A method of manufacturing recycled plastic injection molding containing coconut shell fibers and a composition for injection molding

Abstract

The present invention relates to a method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers and a composition for injection molding. More specifically, the invention relates to an eco-friendly composite resin composition and a method for manufacturing an eco-friendly composite resin injection molded article by mixing coconut shells, which are agricultural byproducts, with recycled polypropylene to use as a filler for the injection molded article. A method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention comprises: (a) a step of preparing coconut shell fibers and recycled polypropylene resin pellets; (b) a step of pre-mixing 0.5 to 20 parts by weight of coconut shell fibers prepared in step (a) and 0.1 to 3 parts by weight of a compatibilizer in a rotary mixer using a simple mechanical mixing method with respect to 100 parts by weight of recycled polypropylene resin pellets; and (c) a step of manufacturing an injection molded article by introducing the mixture from step (b) into an injection molding machine and injecting the mixture into a mold through a nozzle.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers and a composition for injection molding. More specifically, the invention relates to an eco-friendly composite resin composition and a method for manufacturing an eco-friendly composite resin injection molded article by mixing coconut shells, which are agricultural byproducts, with recycled polypropylene to use as a filler for the injection molded article. Background Technology

[0002] While plastic has established itself as an essential material in modern society, the negative environmental impact of its waste is severe. In particular, general-purpose plastic waste, such as polypropylene widely used in disposable products, does not decompose naturally and is a major cause of soil and marine pollution. Consequently, there is a growing movement to reduce the use of petroleum-based new plastics and to recycle waste plastics.

[0003] Furthermore, from the perspective of sustainable resource utilization, research aimed at industrially utilizing discarded biomass is gaining attention. In particular, coconuts are consumed in large quantities worldwide as raw materials for food, cosmetics, and household goods; however, the processing of these products generates massive amounts of coconut shells as a byproduct, which are primarily discarded, landfilled, or incinerated as low-grade fuel.

[0004] Therefore, there is a growing need for ways to effectively recycle waste plastics and coconut shells. The problem to be solved

[0005] The present invention was created to solve the aforementioned problems, and more specifically, aims to provide a method for manufacturing an eco-friendly recycled plastic injection molded product and a plastic injection molding composition by processing discarded agricultural by-products, such as coconut shells, into a fiber form and utilizing them as a filler for recycled polypropylene resin, thereby reducing the use of new plastics and establishing a circular resource structure.

[0006] In addition, the present invention aims to provide a method for manufacturing an injection molded article and an injection molding composition that secure processability suitable for an injection molding process by adding coconut shell fibers to recycled polypropylene resin, prevent deterioration of the physical properties of the recycled resin, and have sufficient mechanical strength and excellent appearance quality. means of solving the problem

[0007] A method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention comprises: (a) a step of preparing coconut shell fibers and recycled polypropylene resin pellets; (b) a step of pre-mixing 0.5 to 20 parts by weight of coconut shell fibers prepared in step (a) and 0.1 to 3 parts by weight of a compatibilizer in a rotary mixer using a simple mechanical mixing method with respect to 100 parts by weight of recycled polypropylene resin pellets; and (c) a step of manufacturing an injection molded article by introducing the mixture from step (b) into an injection molding machine and injecting the mixture into a mold through a nozzle.

[0008] In a method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention, the coconut shell fibers are prepared through a washing step of washing a raw coconut shell to remove impurities, a drying step of drying the raw coconut shell washed in the washing step at 80°C for 24 hours to reduce the moisture content to 4% or less, and a separation step of separating the raw coconut shell dried in the drying step into a fiber form through rotational separation.

[0009] More specifically, the recycled polypropylene resin pellets are characterized by having an average diameter of 1 to 4 mm.

[0010] In a method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers according to one embodiment of the present invention, the compatibilizer is characterized as being MAPP (Maleated Polypropylene).

[0011] In a method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers according to one embodiment of the present invention, the temperature of the injection molding machine is 170°C to 200°C, and the temperature of the nozzle is 200°C to 220°C.

[0012] In a method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention, the rotational speed of the rotary mixer is 30 to 100 mm / s, and simple mixing is performed for 25 to 35 seconds.

[0013] In a method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers according to one embodiment of the present invention, step (b) is characterized by further adding a coloring agent or a pigment.

[0014] A recycled plastic injection molding composition comprising coconut shell fibers according to one embodiment of the present invention is characterized by comprising recycled polypropylene resin in pellet form, coconut shell fibers, and a compatibilizer.

[0015] A recycled plastic injection molding composition comprising coconut shell fibers according to one embodiment of the present invention is characterized by being composed of 0.5 to 20 parts by weight of coconut shell fibers and 0.1 to 3 parts by weight of a compatibilizer per 100 parts by weight of recycled polypropylene resin.

[0016] In a recycled plastic injection molding composition comprising coconut shell fibers according to one embodiment of the present invention, the coconut shell fibers are characterized by being prepared by washing a raw coconut shell to remove impurities, drying the washed raw coconut shell in an 80°C oven for 24 hours to reduce the moisture content to 4% or less, and transforming it into a fiber form through rotational separation. Effects of the invention

[0017] A method for manufacturing a recycled plastic injection molded product containing coconut shell fibers according to one embodiment of the present invention has the effect of being eco-friendly by reducing the amount of virgin plastic used and establishing a circular resource structure.

[0018] In addition, the method for manufacturing a recycled plastic injection molded product including coconut shell fibers according to one embodiment of the present invention can contribute to reducing carbon emissions by reducing plastic usage and solving waste problems through the recycling of discarded coconut shells and plastics, and has the effect of enabling the realization of a circular economy and a response to climate change.

[0019] In addition, the method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention has the effect of reducing raw material costs by using coconut shell fibers and recycled plastic, thereby increasing the price competitiveness of the product.

[0020] In addition, the method for manufacturing a recycled plastic injection molded product containing coconut shell fibers according to one embodiment of the present invention has the effect of enabling product production without additional equipment investment, as existing plastic injection molding equipment can be used as is.

[0021] In addition, a recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention has the effect of having aesthetic beauty due to the natural pattern caused by the coconut shell fibers.

[0022] In addition, a recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention includes coconut shell fibers that act as a reinforcing material, and has the effect of preventing deformation of the finished product by having excellent tensile strength, flexural strength, and elastic modulus.

[0023] In addition, the recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention has the effect of producing a heat-stable product by including coconut shell fibers, which exhibits excellent heat resistance and does not easily deform even at high temperatures.

[0024] In addition, a recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention has the effect of being usable as a sound-absorbing material or vehicle interior material by attenuating noise or vibration by including coconut shell fibers.

[0025] In addition, the recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention has the effect of ensuring processability suitable for the injection molding process by adding coconut shell fibers to recycled polypropylene resin, preventing deterioration of the physical properties of the recycled resin, and having sufficient mechanical strength and excellent appearance quality. Brief explanation of the drawing

[0026] FIG. 1 is a flowchart of a method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention. FIG. 2 is a flowchart of a method for preparing coconut shell fibers in a method for manufacturing a recycled plastic injection molded article including coconut shell fibers according to one embodiment of the present invention. FIG. 3 is a photograph of a raw coconut shell used in a method for manufacturing a recycled plastic injection molded product containing coconut shell fibers according to one embodiment of the present invention. Figure 4 is a photograph of a coconut shell that has undergone a washing step and a drying step in a method for manufacturing a recycled plastic injection molded product containing coconut shell fibers according to one embodiment of the present invention. Figure 5 is a photograph of coconut shell fibers separated through a separation step in a method for manufacturing a recycled plastic injection molded article containing coconut shell fibers according to one embodiment of the present invention. FIG. 6 is a photograph showing the surface pattern of a molded article molded with a recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention. Figure 7 is a photograph showing the surface of a conventional plastic injection molded product. FIG. 8 is a photograph of recycled polypropylene resin pellets used in a recycled plastic injection molding composition containing coconut shell fibers according to one embodiment of the present invention. Specific details for implementing the invention

[0027] The following detailed description of the invention refers to the accompanying drawings, which illustrate specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that various embodiments of the invention are different but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in relation to one embodiment.

[0028] Furthermore, it should be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the following detailed description is not intended to be taken in a limiting sense, and the scope of the invention is limited only by the appended claims, including all equivalents thereof, provided appropriately described. Similar reference numerals in the drawings refer to the same or similar functions across various aspects.

[0029] Hereinafter, in order to enable a person skilled in the art to easily practice the present invention, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

[0031] First, a method for manufacturing a recycled plastic injection molded article containing coconut shell fibers according to one embodiment of the present invention will be described. As illustrated in FIG. 1, the method for manufacturing a recycled plastic injection molded article containing coconut shell fibers according to one embodiment of the present invention is characterized by comprising: (a) a step of preparing coconut shell fibers and recycled polypropylene resin pellets; (b) a step of pre-mixing 0.5 to 20 parts by weight of coconut shell fibers prepared in step (a) and 0.1 to 3 parts by weight of a compatibilizer in a rotary mixer using a simple mechanical mixing method with respect to 100 parts by weight of recycled polypropylene resin pellets; and (c) a step of manufacturing an injection molded article by introducing the mixture from step (b) into an injection molding machine and injecting the mixture into a mold through a nozzle.

[0033] First, step (a) above is the step of preparing coconut shell fibers and recycled polypropylene resin pellets.

[0034] The aforementioned coconut shell fiber is extracted from the outer shell of the coconut fruit and exists as brown fibers ranging in length from several millimeters to several centimeters. It is composed of components such as lignin and cellulose, and is flexible, highly durable, and lightweight. Furthermore, as it is a plant-derived material, it is characterized by being lightweight and biodegradable.

[0035] If the aforementioned coconut shell fibers are mixed with recycled polypropylene resin to produce injection-molded products, the fibers have the effect of distributing loads and suppressing deformation. Additionally, due to the internal structure of the fibers, they can absorb and attenuate vibrations and noise, making them suitable for use in applications such as vehicle interior materials.

[0036] More specifically, as illustrated in FIG. 2, the coconut shell fiber is characterized by being prepared through a washing step of washing a raw coconut shell to remove impurities, a drying step of drying the raw coconut shell washed in the washing step at 80°C for 24 hours to reduce the moisture content to 4% or less, and a separation step of separating the raw coconut shell dried in the drying step into a fiber form through rotational separation.

[0037] The above coconut shell raw material may be the entire outer shell of a coconut fruit, a fibrous separated material, or a raw material provided in the form of pellets in which the fibers are compressed, such as a coir mat as shown in FIG. 3, but is not limited thereto.

[0038] More specifically, the washing step removes impurities mixed in the coconut shell and eliminates proteins or sugars inherently present in the shell. If proteins or sugars are not removed, they may burn or cause unpleasant odors due to high temperatures during the subsequent drying process or injection molding. Additionally, the washing step removes wax or fatty acid components present on the surface of the coconut shell, allowing for good bonding when subsequently mixed with recycled polypropylene resin, thereby enabling the production of a robust molded product.

[0039] The above washing step may use a method selected from lukewarm water washing, hot water washing, alkaline washing, weak acid washing, neutral detergent washing, ultrasonic washing, high-pressure water washing, and steam washing, but is not limited thereto.

[0040] Next, the drying step involves removing moisture adhering to the coconut shells washed in the washing step as well as moisture inherent in the shells to prevent air bubbles in the injection-molded product and to eliminate residual organic matter or microorganisms. Through drying, the durability of the finished product can be enhanced, and the decay of coconut shell fibers within the finished product can be prevented.

[0041] The above drying step may use methods such as oven drying, hot air drying, natural solar drying, and infrared drying, but is not limited thereto.

[0042] Next, the separation step is a step of separating the coconut shell dried in the drying step along the grain direction to obtain fibrous shell fibers. By separating the fibers along the grain direction without cutting them, the fibrous shape is maintained, allowing the coconut shell fibers to effectively perform their role as a reinforcing material when mixed with resin. However, if the fibers are excessively long, clumping may occur at the nozzle during injection molding, so in this case, they may be cut to a length of 2 to 5 cm for use.

[0043] The recycled polypropylene resin pellets described above are made by processing recycled polypropylene material into a pellet form as shown in FIG. 8, and are produced by washing, crushing, melting, and molding waste polypropylene into a pellet form. They may have an average diameter of 1 to 4 mm. The pellets may most preferably have a size of 2 to 3 mm, but are not limited thereto.

[0044] If the pellet size is smaller than 1 mm, fine powder or dust may be generated, which may result in uneven mixing when combined with fibers. In other words, very small powder may rise to the surface due to friction or vibration, leading to uneven mixing. This can result in an uneven melting state, which may compromise the quality uniformity of the final product. Additionally, due to their small size, they melt quickly, posing a problem that they may carbonize due to overheating during kneading.

[0045] In addition, if the pellet size is larger than 4 mm, it takes a long time to melt, and during this process, it may be injected in a semi-molten state. This not only degrades the quality of the finished product due to uneven melting but can also cause clogging of the injection nozzle and damage to the internal screw of the injection molding machine.

[0046] In addition, the pellets may be formed in shapes such as cylindrical, cuboidal, prismatic, spherical, irregularly cut, or chip-shaped, but are not limited thereto.

[0047] Polypropylene exhibits excellent thermal stability and chemical resistance, and because it does not shrink or warp significantly upon cooling, it is easy to manufacture molded products of precise dimensions via injection molding. Furthermore, it maintains minimal molecular structure upon remelting, resulting in minimal changes in mechanical properties and excellent fluidity. Additionally, it is easy to colorize or process, making it suitable for repeated recycling.

[0048] In particular, compared to amorphous resins, polypropylene has high resistance to thermal decomposition and oxidation, and because it maintains its crystallinity and preserves a stable crystalline structure even after regeneration, it is easy to recycle through simple processes such as washing, crushing, and repelling, and the degradation of quality is very minimal even when recycled.

[0049] Furthermore, polypropylene is a thermoplastic resin widely used in various industrial fields such as packaging, automobiles, and household goods; due to its high volume of usage, it is a material with high economic value and a need for recycling.

[0051] Next, step (b) is a step of pre-mixing 0.5 to 20 parts by weight of coconut shell fibers prepared in step (a) and 0.1 to 3 parts by weight of a compatibilizer in a rotary mixer using a simple mechanical mixing method with 100 parts by weight of the recycled polypropylene resin pellets.

[0052] If coconut shell fibers are included in an amount less than 0.5 parts by weight per 100 parts by weight of resin pellets, they may not adequately perform their role as a reinforcing material within the plastic matrix, resulting in reduced strength and durability, and the aesthetic patterns provided by the coconut shell fibers may not be formed. If coconut shell fibers are included in an amount greater than 20 parts by weight, there are problems such as the nozzle becoming clogged, the mold not filling uniformly, or excessive air bubbles occurring during subsequent injection molding. Additionally, due to the excessive inclusion of fibers, they may not mix uniformly with the resin, leading to localized weaknesses and significantly reduced durability.

[0053] The above compatibilizer is an additive that helps two or more types of polymer materials with different properties to mix well. If the above compatibilizer is included in an amount greater than 3 parts by weight per 100 parts by weight of resin pellets, the mechanical properties of the resin pellets change, making curing difficult or reducing strength, and if flexibility increases excessively, it may be difficult to use the molded product for its intended purpose. If the above compatibilizer is less than 0.1 parts by weight, the interfacial bonding between the fibers and the resin becomes uneven, resulting in uneven fiber distribution or fiber aggregation during injection molding. Since the above coconut shell fibers have excellent interfacial bonding strength with recycled polypropylene resin, a certain level of dispersibility and adhesion can be secured even with the use of a small amount of compatibilizer.

[0054] More specifically, MAPP (Maleated Polypropylene) can be used as the aforementioned compatibilizer. This is a modified polypropylene in which maleic anhydride is chemically bonded to polypropylene; by introducing maleic anhydride functional groups with slight polarity into non-polar polypropylene, it makes the material partially polar, thereby increasing the interfacial bonding strength between the fiber and PP. In addition to this, compatibilizers such as silane-based compatibilizers may also be used.

[0055] The above recycled polypropylene resin pellets, coconut shell fibers, and compatibilizer are pre-mixed in a rotary mixer using a simple mechanical method. This is done to ensure uniform dispersion in the subsequent injection molding process by thoroughly mixing the uniform particle structure of the pellet-shaped resin with the irregular shape of the coconut shell fibers in advance. This prevents the fibers from clumping or localized aggregation during injection.

[0056] Furthermore, by performing only pre-mixing using a simple mechanical mixing method, coconut shell fibers are unevenly mixed with recycled polypropylene pellets, allowing for the realization of irregular patterns or textures in the molded product to achieve aesthetic beauty. Additionally, since the material undergoes a second mixing process immediately before injection due to the rotation of the screw inside the injection molding machine, sufficient mixing effects can be obtained through pre-mixing alone at the raw material stage.

[0057] In addition, the rotational speed of the rotary mixer is characterized as being 30 to 100 mm / s. If mixing is performed at a speed faster than 100 mm / s, the coconut shell fibers may break, which may cause wear or malfunction of the rotary mixer. Additionally, if mixing is performed at a speed slower than 30 mm / s, the mixing may not occur uniformly.

[0058] Additionally, in step (b) above, a coloring agent or pigment may be further added to the mixture. By further adding a coloring agent or pigment, the color of the molded article can be controlled to produce a product with a higher level of finish.

[0060] Next, step (c) is a step of manufacturing an injection-molded product by feeding the mixture from step (b) into an injection molding machine and injecting the mixture into a mold through a nozzle. When fed into the injection molding machine, the recycled polypropylene resin pellets are melted by the high temperature and remixed by the screw inside the injection molding machine. Subsequently, the mixture is injected through the nozzle of the injection molding machine, filling the mold connected to the nozzle and enabling the production of a product of the shape desired by the manufacturer.

[0061] At this time, the temperature of the injection molding machine is 170°C to 200°C, and the temperature of the nozzle is 200°C to 220°C. If the temperature of the injection molding machine is lower than 170°C, the polypropylene resin does not melt well because the melting point of the polypropylene resin is 160°C to 170°C, making it difficult to mix the mixture uniformly; if it is higher than 200°C, more energy than necessary is consumed, making it uneconomical, and if heated to an excessively high temperature, thermal decomposition of the resin molecules may occur, leading to a decrease in physical properties. Additionally, since the resin mixture cools immediately after being injected from the nozzle, the temperature of the nozzle is maintained at a slightly higher temperature than the temperature of the injection molding machine.

[0062] In addition, the rotational speed of the screw is characterized as being 30 to 100 mm / s. When mixing at a speed faster than 100 mm / s, coconut shell fibers may break or air bubbles may be introduced, which may cause wear on the screw. In addition, when mixing at a speed slower than 30 mm / s, the mixing may not occur uniformly, and when a compatibilizer is added, it may be difficult for the compatibilizer to act evenly, which may lead to a decrease in mechanical properties.

[0064] Next, a composition for injection molding recycled plastic containing coconut shell fibers will be described. A composition for injection molding recycled plastic containing coconut shell fibers according to one embodiment of the present invention is characterized by comprising recycled polypropylene resin in pellet form, coconut shell fibers, and a compatibilizer.

[0065] The aforementioned coconut shell fiber is extracted from the outer shell of the coconut fruit and exists as brown fibers ranging in length from several millimeters to several centimeters. It is composed of components such as lignin and cellulose, and is flexible, highly durable, and lightweight. Furthermore, as it is a plant-derived material, it is characterized by being lightweight and biodegradable.

[0066] If the aforementioned coconut shell fibers are mixed with recycled polypropylene resin to produce injection-molded products, the fibers have the effect of distributing loads and suppressing deformation. Additionally, due to the internal structure of the fibers, they can absorb and attenuate vibrations and noise, making them suitable for use in applications such as vehicle interior materials.

[0067] More specifically, the coconut shell fiber is characterized by being prepared by washing raw coconut shells to remove impurities, drying the washed raw coconut shells in an 80°C oven for 24 hours to reduce the moisture content to 4% or less, and transforming them into a fiber form through rotational separation. Through washing, organic matter and impurities present in the coconut shells can be removed. Furthermore, by drying the washed shells in an 80°C oven, moisture contained in the coconut shells is removed, thereby increasing the durability of the finished product and preventing the decay of the coconut shells within the finished product. Additionally, microorganisms present in the coconut shells can be removed by drying at a high temperature for a long period of time. Moreover, through rotational separation, the coconut shell fibers can be separated into strands while maintaining their fiber form, allowing the fibers to enhance the aesthetic effect in the injection-molded finished product and perform the role of a reinforcing material more effectively.

[0068] Polypropylene exhibits excellent thermal stability and chemical resistance, and because it does not deform significantly upon cooling, it is easy to manufacture molded products of precise dimensions via injection molding. Furthermore, it is easy to recycle due to its characteristics of minimal change in mechanical properties upon remelting and ease of color processing. In particular, as it is a widely used material, the need for recycling is very high. Additionally, its excellent fluidity upon melting facilitates mixing and dispersion with coconut shell fibers, making it an outstanding material for recycling when used in combination with coconut shell fibers.

[0069] The above compatibilizer is an additive that helps two or more types of polymer materials with different properties to mix well.

[0070] More specifically, the above composition is characterized by being composed of 0.5 to 20 parts by weight of coconut shell fiber and 0.1 to 3 parts by weight of compatibilizer per 100 parts by weight of recycled polypropylene resin.

[0071] If coconut shell fibers are included in an amount less than 0.5 parts by weight per 100 parts by weight of recycled polypropylene resin, they may not adequately perform their role as a reinforcing material within the plastic matrix, resulting in reduced strength and durability, and the aesthetic patterns provided by the coconut shell fibers may not be formed. If coconut shell fibers are included in an amount greater than 20 parts by weight, there are problems such as the nozzle clogging, failure to fill the mold uniformly, or excessive air bubbles during subsequent injection molding. Furthermore, due to the excessive inclusion of fibers, they may not mix uniformly with the resin, leading to localized weaknesses and significantly reduced durability.

[0072] If the above compatibilizer is included in an amount greater than 3 parts by weight per 100 parts by weight of resin, the mechanical properties of the resin may change, making curing difficult or reducing strength, and causing excessive flexibility, making it difficult to use the molded product for its intended purpose. If the above compatibilizer is less than 0.1 parts by weight, the interfacial bonding between the fibers and the resin may become uneven, resulting in an uneven distribution of fibers or the aggregation of fibers during injection molding. Since the above coconut shell fibers have excellent interfacial bonding strength with recycled polypropylene resin, a certain level of dispersibility and adhesion can be secured even when using a small amount of compatibilizer.

[0073] The above polypropylene resin may be used in the form of pellets, flakes, powder, chips, sheets, masterbatch, etc., but is not limited thereto.

[0074] In addition, MAPP (Maleated Polypropylene) can be used as the aforementioned compatibilizer. This is a modified polypropylene in which maleic anhydride is chemically bonded to polypropylene; by introducing maleic anhydride functional groups with slight polarity into non-polar polypropylene, it makes the material partially polar, thereby enhancing the interfacial bonding strength between the fiber and PP. Other compatibilizers, such as silane-based compatibilizers, may also be used.

[0075] As shown in FIGS. 6 and 7, when an injection-molded article is manufactured using a recycled plastic injection-molding composition containing coconut shell fibers according to one embodiment of the present invention, the coconut shell fibers are exposed on the exterior, providing aesthetic beauty. This can be seen to be more pronounced when compared with FIG. 7, which illustrates a general plastic injection-molded article.

[0076] More specifically, the composition of the present invention has the effect of enabling an industrial-style appearance without separate sandblasting, coating, or post-processing because a natural texture pattern is formed on the surface of the injection-molded product due to the uneven dispersion of coconut shell fibers, and also enables weight reduction compared to filler-based composite materials having the same appearance due to the low specific gravity of the coconut fibers.

[0078] Although the present invention has been described above with specific details such as specific components, limited embodiments, and drawings, this is provided only to aid in a more comprehensive understanding of the invention, and the invention is not limited to the above embodiments, and a person skilled in the art to which the invention belongs can make various modifications and variations from this description.

[0079] Accordingly, the scope of the present invention should not be limited to the embodiments described above, and all modifications equivalent to or equivalent to the claims set forth below, as well as the claims described below, shall be considered to fall within the scope of the concept of the present invention.

Claims

Claim 1 A method for manufacturing a recycled plastic injection-molded article comprising coconut shell fibers, comprising: (a) a step of preparing coconut shell fibers and recycled polypropylene resin pellets; (b) a step of pre-mixing 0.5 to 20 parts by weight of the coconut shell fibers prepared in step (a) and 0.1 to 3 parts by weight of a compatibilizer in a rotary mixer using a simple mechanical mixing method with respect to 100 parts by weight of the recycled polypropylene resin pellets; and (c) a step of introducing the mixture from step (b) into an injection molding machine and injecting the mixture into a mold through a nozzle to manufacture an injection-molded article; wherein the coconut shell fibers are prepared through: a washing step of washing raw coconut shells to remove impurities; a drying step of drying the raw coconut shells washed in the washing step at 80°C for 24 hours to improve the moisture content to 4% or less; and a separation step of separating the raw coconut shells dried in the drying step into a fiber form through rotary separation; wherein the coconut shell fibers are in a fiber form that maintains the grain-direction structure of the coconut shells by not being cut or crushed. Claim 2 delete Claim 3 A method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers, wherein, in claim 1, the recycled polypropylene resin pellets are composed of a size with an average diameter of 1 to 4 mm. Claim 4 A method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers, characterized in that, in claim 1, the compatibilizer is MAPP (Maleated Polypropylene). Claim 5 A method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers, characterized in that, in claim 1, the temperature of the injection molding machine is 170°C to 200°C and the temperature of the nozzle is 200°C to 220°C. Claim 6 A method for manufacturing a recycled plastic injection molded article containing coconut shell fibers, wherein, in claim 1, the rotational speed of the rotary mixer is 30 to 100 mm / s and simple mixing is performed for 25 to 35 seconds. Claim 7 In claim 1, step (b) is characterized by further adding a coloring agent or pigment, a method for manufacturing a recycled plastic injection molded article comprising coconut shell fibers. Claim 8 100 parts by weight of recycled polypropylene resin in pellet form; 0.5 to 20 parts by weight of coconut shell fiber; and 0.1 to 3 parts by weight of a compatibilizer; A recycled plastic injection molding composition comprising coconut shell fibers, characterized by being manufactured by mixing using a simple mechanical mixing method, wherein the coconut shell fibers are prepared by washing raw coconut shells to remove impurities, drying the washed raw coconut shells in an 80°C oven for 24 hours to improve the moisture content to 4% or less, and transforming them into a fiber form through rotary separation, and wherein the fibers are in a fiber form that maintains the grain-direction structure of the coconut shells by not being cut or ground. Claim 9 delete Claim 10 delete

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