A method for the production of algal biomass-based bioplastics

Abstract

The invention relates to a method for solving technical problems encountered in the production of algal biomass-based bioplastic products by extrusion technique. In the invention, by optimizing the bioplastic production method process steps, it is ensured that the product obtained can show long-term durability, stability and have equivalent or improved thermal and mechanical properties, and the range of environmentally friendly bioplastic products at affordable costs is expanded.

Description

[0001] A METHOD FOR THE PRODUCTION OF ALGAL BIOMASS-BASED BIOPLASTICS

[0002] TECHNICAL FIELD

[0003] The invention relates to a method for solving technical problems encountered in the production of algal biomass-based bioplastic products by extrusion technique. In the invention, by optimizing the bioplastic production method process steps, it is ensured that the product obtained can show long-term durability, stability and have equivalent or improved thermal and mechanical properties, and the range of environmentally friendly bioplastic products at affordable costs is expanded.

[0004] PRIOR ART

[0005] Plastics are synthetic or semi-synthetic materials typically composed of polymers with high molecular weight. Due to their properties such as flexibility, durability, lightweight nature, and ease of shaping, these materials have a wide range of applications.

[0006] Plastics are generally derived from petroleum-derived raw materials, i.e. fossil fuels. According to recent studies, obtaining plastic materials from petroleum- derived raw materials causes environmental pollution, greenhouse gas emissions and consumption of unsustainable resources. Due to these disadvantages, there is growing interest in plastics derived from renewable resources, such as bioplastics, which are more sustainable and environmentally friendly alternatives. Bioplastics derived from renewable resources such as algal biomass have the potential to replace petroleum-derived plastics and are seen as an important step towards increasing environmental sustainability.

[0007] The use of algal biomasses as raw materials for the production of bioplastic materials is a topic of recent research and development. Algal biomass is the sum of organic matter generated by the growth and development of algae (both microalgae and macroalgae). This biomass comprises of carbon-based organic compounds that algae create by converting sunlight and carbon dioxide into energy through photosynthesis. Algal biomass contains various useful components such as proteins, carbohydrates, lipids and other bioactive compounds, which can be used in a variety of applications such as biofuels, bioplastics, food supplements, animal feed, fertilizers and biomedical products. Algal biomass is recognized as a renewable and sustainable resource and has significant potential for environmental sustainability.

[0008] Extrusion is the most functional production method for obtaining plastic materials in targeted shapes. The extrusion process is the most preferred manufacturing method for shaping plastic materials due to its numerous advantages, including high production efficiency at low costs, versatility and flexibility, the ability to ensure high quality, and its environmentally friendly nature.

[0009] There are some technical problems in the application of the extrusion method, which provides such technical advantages and solutions in the production of algal biomass-based bioplastics. The high moisture content and rapid dehumidification of algae as a biomass can cause moisture problems in the production process, which requires careful optimization of drying and storage conditions. In addition, homogenization problems occur after extrusion production of bioplastics containing algal biomass.

[0010] Due to the technical problems mentioned above, it is difficult to obtain algal biomass-based bioplastics by extrusion method. In order to use the extrusion method with technical solutions and advantages in the production of algal biomassbased bioplastics, it is necessary to optimize the production process steps to eliminate technical problems. BRIEF DESCRIPTION OF THE INVENTION

[0011] Bioplastics derived from renewable and environmentally friendly raw materials are replacing plastic materials derived from petroleum-derived raw materials used in various functions in many different technical fields. The availability of various raw materials and production methods for the production of bioplastic materials, for which research and development activities have recently increased, is being evaluated.

[0012] Recently, the use of algal biomasses as raw materials for the production of bioplastic products has been increasing.

[0013] However, extrusion methods are difficult to apply to formulations in which algal biomasses are used as raw materials in bioplastics production and cause various technical problems. This is because algal biomasses are likely to contain moisture during production and have homogenization problems.

[0014] The present inventors use the extrusion method to produce bioplastics from algal biomass at lower costs, increase formability and produce more products per unit time, and perform optimizations in the production process steps to eliminate technical problems in the use of this extrusion method.

[0015] The primary object of the present invention is to provide an extrusion method for the production of bioplastics from algal biomass.

[0016] A further objective of the present invention is to provide an extrusion method for producing bioplastics from algal biomass, ensuring that homogenization is not a technical problem. DETAILED DESCRIPTION OF THE INVENTION

[0017] In this detailed description, the subject matter of the invention relates to a method for producing bioplastics from algal biomass and is described only by way of nonlimiting examples for a better understanding of the subject matter.

[0018] The method subject to the present invention is a production method integrated with the extrusion method. The extrusion method mentioned here is actually one of the post-processing steps. In order for extrusion processes to be applied with high efficiency, there is a need for pre-processing steps to be applied beforehand. Firstly, a formulation including algal biomass is prepared. In order to make it suitable for extrusion processes, more than one auxiliary component must be included in this formulation in addition to algal biomass. Each component in the formulation and the volume ratios of these components contribute to the production of algal biomass-based raw material suitable for extrusion processes.

[0019] The present inventors have carried out research and development activities for the preparation of this formulation.

[0020] The formulation referred to here is a mixture of more than one component as raw material. Each component must be compatible with each other in terms of technical properties during the extrusion process. The present inventors prevent homogenization problems in the final product, bioplastics, by ensuring that a compatible formulation is prepared as raw material for extrusion processes. As known in the art, one of the technical problems encountered in the extrusion of bioplastics using algal biomass as raw material was the production of an inhomogeneous final product. Thanks to the optimized formulation, the inventors are able to eliminate the homogenization problem encountered in the extrusion production of bioplastics, the final product, by extrusion production method.

[0021] The subject formulation contains algal biomass as the main component. As mentioned before, algal biomass is all organic substances obtained as a result of the growth and development of algae. In the invention, there is no difference between using microalgae and / or macroalgae as algal raw materials. In a preferable embodiment of the present invention, both types of algae can be used as raw materials.

[0022] In a preferred embodiment, algae can also be obtained from wastewater sources. In this way, costs can be reduced and wastewater can be utilized in the circular economy model.

[0023] In a most preferred embodiment, microalgae are used as algae feedstock. The reason why microalgae is preferred as algae feedstock in the invention is that it has high growth rates, nutrient uptake efficiency and minimum space requirements.

[0024] The present inventors may also purchase or produce microalgae commercially.

[0025] In a preferred embodiment, the present inventors are able to culture algae in at least one medium. At least one of raceway ponds, high-rate algal ponds (HRAPs), flat panel bioreactors, tubular bioreactors, buble column bioreactors, myxotropic cultivation, two-stage systems, fermentation group is preferred as said medium.

[0026] Harvesting of algal biomasses obtained by methods known in the art can be carried out using various methods. At least one of the harvesting methods such as centrifugation, filtration, flocculation, sedimentation, decanter can be applied to the algal biomass taken from the media.

[0027] The scope of present invention is not limited to the manner of implementation of the systems and harvesting methods for obtaining algal biomass.

[0028] One of the most important process steps of the method of the present invention is to subject the obtained algal biomass to drying processes and to add it into the formulation in appropriate amounts as a formulation component.

[0029] In a preferred embodiment of the invention, the algae raw materials are pulverized before drying. In a preferred embodiment, this process is carried out with a mechanical grinder. The aim here is to break the cell walls of the algal raw materials. Cell walls are the parts that prevent the algal raw materials from being processed in the intended ways. For example, algal biomass cell walls pose a technical problem for effective drying processes.

[0030] Algal biomass can be subjected to drying processes using at least one of various technical methods. Drying methods such as oven drying, freeze-drying, and spray drying can be preferred. The drying process for algal biomass is carried out at a temperature ranging between 50 and 80°C. The selected drying temperatures are intended to ensure effective moisture removal and quality preservation without causing any damage to the algal biomass, prevent oxidation, maintain nutrient content, minimize thermal stress, and avoid unnecessary energy consumption.

[0031] The duration of the mentioned drying process is between 6 and 10 hours. The algal-based formulation, which will be processed without creating technical problems in the extrusion process, should not contain any algal biomass containing any moisture.

[0032] In a preferred embodiment, if the algal biomass dried during the formulation preparation phase cannot be used immediately, it is preferably kept in a silica gel and / or vacuum environment to remove it from the environment where it can absorb moisture in any way.

[0033] The formulation of the invention contains at least one polymer material.

[0034] In a preferred embodiment, this polymer material is a bioplastic material. Polylactic acid can be used as a bioplastic. However, starch, corn, sugar cane or cellulose from which polylactic acid can be obtained can also be used as a component.

[0035] In a preferred embodiment, at least one polymer material from the group comprising of polyethylene, polyterephthalate, polyamide, polypropylene, polytrimethylene terephthalate, polybutylene succinate, bisphenol A polycarbonate, polyvinyl alcohol, polyhydroxyalkanoate, and polyhydroxybutyrate can also be used as a component in the formulation. In a preferred embodiment, at least one bioplastic and at least one polymer material from the group comprising of polyethylene, polyterephthalate, polyamide, polypropylene, polytrimethylene terephthalate, polybutylene succinate, bisphenol A polycarbonate, polyvinyl alcohol, polyhydroxyalkanoate, and polyhydroxybutyrate can be used as polymer materials in the formulation.

[0036] Before being added to the formulation, it is essential that at least one polymer material is also moisture-free. To achieve this, drying processes are applied to the polymer as well. In a preferred embodiment, this drying process is carried out at a temperature ranging between 60 and 90°C. The duration of this drying process is between 6 and 8 hours. The purpose of conducting this drying process at the specified temperature and duration is to remove moisture from the polymer material, ensure enhanced stability, prevent hydrolysis, and improve processability. Additionally, it aims to prevent unnecessary energy inefficiency in the drying processes.

[0037] Since at least one plastic material must also be added to the formulation in a dry form, it is kept in vacuum and / or silica gel before the process.

[0038] At least one polymer material and algal biomass obtained as a result of these processes are mixed to obtain a homogeneous mixture. The amount of algal biomass:polymer in this mixture is between 1 :9 and 3:7 by volume. The inclusion of components in the formulation in the specified volume ratios is critical for both the final product to be obtained and for ensuring appropriate mechanical and thermal properties for the extrusion process. The mentioned mechanical and thermal properties also affect the processability of the final product. In addition, these ratios can also provide the homogenization required for the final product and process operations.

[0039] The formulation contains at least one compatibilizer. As the compatibilizer, at least one component from maleic anhydride, ethylene / propylene rubber, or diethyl succinate is preferred. In the most preferred embodiment, maleic anhydride is used as the compatibilizer. In the production of the final bioplastic product, the compatibilizer is used to enhance compatibility between different polymers or between polymers and additives, contributing to the overall performance and properties of the bioplastic material.

[0040] It has been determined that the mechanical strength values of the tested samples obtained from formulations in which maleic anhydride is used as a compatibilizing component have increased.

[0041] At least one compatibilizer is added to the homogeneous mixture obtained in the previous process step and the mixing process is applied to obtain a homogeneous mixture. As a result of these processes, the target formulation is obtained. The amount of compatibilizer in the formulation ranges from 0.1% to 2% by volume relative to at least one polymer material in the mixture. The addition of at least one compatibilizer within this specified range is critical for achieving the desired optimal compatibility between the algal biomass and the polymer material. This ensures proper homogenization within the formulation while preventing strength degradation that may result from excessive use of the compatibilizer.

[0042] In a preferred embodiment, the formulation contains at least one plasticizer. The plasticizer may include at least one component from the group comprising of glycerol, octanoic acid, and 1 ,4-butanediol.

[0043] In a most preferred embodiment, the formulation prepared for obtaining bioplastic contains algal biomass: polylactic acid at a value between 1 :9 and 3:7 by volume and maleic anhydride: polylactic acid at a value between 0.001 :1 and 0.02:1 by volume, so that the total volume is 100%.

[0044] The formulated mixture is fed into the extruder for bioplastic granule production, where the extrusion process is carried out.

[0045] The parameters to be applied in the extruder for bioplastic granule production are critical and have been determined through the research and development activities conducted by the inventors. Accordingly, the extruder inlet temperature is set within a range of 140 to 150°C. The outlet temperature (i.e. nozzle temperature) is between 170 and 190 °C. The specified temperature values are the appropriate melting and softening temperatures for the bioplastic to be obtained. At the same time, it is also critical that the bioplastic material to be obtained has appropriate viscosity values in order to be shaped. The specified temperatures are also the temperatures at which the thermal decomposition of the bioplastic material to be obtained does not occur. Thanks to the values considered here, a bioplastic can be obtained in which the processes are carried out without losing homogeneity. When the processes are carried out at temperatures below the specified values, bioplastic production processes are caused by insufficient flow and poor shaping; while in processes carried out above the values, there is an increased risk of thermal decomposition, excessive fluidity and processing difficulties for the bioplastic material.

[0046] Another parameter is the determination of the pressure value. The pressure value in the extruder is between 12.5 and 15 bar. In a preferred embodiment, there is a homogenization process in the extruder process. For this process, mixing is carried out at a value between 50 and 60 rpm.

[0047] As a result of the processes carried out in the extruder, the obtained melt is cooled with water and is preferably shaped into a filament, which is then further processed into granules.

[0048] The obtained algal biomass-containing granules must be subjected to injection molding processes with certain parameters in order to be used in the production of products with targeted designs through molding processes. The parameters determined for the molding process are critical and have been researched and developed by the present inventors.

[0049] Accordingly, the obtained algal biomass-containing granules are fed into the system at a pressure ranging between 140 and 150 bar. For injection molding processes, the feed inlet temperature must be between 140 and 160 °C and the outlet temperature must be between 160 and 180 °C. It is preferably delivered to molds at room temperature for molding. As mentioned in this invention, the production of bioplastic products containing algal biomass by extrusion method in targeted designs is critical, firstly determining the components for the formulation to be used in these processes and making arrangements for the amounts of these components in the formulation. It is critical that the extrusion processes and the molding processes are carried out with the determined parameters with the obtained formulation and again with the determined parameters.

[0050] The glass transition temperature of the bioplastic containing algal biomass obtained by extrusion method is between 60 and 65 °C for samples containing 10% algal biomass by volume. The melting temperature varies between 145 and 160 °C. These values are shared in Figure 1 -A and Figure 1-B. In addition, it was determined in the studies that the melt flow indices obtained for samples containing 10% algal biomass by volume were between 8 and 10 g / 10 min.

[0051] The glass transition temperature of the bioplastic containing algal biomass obtained by extrusion method is between 55 and 65 °C for samples containing 30% algal biomass by volume. The melting temperature varies between 145 and 160 °C. These values are shared in Figure 1 -A and Figure 1-B. In addition, it was determined in the studies that the melt flow indices obtained for samples containing 30% algal biomass by volume were between 22 and 25 g / 10 min.

[0052] The yield strength of the bioplastic containing algal biomass obtained by extrusion method is between 25 and 30 MPa for samples containing 10% algal biomass by volume. The Young Modulus value is between 2000 MPa and 2100 MPa. The tensile strength values are shared in Figure 2-A and Figure 2-B. In addition, in the studies obtained, the unnotched isod impact strength value obtained for samples containing 10% algal biomass by volume is between 120 and 130 J / m, while the notched isod impact strength is between 40 and 45 J / m.

[0053] The yield strength of the bioplastic containing algal biomass obtained by extrusion method is between 14 and 17 MPa for samples containing 30% algal biomass by volume. The Young Modulus value is between 1990 MPa and 2000 MPa. The tensile strength values are shared in Figure 2-A and Figure 2-B. In addition, in the studies obtained, the unnotched isod impact strength value obtained for samples containing 30% algal biomass by volume is between 125 and 140 J / m, while the notched isod impact strength is between 30 and 55 J / m.

[0054] In a preferred embodiment, at least one of the chemicals such as ethanol, IPP (isotactic polypropylene), citric acid, DCP (Dicumyl peroxide), methanol can be added to the formulation to improve the mechanical and thermal properties of the final product containing algal bioplastic.

[0055] All of the values given here are close to or better than the values of the pure form of polylactic acid, a biodegradable material frequently used in the technique. Based on this, it is possible to obtain bioplastics containing algal biomass by extrusion method and the obtained products will have mechanical properties equivalent to frequently used biodegradable materials.

[0056] The scope of protection of the invention is specified in the attached claims and cannot be limited to those explained for sampling purposes in this detailed description. It is evident that a person skilled in the art may exhibit similar embodiments in light of the above-mentioned facts without drifting apart from the main theme of the invention.

Claims

CLAIMS1. A method for production algae biomass-based bioplastic through an extrusion process, characterized by the comprising process steps:- subjecting the obtained algae biomass to drying processes, wherein the drying processes are carried out at a temperature between 50 and 80°C,- subjecting a polymer raw material, selected from at least one of the group comprising of polylactic acid, polyethylene, polyethylene terephthalate, polyamide, polypropylene, polytrimethylene terephthalate, polybutylene succinate, bisphenol A polycarbonate, polyvinyl alcohol, polyhydroxyalkanoate, and polyhydroxybutyrate, to a drying process, wherein the drying process is carried out at a temperature between 60 and 90°C,- subjecting the dried algae biomass and at least one polymer raw material to mixing processes to obtain a first homogeneous mixture,- adding at least one compatibilizer to the obtained first homogeneous mixture and carrying out mixing processes to achieve the target formulation,- adding the obtained formulation to an extruder and obtaining bioplastic granules through extrusion, wherein the said extruder has an inlet temperature between 140 and 150°C and an outlet temperature between 170 and 190°C,- subjecting the obtained bioplastic granules to injection molding processes to produce bioplastic products in the desired designs, wherein the said injection molding processes are carried out at a feeding temperature between 140 and 160°C and an outlet temperature between 160 and 180°C.

2. The method according to claim 1 , wherein the algae biomass raw material comprises at least one from the group of microalgae and / or macroalgae.

3. The method according to one of the preceding claims, wherein the drying processes of the algae biomass are carried out within a duration of 6 to 10 hours.

4. The method according to one of the preceding claims, wherein the polymer raw material is polylactic acid.

5. The method according to one of the preceding claims, wherein the drying process for at least one polymer raw material is carried out within a duration of 6 to 8 hours.

6. The method according to one of the preceding claims, wherein the volumetric ratio of the algae biomass in the homogeneous mixture to at least one polymer raw material is between 1 :9 and 3:7.

7. The method according to one of the preceding claims, wherein the compatibilizer is maleic anhydride.

8. The method according to one of the preceding claims, wherein the compatibilizer is present in the homogeneous mixture at a volumetric ratio of 0.1% to 2% relative to the polymer material.

9. The method according to one of the preceding claims, wherein the pressure value in the extruder is between 12.5 bar and 15 bar.

10. The method according to one of the preceding claims, wherein the pressure value in the injection molding process is between 140 bar and 150 bar.

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