PLA-based agricultural waste and graphene-containing masterbatch and filament production method from these masterbatches

Abstract

The invention relates to the production of PLA (polylactic acid) masterbatches based on agricultural waste and graphene and filament production from these masterbatches. The invention provides for the reuse of agricultural waste and the preparation of biodegradable polymers reinforced with graphene.

Description

[0001] PLA-BASED AGRICULTURAL WASTE AND GRAPHENE-CONTAINING MASTERBATCH AND FILAMENT PRODUCTION METHOD FROM THESE MASTERBATCHES

[0002] TECHNICAL FIELD

[0003] The invention relates to the production of PLA (polylactic acid) masterbatches based on agricultural waste and graphene and filament production from these masterbatches. The invention provides for the reuse of agricultural waste and the preparation of biodegradable polymers reinforced with graphene.

[0004] BACKGROUND

[0005] Masterbatch is an additive in the form of a concentrate used to improve the properties of polymers or to impart specific properties. The production of PLA (polylactic acid) masterbatches based on agricultural waste and graphene and the production of filaments from these masterbatches is a technical field for the reuse of agricultural waste and the preparation of biodegradable polymers reinforced with graphene. PLA masterbatches based on agricultural waste and PLA masterbatches based on agricultural waste and graphene are a combination used for the recycling and reuse of agricultural waste.

[0006] Wastes generated as a result of agricultural activities can take various forms such as crop residues, agricultural by-products, agricultural processing residues and animal wastes. The management and disposal of these wastes can cause environmental problems. Therefore, utilization and recycling of agricultural wastes has become an important goal. Recycling and incorporating these wastes into masterbatches ensures efficient use of resources.

[0007] Polylactic acid (PLA) is a polymer derived from renewable resources. It is usually produced from corn starch or sugar cane and has biodegradable properties. PLA is a common bioplastic material used in a variety of applications. Graphene is a single atom thick graphitic structure formed by arranging carbon atoms in a planar structure. It has high mechanical strength, conductivity, thermal stability and other properties. Therefore, graphene is recognized as an important material used to improve various materials and give them new functions. Graphene particles are added to PLA polymer to form masterbatches. Graphene reinforcement improves the mechanical strength, thermal conductivity, electrical properties and barrier properties of PLA. Furthermore, graphene reinforcement improves the environmental effectiveness of the masterbatches.

[0008] US2015 / 0294752 numbered patent application titled “GRAPHENE MASTERBATCH” relates generally to graphene masterbatch, and more specifically to a graphene masterbatch comprising surface-modified graphene nanoplatelets with improved compatibility with carbon black and polymer material to obtain a homogeneous mixture and greatly increase the cohesive strength of the joint. The present invention may include at least one of polyolefin, polyester, polycarbonate (PC), polyurethane (PU) and acrylonitrile-butadiene-styrene copolymer (ABS) for the graphene masterbatch.

[0009] CN 103073930 numbered patent application discloses a composite material comprising alkylated functional graphene and Nylon 66 (PA66).

[0010] WO 2012 / 151433 numbered patent application discloses a nanocomposite comprising a polymer comprising polyethylene terephthalate (PET) and a nanoparticulate substrate such as graphene. The nanocomposite material is obtained by the steps of mixing polymer and nanoparticles to form a master batch product and injection or blow molding the master batch product. This improves the mechanical strength for PET. As can be seen, the present invention involves the production of PET-based graphene masterbatch.

[0011] TR2021 / 004254 numbered patent application “USING AGRICULTURAL WASTES IN THE PRODUCTION OF FILAMENT USED IN THREE-DIMENSIONAL PRINTERS” includes a production of polymer filaments consisting of ABS, PLA, nylon, PETG, HIPS and / or polyolefins using a wide variety of vegetable and / or agricultural wastes as raw materials, including rice and sunflower. Rice and sunflower wastes are mentioned in the invention, but there is no detailed information on which parts of these wastes are used and how they are processed. In addition, there is no graphene additive in this invention. This limits the usability of the invention.

[0012] In patents numbered CN103073930 and WO2012 / 151433A2, graphene doping is used with polymer bases made of Nylon 66 (PA66) and polyethylene terephthalate (PET). These patents use the electrically conductive materials carbon black, carbon fiber and graphene. No agricultural waste was used and although a wide variety of polymers were used, PLA polymer was not included. Among the filaments used in 3D printers, PLA-based filaments are largely used. Therefore, the inventions achieved are largely limited. Therefore, there is a great need to provide graphene masterbatches with new ingredients and accompanying filaments.

[0013] In our invention, sunflower stalk and rice husk wastes as agricultural waste as well as graphene additives are used in PLA-based masterbatches and filaments. Thus, the technical problems of the prior art are overcome.

[0014] AIM OF THE INVENTION

[0015] PLA masterbatches based on agricultural waste and graphene are a composition for adding graphene and agricultural waste particles to PLA polymer. These masterbatches aim to improve the mechanical strength, thermal conductivity, electrical properties and other properties (antimicrobial and biodegradable) of PLA. Graphene particles create a reinforcing effect in the PLA matrix and increase the durability of the material. This property enables the masterbatches to be used in engineering applications, building materials and the packaging industry.

[0016] Graphene has high thermal conductivity. Therefore, graphene reinforcement improves the thermal conductivity properties of PLA masterbatches based on agricultural waste and graphene.

[0017] PLA is a biodegradable polymer and PLA masterbatches based on agricultural waste and graphene retain this property. The production of these masterbatches is important for industrial and environmental sustainability.

[0018] Filament is a thin, long piece of material used in additive manufacturing methods such as 3D printers. The production of filaments from PLA masterbatches based on agricultural waste and graphene is a process of adding these masterbatches to PLA polymer to form filaments. These filaments can be used in 3D printers to produce a variety of strong, lightweight and durable objects.

[0019] One aim of the invention is that the obtained PLA-based graphene masterbatch and PLA-based agricultural waste masterbatch can be used in many sectors where PLA-based products are produced, especially in the packaging, food and toy sectors.

[0020] Another aim of the invention is to use PLA-based graphene filament, PLA-based agricultural waste filament and PLA-based agricultural waste-graphene filament products produced from the masterbatches described above in 3D printers, toy industry, hospital equipment, medical devices, packaging, aviation and automotive industry. Another aim of the invention is to enable the printing of products with higher resolution, lighter weight and higher thermal properties than standard PLA filaments, thanks to the real sunflower stalk and rice husk waste reinforcement materials contained in the filaments prepared from the masterbatches produced.

[0021] Another purpose of the invention is that the nano-sized graphene particles added to the filaments can be used to design sensors, home decoration products, EMI / RF shields, capacitive sensing, high-strength mechanical and functional parts.

[0022] FIGURE LIST

[0023] Figure 1a. Masterbatch Production Flow Chart from PLA Based Sunflower Waste

[0024] Figure 1b. Masterbatch Production Flow Chart from PLA Based Rice Waste

[0025] Figure 2. Flow Chart of PLA Based Graphene Masterbatch Production

[0026] Figure 3. Flow Chart of PLA Based Agricultural Waste-Graphene Masterbatch Production

[0027] Figure 4. Flow Chart for the Production of PLA-based Agricultural Waste, Graphene and Agricultural Waste-Graphene Filaments

[0028] Corresponding references to the process steps in the figures: la. Collecting dried sunflower stalks left in the field after harvest lb. Drying at 40 degrees lc. Grinding, washing with mains water and drying at 40 degrees ld. Screening to size below 50um le. Mixing sunflower stalk powders with PLA granules at 1-30 wt% of the polymer lf. Feeding the mixture into a twin-screw extruder and processing at a temperature range of 180-200 degrees lg. Cooling the melt mixture into pellets lh. Supply of rice husks from rice producers and sieving and dust removal

[0029] 1 i. Washing rice husks with tap water

[0030] 1 j. Drying at 40 degrees

[0031] 1k. Screening to size below 50um

[0032] 1m. Mixing sunflower stalk powders with PLA granules at 1-30 wt% of the polymer 1 n. Feeding the mixture into a twin-screw extruder and processing at a temperature range of 180-200 degrees

[0033] 1 p. Cooling the melt mixture into pellets

[0034] 2a. Mixing the polymer with 1-20 wt% graphene PLA granules

[0035] 2b. Feeding the mixture into a twin-screw extruder and processing at 180-200 degree temperature ranges

[0036] 2c. Cooling the melt mixture into pellets

[0037] 3a. Agricultural waste (one of sunflower stalk or rice husk powders) in proportions of 1-30 wt% of the polymer sieved to sizes below 50um

[0038] 3b. 1-20 wt% graphene in the polymer

[0039] 3c. Mixing with PLA granules

[0040] 3d. Feeding the mixture into a twin-screw extruder and processing at a temperature range of 180-200 degrees

[0041] 3e. Cooling the melt mixture into pellets

[0042] 4a. Re-passing the prepared masterbatches through an extruder with a diameter automated hot water cooling pool operated in the temperature range of 150- 200 degrees and a single pitch screw

[0043] 4b. Winding PLA-based agricultural waste and graphene filaments with diameters of 1.75 mm on spools

[0044] DETAILED DESCRIPTION OF THE INVENTION

[0045] Rice and sunflower have an important agricultural potential. Approximately 50% of the vegetable oils produced in Turkey are produced from sunflower. In line with the increasing demand for vegetable oil, the cultivation area of sunflower seeds has also expanded. However, rice husks are by-products of rice cultivation, accounting for more than 50% of the total weight of the rice crop. Therefore, these wastes can be easily managed because they do not require separation from other wastes. Therefore, these wastes were considered as sustainable natural fiber sources for the preparation of masterbatches and filaments and sunflower stalks and rice husks were selected as agricultural wastes for the preparation of PLA-based agricultural waste and graphene masterbatches and filaments of these masterbatches. This natural fiber additive improves the thermal and physical properties of the inventive material.

[0046] PLA-based agricultural waste and graphene masterbatches can be used in the packaging industry, and especially the filaments of these masterbatches can be used in almost all commercially available desktop 3D printers to 3D print prototype 3D models, toys, building elements, daily use items, components that conduct electricity, etc. The PLA-based agricultural waste and graphene filaments developed within the scope of the invention can be easily processed on conventional printing equipment. The material is stable as a filament provided it is stored in a dry environment. It is enriched with graphene for conductivity, antimicrobial surfaces and improved mechanical properties.

[0047] The method steps of the invention are as follows:

[0048] - Rice husks and sunflower stalks were washed and dried (1c, 1 i, 1 j), then ground and the powders obtained from these agricultural wastes were sieved to a size below 50 pm (1 d, 1 k). The reason for this is to prevent the powder additives added to the filament production from clogging the nozzles of the 3D printers during the use of the filaments to be produced.

[0049] - PLA-based agro-waste masterbatches contain 1-30 wt% of the PLA used as a polymer with powders obtained from rice husks or sunflower stalks (1e, 1m). This ratio is not exceeded since mixing the polymer with a higher proportion of agricultural waste powders would cause brittle / fragile structures. The polymer and agricultural waste content are mixed until homogeneous and fed into a twin- screw extruder with a temperature range of 180-200 °C from the inlet temperature to the outlet of the extruder in a twin-screw extruder with temperature adjustment in seven different zones and homogeneous mixing is ensured in the device (2b). Acrylonitrile-Butadiene-Styrene (ABS), Thermoplastic Polyurethane (TPU), Acrylonitrile Styrene Acrylate (ASA), Polyamide 6, 6.6,12, Polyethylene terephthalate G (PET-G), Polypropylene (PP) polymers can be used as an alternative to PLA.

[0050] - After the melt mixture is cooled, it is cut into pellets in a crusher to prepare masterbatches (2c).

[0051] In another embodiment of the invention, PLA-based graphene masterbatches are prepared in a twin-screw extruder by mixing 1-20 wt% of the polymer with graphene, PLA granules in the specified environment by applying the above steps exactly with the addition of graphene instead of agricultural waste content (2a).

[0052] In another embodiment of the invention, PLA granules are simultaneously mixed with 1-30 wt% of agricultural waste powders, 1-20 wt% of nano-sized graphene and PLA granules to prepare PLA-based agricultural waste and graphene masterbatches in a twin screw extruder (3a, 3b).

[0053] Table 1. Sample masterbatch formulation table (ingredient ratios can be changed).

[0054] Materbatches prepared in any of the above configurations are processed in a single screw extruder with four temperature zones to produce filaments. In the extruder, zone 1 is the feed zone and is set to a temperature in the range of 160-175°C. This temperature ensures that the PLA matrix has a fluidity 20% below the flow index. In this way, a gel-like structure is formed and this structure allows the extruder screw to reach the polymeric material to the melting zone, which is the next stage, and to create a constant pressure in the extruder mirror. The 2nd zone is the melting zone, a section reserved for the melting of the polymer. Here, the material both reaches the melting point and gains pressure thanks to the conical structure of the shaft. The temperature of this zone is set to around 200°C. The next stage is the 3rd zone, called the transfer zone. Here, the pressurized and now liquid polymer is pushed towards the extruder mirror with a regular flow. In this zone, the temperature is set to 210°C, which is the melting zone of PLA, so that the melt fluid continues to flow at the same temperature. The last zone is the head and mirror zone. In this region, the temperature is kept around 205°C and the flow index of the melt fluid is slightly reduced, thus producing a more solid material in the extrusion process and producing a fixed diameter filament with reduced ovality.

Claims

CLAIMS1 . A PLA-based masterbatch production method with agricultural waste content, characterized by comprising the steps below;- Rice husks and sunflower stalks are washed, dried, ground and sieved to sizes below 50 pm,- Adding powders obtained from rice husks or sunflower stalks at a rate of 1-30% of the PLA weight to be used,- Mixing PLA and agricultural waste content until homogeneous,- Feeding the mixture into a twin-screw extruder with a temperature range of 180-200°C from the inlet temperature to the outlet of the extruder in a twin-screw extruder with temperature adjustment in seven different zones,- Converting the molten mixture into pellets after cooling.

2. A PLA-based graphene-containing masterbatch production method, characterized by comprising the steps below;- Adding graphene at a rate of 1 -20% of the PLA weight to be used,- Mixing PLA and graphene content until homogeneous,- Feeding the mixture into a twin-screw extruder with a temperature range of 180-200°C from the inlet temperature to the extruder outlet in a twin- screw extruder with temperature adjustment in seven different zones,- Turning the molten mixture into pellets after cooling.

3. A PLA-based agricultural waste and graphene-containing masterbatch production method, characterized by comprising the steps below;- Rice husks and sunflower stalks are washed, dried, ground and sieved to sizes below 50 pm,- Adding 1-30% of rice husk or sunflower stalk powders and 1-20% of graphene by weight of PLA to be used,- Mixing PLA, graphene and agricultural waste content until homogeneous,- Feeding the mixture into a twin-screw extruder with a temperature range of 180-200°C from the inlet temperature to the extruder outlet in a twin- screw extruder with temperature adjustment in seven different zones,- Turning the molten mixture into pellets after cooling.

4. The method of producing filaments using a masterbatch obtained by performing the method steps according to any one of the preceding claims, characterized in that the masterbatches are re-treated in an extruder and wound on spools as filaments.

5. The method of producing a filament according to claim 4, characterized in that the filament is produced in a single screw extruder with four temperature zones;- Setting a temperature in the range of 160-175°C in zone 1 , which is the feed zone,- In the 2nd melting zone, the melting zone, the material both reaches the melting point and gains pressure thanks to the conical structure of the shaft,- In the 3rd zone, called the transfer zone, the polymer is pushed towards the extruder mirror with a steady flow,- The last zone, the head and chuck zone, is characterized by the steps of reducing the flow index of the melt fluid and thereby producing a filament of constant diameter with reduced ovality by extruding a more rigid material in the extrusion process.