Biodegradable polymer composite material

Abstract

To provide biodegradable polymer composite materials in which decomposition ability of biodegradable polymers by enzymes is maintained even in water.SOLUTION: A biodegradable polymer composite material 1 comprises a substrate 10 containing a biodegradable polymer, an enzyme 12 having a decomposing activity for the biodegradable polymer supported on the substrate 10, and a biodegradable polymer coating 20 provided on the substrate 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to biodegradable polymer composite materials. [Background technology]

[0002] Plastic waste, such as containers such as PET bottles, packaging, and household items, is polluting the environment, and there is a demand for environmentally friendly plastic materials. In particular, there is a high risk of plastic fishing gear, such as fishing nets and ropes, being discharged into the ocean, and since fibers released into the ocean can become entangled with living organisms and affect the ecosystem, measures are urgently needed.

[0003] Patent Document 1 discloses a packaging material or container containing a biodegradable resin and a microcapsule encapsulating a substance that promotes the decomposition of the biodegradable resin, characterized in that the microcapsule has an outer shell containing a resin composition having photodegradability. A microorganism or enzyme that promotes the decomposition of the biodegradable resin is encapsulated in the microcapsule, and when the packaging material or container is opened, the decomposition promoter is subjected to a physical stimulus and acts on the biodegradable resin, thereby starting the decomposition of the biodegradable resin.

[0004] Patent Document 2 discloses a biodegradable plastic article comprising at least one polyester and a biological substance having polyester decomposition activity, the biodegradable plastic article comprising a carrier selected from polysaccharides and, optionally, a carrier polymer having a melting temperature of less than 140° C. and / or a glass transition temperature of less than 70° C., the biological substance being capable of decomposing the polyester and being uniformly dispersed in the plastic article. The biological substance includes, for example, an enzyme having at least polyester decomposition activity. In this configuration, the enzyme is uniformly dispersed in the plastic article, meeting the decomposition characteristics expected of a disposable, short-life plastic article. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2023-058234 [Patent Document 2] Patent Publication No. 2020-531671 Summary of the Invention [Problem to be solved by the invention]

[0006] In known techniques such as Patent Documents 1 and 2, in order to promote the decomposition of a biodegradable resin, an enzyme that promotes the decomposition of the biodegradable resin is encapsulated or dispersed in the biodegradable resin.

[0007] Some biodegradable plastics degrade in composting environments but not in marine environments. Embedding or coating with enzymes can increase the decomposition ability of biodegradable plastics and make them biodegradable in seawater.

[0008] However, in water such as seawater, the enzymes encapsulated or dispersed in the biodegradable resin flow out into the water, decreasing the decomposition ability of the enzymes.

[0009] An object of the present invention is to provide a biodegradable polymer composite material in which the decomposition ability of a biodegradable polymer by an enzyme is maintained or accelerated even in water. [Means for solving the problem]

[0010] The present invention encompasses the embodiments described below. Section 1. A substrate comprising a biodegradable polymer; an enzyme supported on the substrate and having activity of decomposing the biodegradable polymer; a biodegradable polymer coating disposed on the substrate; A biodegradable polymer composite comprising: Section 2. Item 2. The biodegradable polymer composite material according to item 1, wherein the biodegradable polymer of the substrate and the polymer that is a component of the biodegradable polymer coating are the same substance or the same type. Section 3. Item 2. The biodegradable polymer composite material according to item 1, wherein the substrate is a fiber or a molded article. Section 4. Item 2. The biodegradable polymer of the substrate and the polymer that is a component of the biodegradable polymer coating are the same or different and are selected from the group consisting of polyesters, polycarbonates, polyurethanes, polyvinyl alcohols, polysaccharides and polysaccharide esters. Section 5. Item 2. The biodegradable polymer composite material according to item 1, wherein the enzyme is embedded in the biodegradable polymer. Section 6. Item 6. The biodegradable polymer composite material according to item 1 or 5, wherein the thickness of the biodegradable polymer coating is 0.001 mm to 5 mm. Section 7. Item 1. Use of the biodegradable polymer composite material according to item 1 for the manufacture of containers, packaging, building materials, agricultural tools, or fishing tools. Section 8. Mixing a biodegradable polymer with an enzyme having an activity of degrading the biodegradable polymer to form a substrate in which the enzyme having an activity of degrading the biodegradable polymer is supported within the biodegradable polymer; and providing a biodegradable polymeric coating over said substrate; A method for producing a biodegradable polymer composite material comprising: Effect of the Invention

[0011] According to the present invention, it is possible to provide a biodegradable polymer composite material in which the decomposition ability of a biodegradable polymer by an enzyme is maintained or accelerated even in water. [Brief description of the drawings]

[0012] [Figure 1](A) A schematic diagram showing an example of a substrate comprising a biodegradable polymer (B) A schematic diagram of a biodegradable polymer composite according to an embodiment of the present invention. [Diagram 2] Photograph of enzyme-embedded fiber. [Diagram 3] Graph showing the relationship between decomposition time and weight loss rate for enzyme-embedded fiber and enzyme-unembedded fiber. [Figure 4] Electron micrographs of enzyme-embedded fibers over time. [Diagram 5] Graph showing the relationship between decomposition time and weight loss rate for enzyme-embedded fiber and enzyme-unembedded fiber. [Figure 6] Electron micrographs of enzyme-embedded fibers over time. [Figure 7] Lateral surfaces (top row) and cross sections (bottom row) of enzyme-embedded fibers before (left column) and after (right column) coating. [Figure 8] 1 is a graph showing the relationship between decomposition time and weight loss rate for the biodegradable polymer composite material of Example 1 and the enzyme-embedded fiber of Comparative Example 1. [Figure 9] Electron micrographs of the biodegradable polymer composite material of Example 1 over time. [Figure 10] Electron microscope photographs of enzyme-embedded fiber of Comparative Example 1 over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] As used herein, the singular forms (a, an, the) are intended to include both the singular and the plural unless otherwise expressly stated in the specification or clearly contradictory in context.

[0014] In this specification, the term "comprise" is a concept that encompasses "consist essentially of" and "consist only of."

[0015] In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range can be arbitrarily combined with the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in an example or a value that can be unambiguously derived from an example. Furthermore, in this specification, a numerical value connected with "~" means a numerical range that includes the numerical values ​​before and after "~" as the lower and upper limits.

[0016] In one aspect of the present invention, a biodegradable polymer composite material is provided, comprising a substrate containing a biodegradable polymer, an enzyme supported on the substrate and having decomposition activity of the biodegradable polymer, and a biodegradable polymer coating provided on the substrate.

[0017] FIG. 1(A) is a schematic diagram showing an example of a substrate including a biodegradable polymer, and FIG. 1(B) is a schematic diagram showing an example of a biodegradable polymer composite material.

[0018] In FIG. 1(A), a substrate 10 containing a biodegradable polymer contains a biodegradable polymer, and an enzyme 12 having activity of decomposing the biodegradable polymer is supported on the substrate 10. In this example, the substrate 10 is a long member, and the enzyme 12 is dispersed in the biodegradable polymer constituting the substrate 10 and embedded in the biodegradable polymer. In other words, the substrate 10 is formed from a biodegradable polymer composition containing a biodegradable polymer and the enzyme 12 embedded in the biodegradable polymer. Note that this example shows a part of the embodiment and is not limited by the shape. A part of the enzyme 12 may be exposed on the surface of the substrate 10.

[0019] As shown in FIG. 1(B), the biodegradable polymer composite material 1 includes such a substrate 10 and a biodegradable polymer coating 20 provided on the substrate 10. The enzyme 12 is not embedded or dispersed inside the biodegradable polymer coating 20. In addition, the enzyme having the activity of decomposing the biodegradable polymer constituting the biodegradable polymer coating 20 is not embedded or dispersed inside the biodegradable polymer coating 20. The biodegradable polymer coating 20 covers substantially the entire outer circumferential surface of the substrate 10. In this example, the biodegradable polymer coating 20 has a hollow, substantially cylindrical shape that accommodates the substrate 10, and both ends are closed. In other words, neither the side surface nor both ends in the longitudinal direction of the substrate 10 are exposed to the outside, but are covered by the degradable coating 20. The case where the biodegradable polymer coating 20 is provided on the substrate 10 includes a case where the biodegradable polymer coating 20 is provided directly on the substrate 10, and a case where the biodegradable polymer coating 20 is provided indirectly on the substrate 10 via the enzyme 12 or the like.

[0020] When the biodegradable polymer composite material 1 is immersed in water, the water comes into contact with the biodegradable polymer coating 20. However, immediately after the start of use of the biodegradable polymer composite material 1, water does not penetrate the biodegradable polymer coating 20 at all or hardly penetrates it at all. After that, as time passes, water passes through the biodegradable coating 20 due to permeation or physical wear, and reaches the substrate 10. The water also comes into contact with the enzyme 12, and the enzyme 12 activated by contact with water starts to promote the decomposition of the biodegradable polymer in the substrate 10. Although hydrolysis of the biodegradable polymer coating 20 also occurs due to contact between the biodegradable polymer coating 20 and water, the decomposition of the biodegradable polymer of the substrate 10 is promoted to the extent that the enzyme 12 is supported on the substrate 10, and the decomposition of the biodegradable polymer of the substrate 10 proceeds faster than the decomposition of the biodegradable polymer coating 20. With such a configuration of the biodegradable polymer composite material 1, even if the biodegradable polymer composite material 1 is released into water such as seawater, the outflow of the enzyme 12 to the outside of the biodegradable polymer composite material 1 is suppressed, the decomposition ability of the enzyme 12 of the biodegradable polymer is maintained as much as possible, and decomposition from the inside of the biodegradable polymer composite material 1 is promoted. As the decomposition of the biodegradable polymer by the enzyme 12 progresses, the substrate 10 disintegrates. Thereafter, the fragmented biodegradable polymer and the external biodegradable polymer coating 20 are decomposed by hydrolysis.

[0021] If the substrate 10 does not have the biodegradable polymer coating 20, the enzyme 12 will flow into the water when exposed to water, reducing the ability of the enzyme 12 to decompose the biodegradable polymer in the substrate 10. However, according to the configuration of this example, the ability of the enzyme 12 to decompose the biodegradable polymer even in water is maintained, and the decomposition of the biodegradable polymer proceeds more efficiently, compared to when the biodegradable polymer coating 20 is not provided.

[0022] The biodegradable polymer, which is a component of the substrate, and the polymer, which is a component of the biodegradable coating, may be the same material or different materials, but in terms of compatibility between the biodegradable polymer and the biodegradable polymer coating, it is preferable that they are the same substance or the same type. The same type refers to the same type, such as PBAT, but not the same substance, such as having different molecular weights or copolymerization ratios. The biodegradable polymer and the polymer, which is a component of the biodegradable polymer coating, may each be a single type of biodegradable polymer or two or more types of biodegradable polymers.

[0023] Examples of the biodegradable polymer that is a component of the substrate and the biodegradable coating include biodegradable polymers that may be the same or different and are selected from the group consisting of polyesters, polyvinyl alcohols, polycarbonates, polyurethanes, polysaccharides, and polysaccharide derivatives.

[0024] Examples of polyesters include aliphatic polyesters, alicyclic polyesters, aromatic polyesters, and aliphatic-aromatic polyesters. From the viewpoint of promoting biodegradation, aliphatic polyesters, aromatic polyesters, and aliphatic-aromatic polyesters are preferred.

[0025] The polyester can be prepared by the polycondensation reaction of a dicarboxylic acid with a diol, a hydroxycarboxylic acid, or a dicarboxylic acid, a diol and a hydroxycarboxylic acid. The dicarboxylic acid is preferably a saturated dicarboxylic acid.

[0026] Aliphatic polyesters include polycaprolactone (PCL), polypivalolactone, polylactic acid (PLA), polyglycolic acid (PGA), polyhydroxyalkanoic acid (PHA), copolymers thereof, or combinations thereof. Copolymers include polyhydroxyalkanoates (PHAs) such as poly(3-hydroxybutyrate-co-hydroxyhexanoate) (3HB-co-3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (3HB-co-3HV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (3HB-co-4HB), polylactic acid-co-polyglycolic acid (PLA / PGA), polylactic acid-co-polycaprolactone, polyethylene succinate (PES), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and the like.

[0027] Examples of alicyclic polyesters include polyC2-6 alkylene C6-12 cycloalkanoates such as polyethylene cyclohexanoate, where C6-12 refers to a carbon number of 6 to 12.

[0028] Examples of aromatic polyesters include polyethylene terephthalate (PET), polypropylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polytrimethylene naphthalate, and polytetramethylene naphthalate.

[0029] Aliphatic-aromatic polyesters include polyethylene adipate-co-terephthalate (PEAT), polybutylene adipate-co-terephthalate (PBAT), polytetramethylene adipate-co-terephthalate, polyethylene terephthalate succinate (PETS), and the like.

[0030] Examples of polysaccharides include cellulose, amylose, xylene, glucomannan, pullulan, curdlan, paramylon, alginic acid, chitin, chitosan, etc. Polysaccharides in which all or a part of the hydroxyl groups have been replaced with ester groups or the like are called polysaccharide derivatives.

[0031] Biodegradable polymers selected from the group consisting of polyesters, polycarbonates, polyurethanes, polysaccharides and polysaccharide esters are preferred because they are difficult to degrade in a deep sea environment but can be degraded in the presence of enzymes.

[0032] In one embodiment, the biodegradable polymer constituting the substrate and the polymer constituting the biodegradable polymer coating are both biodegradable polyesters.

[0033] In one embodiment, the biodegradable polymer constituting the substrate and the polymer constituting the biodegradable polymer coating are both the same biodegradable polyester.

[0034] The molecular weight of the biodegradable polymer, which is a component of the substrate, is not particularly limited and may be 5,000 to 2,000,000, and may be, for example, a low molecular weight of about 500 to less than 10,000, or a high molecular weight of about 10,000 to 2,000,000. The molecular weight may be a weight average molecular weight (Mw) or a number average molecular weight (Mn), but the weight average molecular weight is preferred. The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured by a method known in the art, such as high pressure liquid chromatography (HPLC), size exclusion chromatography (SEC), or gel permeation chromatography (GPC).

[0035] The amount of biodegradable polymer in the substrate (and the biodegradable polymer composition constituting the substrate) is not particularly limited, but is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0036] In one embodiment, the biodegradable polymer is a biodegradable resin. In this specification, the term "biodegradable polymer" may be replaced with the term "biodegradable resin."

[0037] Enzymes having biodegradable polymer decomposition activity may be produced by known techniques or may be commercially available. Enzymes capable of decomposing polyesters, polycarbonates, polyurethanes, polyvinyl alcohols, polysaccharides, polysaccharide esters, cellulose acetate, and the like are known. Examples of suitable enzymes having polyester decomposition activity for use in the present invention include depolymerases, esterases, lipases, cutinases, carboxylesterases, proteases, polyesterases, or any enzymes known to decompose polyesters. The enzymes are preferably Novozyme 51032 (registered trademark, cutinase derived from Humicola insolens), Lipozyme CALB L (registered trademark, lipase derived from Candida antarctica), and proteinase K derived from (Tritirachium album). Enzymes having biodegradable polymer decomposition activity may be one type or two or more types. The enzyme having a decomposition activity of a biodegradable polymer may include i) one or more enzymes having a decomposition activity against a biodegradable polymer contained in a substrate, and ii) one or more enzymes of the same or different type as the enzyme of i) having a decomposition activity against a biodegradable polymer that is the same or different from the polymer of i) that is a component of the biodegradable polymer coating. Those skilled in the art can appropriately select a combination of a biodegradable polymer, an enzyme having a decomposition activity against a biodegradable polymer, and a biodegradable polymer to be used in the biodegradable polymer coating with ordinary skill. The enzyme may be used in a powder form or a solution form, and is preferably in a pure powder form or a powder form isolated from a solution.

[0038] The substrate (and the biodegradable polymer composition constituting the substrate) may contain additives other than the biodegradable polymer and the enzyme having activity of decomposing the biodegradable polymer. Examples of such additives include plasticizers, surfactants, lubricants, organic or inorganic fillers, dispersants, antioxidants, light stabilizers, ultraviolet absorbers, colorants, preservatives, and antibacterial agents. These additives may be used alone or in combination of two or more.

[0039] In the example of FIG. 1(A), the enzyme 12 having the activity of decomposing a biodegradable polymer is dispersed in the biodegradable polymer, but the enzyme having the activity of decomposing a biodegradable polymer may be supported or applied to the surface of the substrate, or may be embedded inside the biodegradable polymer of the substrate, or both. In one embodiment, the enzyme having the activity of decomposing a biodegradable polymer is embedded in the biodegradable polymer of the substrate. In another embodiment, the enzyme having the activity of decomposing a biodegradable polymer is dispersed approximately uniformly inside the biodegradable polymer of the substrate.

[0040] The substrate may be of any shape. For example, the substrate may be a fiber or a molded body. Examples of molded bodies include a sheet, a film, and an injection molded product. In this specification, a sheet refers to a thin plastic plate having a thickness of 250 μm or more, and a film refers to a plastic membrane having a thickness of less than 250 μm.

[0041] In one embodiment, the substrate is water permeable. In particular, the biodegradable polymer in the substrate is water permeable. For example, the substrate and / or the biodegradable polymer has a fibrous, net-like, or porous structure. With such a configuration, the timing of the degradation of the biodegradable polymer by the enzyme can be adjusted. When the biodegradable polymer composite material is immersed in water, water penetrates into the substrate, contacts at least a part of the enzyme, and promotes the degradation of the biodegradable polymer by the enzyme. In addition, even if an enzyme having a decomposition activity of the biodegradable polymer is embedded in the substrate and is not present on the surface of the substrate, water can reach the enzyme by penetrating into the substrate, and the degradation of the biodegradable polymer by the enzyme can be promoted.

[0042] The molecular weight of the biodegradable polymer coating is not particularly limited and may be 5,000 to 2,000,000, for example, a low molecular weight of about 500 to less than 10,000, or a high molecular weight of about 10,000 to 2,000,000.

[0043] The amount of the biodegradable polymer, which is a component of the biodegradable polymer coating, is not particularly limited, but is preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more.

[0044] In one embodiment, the biodegradable polymer coating is a biodegradable resin coating. In this specification, the term "biodegradable polymer coating" may be replaced with "biodegradable resin coating."

[0045] The biodegradable polymer coating may further contain additives, such as plasticizers, surfactants, lubricants, organic or inorganic fillers, dispersants, antioxidants, light stabilizers, UV absorbers, colorants, preservatives, antibacterial agents, etc. These additives may be used alone or in combination of two or more.

[0046] The thickness of the biodegradable polymer coating is not particularly limited, but in order to maintain the original properties of the biodegradable polymer composite material and enable it to decompose within a reasonable period of time, the thickness is preferably, for example, 0.001 mm to 5 mm, and more preferably 10 to 200 μm.

[0047] The area on which the biodegradable polymer coating is applied on the substrate containing a biodegradable polymer is not particularly limited, but the larger the coverage area, the more the enzymes having the activity of decomposing the biodegradable polymer can be prevented from flowing out into water when the biodegradable polymer composite material is immersed in water. The coverage area is, for example, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the total area of ​​the outer surface of the substrate. It is preferable that the biodegradable polymer coating is applied on the entire outer surface of the substrate, but the biodegradable polymer coating may be applied on a portion of the outer surface of the substrate, and a material other than the biodegradable polymer coating, such as a non-biodegradable polymer (particularly a non-biodegradable synthetic resin), metal, or wood, may be applied on the remaining portion.

[0048] The biodegradable polymer composite material of the present invention can be used in various applications, such as fishing equipment, agricultural tools, building materials, containers, and packaging that include nets that include the biodegradable polymer composite material.

[0049] Next, a method for producing the biodegradable polymer composite material of the present invention will be described.

[0050] In one embodiment, a method for producing a biodegradable polymer composite material includes mixing a biodegradable polymer with an enzyme having degrading activity for the biodegradable polymer to form a substrate in which the enzyme having degrading activity for the biodegradable polymer is supported within the biodegradable polymer, and providing a biodegradable polymer coating on the substrate.

[0051] Details of the biodegradable polymer, the enzyme having activity of decomposing the biodegradable polymer, and the biodegradable polymer coating are as explained above in the description of the biodegradable polymer composite material.

[0052] The biodegradable polymer may be mixed with the enzyme having the activity of decomposing the biodegradable polymer in a solvent, or the biodegradable polymer and the enzyme may be melt-mixed without using a solvent. Any organic solvent including chloroform, acetone, dichloromethane, dimethyl sulfoxide, and dimethylacetamide may be used as the solvent. Those skilled in the art can appropriately select an organic solvent suitable for dissolving the biodegradable polymer.

[0053] A mixture of a biodegradable polymer and an enzyme having activity of decomposing the biodegradable polymer can be processed into any shape, such as by spinning into fibers or by molding into molded articles by press molding, extrusion molding, injection molding, blow molding, etc. Processing methods for molding polymer compositions or resin compositions are well known.

[0054] Providing a biodegradable polymer coating on a substrate includes dissolving or melting a polymer constituting the biodegradable polymer coating with or without a solvent, and applying the dissolved or melted product onto the substrate. Providing a biodegradable polymer coating on a substrate includes applying the biodegradable polymer coating directly to the surface of the substrate. The application may be any method, such as coating or spraying. The thickness of the biodegradable polymer coating is not limited, but it is provided on the substrate so that the dry film thickness is preferably 0.001 mm to 5 mm, more preferably 10 to 300 μm. When the decomposition of the biodegradable polymer composite material in a solvent such as water or seawater is immediately promoted, the thickness of the biodegradable polymer coating is preferably set to a thin value of about 100 μm or less, but when the decomposition of the biodegradable polymer composite material is caused after the biodegradable polymer composite material is used for a certain period of time according to its intended use, the thickness of the biodegradable polymer coating is preferably set to a thick value. By making the surface coating thicker, the penetration of water is slowed, and the timing of contact between the enzyme having the decomposition activity of the biodegradable polymer and water can be delayed.

[0055] In another embodiment, a method for producing a biodegradable polymer composite material includes providing a substrate comprising a biodegradable polymer, applying an enzyme having biodegradable polymer degrading activity onto the substrate, and providing a biodegradable polymer coating on the enzyme-coated substrate.

[0056] Substrates containing biodegradable polymers can be processed into any shape, such as by spinning into fibers or by molding into molded articles by press molding, extrusion molding, injection molding, blow molding, etc. Processing methods for molding polymer compositions or resin compositions are well known.

[0057] Applying an enzyme having a degrading activity against a biodegradable polymer onto a substrate includes directly applying the enzyme to the surface of the substrate, and includes, for example, painting or spraying a solution containing the enzyme onto the substrate and removing the solvent.

[0058] Providing a biodegradable polymer coating on a substrate includes dissolving or melting a polymer constituting the biodegradable polymer coating with or without a solvent, and applying the dissolved or melted product onto the substrate. Providing a biodegradable polymer coating on a substrate includes applying the biodegradable polymer coating directly to the surface of the substrate. The application may be by any method, such as painting or spraying. The thickness of the biodegradable polymer coating is not limited, but it is preferably provided on the substrate so that the dry film thickness is 0.001 mm to 5 mm, more preferably 10 to 200 μm.

[0059] The disclosures of all patent applications and publications cited herein are hereby incorporated by reference in their entireties.

[0060] The following examples are intended for illustrative purposes only and are not intended to limit the scope of the present invention in any way. Unless otherwise specified, reagents are commercially available or are obtained or prepared according to conventional techniques or procedures known in the art. EXAMPLES

[0061] Production Example 1: Production of enzyme-embedded fibers using cast film Poly(butylene adipate-co-terephthalate) (PBAT) (Mw = 1.6 × 105, Tm = 115 ° C) was used to prepare the fibers. In addition, PBAT decomposition enzyme was used as the embedded enzyme. PBAT pellets and enzyme were placed in chloroform, and the solvent was volatilized to prepare a PBAT cast film containing the enzyme. Enzyme-embedded fibers (biodegradable polymer compositions) were prepared by melt spinning this film. In addition, fiber samples with different fiber diameters were prepared by setting the winding speed to 2, 7, and 17 m / min. Since the discharge speed of each fiber was constant, the diameter of the fiber became smaller when the winding speed was fast. The diameters of the fibers wound at 17, 7, and 2 m / min were 250 μm, 400 μm, and 850 μm, respectively.

[0062] Figure 2 shows the enzyme-embedded fiber that was actually produced.

[0063] Test 1: Decomposition test of enzyme-embedded fiber In the decomposition experiments described below, sterilized tools were used and disposable gloves were worn to prevent contact with bare hands, thereby avoiding the introduction of germs.

[0064] The following experiment was carried out to investigate the decomposition of the enzyme-embedded fiber prepared in Production Example 1. A phosphate buffer solution (pH = 7) was prepared, and then the enzyme-embedded fiber prepared in Production Example 1 was added and sealed. Similarly, one fiber was placed in one sample tube for the fibers prepared at different winding speeds. In addition, PBAT fiber without enzyme embedded was also added to a sample tube containing phosphate buffer as a control. These were placed in a shaker and kept in a thermostatic bath to start decomposition. After reaching a predetermined time, the fiber was removed from each sample tube, the moisture remaining on the surface was wiped off, and the weight was measured to measure the remaining weight after decomposition. The difference between the remaining weight and the initial weight was taken as the loss weight, and was calculated as the weight loss rate relative to the initial weight. The presence or absence of decomposition ability of the enzyme-embedded fiber was evaluated by plotting the weight loss rate against the decomposition time.

[0065] The relationship between the decomposition time and the weight loss rate for enzyme-embedded fibers prepared at different winding speeds and enzyme-unembedded fibers (control) is shown in Figure 3. The horizontal axis is the decomposition time, and the vertical axis is the ratio of the weight lost to the initial weight (weight loss rate). From the top, the results are for thin fibers (17 m / min, diameter 240 μm), medium-thickness fibers (7 m / min, diameter 400 μm), and thick fibers (2 m / min, diameter 850 μm), and the bottom is the result for the control fiber without enzyme. The x on the data plot indicates the area where the fiber was fragmented to the point where sampling was impossible. The weight loss rate of each fiber increased with the progression of decomposition time, and the fiber prepared at 17 m / min had decomposed to the point where it was impossible to recover after 10 days (240 hours). The decomposition rate of each fiber increased with increasing winding speed. Therefore, it can be said that the decomposition rate increases as the ratio of surface area to unit weight increases. In contrast, the weight loss of the fiber without embedded enzymes (control) was 0% even after 13 days (312 hours), and no decomposition occurred. These results indicate that the enzymes embedded in the enzyme-embedded fiber become active when they come into contact with water, and it can be concluded that the enzyme-embedded fiber has been successfully imparted biodegradability by embedding the enzymes.

[0066] Next, Figure 4 shows the results of observing the process of decomposition of a fiber with a winding speed of 2 m / min (diameter 850 μm) using an electron microscope. The top row shows the surface morphology of the fiber. The fiber was also frozen in liquid nitrogen and cut with a sharp blade to expose the cross section. The bottom row of Figure 4 shows this cross section. 0 h shows the morphology before the start of decomposition, and then 24, 96, and 192 hours later, the figures show the morphology.

[0067] Before decomposition, the fiber has a smooth surface (top) and cross section (bottom). The small black dots are air bubbles trapped during melt spinning. As the fiber decomposition time progresses, the surface becomes rough, and as the decomposition progresses further, the decomposition progresses to a worm-hole-like shape.

[0068] Production Example 2: Production of enzyme-embedded fiber including a kneading process Using the same PBAT pellets and decomposition enzymes as those used in Production Example 1, enzyme-embedded fibers were produced by a dry process. That is, the PBAT fiber and enzyme powder were thoroughly mixed, and the mixture was thermally kneaded in a melt kneader to prepare enzyme-embedded pellets. These pellets were fed into a melt spinning machine, and the extruded yarn was wound up to prepare enzyme-embedded fiber. This fiber was also wound up at three speeds as in Production Example 1, and samples with different fiber diameters were prepared.

[0069] Test 2: Decomposition test of enzyme-embedded fiber The degradation test of the enzyme-embedded fiber produced in Production Example 2 was carried out under the same environment as in Test 1. Figure 5 shows the relationship between the weight loss rate and decomposition time for enzyme-embedded fibers prepared at different winding speeds using the melt spinning method, and for enzyme-free fibers (control). As in Test 1, the faster the winding speed (fibers with a larger surface area per weight ratio), the faster the decomposition rate. Compared to the control fiber without enzyme, the weight loss rate is clearly higher. These results show that the enzyme does not lose its activity even when enzyme-embedded fibers are produced using the melt spinning method, which includes a heating step, and that biodegradability was successfully imparted by the addition of the enzyme.

[0070] Figure 6 shows scanning electron microscope images of the fiber side surface over the course of the decomposition experiment. The top image shows the fiber side surface, and the bottom image shows the cut surface (cross section) perpendicular to the fiber axis. From the left, the images are SEM images of the fiber after 0 hours (before decomposition), 24 hours, 96 hours, and 192 hours of decomposition.

[0071] Focusing on the side surface of the fiber (top), a rough surface and voids were observed after 96 hours. Observation of the cut surface showed that after 24 hours, some decomposed voids had appeared near the center, and after 96-192 hours, voids had spread across the entire cut surface. After 192 hours, large voids due to decomposition were observed. From these results, it is inferred that although the decomposition behavior differs slightly from that of the enzyme-embedded fiber via the cast film in Production Example 1, decomposition is progressing not only from the surface but also from the inside.

[0072] Production Example 3: Preparation of surface-coated fiber In both Tests 1 and 2, we succeeded in imparting biodegradability by embedding the enzyme in the fiber. Next, we attempted to cover (coat) the surface of the enzyme-embedded fiber with a thin film to prevent the enzyme embedded in the fiber from being released to the outside world. In this case, PBAT, the same as the base material of the enzyme-embedded fiber, was selected as the coating material. First, PBAT was dissolved in chloroform to prepare a PBAT solution. The enzyme-embedded fiber prepared in Test 2 was immersed in this PBAT solution, and the entire fiber, including the fiber side surfaces and both end faces, was completely covered with the PBAT solution. By drying in a hollow space, an enzyme-embedded fiber (biodegradable polymer composite material) coated with PBAT was prepared. As a result of observing this with an SEM (Figure 7), it was possible to distinguish the coated surface in a photograph of the surface cut perpendicular to the fiber axis, and the thickness of this surface was about 20 μm (Table 1).

[0073] [Table 1]

[0074] Test 3: Decomposition test of enzyme-embedded fiber with surface coating The decomposition test was carried out in an environment similar to that of Tests 1 and 2, using enzyme-embedded fiber (enzyme-embedded fiber of Example 1) produced by the method of Production Example 2 and coated with the coating of Production Example 3. To investigate the effect of the presence or absence of a coating, an experiment was also carried out simultaneously with an uncoated enzyme-embedded fiber (enzyme-embedded fiber of Comparative Example 1). The weight loss rate versus decomposition time for these fibers is shown in Figure 8. While decomposition proceeded slowly in the enzyme-embedded fiber of Comparative Example 1, decomposition proceeded rapidly in the enzyme-embedded fiber of Example 1, with the decomposition rate increasing by about five times.

[0075] The results of SEM observation of the enzyme-embedded fiber of Example 1 are shown in Figure 9. The upper part of the figure shows the side surface of the fiber, and the lower part of the figure shows the morphology of the active cross section. From the left, the decomposition times are 0 hours (before decomposition), 24 hours, 96 hours, and 192 hours. Focusing on the surface morphology of the fiber, it can be seen that the enzyme-embedded fiber of Example 1 has a coated portion on the surface. As the decomposition days progressed, the surface layer of the coating showed a morphology that appeared to have cracks. The weight loss rates at 0, 24, 96, and 192 hours were 0%, 9%, 25%, and 40%, respectively.

[0076] The results of SEM observation of the enzyme-embedded fiber of Comparative Example 1 are shown in Figure 10. In the enzyme-embedded fiber of Comparative Example 1, unlike the surface morphology of Example 1, decomposition had progressed in a worm-eaten pattern on the surface layer. Focusing on the active cross section in Figure 9, it was observed that in the coated fiber, the decomposition rate was indeed slow on the surface layer, with decomposition preferentially occurring from the center. The weight loss rates at 0, 24, 96, and 192 hours were 0%, 2%, 12%, and 34%, respectively.

[0077] These results demonstrated that the PBAT coating accelerated the degradation of the PBAT enzyme-embedded fiber compared to the uncoated enzyme-embedded fiber at this thickness, possibly because the coating prevented the enzyme from being released into the external system. [Explanation of symbols]

[0078] 1...biodegradable polymer composite, 10...substrate, 12...enzyme, 20...biodegradable polymer coating.

Claims

1. A substrate comprising a biodegradable polymer; an enzyme supported on the substrate and having activity of decomposing the biodegradable polymer; a biodegradable polymer coating disposed on the substrate; A biodegradable polymer composite comprising:

2. The biodegradable polymer composite material according to claim 1 , wherein the biodegradable polymer of the substrate and the polymer constituting the biodegradable polymer coating are of the same substance or type.

3. The biodegradable polymer composite material according to claim 1 , wherein the substrate is a fiber or a molded body.

4. The biodegradable polymer composite material according to claim 1, wherein the biodegradable polymer of the substrate and the polymer that is a component of the biodegradable polymer coating are the same or different and comprise a biodegradable polymer selected from the group consisting of polyesters, polycarbonates, polyurethanes, polyvinyl alcohols, polysaccharides and polysaccharide esters.

5. The biodegradable polymer composite material of claim 1 , wherein the enzyme is embedded in the biodegradable polymer.

6. The biodegradable polymer composite material according to claim 1 or 5, wherein the thickness of the biodegradable polymer coating is from 0.001 mm to 5 mm.

7. 13. Use of the biodegradable polymer composite material according to claim 1 for the manufacture of containers, packaging, building materials, agricultural tools or fishing equipment.

8. Mixing a biodegradable polymer with an enzyme having an activity of degrading the biodegradable polymer to form a substrate in which the enzyme having an activity of degrading the biodegradable polymer is supported within the biodegradable polymer; and providing a biodegradable polymeric coating over said substrate; A method for producing a biodegradable polymer composite material comprising:

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