried out in parallel using a general plastic sealed container.
As a result, mold grew on the mandarin oranges placed inside the plastic airtight container and on the lid of the comparative example, causing them to rot, whereas no mold growth was observed on the mandarin oranges placed inside the airtight container and on the lid of the example molded from the biodegradable resin composition, causing them to rot (Figure 1).
The above results demonstrate that the biodegradable resin composition of the present invention has excellent antibacterial activity.

<Test Example 3>
The biodegradable resin composition of the present invention produced in Test Example 1 was placed in a closed room, and an area at a certain distance from the place where it was placed was wiped, and this was measured with a measuring device (Lumitester, manufactured by Kikkoman Corporation) that uses ATP as a contamination indicator, to test the cleaning effect against contamination by microorganisms floating in the indoor space. As a comparative example, a similar test was also carried out using ordinary plastic.
As a result, the reading on the measuring device before the test was 4,322 had dropped to 233 after two hours, and two hours after that to 171. On the other hand, no such reduction in reading was observed in the test using the comparative plastic.
This result indicates that the antibacterial effect of the biodegradable resin composition of the present invention can clean up the indoor space.

<Test Example 4>
The pellets produced in Test Example 1 were heat-molded to produce seedling pots (Figure 2). When these seedling pots were buried in soil and left to stand, they were decomposed by soil bacteria (Figure 3).
These results show that the biodegradable resin composition of the present invention not only has an excellent antibacterial effect as shown in Test Examples 1 to 3, but also exhibits excellent biodegradability.

<Test Example 5>
Except for adjusting the amount of antibacterial agent added as appropriate, the biodegradable resin composition of the present invention was produced in the same manner as in Test Example 1. By adjusting the amount of antibacterial agent added, biodegradable resin compositions were produced in which the total content of each metal atom and ion in the biodegradable resin composition was 1%, 2%, 3%, 4%, 5%, 6%, and 7%.
These biodegradable resin compositions were subjected to the same tests as in Test Examples 1 to 4, and excellent antibacterial activity and biodegradability were confirmed in all compositions containing metal at any concentration.

According to the present invention, it is possible to provide a biodegradable resin composition that is biodegradable despite having antibacterial properties.

Claims (10)

A biodegradable resin composition for cleaning airborne microorganisms in a space,
As an active ingredient for purifying space, all transition metals selected from titanium, silver, vanadium, copper, and zinc and/or oxides or ions thereof;
1% by mass or more of bamboo powder;
As a biodegradable polymer, polybutylene adipate terephthalate, polybutylene succinate, and/or polylactic acid;
Including,
the transition metal and/or its oxide are present in the form of fine particles dispersed therein;
Alternatively, the transition metal is present in the form of a metal ion.
A biodegradable resin composition for cleaning spaces. the heated biodegradable polymer;
The bamboo powder,
an aqueous solution containing a surfactant and in which the transition metal and/or its oxide is dispersed;
2. The space-cleaning biodegradable resin composition according to claim 1, which is produced by mixing the above components, molding the resulting mixture, and cooling it. The biodegradable resin composition for space purification described in claim 2, wherein the aqueous solution is a dispersion in which fine particles of titanium, copper, silver, vanadium, and zinc oxide are dispersed in a surfactant aqueous solution, and contains metal ions eluted from the fine particles and metal ions generated by the dissolution of these metals. The space-cleaning biodegradable resin composition according to claim 3, wherein the total content of the transition metal atoms and ions in the space-cleaning biodegradable resin composition is 1% to 7%. The biodegradable resin composition for space purification described in any one of claims 1 to 4 is further used to maintain the freshness of food and beverages by its antifungal effect. transition metals selected from titanium, silver, vanadium, copper, and zinc and/or oxides or ions thereof;
1% by mass or more of bamboo powder;
As a biodegradable polymer, polybutylene adipate terephthalate, polybutylene succinate, and/or polylactic acid;
Including,
the transition metal and/or its oxide are present in the form of fine particles dispersed therein;
Alternatively, the transition metal is present in the form of a metal ion.
placing a biodegradable resin composition in a space;
A space cleaning method for cleaning contamination caused by microorganisms floating in the space. The biodegradable resin composition is
the heated biodegradable polymer;
The bamboo powder,
an aqueous solution containing a surfactant and in which the transition metal and/or its oxide is dispersed;
7. The space cleaning method according to claim 6, wherein the biodegradable resin composition is produced by mixing the above components, molding the resulting mixture, and cooling it. The space purification method described in claim 7, wherein the aqueous solution is a dispersion in which fine particles of titanium, copper, silver, vanadium, and zinc oxide are dispersed in a surfactant aqueous solution, and contains metal ions eluted from the fine particles and metal ions generated by the dissolution of these metals. The space purification method described in claim 8, wherein the total content of the transition metal atoms and ions in the biodegradable resin composition is 1% to 7%. The space purification method described in any one of claims 6 to 9 is a method for maintaining the freshness of food and beverages through its anti-mold effect.