High-functionality biodegradable plastic compound using recycled biodegradable plastic and its manufacturing method

Abstract

The present invention relates to a biodegradable plastic compound comprising PLA, rPLA, PBAT, an impact modifier, and a chain extender.

Description

Technology Field

[0001] The present invention relates to a high-performance biodegradable plastic compound comprising PLA (Polylactic Acid), rPLA (Recycled PLA), PBAT (Polybutylene Adipate Terephthalate), an impact modifier, a chain extender, and a nanofiller, and a method for manufacturing the same. In particular, the present invention provides an eco-friendly composite material capable of self-healing properties, electrical conductivity, and controllable biodegradation rate. Background Technology

[0002] Despite their eco-friendly advantages, existing biodegradable plastics face challenges that hinder their widespread industrial use due to insufficient mechanical strength and impact resistance. In particular, PLA-based biodegradable plastics exhibit high stiffness but low impact resistance, while PBAT-based plastics offer excellent impact resistance but have a relatively slow biodegradation rate. Furthermore, existing biodegradable plastic compounds have limited processability, and some products suffer from poor durability due to a lack of self-healing capabilities. Therefore, the development of new materials is necessary to address these issues.

[0003] The prior art is as follows.

[0004] Publication No. 10-2021-0037189: Recycling method for biodegradable plastics The problem to be solved

[0005] The present invention aims to solve the problem of providing a biodegradable plastic compound that offers improved mechanical strength compared to existing PLA-based biodegradable plastics by maintaining a balance of PLA and rPLA and adding an impact modifier and PBAT to overcome the limitations of existing biodegradable plastics.

[0006] In addition, the present invention aims to solve the problem of lowering product durability if the biodegradation rate is too fast and lowering environmental friendliness if it is too slow by providing a biodegradable plastic compound that can control the biodegradation rate by including nanofillers.

[0007] In addition, the present invention aims to solve the problem of providing a biodegradable plastic compound with improved durability compared to existing biodegradable plastics by applying MBS / ABS polymer-based microcapsules to enable automatic restoration when microcracks occur.

[0008] In addition, the present invention aims to solve the problem of providing a plastic compound with improved electrical conductivity that includes nanofillers such as CNTs and graphene, so that it can be applied to electronic products and applications requiring anti-static properties. means of solving the problem

[0009] To solve the aforementioned problem, the present invention provides a biodegradable plastic compound comprising PLA, rPLA, PBAT, an impact modifier, and a chain extender as a means of solving the problem.

[0010] In addition, the solution to the problem is to provide a biodegradable plastic compound comprising 30 to 36 weight% of PLA, 25 to 36 weight% of rPLA, 10 to 15 weight% of PBAT, 5 to 10 weight% of an impact modifier, and 1 to 3 weight% of a chain extender.

[0011] In addition, providing a biodegradable plastic compound characterized by further including nanofillers is a means of solving the problem.

[0012] In addition, the solution to the problem is to provide a biodegradable plastic compound characterized by having the above-mentioned nanofiller in an amount of 1 to 3 weight %.

[0013] In addition, the solution to the problem provides a method for manufacturing a biodegradable plastic compound comprising PLA, rPLA, PBAT, an impact modifier, and a chain extender, and including the following process.

[0014] A step of washing rPLA in water at 80 to 90°C for 2 hours and drying at 120°C for 4 hours; a step of mixing PLA, rPLA, PBAT, impact modifier, and chain extender at 180 to 200°C for 30 to 60 minutes and additionally mixing nanofillers at 190°C; a step of extruding the mixed material at 200 to 220°C to form pellets; and a step of drying the molded pellets at 60 to 80°C for 48 hours. Effects of the invention

[0015] The present invention can provide a biodegradable plastic compound that provides improved mechanical strength compared to existing PLA-based biodegradable plastics by adding an impact modifier and PBAT while maintaining a balance of PLA and rPLA to overcome the limitations of existing biodegradable plastics.

[0016] In addition, the present invention can provide a biodegradable plastic compound that includes nanofillers to control the biodegradation rate, due to the problem that if the biodegradation rate is too fast, product durability is reduced, and if it is too slow, environmental friendliness is reduced.

[0017] In addition, the present invention can provide a biodegradable plastic compound with improved durability compared to existing biodegradable plastics by applying MBS / ABS polymer-based microcapsules to enable automatic restoration when microcracks occur.

[0018] In addition, the present invention can provide a plastic compound with improved electrical conductivity by including nanofillers such as CNTs and graphene so that it can be applied to electronic products and applications requiring anti-static properties. Specific details for implementing the invention

[0019] The present invention is susceptible to various modifications and may take various forms, and embodiments are to be described in detail in the text. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each figure. Terms such as "first," "second," etc., may be used to describe various components, but said components should not be limited by said terms.

[0020] The above terms are used solely for the purpose of distinguishing one component from another. The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0021] In this application, terms such as "comprising" or "consisting of" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0022] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0023] A biodegradable plastic compound according to one embodiment of the present invention may be provided to include 30 to 36 weight% of PLA, 25 to 36 weight% of rPLA, 10 to 15 weight% of PBAT, 5 to 10 weight% of an impact modifier, and 1 to 3 weight% of a chain extender.

[0024] In addition, it may be provided to include 1 to 3 weight percent of nanofillers.

[0025] If nanofillers are included, the total amount must not exceed 100 weight %.

[0026] The range of each composition ratio of the present invention and its critical significance are as follows.

[0027] PLA can be provided in an amount of 30 to 36%.

[0028] When PLA is present in an amount of less than 30%, there is a problem of reduced mechanical strength and reduced durability due to insufficient stiffness, and when it exceeds 36%, there is a problem of reduced biodegradation rate and difficulty in processing.

[0029] rPLA (recycled PLA) can be provided in an amount of 25 to 35%.

[0030] When rPLA is present in an amount of less than 25%, the recycling effect is reduced, leading to a decrease in eco-friendliness, and when it exceeds 35%, the physical properties become unbalanced, resulting in a decrease in the durability of the product.

[0031] PBAT can be provided in an amount of 10 to 15%.

[0032] When PBAT is provided at less than 10%, there is a problem of reduced impact strength due to a lack of flexibility, and when it exceeds 15%, there is a problem of reduced biodegradation rate and increased production costs.

[0033] Impact modifiers (MBS, ABS, etc.) may be provided in an amount of 5~10%.

[0034] When the impact modifier is provided in an amount of less than 5%, there is a problem that the product breaks easily due to insufficient impact resistance, and when it exceeds 10%, there is a problem that processability is reduced and homogeneous dispersion is difficult.

[0035] Chain extenders (such as poly styrene-based ones) may be provided in an amount of 1 to 3%.

[0036] When the chain extender is provided in an amount of less than 1%, there is a problem of reduced physical properties due to insufficient molecular weight increase effect, and when it exceeds 3%, there is a problem of reduced processability due to excessive viscosity increase.

[0037] Nanofillers (CNT, graphene, nanocellulose, etc.) may be provided in an amount of 1 to 3%.

[0038] When nanofillers are provided in an amount of less than 1%, there is a problem of insufficient biodegradation promotion and conductivity effects, and when they exceed 3%, filler aggregation occurs, resulting in a decrease in homogeneity.

[0039] An example of the optimal composition ratio of the present invention is as follows.

[0040] [Optimal Composition Ratio (Best Mode) of the Present Invention]

[0041] PLA (Virgin Plastic): 35%

[0042] rPLA (Recycled PLA): 30%

[0043] PBAT: 15%

[0044] Impact modifiers (MBS, ABS-based modifiers, etc.): 10%

[0045] Chain extender (Poly Styrene-based, etc.): 2%

[0046] Nanofillers (CNT, graphene, nanocellulose, etc.): 3%

[0047] Other additives (plasticizers, stabilizers, etc.): 5%

[0048] The above optimal composition ratio was achieved by adjusting the sum of the ratios of PLA and rPLA to 65% and the rPLA ratio to 30% to increase the usability of recycled materials while preventing a decrease in mechanical properties.

[0049] By adjusting PABT to 15%, elasticity and flexibility were enhanced and impact strength was increased, while maintaining a balance between biodegradation rate and mechanical properties.

[0050] The impact modifier was an MBS and ABS-based modifier, and the ratio was adjusted to 10% to improve the IZOD impact strength to 64 KJ / m² or higher.

[0051] The chain extender is a Poly Styrene-based material, and the ratio was adjusted to 2% to increase the molecular weight, thereby securing mechanical strength.

[0052] Nanocellulose, a nano-filler, was adjusted to a 3% ratio to act as a biodegradation promoter and control the degradation rate in specific environments.

[0053] The test results for IZOD impact strength, tensile strength, and elongation are as follows.

[0054] IZOD kJ / m3 Tensile strength Mpa Growth rate % Sample name PLA r-PLA PABT Shock reinforcement Chain extension total KS M ISO 180 ASTM D638-22 r-PLA 50 33.5% 33.5% 20% 10% 3% 100% 64.0 26.1 144

[0056] A method for manufacturing a biodegradable plastic compound according to one embodiment of the present invention is as follows.

[0057] 1. Material preparation stage

[0058] In the material preparation step, rPLA is washed in water at 80–90°C for 2 hours to remove impurities.

[0059] At 80℃, there is a problem where the possibility of impurities remaining increases due to insufficient washing, and at temperatures exceeding 90℃, there is a problem where PLA structural deformation and mechanical property degradation occur.

[0060] After drying, heat treat at 120℃ for 4 hours.

[0061] If the temperature is below 120℃, residual moisture is not removed, which increases the risk of bubble formation in subsequent processes, and if the temperature exceeds 140℃, thermal decomposition of PLA occurs, leading to a decrease in strength.

[0062] 2. Compounding Process

[0063] In the compounding process, PLA, rPLA, PBAT, impact modifier, and chain extender are mixed at 180 to 200°C for 30 to 60 minutes.

[0064] At temperatures below 180℃, the material is not completely mixed, which leads to a decrease in physical properties, and at temperatures above 200℃, there is a problem with reduced processability due to PLA thermal decomposition and plasticizer evaporation.

[0065] If the mixing time is less than 30 minutes, it is difficult to achieve uniform mixing, which leads to an imbalance in product quality, and if the mixing time exceeds 60 minutes, there is a problem of reduced molecular weight due to excessive thermal stress.

[0066] Afterwards, nanofillers are added at 190°C to produce a uniform mixture.

[0067] At temperatures below 190°C, there is a problem where the uniformity of physical properties is reduced due to insufficient filler dispersion, and at temperatures above 210°C, there is a problem where the homogeneity of the composite material is damaged due to excessive aggregation of the filler.

[0068] 3. Filleting Process

[0069] In the filleting process, the mixture is extruded at 200 to 220°C and formed into a pellet.

[0070] At this time, if the extrusion temperature is below 200℃, there is a problem of reduced productivity due to decreased extrudability, and if it exceeds 220℃, there is a problem of reduced mechanical strength due to the thermal decomposition of PLA.

[0071] Afterward, the final drying is performed at a drying temperature of 60°C or higher for a drying time of 4 to 8 hours, and then packaged according to the intended use.

[0072] At this time, if the drying temperature is below 60℃, there is a problem that the possibility of quality degradation during storage increases due to residual moisture.

[0073] In addition, if the drying time is less than 4 hours, the product defect rate increases due to the failure to completely remove moisture, and if the drying time exceeds 8 hours, there are problems of energy waste and excessive hardening.

[0074] Although the invention has been described with reference to embodiments, a person skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims.

Claims

Claim 1 A biodegradable plastic compound characterized by comprising PLA, rPLA, PBAT, an impact modifier, and a chain extender, and further comprising 1 to 3 weight percent of a nanofiller comprising CNT or graphene to impart electrical conductivity. Claim 2 A biodegradable plastic compound according to claim 1, comprising 30 to 36 weight% of PLA, 25 to 36 weight% of rPLA, 10 to 15 weight% of PBAT, 5 to 10 weight% of impact modifier, and 1 to 3 weight% of chain extender. Claim 3 A biodegradable plastic compound characterized by further including nanofillers in claim 2. Claim 4 A biodegradable plastic compound according to claim 3, characterized in that the nanofiller is provided in an amount of 1 to 3 weight %. Claim 5 delete