Method for manufacturing rice-based thermoplastic bioplastic

Abstract

A method for manufacturing a rice-based thermoplastic bioplastic according to an embodiment of the present invention may comprise: a drying step of drying pre-prepared rice; a pulverizing step of pulverizing the dried rice into powder; a mixing step of mixing the powdered rice, a thermoplastic resin, and a modifier to prepare a rice-modified mixture; an extrusion step of extruding and compounding the rice-modified mixture to prepare rice-based thermoplastic bioplastic pellets; and a molding step of molding the prepared rice-based thermoplastic bioplastic pellets to have a preset product shape.

Description

Method for manufacturing rice-based thermoplastic bioplastic

[0001] The present invention relates to a rice-based thermoplastic bioplastic and a method for manufacturing the same.

[0002] The present invention is derived from research conducted as part of the Ministry of Environment's 2025 Small and Medium Environmental Enterprise Commercialization Support Project (Commercialization Field) (Project Unique Number: Not Assigned, Project Number: RQ2025010636, Research Management Agency: Korea Environmental Industry & Technology Institute, Research Project Name: Ricetic: Advanced Bioplastic Project for Waste Rice, Lead Agency: Touch for Good Co., Ltd., Research Period: 2025.04.01 ~ 2025.11.30).

[0003] Meanwhile, the Korean government has no property interest in all aspects of the present invention.

[0004]

[0005] Plastics have long been used in various industrial fields due to their excellent insulation, mechanical durability, and ease of processing. In addition, plastics are widely used in daily life because they are relatively inexpensive and lightweight.

[0006] However, there are problems such as excessive carbon emissions during the manufacturing and disposal processes, and environmental pollution as it does not decompose in the natural environment for a long time. In addition, since petroleum resources are used in the manufacture of plastics, problems resulting from resource depletion are also expected to arise.

[0007] Therefore, governments around the world are striving for sustainable growth by implementing policies to reduce carbon emissions and plastic use, such as the Paris Agreement, carbon emission trading schemes, and regulations on single-use plastics. However, the effectiveness of these policies is not yet sufficient.

[0008] Meanwhile, South Korea's rice production stood at 3.702 million tons as of 2023, and rice is used for the manufacture of food and beverages, including staple grains, alcohol, confectionery, and bread. This production volume has exceeded consumption, with an overproduction of 150,000 tons of rice occurring in 2022 alone.

[0009] Accordingly, the government is implementing policies to consume surplus rice through the development of processed rice products and the diversification of consumption outlets; however, additional measures are needed to resolve the problem of rice overproduction.

[0010]

[0011] The method for manufacturing a rice-based thermoplastic bioplastic according to an embodiment of the present invention is proposed to solve the above-mentioned problems. By manufacturing a rice-based thermoplastic bioplastic comprising rice, a thermoplastic resin, and a modifier, the mechanical properties of the bioplastic can be improved, and at the same time, the environment can be protected by utilizing surplus rice.

[0012]

[0013] According to one embodiment of the present invention, a method for manufacturing a rice-based thermoplastic bioplastic may comprise: a drying step of drying pre-prepared rice; a grinding step of grinding the dried rice to pulverize it; a mixing step of mixing the pulverized rice, a thermoplastic resin, and a modifier to prepare a rice modification mixture; an extrusion step of extrusion compounding the rice modification mixture to produce a rice-based thermoplastic bioplastic pellet; and a molding step of molding the produced rice-based thermoplastic bioplastic pellet to have a predetermined product shape.

[0014] In addition, the drying step may be a step of drying the pre-prepared rice at a temperature of 50 to 130°C for 6 to 24 hours so that the moisture content becomes 5% by weight or less.

[0015] In addition, the grinding step may be a step of pulverizing the dried rice so that its particle size satisfies a particle size range of 50 to 300 mesh.

[0016] In addition, in the mixing step, the rice modification mixture may comprise 20 to 30 weight% of the powdered rice, 65 to 75 weight% of the thermoplastic resin, and 2 to 6 weight% of the modification agent, based on 100 weight% of the rice modification mixture.

[0017] In addition, the thermoplastic resin may include one or more materials selected from the group consisting of polypropylene, polyethylene, acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoates (PHA), and polyhydroxybutyrate (PHB).

[0018] Additionally, the modifier comprises one or more substances selected from the first modifier and the second modifier, wherein the first modifier comprises one or more substances selected from the group consisting of a silane coupling agent, a cyclic unsaturated anhydride compatibilizer, an unsaturated anhydride compatibilizer, a diisocyanate-based crosslinking agent, and an epoxy-based crosslinking agent, and the second modifier may comprise a lubricant and a filler.

[0019] Additionally, the extrusion step may include an extrusion compounding process for producing rice-based thermoplastic bioplastics by performing the process at a temperature of 100 to 300°C; and a cutting process for pelletizing the produced rice-based thermoplastic bioplastics.

[0020] In addition, the molding step may be a step of injection molding the manufactured rice-based thermoplastic bioplastic pellets at a temperature of 150 to 250°C.

[0021] According to one embodiment of the present invention, a rice-based thermoplastic bioplastic may be provided, obtained through the following steps: drying pre-prepared rice; grinding the dried rice to form a powder; mixing the powdered rice, a thermoplastic resin, and a modifier to produce a rice-modified mixture; extrusion compounding the rice-modified mixture to produce rice-based thermoplastic bioplastic pellets; and molding the produced rice-based thermoplastic bioplastic pellets to have a predetermined product shape.

[0022] In addition, the dried rice may satisfy a moisture content of 5% by weight or less.

[0023] In addition, the powdered rice may satisfy a particle size range of 50 to 300 mesh.

[0024] In addition, the rice modification mixture may comprise 20 to 30 weight percent of the powdered rice, 65 to 75 weight percent of the thermoplastic resin, and 2 to 6 weight percent of the modification agent, based on 100 weight percent of the rice modification mixture.

[0025]

[0026] The method for manufacturing a rice-based thermoplastic bioplastic according to an embodiment of the present invention has the effect of improving the mechanical properties of the bioplastic while simultaneously protecting the environment by utilizing surplus rice, by manufacturing a rice-based thermoplastic bioplastic comprising rice, a thermoplastic resin, and a modifier.

[0027]

[0028] FIG. 1 is a flowchart illustrating a method for manufacturing a rice-based thermoplastic bioplastic according to one embodiment of the present invention.

[0029] FIG. 2 is a photograph of samples manufactured according to embodiments of the present invention.

[0030] Figure 3a is a drawing showing a specimen for a tensile test according to ASTM D638 Type 4 standards, prepared by the method of Example 2.

[0031] FIG. 3b is a drawing showing a specimen for a bending test according to ASTM D790 standards, prepared by the method of Example 2.

[0032] FIG. 3c is a drawing showing fork-shaped and knife-shaped products manufactured by the method of Example 2.

[0033] Figure 4 is a diagram showing the results of evaluating water resistance and pigment leaching of a standard specimen according to embodiments of the present invention.

[0034] Figure 5 is a diagram showing the results of a heat resistance evaluation of a rice-based thermoplastic bioplastic according to one embodiment of the present invention.

[0035]

[0036] Specific embodiments of the present invention will be described in detail below with reference to the drawings.

[0037] The present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications and changes. The description of the embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention. In the attached drawings, the components are depicted enlarged from their actual size for convenience of explanation, and the proportions of each component may be exaggerated or reduced.

[0038] The terms used in this specification are for describing the embodiments and are not intended to limit the invention. Furthermore, unless otherwise defined, the terms used in this specification may be interpreted in the sense commonly known to those skilled in the art. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used in this specification, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0039] Where in this specification a layer is referred to as being 'on' another layer, it may be formed directly on the upper surface of the other layer, or a third layer may be interposed between them. Although terms such as first, second, etc., have been used in this specification to describe various regions, layers, etc., these regions and layers should not be limited by such terms. These terms are used merely to distinguish one specific region or layer from another region or layer. Accordingly, a part referred to as the first part in one embodiment may be referred to as the second part in another embodiment. The embodiments described and illustrated herein also include their complementary embodiments. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0040]

[0041] In this invention, by manufacturing a rice-based thermoplastic bioplastic comprising rice, a thermoplastic resin, and a modifier, a method is secured to improve the mechanical properties of the bioplastic while simultaneously protecting the environment by utilizing surplus rice.

[0042] Method for manufacturing rice-based thermoplastic bioplastic (S10)

[0043] FIG. 1 is a flowchart illustrating a method for manufacturing a rice-based thermoplastic bioplastic according to one embodiment of the present invention.

[0044] Referring to FIG. 1, a method for manufacturing a rice-based thermoplastic bioplastic may include a drying step (S100), a grinding step (S200), a mixing step (S300), an extrusion step (S400), and a molding step (S500).

[0045] Drying step (S100): Rice preparation and drying

[0046] First, in the drying step (S100), rice used for manufacturing rice-based thermoplastic bioplastic can be prepared in advance.

[0047] Here, rice varieties such as Koshihikari, Milky Queen, Chucheongmi, Odaemi, Samgwangmi, Ilpummi, Haiami, Saecheongmu, Sindongjin, Yeonghojinmi, Hitomebore, Chamdeurim, and Saeilmi may be used, but are not limited to these.

[0048] Preferably, the drying step (S100) can be carried out using surplus rice that has been milled after harvest.

[0049] In addition, the drying step (S100) may dry the prepared rice at a temperature of 50 to 130°C for 6 to 24 hours so that the moisture content becomes 5% by weight or less.

[0050] Preferably, the moisture content of the dried rice can be 3 weight percent or less.

[0051] Generally, the moisture content of rice at harvest is 22 to 25 weight percent, and even after milling and processing, 15 weight percent of moisture may remain in the rice.

[0052] If the moisture content in the prepared rice exceeds 5% by weight, bacteria can easily multiply, and problems such as the generation of bubbles during extrusion compounding may occur, which impair quality.

[0053] The drying step (S100) may be carried out by any one of the drying methods of hot air drying, microwave drying, vacuum drying and solar drying, but is not limited thereto.

[0054] Grinding step (S200): Powdering of dried rice

[0055] In the grinding step (S200), dried rice can be ground to produce powdered rice. Specifically, the grinding step (S200) may be a step of powdering dried rice so that the particle size satisfies a particle size range of 50 to 300 mesh.

[0056] By proceeding with the crushing step (S200), efficient compounding is possible in the subsequent mixing step (S300) and extrusion step (S400), and the deterioration of the physical properties of the bioplastic can be prevented.

[0057] Meanwhile, the grinding step (S200) can perform two grinding processes using grinding equipment. That is, the grinding step (S200) can grind the dried rice to a set size by performing first and second grinding processes.

[0058] For example, in the first grinding process, dried rice can be ground into small particles. Then, in the second grinding process, the small particles can be ground into a preset size to produce the product.

[0059] Here, the grinding equipment may be selected from one or more of the following: an Air Classifying Mill (ACM), a Pin Mill, a Hammer Mill, a Grinder, a Spiral Classifier, a Ball Mill, a Disk Mill, a Rotary Mill, and a High Shear Inline Mixer, but is not limited thereto.

[0060] At this time, a separation device for separating and obtaining rice powdered to a particle size smaller than a set size can be additionally installed in the grinding equipment.

[0061] For example, the separation device may select and use one or more of the following equipment, including a sieve, a vacuum screener, a rotary screener, a vibrating sieve, and a micro sieve, but is not limited thereto.

[0062] Meanwhile, the rice powdered through the grinding step (S200) can satisfy a particle size range of 50 to 300 mesh.

[0063] Here, if the particle size of the powdered rice exceeds 50 mesh, large particles may act as aggregation nuclei, which can impair the physical properties of the bioplastic. Additionally, if the particle size is small (less than 300 mesh), dispersion becomes difficult, which can increase the difficulty of processing.

[0064] Meanwhile, during the first and second grinding processes, the moisture content of the rice can be maintained at 10% by weight or less. Therefore, additional drying may not be required after the grinding step (S200).

[0065] In the grinding step (S200), the moisture content of the rice can be maintained by one or more methods selected from the use of moisture-proof grinding equipment, reduction of working time, and sealing of the workspace, but is not limited thereto.

[0066] Mixing step (S300): Preparation of rice modification mixture

[0067] In the mixing step (S300), powdered rice, a thermoplastic resin, and a modifier are mixed to produce a rice modified mixture with improved affinity and mechanical properties between the materials.

[0068] Specifically, the rice modification mixture may comprise 20 to 30 weight% of powdered rice, 65 to 75 weight% of a thermoplastic resin, and 2 to 6 weight% of a modifier, based on 100 weight% of the rice modification mixture, but is not limited thereto.

[0069] Here, the modifier may include one or more substances selected from the first modifier and the second modifier.

[0070] Meanwhile, it is preferable that powdered rice be included in an amount of 30% by weight relative to 100% by weight of the rice modification mixture.

[0071] If the content of powdered rice in the mixing step (S300) exceeds 30% by weight relative to 100% by weight of the rice modification mixture, mechanical properties may deteriorate and leaching may occur. Additionally, if the content of powdered rice is less than 30% by weight relative to 100% by weight of the rice modification mixture, it may not meet domestic and international bioplastic certification standards (20% by weight or more).

[0072] Therefore, considering domestic and international bioplastic certification standards (20% by weight or more), mechanical properties, and material characteristics, the content of powdered rice is preferably 30% by weight.

[0073] Meanwhile, rice, a starch-based biomass, is a hydrophilic substance containing numerous hydroxyl groups, whereas thermoplastic resins are hydrophobic substances with long-chain structures containing carbon and hydrogen.

[0074] Therefore, in the mixing step (S300), a first modifier can be added to increase the affinity between the powdered rice and the thermoplastic resin.

[0075] Here, the thermoplastic resin may be one or more materials selected from the group consisting of polypropylene, polyethylene, acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoates (PHA), and polyhydroxybutyrate (PHB), but is not limited thereto.

[0076] Here, the first modifier may use one or more materials selected from the group consisting of silane coupling agents, cyclic unsaturated anhydride compatibilizers, unsaturated anhydride compatibilizers, diisocyanate-based crosslinking agents, and epoxy-based crosslinking agents, but is not limited thereto.

[0077] Here, the silane coupling agent may be one or more substances selected from aminosilane, styrylsilane, vinylsilane, epoxysilane, acrylsilane, alkylsilane, methacryloxysilane, mercaptosilane, and isocyanatesilane, but is not limited thereto.

[0078] Here, the cyclic unsaturated anhydride compatibilizer may be one or more substances selected from cyclohexene anhydride and cyclopentadiene anhydride, but is not limited thereto.

[0079] Here, the unsaturated anhydride compatibilizer may be one or more substances selected from maleic anhydride, vinyl anhydride, and butyl anhydride, but is not limited thereto.

[0080] Here, the diisocyanate-based crosslinking agent may be one or more substances selected from methylene diphenyl diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and isophorone diisocyanate, but is not limited thereto.

[0081] Here, the epoxy-based crosslinking agent may be one or more substances selected from epoxidized soybean oil, bisphenol A epoxy, bisphenol F epoxy, and 1,4-butanediol diglycidyl ether, but is not limited thereto.

[0082] Meanwhile, if an amount less than the content of the first modifier described above is added, the effect on mechanical properties and material characteristics may not be sufficient. In addition, if an excessive amount is added compared to the content of the first modifier described above, the flexibility of the product may be reduced, making it susceptible to bending deformation.

[0083] In the mixing step (S300), a second modifier is added to improve the dispersibility of the powdered rice and to strengthen the mechanical properties of the rice-based thermoplastic bioplastic being manufactured.

[0084] Specifically, the second modifier includes a lubricant and a filler, and may additionally include a deodorizing additive to impart deodorizing ability to the rice-based thermoplastic bioplastic.

[0085] Here, the lubricant improves the dispersibility of the powdered rice and can act as a lubricant when proceeding with the mixing step (S300).

[0086] In addition, the filler enhances the mechanical properties of the manufactured rice-based thermoplastic bioplastic and, in some cases, can act as an opacifier.

[0087] Meanwhile, deodorizing additives can impart deodorizing ability to the manufactured rice-based thermoplastic bioplastic.

[0088] Preferably, the second modifier of the mixing step (S300) may include a lubricant and a filler.

[0089] Here, the lubricant may be one or more substances selected from stearic acid, calcium stearate, zinc stearate, sodium stearate, polyethylene wax, and polypropylene wax, but is not limited thereto.

[0090] Here, the filler may be one or more substances selected from talc, silicon dioxide, calcium carbonate, titanium dioxide, and kaolin, but is not limited thereto.

[0091] Here, the deodorizing additive may use one or more materials selected from the group consisting of charcoal, zeolite, activated carbon, silica gel, polyurethane, platinum (Pt), palladium (Pd), iron (Fe), and cobalt (Co), but is not limited thereto.

[0092] Meanwhile, if an amount less than the content of the second modifier described above is added, the effect may not be sufficient. In addition, if an excessive amount is added compared to the content of the second modifier described above, the tensile strength and flexural strength of the product may be significantly reduced, and the durability may be reduced.

[0093] Meanwhile, in the mixing step (S300), stirring equipment may be used to produce a uniformly mixed rice modification mixture.

[0094] For example, one or more pieces of equipment selected from the group including a homo mixer, a ball mill, a rotary mill, a conical mixer, and a double conical mixer may be used. However, not limited thereto, the mixing step (S300) may be performed by using various stirring equipment or by direct stirring.

[0095] Extrusion step (S400): Manufacturing rice-based thermoplastic bioplastic pellets

[0096] The extrusion step (S400) can produce rice-based thermoplastic bioplastic pellets by extruding and compounding the prepared rice modified mixture.

[0097] Specifically, the extrusion step (S400) may include an extrusion compounding process for manufacturing rice-based thermoplastic bioplastics by performing the process at a temperature of 100 to 300°C, and a cutting process for pelletizing the manufactured rice-based thermoplastic bioplastics.

[0098] The extrusion compounding process can produce rice-based thermoplastic bioplastics by extrusion compounding the prepared rice modified mixture at a temperature of 100 to 300°C.

[0099] In the extrusion compounding process at temperatures below 100℃, the thermoplastic resin does not melt, so the efficiency of compounding may be very low.

[0100] In addition, at temperatures exceeding 300°C, the viscosity of the thermoplastic resin decreases, which may cause problems that make it difficult to proceed with the pelletization process. Therefore, it is preferable to carry out the extrusion compounding process at a temperature of 100 to 300°C.

[0101] Meanwhile, in the extrusion compounding process, rice-based thermoplastic bioplastics can be manufactured using an extruder.

[0102] Here, the extruder may use one or more selected from a single extruder, a twin-screw extruder, and a pelletizer, but is not limited thereto. Preferably, the extrusion compounding process can be carried out using a twin-screw extruder.

[0103] Here, the screw rotation speed of the extruder may be 5 to 30 rpm. If the screw rotation speed of the extruder is less than 5 rpm, compounding may not proceed smoothly, and productivity may be significantly reduced.

[0104] On the other hand, if the rotational speed of the extruder screw is 30 rpm or higher, the internal pressure and temperature of the extruder may rise, causing severe carbonization of the rice modified mixture.

[0105] However, in the extrusion compounding process, the rotational speed of the extruder screw is not limited to this and can vary depending on the content of the dried rice.

[0106] Meanwhile, the cutting process can cut and pelletize rice-based thermoplastic bioplastics manufactured by the extrusion compounding process.

[0107] Specifically, the cutting process can pelletize the manufactured rice bioplastic by cutting or die-phase hot cutting methods. However, the cutting and pelletization methods are not limited to this and can be varied.

[0108] Molding Step (S500): Manufacturing of standard specimens and products of rice-based thermoplastic bioplastics

[0109] In the molding step (S500), the manufactured rice-based thermoplastic bioplastic can be injection molded to produce standard specimens and products of a preset shape.

[0110] Specifically, the molding step (S500) may be a step of injection molding the manufactured rice-based thermoplastic bioplastic at a temperature of 150 to 250°C.

[0111] Here, the standard specimens may include specimens for tensile testing manufactured according to ASTM D638 and specimens for flexural testing manufactured according to ASTM D790.

[0112] Here, the product with a pre-set shape may be one or more shapes selected from a fork shape, a knife shape, a spoon shape, a plate shape, and a teapot shape. However, the product with a pre-set shape is not limited to these and may have various shapes.

[0113] The temperature at which the molding step (S500) is performed can be set by considering process conditions including the thermal characteristics of the injection molded product, the mold shape, and the injection pressure.

[0114] For example, at low temperatures of 150°C or lower, the fluidity of the thermoplastic resin decreases, so molding into a preset shape may not occur.

[0115] On the other hand, at high temperatures above 250°C, excessive irregular burrs may occur at the mold joints and parting lines, and gas may be generated. In addition, color changes and deterioration of mechanical properties may occur due to the carbonization of rice, which is the raw material for bioplastics.

[0116] Accordingly, the molding step (S500) for manufacturing standard specimens and products is preferably carried out at a temperature of 150 to 250°C.

[0117]

[0118] Example 1. Preparation of a specimen of rice-based thermoplastic bioplastic 1

[0119] Prepare surplus rice that has been milled after harvest. Dry the prepared rice so that the moisture content of the dried rice is 3% by weight or less.

[0120] Dried rice is subjected to primary and secondary grinding using an air-classifying mill, and powdered rice of 150 mesh is obtained through a sieve.

[0121] 30% by weight of powdered rice, 68% by weight of thermoplastic resin (polypropylene), and 2% by weight of first modifier (Amino silane) are placed in a homogenizer mixer and stirred at 100°C and 500 rpm for 1 hour to prepare a rice modification mixture.

[0122] After feeding the rice modified mixture into a twin-screw extruder, extrusion compounding and cutting are performed at a temperature of 165°C with a screw rotation speed of 10 rpm and a winder rotation speed of 550 rpm to produce rice-based thermoplastic bioplastic pellets.

[0123] The manufactured rice-based thermoplastic bioplastic pellets are fed into an injection molding machine, and injection molding is performed at a temperature of 185°C. Here, specimens for tensile testing are manufactured according to ASTM D638 standards, and specimens for flexural testing are manufactured according to ASTM D790 standards.

[0124]

[0125] Example 2. Preparation of specimens of rice-based thermoplastic bioplastics 2

[0126] Prepare surplus rice that has been milled after harvest. Dry the prepared rice so that the moisture content of the dried rice is 3% by weight or less.

[0127] Dried rice is subjected to primary and secondary grinding using an air classification mill, and powdered rice of 150 mesh is obtained through a sieve.

[0128] 30% by weight of powdered rice, 67% by weight of thermoplastic resin (polypropylene), and 3% by weight of first modifier (Amino silane) are placed in a homogenizer mixer and stirred at 100°C and 500 rpm for 1 hour to prepare a rice modification mixture.

[0129] After feeding the rice modified mixture into a twin-screw extruder, extrusion compounding and cutting are performed at a temperature of 165°C with a screw rotation speed of 10 rpm and a winder rotation speed of 550 rpm to produce rice-based thermoplastic bioplastic pellets.

[0130] The manufactured rice-based thermoplastic bioplastic pellets are fed into an injection molding machine, and injection molding is performed at a temperature of 185°C. Here, specimens for tensile testing are manufactured according to ASTM D638 standards, and specimens for flexural testing are manufactured according to ASTM D790 standards.

[0131]

[0132] Example 3. Preparation of rice-based thermoplastic bioplastic specimens 3

[0133] Prepare surplus rice that has been milled after harvest. Dry the prepared rice so that the moisture content of the dried rice is 3% by weight or less.

[0134] Dried rice is subjected to primary and secondary grinding using an air classification mill, and powdered rice of 150 mesh is obtained through a sieve.

[0135] 30% by weight of powdered rice, 65% by weight of thermoplastic resin (polypropylene), 3% by weight of first modifier (Amino silane), and 2% by weight of second modifier including a lubricant (Stearic acid) and a filler (talc) are placed in a homogenizer mixer and stirred at 100°C and 500 rpm for 1 hour to prepare a rice modification mixture.

[0136] After feeding the rice modified mixture into a twin-screw extruder, extrusion compounding and cutting are performed at a temperature of 165°C with a screw rotation speed of 10 rpm and a winder rotation speed of 550 rpm to produce rice-based thermoplastic bioplastic pellets.

[0137] The manufactured rice bioplastic pellets are fed into an injection molding machine, and injection molding is performed at a temperature of 185°C. Here, specimens for tensile testing are manufactured according to ASTM D638 standards, and specimens for flexural testing are manufactured according to ASTM D790 standards.

[0138]

[0139] Comparative Example 1. Preparation of comparative specimens of rice-based thermoplastic bioplastics 1

[0140] A rice-based thermoplastic bioplastic was prepared by the same method as in Example 3 described above, but with a rice mixture of 30% by weight of powdered rice and 70% by weight of thermoplastic resin (polypropylene) in the mixing step.

[0141] Here, specimens for tensile testing are manufactured in accordance with ASTM D638, and specimens for bending testing are manufactured in accordance with ASTM D790.

[0142]

[0143] <Characteristics Evaluation>

[0144] Experimental Example 1. Evaluation of Mechanical Properties of Rice-Based Thermoplastic Bioplastics

[0145] Rice-based thermoplastic bioplastic pellets were manufactured through the extrusion step described above. FIG. 2 is a photograph of samples manufactured according to embodiments of the present invention. Here, the sample may be a pellet manufactured in the extrusion step.

[0146] Referring to FIG. 2, the rice-based thermoplastic bioplastic pellets are prepared by the methods of Comparative Example 1 and Examples 1 to 3, sequentially from the left in FIG. 2.

[0147] Subsequently, the forming step was carried out to manufacture tensile specimens according to ASTM D638 Type 4 and flexural specimens according to ASTM D790.

[0148] Figure 3a is a drawing showing a specimen for a tensile test according to ASTM D638 Type 4 standards, prepared by the method of Example 2.

[0149] In addition, FIG. 3b is a drawing showing a specimen for a bending test according to ASTM D790 standards prepared by the method of Example 2.

[0150] In addition, FIG. 3c is a drawing showing fork-shaped and knife-shaped products manufactured by the method of Example 2.

[0151] Tensile Strength (MPa) Tensile Modulus (MPa) Elongation (%) Flexural Strength (MPa) Flexural Strain (%) Comparative Example 1 22.24±0.66 30 3.87±12.47 14.20±2.18 46.58±1.58 8.68±0.49 Example 1 22.71±0.44 30 8.82±7.18 12.52±0.96 48.78±1.11 7.74±1.20 Example 2 25.42±2.99 37 3.42±18.06 10.51±1.31 51.40±2.11 4.85±0.89 325.63±1.61315.24±20.4512.67±1.6148.36±3.105.57±0.66

[0152]

[0153] Referring to [Table 1], it can be seen that as the amount of the first modifier increases, the mechanical strength increases, while the elongation and flexural strain tend to decrease.

[0154] Specifically, when comparing Example 2 and Example 1, it can be seen that as the amount of the first modifier added increases, the mechanical strength increases, but the elongation and flexural strain decrease.

[0155] In addition, it can be seen that Example 2 has a tensile strength of 14.43% and a tensile modulus of 22.89% increased compared to Comparative Example 1.

[0156] Meanwhile, referring to [Table 1], it can be seen that when both the first and second modifiers are added, the elongation and bending strain that had decreased are recovered while maintaining mechanical strength.

[0157] Specifically, it can be confirmed that Example 3 maintains tensile strength and flexural strength compared to Example 2, while the elongation and flexural strain that had decreased are slightly recovered.

[0158]

[0159] Experimental Example 2. Evaluation of Water Resistance and Pigment Leaching of Rice-Based Thermoplastic Bioplastics

[0160] Figure 4 is a diagram showing the results of evaluating the water resistance and pigment leaching of a rice-based thermoplastic bioplastic produced by the manufacturing method of the present invention.

[0161] To evaluate the water resistance and the presence or absence of pigment leaching of rice-based thermoplastic bioplastics, rice bioplastic specimens prepared in Comparative Example 1, Example 2, and Example 3 (specimens prepared according to ASTM D790 standards) were immersed in distilled water for 120 hours.

[0162] Referring to FIG. 4, it can be confirmed that no degradation of physical properties, such as deformation or warping, was observed in Comparative Example 1, Example 2, and Example 3. In addition, no significant pigment elution was observed in Comparative Example 1, Example 2, and Example 3.

[0163]

[0164] Experimental Example 3. Evaluation of Heat Resistance of Rice-Based Thermoplastic Bioplastic

[0165] Figure 5 is a diagram showing the results of a heat resistance evaluation of a rice-based thermoplastic bioplastic produced by the manufacturing method of the present invention.

[0166] To evaluate the heat resistance of rice-based thermoplastic bioplastics, a rice-based thermoplastic bioplastic specimen prepared by the method of Example 3 (a specimen prepared according to ASTM D790 standards) was immersed in distilled water at 100°C for 30 minutes, and deformation, warping, and mechanical properties were observed.

[0167] Referring to Fig. 5, it can be confirmed that no significant difference in mechanical properties was observed before and after infiltration in the specimen prepared by the method of Example 3.

[0168] Therefore, it can be seen that the rice-based thermoplastic bioplastic prepared by the method of Example 3 has excellent heat resistance performance.

[0169]

[0170] Although a method for manufacturing a rice-based thermoplastic bioplastic according to an embodiment of the present invention has been described above as a specific embodiment, this is merely illustrative and the present invention is not limited thereto, but should be interpreted as having the broadest scope in accordance with the basic concept disclosed in this specification. Those skilled in the art may implement patterns of shapes not specified by combining or substituting the disclosed embodiments, and this also does not deviate from the scope of the present invention. Furthermore, those skilled in the art may easily change or modify the disclosed embodiments based on this specification, and it is evident that such changes or modifications also fall within the scope of the rights of the present invention.

Claims

1. A drying step for drying pre-prepared rice; A grinding step for grinding dried rice into powder; A mixing step for preparing a rice modification mixture by mixing powdered rice, a thermoplastic resin, and a modifier; An extrusion step of manufacturing rice-based thermoplastic bioplastic pellets by extrusion compounding the above rice modification mixture; and A molding step comprising molding manufactured rice-based thermoplastic bioplastic pellets to have a preset product shape; Method for manufacturing rice-based thermoplastic bioplastic.

2. In Paragraph 1, The above drying step is, A step of drying the above-mentioned pre-prepared rice at a temperature of 50 to 130°C for 6 to 24 hours so that the moisture content becomes 5% by weight or less, Method for manufacturing rice-based thermoplastic bioplastic.

3. In Paragraph 2, The above grinding step is, A step of pulverizing the above-mentioned dried rice so that its particle size satisfies a particle size range of 50 to 300 mesh, Method for manufacturing rice-based thermoplastic bioplastic.

4. In Paragraph 3, In the above mixing step, The above rice modification mixture comprises, based on 100 weight% of the above rice modification mixture, 20 to 30 weight% of the powdered rice, 65 to 75 weight% of the thermoplastic resin, and 2 to 6 weight% of the modifier. Method for manufacturing rice-based thermoplastic bioplastic.

5. In Paragraph 4, The above thermoplastic resin is, Comprising one or more materials selected from the group consisting of polypropylene, polyethylene, acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polyhydroxyalkanoates (PHA), and polyhydroxybutyrate (PHB), Method for manufacturing rice-based thermoplastic bioplastic.

6. In Paragraph 5, The above modifier is, It comprises one or more substances selected from the first modifier and the second modifier, The first modifier comprises one or more materials selected from the group consisting of silane coupling agents, cyclic unsaturated anhydride compatibilizers, unsaturated anhydride compatibilizers, diisocyanate-based crosslinking agents, and epoxy-based crosslinking agents. The above second modifier comprises a lubricant and a filler, Method for manufacturing rice-based thermoplastic bioplastic.

7. In Paragraph 6, The above extrusion step is, A method comprising an extrusion compounding process for manufacturing rice-based thermoplastic bioplastics by performing the process at a temperature of 100 to 300°C, and a cutting process for pelletizing the manufactured rice-based thermoplastic bioplastics. Method for manufacturing rice-based thermoplastic bioplastic.

8. In Paragraph 7, The above molding step is, The step of injection molding the above-mentioned rice-based thermoplastic bioplastic pellets at a temperature of 150 to 250°C, Method for manufacturing rice-based thermoplastic bioplastic.

9. The process of drying pre-prepared rice; The process of grinding dried rice into powder; A process of preparing a rice modification mixture by mixing powdered rice, a thermoplastic resin, and a modifier; A process of manufacturing rice-based thermoplastic bioplastic pellets by extrusion compounding the above rice modification mixture; and A process of molding manufactured rice-based thermoplastic bioplastic pellets to have a preset product shape; obtained through, Rice-based thermoplastic bioplastic.

10. In Paragraph 9, The above dried rice is, Satisfying a moisture content of 5% by weight or less, Rice-based thermoplastic bioplastic.

11. In Paragraph 9, The above-mentioned powdered rice is, Satisfying a particle size range of 50 to 300 mesh, Rice-based thermoplastic bioplastic.

12. In Paragraph 9, The above rice modification mixture is, Based on 100% by weight of the above rice modification mixture, comprising 20 to 30% by weight of the powdered rice, 65 to 75% by weight of the thermoplastic resin, and 2 to 6% by weight of the modification agent, Rice-based thermoplastic bioplastic.

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