Biodegradable plastic including enzyme and method for the same

Abstract

The present invention relates to a biodegradable plastic comprising a polymer carrier, a masterbatch containing a polysaccharide and an enzyme, and a biodegradable polymer. The enzyme may be encapsulated by the polymer carrier, and the polysaccharide may form a metal ion environment and promote degradation due to its hydrophilicity. By dispersing the masterbatch containing the enzyme in the biodegradable polymer, a biodegradable plastic with excellent degradation rate and efficiency in a room temperature environment can be provided.

Description

Technology Field

[0001] The present invention relates to a biodegradable plastic containing an enzyme and a method for manufacturing the same. Background Technology

[0002] Sustainable plastic materials are gaining attention due to the risks of climate change and landfill issues. Conventional non-biodegradable plastics have been identified as a major cause of environmental pollution because they do not decompose easily even when buried in soil. Consequently, there is a growing need for the development of bio-based plastic materials that can naturally decompose due to their biodegradability when landfilled.

[0003] Polylactic acid (PLA) can be cited as an example of a biodegradable, bio-based polymer material. PLA has attracted attention as a promising candidate for sustainable, eco-friendly plastic materials because it can decompose within six months in a high-temperature, high-humidity microbial environment of 50 to 60°C. However, under typical room temperature conditions of 25°C, it takes more than five years to practically decompose completely, which has limited its commercialization. Accordingly, a method has been proposed to add microorganisms and enzymes capable of degrading biodegradable polymer materials in order to accelerate the decomposition rate.

[0004] Maintaining enzyme activity is a critical challenge for improving the degradation rate of biodegradable plastics by adding enzymes. To preserve this activity, one approach is to encapsulate the enzymes and introduce them into the biodegradable plastics. However, conventional enzyme encapsulation methods have presented problems, such as inhibited enzyme activity due to heat treatment during the encapsulation process, or the risk of microplastic generation caused by the use of non-biodegradable materials. Furthermore, the organic solvents used in the encapsulation process have also caused environmental pollution issues.

[0005] Therefore, there is a need for technology that can commercialize eco-friendly biodegradable plastics with high degradation efficiency by encapsulating enzymes to introduce them into the plastic, thereby providing thermal and storage stability. The problem to be solved

[0006] The present invention aims to provide a biodegradable plastic with excellent biodegradability, in which enzyme activity and thermal stability are maintained.

[0007] The present invention aims to provide a method for manufacturing a biodegradable plastic capable of overcoming temperature limitations by master-batching an enzyme together with a polymer carrier and a polysaccharide containing metal ions. means of solving the problem

[0008] One embodiment of the present invention provides a biodegradable plastic comprising a polymer carrier, a masterbatch comprising a polysaccharide containing metal ions and an enzyme, and a biodegradable polymer.

[0009] The above polymer carrier may have a melting point of 40°C or higher and 65°C or lower.

[0010] The above polymer carrier may be one or more selected from the group consisting of poly(propylene succinate), polycaprolactone (PCL), poly(ethylene adipate) (PEA), poly(ethylene glycol adipate), or a combination thereof.

[0011] The above enzyme may form ionic bonds with at least some of the metal ions contained in the above polysaccharide.

[0012] The above polysaccharides may be one or more selected from the group consisting of carboxymethylcellulose, alginic acid, pectin, chitosan, oxalylated cellulose, phosphorylated cellulose complex, TEMPO-oxidized cellulose, or combinations thereof.

[0013] The above enzyme may be one or more selected from the group consisting of Proteinase K, Lipase, Cutinase, Esterase, or combinations thereof.

[0014] The above masterbatch may contain the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:1.

[0015] The above enzyme may be included in an amount of 1 to 20 parts by weight per 100 parts by weight of the above masterbatch.

[0016] The above biodegradable polymer may be one or more selected from the group consisting of PLA, PCL, PBS, PHB, PHBV, PGA, PLGA, PBAT, or combinations thereof.

[0017] The above masterbatch may be included in an amount of 1 to 20 parts by weight per 100 parts by weight of the above biodegradable polymer.

[0018] The above masterbatch may have a degree of crystallization of 20% or less.

[0019] The above biodegradable plastic may satisfy ISO014855 or ISO014855-1 regulations.

[0020] One embodiment of the present invention provides a method for manufacturing a biodegradable plastic comprising the steps of: manufacturing a support comprising a polymer carrier and a polysaccharide comprising a metal ion; manufacturing a masterbatch comprising the support and an enzyme; and manufacturing a biodegradable plastic comprising the masterbatch and a biodegradable polymer.

[0021] The step of manufacturing the above support may involve mixing the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:1 at 100 to 150 ℃ and injecting.

[0022] The step of manufacturing the above masterbatch is,

[0023] The enzyme may be mixed in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the support at 70 ℃ or lower and injected.

[0024] The step of manufacturing the above biodegradable plastic may involve mixing 1 to 20 parts by weight of the masterbatch with 100 parts by weight of the above biodegradable polymer at 150 to 200 ℃ and injecting.

[0025] The above method for manufacturing biodegradable plastic may further include a step of pre-treating by stirring the enzyme with metal ions.

[0026] The above method for manufacturing biodegradable plastic may further include a step of pre-treating polysaccharides by stirring them with metal ions. Effects of the invention

[0027] The biodegradable plastic according to the present invention has excellent enzyme activity and thermal stability, so the decomposition rate and efficiency can be excellent.

[0028] The method for manufacturing biodegradable plastic according to the present invention allows the activity of the enzyme to be maintained even when injected at high temperatures, as the enzyme is encapsulated. Brief explanation of the drawing

[0029] Figure 1 is a graph showing the weight loss over time for (a) Comparative Experiment Example 1-2 (PPS + Pro K 1%) and Experiment Example 1-1 (Pro K 1% in PPS), and (b) Comparative Experiment Example 1-3 (PPS + Pro K 5%) and Experiment Example 1-2 (Pro K 5% in PPS). Figure 2 shows SEM images of the PPS film of Comparative Experimental Example 1-2 before (a) and after (a-1) 60 days of experiment, and SEM images of the PPS film containing the enzyme of Experimental Example 1-1 before (b) and after (b-1) 60 days of experiment. Figure 3 is a graph showing the weight loss over time for Experimental Example 2-1 (PPS + Pro K 1%) and Experimental Example 2-2 (Pro K in PPSCC). Figure 4 shows SEM images of the enzyme-embedded PPS film of Experimental Example 2-1 before (a) and after (a-1) 60 days, and SEM images of the enzyme-embedded PPSCC film of Experimental Example 2-2 before (b) and after (b-1) 60 days. Figure 5 is a graph showing the weight loss over time for Comparative Experiment Example 3-1 (PPSCC), Experiment Example 3-1 (PPSCC 60), Experiment Example 3-2 (PPSCC 80), Experiment Example 3-3 (PPSCC 100), and Experiment Example 3-4 (PPSCC 150). Figure 6 is a graph showing the weight loss over time of Comparative Experiment Example 3-2 (PPS), Comparative Experiment Example 3-3 (PPS 60), Comparative Experiment Example 3-4 (PPS 100), and Comparative Experiment Example 3-5 (PPS 150). Figure 7 is a graph showing the weight loss over time of Comparative Experiment Example 3-1 (PPSCC), Experiment Example 3-1 (PPSCC 60), Experiment Example 3-3 (PPSCC 100), and Experiment Example 3-4 (PPSCC 150). FIG. 8 is an SEM image of the PPSCC films of (a) Experimental Example 3-1, (b) Experimental Example 3-2, (c) Experimental Example 3-3, and (d) Experimental Example 3-4 before the experiment, and an SEM image of the PPSCC films of (e) Experimental Example 3-1, (f) Experimental Example 3-2, (g) Experimental Example 3-3, and (h) Experimental Example 3-4 after 60 days. Figure 8 shows (i) an SEM image and (j) a calcium element mapping image of the PPSCC film (enzyme-containing masterbatch support) of Experimental Example 3 before the experiment, and (k) an SEM image and (l) a calcium element mapping image of the PPSCC film (enzyme-containing masterbatch support) of Experimental Example 3 after 60 days. Figure 9 is an image showing the decomposition process of (a) Comparative Experiment Example 4-1 (Neat PLA) and (b) Experiment Example 4-1 (PLA Msb). Figure 10 is a graph of the ISO14855 soil decomposition test of Comparative Experiment Example 4-1 (PLA) and Experiment Example 4-1 (PLA-M). Figure 11 is an XRD analysis graph of (a) PPS film and (b) PPSCC film. Figure 12 is a DSC analysis graph of PLA containing the masterbatch of Experimental Example 4-1 (PLA-M). FIG. 13 is (a) a tensile test graph of a single PLA and a PLA with a masterbatch of Experimental Example 4-1 (PLA-M) embedded therein, and (b) a tensile test graph of a PLA with a masterbatch of Experimental Example 4-1 (PLA-M) embedded therein. Specific details for implementing the invention

[0030] Hereinafter, each component of the present invention is described in more detail so that a person skilled in the art to which the present invention pertains can easily implement it; however, this is merely an example, and the scope of the rights of the present invention is not limited by the following.

[0031] The term “comprising” as used herein is used when listing materials, compositions, devices, and methods useful for the present invention, and is not limited to the examples listed.

[0032] As used herein, "about" and "substantially" are used to mean a range of numerical values ​​or degrees or approximations thereof, taking into account inherent manufacturing and material tolerances, and are used to prevent an infringer from unfairly exploiting the disclosure in which precise or absolute figures provided to aid in understanding the invention are mentioned.

[0033] Although the present invention has been described below by specific examples and embodiments, the present invention is not limited thereto and may include a combination of one or more of the specific examples and embodiments by those skilled in the art to which the present invention belongs, and various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below.

[0035] One embodiment of the present invention provides a biodegradable plastic comprising a polymer carrier, a masterbatch comprising a polysaccharide containing metal ions and an enzyme, and a biodegradable polymer.

[0036] The above polymer carrier can encapsulate the enzyme and may be a polymer material having a low melting point.

[0037] The above polymer carrier may have a melting point of 40°C or higher and 65°C or lower. Specifically, the above polymer carrier may have a melting point of 45°C or higher and 65°C or lower, 50°C or higher and 65°C or lower, 55°C or higher and 65°C or lower, 45°C or higher and 60°C or lower, 50°C or higher and 60°C or lower, or 55°C or higher and 60°C or lower. To prevent denaturation of the enzyme and reduction of activity, the above polymer carrier may be selected as a material that melts at a low temperature and is mixed with the enzyme and polysaccharide and then injected. The melting point of the above polymer carrier may be selected according to the temperature at which the enzyme activity decreases, but generally, a polymer material that is mixed and injected at a temperature of about 60°C may be selected due to a low melting point of 65°C or lower.

[0038] The above polymer carrier may be one or more selected from the group consisting of poly(propylene succinate), polycaprolactone (PCL), poly(ethylene adipate) (PEA), poly(ethylene glycol adipate), or combinations thereof. In one embodiment of the present invention, poly(propylene succinate) (PPS) was used as the polymer carrier, but is not limited thereto. Polymer materials of the above types have a low melting point, can be degraded by enzymes as they contain an ester structure, and have excellent processability, so they can be used as a carrier for dispersing enzymes and polysaccharides.

[0040] The above PPS can be synthesized by esterifying and polycondensing succinic acid and propanediol. Specifically, the above PPS can be synthesized by polycondensing the above succinic acid and the above propanediol in a weight ratio of 1:1 to 1:5. Specifically, the above PPS can be synthesized as shown in Reaction Scheme 1 below.

[0041] [Reaction Equation 1]

[0042]

[0044] Due to its hydrophilicity, the above polysaccharide can absorb moisture from the surroundings when exposed to a soil environment, thereby inducing swelling of the biodegradable polymer chains and promoting the hydrolysis reaction of the biodegradable polymer. In addition, the above polysaccharide may contain metal ions, so a metal ion environment that improves enzyme activity and temperature stability can be created within the masterbatch.

[0045] The above polysaccharide may be one or more selected from the group consisting of carboxymethylcellulose, alginic acid, pectin, chitosan, oxalylated cellulose, phosphorylated cellulose complex, TEMPO-oxidized cellulose, or combinations thereof. The polysaccharide materials of the above types are hydrophilic polymers that can aid in biodegradability and can easily introduce metal ions through terminal modification. For example, the above polysaccharide can easily incorporate metal ions either directly or by modifying the terminals.

[0046] The above polysaccharide may contain metal ions. Specifically, the above polysaccharide may contain one or more selected from the group consisting of calcium ions, manganese ions, magnesium ions, strontium ions, or combinations thereof. Preferably, the above polysaccharide may contain calcium ions.

[0047] In one embodiment of the present invention, calcium ion-modified carboxymethylcellulose (CMC) was used as the polysaccharide containing the metal ion, but is not limited thereto. The carboxymethylcellulose has a carboxyl group (COO) at the terminal end. - Calcium ions (Ca ) including cations 2+ Metal ions such as ) can be easily introduced. When the metal ions are dispersed on a polymer carrier together with the enzyme, a metal ion environment can be created to improve the activity and thermal stability of the enzyme.

[0048] The enzyme may be a microorganism or protein capable of promoting the degradation of a biodegradable polymer or biodegradable plastic. The enzyme may be one or more selected from the group consisting of Proteinase K, Lipase, Cutinase, Esterase, or combinations thereof. By encapsulating and introducing the aforementioned types of enzymes into a bio-based biodegradable polymer, the degradation rate and stability can be improved.

[0049] The enzyme may form ionic bonds with at least some of the metal ions contained in the polysaccharide. The enzyme's activity is enhanced by ionic bonding with the metal ions. In one embodiment of the present invention, the enzyme may be primarily pretreated by contacting it with metal ions, and a metal ion environment may be secondarily created by encapsulating it together with a polysaccharide containing metal ions. When the enzyme is exposed to a metal ion environment, its tertiary structure may be stabilized through ionic bonding, thereby improving thermal stability. Through the stabilization of the tertiary structure, structural denaturation of the enzyme is minimized and its activity is maintained, thereby improving storage stability.

[0050] The above masterbatch may be prepared by mixing and injecting the polymer carrier and the polysaccharide containing the metal ion to form a support for encapsulating an enzyme, and mixing and injecting the support and the enzyme.

[0051] The above masterbatch may comprise the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:1. Specifically, the above masterbatch may comprise the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:1, 10:1 to 7:1, or 10:1 to 9:1. If the polysaccharide is included in excess of the above-described range, encapsulation of the enzyme may not occur. If the polymer carrier is included in excess of the above-described range, a metal ion environment may not be formed, which may inhibit the activity of the enzyme. By preparing a masterbatch with the above-described weight range, the enzyme can be stably encapsulated, a metal ion environment can be formed, and the degradation efficiency of the biodegradable polymer can be improved due to hydrophilicity.

[0052] The enzyme may be included in an amount of 1 to 20 parts by weight per 100 parts by weight of the masterbatch. Specifically, the enzyme may be included in an amount of 1 to 20 parts by weight, 1 to 10 parts by weight, or 1 to 5 parts by weight per 100 parts by weight of the masterbatch. By including the enzyme in the masterbatch within the above-described range, the degradation rate and efficiency of the biodegradable polymer can be improved.

[0053] The above masterbatch may have a degree of crystallization of 20% or less. Specifically, the above masterbatch may have a degree of crystallization of 20% or less, 15% or less, or 5% or more. The degree of crystallization can be measured through XRD analysis. The above masterbatch can maximize the amorphous structure by reducing the degree of crystallization of the polymer carrier through mixing the polysaccharide with the polymer carrier and injecting it. When the degree of crystallization of the above masterbatch is within the range described above, the activity of the enzyme can be protected, and at the same time, during biodegradation, the enzyme can break out of the masterbatch effectively, thereby enabling efficient biodegradation and encapsulation to be achieved simultaneously.

[0054] The above-mentioned biodegradable plastic may be manufactured by mixing a masterbatch containing the enzyme with a biodegradable polymer and injecting it. Specifically, the above-mentioned biodegradable plastic may be one in which the masterbatch containing the enzyme is dispersed in the biodegradable polymer.

[0055] The above-mentioned biodegradable polymer may be one or more selected from the group consisting of PLA, PCL (Polycaprolactone), PBS (Polybutylene Succinate), PHB (Polyhydroxybutyrate), PHBV, PGA (Polyglycolic Acid), PLGA, PBAT (Polybutylene Adipate Terephthalate), or combinations thereof. By using the above-mentioned types of biodegradable polymer materials, self-degradation can occur in a soil environment, and the degradation rate and efficiency can be increased due to the activity of the enzyme included in the masterbatch.

[0056] In one embodiment of the present invention, PLA was used as the biodegradable polymer, but is not limited thereto.

[0057] The above-mentioned PLA (polylactic acid) is a biodegradable polymer having repeating ester units and can be synthesized using lactic acid derived from corn starch, sugarcane, tapioca, etc. Although the above-mentioned PLA possesses inherent biodegradability, it has been difficult to commercialize because it takes a long time to completely decompose in a soil environment at room temperature. By mixing a masterbatch containing an enzyme according to the present invention with a biodegradable polymer such as the above-mentioned PLA and extruding and dispersing it, the decomposition speed and efficiency are increased, thereby providing a biodegradable polymer that self-decomposes in a soil environment.

[0058] The masterbatch may be included in an amount of 1 to 20 parts by weight per 100 parts by weight of the biodegradable polymer. Specifically, the masterbatch may be included in an amount of 1 to 10 parts by weight, 1 to 10 parts by weight, or 1 to 5 parts by weight per 100 parts by weight of the biodegradable polymer. By including the masterbatch within the above-described range, the mechanical properties of the plastic material, which can be used in commercially available food containers, packaging containers, disposable straws, etc., can be maintained.

[0059] The above-mentioned biodegradable plastic may satisfy the ISO 14855 standard or the ISO 14855-1 standard. The ISO 14855 standard is an international standard for evaluating the degree of decomposition of materials, such as biodegradable plastics, in a composting soil environment. The ISO 14855-1 standard is an international standard for verifying the biodegradability of a sample through the decomposition rate calculated by measuring the carbon dioxide generated after placing the sample in a stationary composting reactor.

[0060] The above-mentioned biodegradable plastic may exhibit excellent biodegradability by satisfying the ISO 014855 international standard as a masterbatch comprising encapsulated enzymes, a polymer carrier, and hydrophilic polysaccharides is included or dispersed in the biodegradable polymer.

[0061] The above-mentioned biodegradable plastic has excellent processability and can be used as a biodegradable plastic material for food containers, packaging containers, disposable items, etc. In addition, the biodegradable plastic has excellent biodegradability and can contribute to solving environmental problems.

[0063] One embodiment of the present invention provides a method for manufacturing a biodegradable plastic comprising the steps of: manufacturing a support comprising a polymer carrier and a polysaccharide comprising a metal ion; manufacturing a masterbatch comprising the support and an enzyme; and manufacturing a biodegradable plastic comprising the masterbatch and a biodegradable polymer. Any content overlapping with that described in the biodegradable plastic is replaced by the description of the preceding embodiment.

[0064] The step of manufacturing the above support may involve mixing the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:1 at 100 to 150 ℃ and injecting.

[0065] The step of preparing the above masterbatch may involve mixing 1 to 20 parts by weight of the enzyme with 100 parts by weight of the support at 70°C or lower and injecting. Through the above-described step, the enzyme can be encapsulated by uniformly dispersing it within the masterbatch without inhibiting the activity of the enzyme. As the enzyme is encapsulated through the above-described step, the enzyme's activity is maintained even when exposed to a high-temperature environment for subsequent mixing with other polymer materials and injection, thereby ensuring excellent thermal stability.

[0066] The step of manufacturing the above biodegradable plastic may involve mixing 1 to 20 parts by weight of the masterbatch with 100 parts by weight of the biodegradable polymer at 150 to 200 ℃ and injecting. Through the above-described step, the masterbatch can be uniformly dispersed within the biodegradable polymer. In addition, since the enzyme is stably encapsulated within the masterbatch, the enzyme's activity can be maintained even when exposed to a high-temperature environment within the above-described temperature range.

[0067] The above method for manufacturing biodegradable plastic may further include a step of pre-treating an enzyme by stirring it with metal ions. By pre-treating the enzyme by stirring it with metal ions, the three-dimensional structure is stabilized due to ionic bonding between the enzyme and the metal ions, thereby improving thermal stability.

[0068] The above method for manufacturing biodegradable plastic may further include a step of pre-treating a polysaccharide by stirring it with metal ions. By stirring the polysaccharide with metal ions, metal ions can be introduced to the terminals, and a metal ion environment that maintains enzyme activity can be created as the polysaccharide is included together with an enzyme in a masterbatch.

[0069] The injection step performed in the above method for manufacturing biodegradable plastic may be carried out using a mini-jet injection machine (twin-screw injection machine, Mini Jet Haake). The mini-jet injection machine can process masterbatches or biodegradable polymers by melting the polymer itself without using toxic solvents. In addition, the mini-jet injection machine can maintain constant temperature conditions during the mixing and injection processes, making it effective for temperature control.

[0071] The present invention will be explained in more detail below through specific embodiments and experimental examples. The following embodiments and experimental examples are intended to illustrate the present invention, and the present invention is not limited by the following embodiments and experimental examples.

[0073] Examples

[0074] Activation of decomposition enzymes

[0075] Proteinase K (purchased from Aldrich) was prepared as the enzyme. The enzyme and CaCl2 were mixed in a weight ratio of 10:1 in a 50 mM Tris buffer solution and stirred at room temperature for 20 minutes. After stirring, the solution was freeze-dried for 24 hours to recover it in powder form, thereby obtaining the activated enzyme.

[0077] Preparation of enzyme supports

[0078] Poly(propylene succinate) (hereinafter referred to as "PPS") was prepared by esterifying and polymerizing succinic acid and propanediol in a ratio of 1:1.2.

[0079] Carboxymethylcellulose (CMC) and CaCl2 were mixed in a weight ratio of 1.5:1 in a 50 mM Tris buffer solution and stirred for 3 hours, then freeze-dried for 24 hours to recover the calcium-modified cellulose (hereinafter referred to as "CaCMC").

[0080] A support was manufactured by mixing the above PPS and CaCMC in a weight ratio of 9:1 at 130°C for 15 minutes and then injecting. A Mini Jet Haake was used for the above process, and the temperature of both the cylinder section and the mold section was fixed at 130°C.

[0082] Manufacture of masterbatch

[0083] A masterbatch was prepared by mixing the above-prepared support and the above-obtained enzyme in a weight ratio of 95:5 using a mini-jet injector at 60°C for 10 minutes and then injecting.

[0085] PLA manufacturing with built-in masterbatch

[0086] Polylactic acid (PLA) and the masterbatch prepared above were mixed in a weight ratio of 95:5 using a mini-jet injection molder at 180°C for 10 minutes and then injected to produce a final PLA polymer.

[0088] Experimental Example 1. Comparison of Degradation of PPS by Enzyme Ingestion

[0089] It was confirmed that the activity of the Proteinase K enzyme was maintained even after the masterbatch injection process maintained at 60°C. Film samples (40 mm × 40 mm, thickness 2.5 mm, weight 0.6 g) were immersed in a 50 mM Tris buffer solution at pH 8.0 and incubated at 50 RPM in a 37°C incubator. The weight loss rate was recorded every 24 hours, and the experiment was conducted for a total of 8 weeks.

[0090] Comparative Experiment Example 1-1.

[0091] A single PPS film was used as the film sample.

[0092] Comparative Experiment Example 1-2. PPS + Pro K 1%

[0093] A single PPS film was immersed in a buffer solution, and 1 wt% of Proteinase K enzyme relative to the weight of the single PPS film was separately dispersed in the buffer solution.

[0094] Experimental Example 1-1. Pro K 1% in PPS

[0095] For the film sample, a PPS film was used that was injected after mixing PPS film and Proteinase K enzyme in a weight ratio of 99:1 using a mini-jet injection machine at 60°C for 10 minutes.

[0096] Comparative Experiment Example 1-3. PPS + Pro K 5%

[0097] A single PPS film was immersed in a buffer solution, and 5 wt% of Proteinase K enzyme relative to the weight of the single PPS film was separately dispersed in the buffer solution.

[0098] Experimental Example 1-2. Pro K 5% in PPS

[0099] For the film sample, a PPS film was used that was injected after mixing PPS film and Proteinase K enzyme in a weight ratio of 95:5 using a mini-jet injection machine at 60°C for 10 minutes.

[0101] Comparative Experiment Example 1-1 Comparative Experiment Example 1-2 Experimental Example 1-1 Comparative Experiment Examples 1-3 Experimental Example 1-2 Types of support PPS PPS PPS PPS PPS Support:Enzyme weight ratio 100:0 100:0 (1 wt% dispersion in solution) 99:1 100:0 (5 wt% dispersed in solution) 95:5 Weight loss rate (%) 4 17.75 19.79 18.61 20.92

[0103] Figure 1 is a graph showing the weight loss over time for (a) Comparative Experiment Example 1-2 (PPS + Pro K 1%) and Experiment Example 1-1 (Pro K 1% in PPS), and (b) Comparative Experiment Example 1-3 (PPS + Pro K 5%) and Experiment Example 1-2 (Pro K 5% in PPS).

[0104] Referring to Table 1 and Figure 1 above, it can be confirmed that the activity of the enzyme is maintained even when exposed to a temperature environment of 60°C during the process of mixing the enzyme with the support and injection. Referring to the weight loss rate in Table 1 above, it was confirmed that the weight loss rate of Experimental Examples 1-1 and 1-2, in which the enzyme is embedded in the support, is superior to the values ​​of Comparative Experimental Examples 1-2 and 1-3, in which the enzyme is separately dispersed in a buffer solution without being exposed to a temperature environment of 60°C.

[0106] Figure 2 shows SEM images of the PPS film of Comparative Experimental Example 1-2 before (a) and after (a-1) 60 days of experiment, and SEM images of the PPS film containing the enzyme of Experimental Example 1-1 before (b) and after (b-1) 60 days of experiment.

[0107] Referring to Figure 2 above, it can be seen that in the case of Comparative Experimental Example 1-2, decomposition occurred only on the surface of the film, whereas in the case of Experimental Example 1-1, the enzyme maintained its activity even when mixed and injected at a temperature of 60°C, and as it was embedded inside the film, it was confirmed that deep decomposition occurred overall from the inside of the film.

[0108] From the above results, it was confirmed that when the enzyme was directly introduced into the PPS film compared to simply dispersing it in a buffer solution, the weight loss due to enzyme activity was higher as the specific surface area in contact with the support increased, and it was also confirmed that the enzyme activity was maintained even when extruded by a twin screw.

[0110] Experimental Example 2. Confirmation of maintenance of enzyme activity following the inclusion of CaCMC

[0111] We verified whether the enzyme could maintain activity using a support masterbatch containing PPS and CaCMC, and confirmed whether the stabilization and storage stability of Proteinase K were improved by introducing calcium ions. Film samples (40 mm × 40 mm, thickness 2.5 mm, weight 0.6 g) were immersed in a 50 mM Tris buffer solution at pH 8.0 and incubated at 50 RPM in a 37 ℃ incubator. The weight loss rate was recorded every 24 hours, and the experiment was conducted for a total of 8 weeks.

[0112] Comparative Experiment Example 2-1.

[0113] A single PPS film was used as the film sample.

[0114] Experimental Example 2-1. Pro K 1% in PPS

[0115] For the film sample, a PPS film was used that was injected after mixing PPS film and Proteinase K enzyme in a weight ratio of 99:1 using a mini-jet injection machine at 60°C for 10 minutes.

[0116] Experimental Example 2-2. Pro K in PPSCC

[0117] A support film (PPSCC) was prepared by mixing PPS and CaCMC in a weight ratio of 9:1 using a mini-jet injection molder at 130°C for 15 minutes and then injecting. A PPSCC film sample containing the enzyme was prepared by mixing the support film and Proteinase K enzyme in a weight ratio of 99:1 using a mini-jet injection molder at 60°C for 10 minutes and then injecting.

[0118] As a film sample, a PPSCC film containing the enzyme prepared above was used.

[0120] Comparative Experiment Example 2-1 Experimental Example 2-1 Experimental Example 2-2 Types of support PPS PPS PPSCC Support:Enzyme weight ratio 100:0 99:1 99:1 Weight loss rate (%) 4 19.79 34.05

[0122] Figure 3 is a graph showing the weight loss over time for Experimental Example 2-1 (PPS + Pro K 1%) and Experimental Example 2-2 (Pro K in PPSCC).

[0123] Referring to Table 2 and Figure 3 above, it was confirmed that by preparing a support by mixing calcium ion-introduced cellulose with PPS, the activity of Proteinase K enzyme is significantly increased when the enzyme is embedded and exposed to a calcium ion atmosphere.

[0124] Referring to Figure 3, it can be seen that the point at which the enzyme activity decreases to 90% is 9 days for Experimental Example 2-1 and 14 days for Experimental Example 2-2. Through the above results, it was confirmed that by introducing CaCMC into the masterbatch, the storage stability of the enzyme can be improved by enhancing the duration of activity maintenance of the Proteinase K enzyme.

[0126] Figure 4 shows SEM images of the enzyme-embedded PPS film of Experimental Example 2-1 before (a) and after (a-1) 60 days, and SEM images of the enzyme-embedded PPSCC film of Experimental Example 2-2 before (b) and after (b-1) 60 days.

[0127] Referring to Figure 4, it was confirmed that film degradation occurred more locally and significantly when the masterbatch was prepared by embedding the enzyme in a support to which CaCMC was introduced.

[0129] Experimental Example 3. Confirmation of the thermal stability of the enzyme with the inclusion of CaCMC

[0130] We investigated whether the thermal stability of Proteinase K was improved by introducing calcium ions. Film samples (40 mm × 40 mm, thickness 2.5 mm, weight 0.6 g) were immersed in a 50 mM Tris buffer solution at pH 8.0 and incubated at 50 RPM in a 37 ℃ incubator. The weight loss rate was recorded every 24 hours, and the experiment was conducted for a total of 8 weeks.

[0132] Comparative Experiment Example 3-1. PPSCC

[0133] As a film sample, a PPSCC film without enzyme mixing (PPS:CaCMC=9:1 weight ratio) was used. At this time, the film injection temperature was maintained at 60 ℃.

[0134] Experimental Example 3-1. PPSCC 60

[0135] A PPSCC film containing enzymes was used, which was produced by mixing a film sample, a PPSCC support film, and a Proteinase K enzyme in a weight ratio of 99:1 using a mini-jet injector at 60°C for 10 minutes and then injecting.

[0136] Experimental Example 3-2. PPSCC 80

[0137] In the above Experimental Example 3-1, the experiment was conducted in the same manner as Experimental Example 3-1, except that the temperature was set to 80 ℃.

[0138] Experimental Example 3-3. PPSCC 100

[0139] In Experimental Example 3-1 above, the experiment was conducted in the same manner as Experimental Example 3-1 above, except that the temperature was set to 100 ℃.

[0140] Experimental Example 3-4. PPSCC 150

[0141] In the above Experimental Example 3-1, the experiment was conducted in the same manner as Experimental Example 3-1, except that the temperature was set to 150 ℃.

[0143] Comparative Experiment Example 3-1 Experimental Example 3-1 Experimental Example 3-2 Experimental Example 3-3 Experimental Example 3-4 Types of support PPSCC PPSCC PPSCC PPSCC PPSCC Support:Enzyme weight ratio 100:0 99:1 99:1 99:1 99:1 Injection temperature (°C) 60 60 80 100 150 Weight loss rate (%) 10.41 34.05 34.46 34.92 26.09

[0145] Figure 5 is a graph showing the weight loss over time for Comparative Experiment Example 3-1 (PPSCC), Experiment Example 3-1 (PPSCC 60), Experiment Example 3-2 (PPSCC 80), Experiment Example 3-3 (PPSCC 100), and Experiment Example 3-4 (PPSCC 150).

[0146] Referring to Table 3 and Figure 5 above, it was confirmed that Proteinase K enzyme, which generally loses activity when exposed to temperatures above 60°C, can maintain significant activity even when injected at 100°C due to the calcium ion environment created by CaCMC.

[0148] Comparative Experiment Example 3-2.

[0149] In the above Comparative Experiment Example 3-1, the experiment was conducted in the same manner as in Comparative Experiment Example 3-1, except that a PPS film was used.

[0150] Comparative Experiment Example 3-3.

[0151] In Experimental Example 3-1 above, the experiment was conducted in the same manner as Experimental Example 3-1, except that a PPS film containing an enzyme was used.

[0152] Comparative Experiment Example 3-4.

[0153] In Experimental Example 3-3 above, the experiment was conducted in the same manner as Experimental Example 3-3 above, except that a PPS film containing an enzyme was used.

[0154] Comparative Experiment Example 3-5.

[0155] In the above Experimental Example 3-4, the experiment was conducted in the same manner as in Experimental Example 3-4, except that a PPS film containing an enzyme was used.

[0156] Comparative Experiment Example 3-2 Comparative Experiment Example 3-3 Comparative Experiment Example 3-4 Comparative Experiment Example 3-5 Types of support PPS PPS PPS PPS Support:Enzyme weight ratio 100:0 99:1 99:1 99:1 Injection temperature (°C) 60 60 100 150 Weight loss rate (%) 10.41 16.04 15.21 14.97

[0158] Figure 6 is a graph showing the weight loss over time of Comparative Experiment Example 3-2 (PPS), Comparative Experiment Example 3-3 (PPS 60), Comparative Experiment Example 3-4 (PPS 100), and Comparative Experiment Example 3-5 (PPS 150).

[0159] Figure 7 is a graph showing the weight loss over time of Comparative Experiment Example 3-1 (PPSCC), Experiment Example 3-1 (PPSCC 60), Experiment Example 3-3 (PPSCC 100), and Experiment Example 3-4 (PPSCC 150).

[0161] Referring to Figures 6 and 7, it can be observed that the degradation rate of the enzyme tends to increase as it is exposed to a calcium ion environment, and it was confirmed that the inclusion of CaCMC in the masterbatch can increase the degradation rate of the enzyme by causing salt dissociation in the aqueous phase. In addition, it was confirmed that the storage stability of the enzyme can also be improved, as the period during which the enzyme activity is maintained at 90% was 9 days on the PPS support, but was extended from 14 days to a maximum of 22 days on the PPSCC support depending on the injection temperature.

[0163] FIG. 8 is an SEM image of the PPSCC films of (a) Experimental Example 3-1, (b) Experimental Example 3-2, (c) Experimental Example 3-3, and (d) Experimental Example 3-4 before the experiment, and an SEM image of the PPSCC films of (e) Experimental Example 3-1, (f) Experimental Example 3-2, (g) Experimental Example 3-3, and (h) Experimental Example 3-4 after 60 days.

[0164] Figure 8 shows (i) an SEM image and (j) a calcium element mapping image of the PPSCC film (enzyme-containing masterbatch support) of Experimental Example 3 before the experiment, and (k) an SEM image and (l) a calcium element mapping image of the PPSCC film (enzyme-containing masterbatch support) of Experimental Example 3 after 60 days.

[0165] Referring to Fig. 8, it was confirmed that the film degradation occurred smoothly even when extruded in a high-temperature environment as the enzyme was embedded in a support containing CaCMC. Additionally, referring to the calcium element mapping image, it was confirmed that calcium ions were uniformly dispersed in the support using a twin-screw melt extrusion device (mini-jet extrusion machine), thereby creating a metal ion environment that enhances the activity of the enzyme.

[0167] Experimental Example 4. Confirmation of soil decomposition according to ISO 14855 standards

[0168] The degree of decomposition in actual soil was verified in accordance with the ISO 14855 soil decomposition test standard.

[0169] Comparative Experiment Example 4-1.

[0170] 20 g of solid PLA polymer molded at 180 ℃ was diluted in 120 g of compost and stored at 60 ℃. The degradation rate of the polymer was measured for 45 days by measuring the amount of carbon dioxide generated using a soil decomposition device.

[0171] At this time, the decomposition rate was calculated using the following Equations 1 and 2.

[0172] [Equation 1]

[0173] ThCO2= M TOT × C TOT × 44 / 12

[0174] [Equation 2]

[0175] D t = {(CO2) T - (CO2) B} / ThCO2

[0176] The above ThCO2 refers to the theoretical amount of carbon dioxide generated, and the above M TOT represents the mass of solids added to the compost at the start of the test, and the above C TOT represents the ratio (g / g) of organic carbon contained in the total dry solid content of the test substance.

[0177] The above D t represents biodegradability, and the above (CO2) T represents the cumulative amount of carbon dioxide (g / container) generated from the composting container containing the test material, and the above (CO2) B represents the average (g / container) of the cumulative amount of carbon dioxide generated from the inoculum container.

[0179] Experimental Example 4-1.

[0180] 20 g of solid PLA polymer containing the masterbatch prepared in the above example was diluted in 120 g of compost and stored at 60 ℃. The degradation rate of the polymer was measured for 45 days by measuring the amount of carbon dioxide generated using a soil degradation device.

[0182] Figure 9 is an image showing the decomposition process of (a) Comparative Experiment Example 4-1 (Neat PLA) and (b) Experiment Example 4-1 (PLA Msb).

[0183] Referring to Fig. 9, it was confirmed that in the case of the polymer according to the embodiment of the present invention, the amount of remaining material at week 7 is significantly small, thus confirming that a high degree of decomposition can be achieved.

[0185] Figure 10 is a graph of the ISO14855 soil decomposition test of Comparative Experiment Example 4-1 (PLA) and Experiment Example 4-1 (PLA-M).

[0186] Referring to Fig. 10, in the ISO 14855 test, which is an international standard for the degradation rate of biodegradable plastics in a soil environment, it can be seen that the degradation rate of the biodegradable PLA polymer embedded with the enzyme-containing masterbatch of Experimental Example 4-1 according to one embodiment of the present invention is more than twice that of Comparative Experimental Example 4-1. In addition, while it takes 17 days for the general Comparative Experimental Example 4-1 PLA to begin hydration, it was observed that Experimental Example 4-1 began degradation immediately without any time required for hydration. It was confirmed that the above results are due to the inclusion of hydrophilic CaCMC in the masterbatch support.

[0188] Experimental Example 5. Confirmation of the degree of crystallization of the masterbatch support according to the inclusion of CaCMC

[0189] In the same manner as in Experimental Example 2 above, a PPSCC film containing CaCMC and a PPS film not containing CaCMC were prepared. The crystallinity of the prepared polymer films was compared through X-ray Diffraction (XRD) analysis.

[0190] Figure 11 is an XRD analysis graph of (a) a PPS film and (b) a PPSCC film. Referring to Figure 11 and the XRD analysis results, it was confirmed that the crystallinity of the PPS film is 22% and the crystallinity of the PPSCC film is 15%. Through these results, it was confirmed that the inclusion of CaCMC in the masterbatch support further reduces the crystallinity of the amorphous PPS polymer, thereby allowing the embedded enzyme to be released more easily from the masterbatch support, which can improve the degradation rate of the support polymer and the biodegradable polymer.

[0192] Experimental Example 6. Example: Confirmation of the melting point of a biodegradable polymer

[0193] The melting point of a biodegradable PLA polymer containing a masterbatch including an enzyme according to an embodiment of the present invention was confirmed through Differential Scanning Calorimetry (DSC) analysis.

[0194] Figure 12 is a DSC analysis graph of PLA containing the masterbatch of Experimental Example 4-1 (PLA-M). Referring to Figure 12, the melting point of the biodegradable PLA polymer containing the enzyme masterbatch of the example was measured to be 165.37 °C, confirming that it does not differ significantly from the melting point of general PLA. As a result of the above, it was confirmed that biodegradable polymers such as PLA can be utilized in the melt extrusion process using a mini-jet injection molding machine, and that even with the inclusion of enzymes, there is no change in thermal properties, so they can still be utilized in injection molding through the melt extrusion process.

[0196] Experimental Example 7. Example: Confirmation of mechanical properties of biodegradable PLA

[0197] FIG. 13 is (a) a tensile test graph of a single PLA and a PLA with a masterbatch of Experimental Example 4-1 (PLA-M) embedded therein, and (b) a tensile test graph of a PLA with a masterbatch of Experimental Example 4-1 (PLA-M) embedded therein.

[0199] Tensile strength (MPa) Growth rate (%) Young's modulus (GPa) PLA 69.86 ± 1.1 4.33 ± 2 3.3 ± 0.4 PLA-M 46.5 ± 0.7 9.89 ± 1.6 2.62 ± 0.07

Claims

Claim 1 A biodegradable plastic comprising a polymer carrier, a polysaccharide containing metal ions and an enzyme, and a masterbatch; wherein the polymer carrier encapsulates the polysaccharide and the enzyme, and the masterbatch has a degree of crystallinity of 20% or less. Claim 2 In claim 1, the polymer carrier is a biodegradable plastic having a melting point of 40°C or higher and 65°C or lower. Claim 3 The biodegradable plastic according to claim 1, wherein the polymer carrier is one or more selected from the group consisting of poly(propylene succinate), polycaprolactone (PCL), poly(ethylene adipate) (PEA), poly(ethylene glycol adipate), or combinations thereof. Claim 4 A biodegradable plastic according to claim 1, wherein the enzyme forms an ionic bond with at least some of the metal ions contained in the polysaccharide. Claim 5 The biodegradable plastic according to claim 1, wherein the polysaccharide is one or more selected from the group consisting of carboxymethylcellulose, alginic acid, pectin, chitosan, oxalylated cellulose, phosphorylated cellulose complex, TEMPO-oxidized cellulose, or combinations thereof. Claim 6 A biodegradable plastic according to claim 1, wherein the enzyme is one or more selected from the group consisting of Proteinase K, Lipase, Cutinase, Esterase, or combinations thereof. Claim 7 A biodegradable plastic according to claim 1, wherein the masterbatch comprises the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:

1. Claim 8 A biodegradable plastic according to claim 1, comprising 1 to 20 parts by weight of the enzyme per 100 parts by weight of the masterbatch. Claim 9 In claim 1, the biodegradable plastic is one or more selected from the group consisting of PLA, PCL, PBS, PHB, PHBV, PGA, PLGA, PBAT, or combinations thereof. Claim 10 A biodegradable plastic according to claim 1, comprising 1 to 20 parts by weight of the masterbatch per 100 parts by weight of the biodegradable polymer. Claim 11 delete Claim 12 delete Claim 13 A method for manufacturing a biodegradable plastic comprising the steps of: manufacturing a support comprising a polymer carrier and a polysaccharide comprising metal ions; manufacturing a masterbatch comprising the support and an enzyme; and manufacturing a biodegradable plastic comprising the masterbatch and a biodegradable polymer. Claim 14 A method for manufacturing a biodegradable plastic according to claim 13, wherein the step of manufacturing the support is to mix the polymer carrier and the polysaccharide in a weight ratio of 10:1 to 5:1 at 100 to 150 ℃ and inject. Claim 15 A method for manufacturing biodegradable plastic according to claim 13, wherein the step of manufacturing the masterbatch is to mix 1 to 20 parts by weight of the enzyme with 100 parts by weight of the support at 70°C or lower and inject. Claim 16 A method for manufacturing a biodegradable plastic according to claim 13, wherein the step of manufacturing the biodegradable plastic is to mix 1 to 20 parts by weight of the masterbatch with 100 parts by weight of the biodegradable polymer at 150 to 200 ℃ and inject. Claim 17 A method for manufacturing biodegradable plastic according to claim 13, further comprising the step of pre-treating by stirring the enzyme with metal ions. Claim 18 A method for manufacturing biodegradable plastic according to claim 13, further comprising the step of pre-treating polysaccharides by stirring them with metal ions.

Images