PLA-based composite material, method of producing PLA-based composite material, use of PLA- based composite material

Abstract

The invention relates to a PLA-based composite material which contains wool of animal origin of virgin and / or recycled type in an amount of 1% to 60% by weight with respect to the two-component composite. The invention includes a method of its production and its use in the form of a filament and pellets.

Description

[0001] PLA-based composite material, method of producing PLA-based composite material, use of PLA- based composite material

[0002] The invention relates to a PLA-based composite material, a method of its preparation, and its use in various forms, i.e. as a filament, string, thread and pellets. A PLA-based filament obtained from the material can be used as a printing material to create various 3D objects such as figurines, ornaments, accessories or structural elements that are both functional and visually appealing. The resulting form of the material can be used in injection moulding technology - pellets. Normative studies include information and descriptions on the composition and preparation processes of PLA-based materials with the addition of natural ingredients. These studies use i.a. flax, hemp, wood, cellulose as an additive in the form of natural fibres.

[0003] 3D filaments are materials used in 3D printing technology. One of the most common types of 3D filaments is PLA (polylactide), which is a low-density and high-flexibility biodegradable synthetic polymer. PLA is a material with a very wide range of application due to its origin and properties. It can be used for both professional purposes, e.g. biomedical, construction purposes and for prototypes of machine components, as well as hobby purposes. There are plans to use polylactide as a substitute for polyolefins and other polymers derived from non-renewable raw materials. Polylactide is also used to produce disposable bottles and utensils. Nowadays, it is also used as a filament (printing material) in home and professional 3D printers (using FMF / FFF / FGF - fused deposition modelling technique). PLA can be easily printed using a variety of 3D printing methods and dyed, giving it a wide variety of aesthetic effects. However, PLA also has some disadvantages, such as low resistance to heat, moisture and abrasion, limiting its use in some fields.

[0004] Various additives, such as natural or synthetic fibres, nanoparticles, fillers or plasticisers, can be added to PLA to improve its properties. These additives can affect the mechanical, thermal, chemical, biological or optical properties of PLA, increasing its strength, stability, biocompatibility or visual appeal.

[0005] Studies on the use of banana fibres derived from tree bark, tree leaves and peels for the production of composites based on polymers, such as PLA, produced by injection moulding, are described. These methods are described e.g. in 1, 2, 3, 4. Plastic compositions with different types of fibres are also described, e.g. a composite of PLA with banana tree fibre, composite of PBS / PLA / PHA with poplar bark powder, banana tree fibre, sisal fibre, a composite of thermosetting polymers with bast fibres, which can include hemp, kenaf, jute, flax, banana or a combination thereof, a composite with plant fibres (hemp fibres, banana tree leaf fibres, bamboo fibres and palm fibres). These methods are described e.g. in 5-7. Biodegradable bags made of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL) and polybutylene succinate (PBS) containing banana peel powder have also been described. These bags are described in 8. Some research on the use of other plant waste as additives for PLA to improve some properties of the material were described. This research provides good guidance on the processing, properties and applications of PLA filaments with the addition of natural plant materials. A PLA-based composite with an admixture of powdered citrus peels such as orange and mandarin, lime peels, a PLA-based composite with cellulose fibres derived from nut and apricot shells, a PLA-based composite foil with powdered pomegranate peel or cellulose of microbiological origin prepared from kombucha fermented in Yerba Mate waste or with lingocellulose obtained from kiwi peels, a PLA-based composite from coffee grounds intended for printing were described. These methods and composites are described e.g. in 9-15.

[0006] Publications:

[0007] S. K. Majhi, S. K. Nayak, S. Mohanty, and L. Unnikrishnan, "Mechanical and fracture behavior of banana fiber reinforced Polylactic acid biocomposites," International Journal of Plastics Technology, vol. 14, no. SI, pp. 57-75, Dec. 2010, doi: 10.1007 / sl2588-010-0010-6.

[0008] A. S. Pannu, S. Singh, and V. Dhawan, "Thermo-mechanical and morphological characterization of biodegradable composite rod composed of banana waste reinforcement in PLA matrix," Mater Res Express, vol. 6, no. 10, p. 105321, Aug. 2019, doi: 10.1088 / 2053-1591 / ab3819.

[0009] M. A. Naeem, Q. Siddiqui, M. Mushtaq, A. Farooq, Z. Pang, and Q. Wei, "Insitu Self-Assembly of Bacterial Cellulose on Banana Fibers Extracted from Peels," Journal of Natural Fibers, vol. 17, no. 9, pp. 1317- 1328, Sep. 2020, doi: 10.1080 / 15440478.2018.1563580.

[0010] Y.-F. Shih and C.-C. Huang, "Polylactic acid (PLA) / banana fiber (BF) biodegradable green composites," Journal of Polymer Research, vol. 18, no. 6, pp. 2335-2340, Nov. 2011, doi: 10.1007 / sl0965-011-9646-

[0011] Y-

[0012] "Prostredek pro zlepsen vlastnost pudy," CZ25310U1, Oct. 25, 2012.

[0013] "PBS (Polybuthylenesuccinate) / PLA (Polylactic Acid) / PHA (Polyhydroxyalkanoate) biodegradable composite material and preparation method thereof," CN105907061A, May 06, 2016.

[0014] Tree Protector," US2010015365A1, Jun. 23, 2009.

[0015] "compound for biodegradable plastic and manufacturing method of eco-friendly biodegradable plastic bag," KR102264798B1, Dec. 30, 2020. N. S. Sambudi, W. Y. Lin, N. Y. Harun, and D. Mutiari, "Modification of Poly (lactic acid) with Orange Peel Powder as Biodegradable Composite," Polymers (Basel), vol. 14, no. 19, Oct. 2022, doi: 10.3390 / POLYM14194126.

[0016] A. Bassani, S. Montes, E. Jubete, J. Palenzuela, A. P. Sanjuan, and G. Spigno, "Incorporation of waste orange peels extracts into PLA films," Chem Eng Trans, vol. 74, pp. 1063-1068, 2019, doi: 10.3303 / CET1974178.

[0017] S. K. Jang, C. D. Jung, H. Seong, S. Myung, and H. Kim, "An integrated biorefinery process for mandarin peel waste elimination," J Clean Prod, vol. 371, p. 133594, Oct. 2022, doi: 10.1016 / J.JCLEPRO.2022.133594.

[0018] H. Sharma, I. Singh, and J. P. Misra, "Mechanical and thermal behaviour of food waste (Citrus limetta peel) fillers-based novel epoxy composites," Polymers and Polymer Composites, vol. 27, no. 9, pp. 527535, Nov. 2019, doi: 10.1177 / 0967391119851012 / ASSET / IMAGES / LARGE / 10.1177_0967391119851012-FIG7.JPEG.

[0019] Y. Mahmoud, N. Belhanche-Bensemra, and Z. Safidine, "Impact of microcrystalline cellulose extracted from walnut and apricots shells on the biodegradability of Poly (lactic acid)," Front Mater, vol. 9, Sep. 2022, doi: 10.3389 / FMATS.2022.1005387.

[0020] L. Dai, R. Li, Y. Liang, Y. Liu, W. Zhang, and S. Shi, "Development of Pomegranate Peel Extract and Nano ZnO Co-Reinforced Polylactic Acid Film for Active Food Packaging," Membranes (Basel), vol. 12, no. 11, Nov. 2022, doi: 10.3390 / MEMBRANES12111108.

[0021] A. Aguero et al., "Plasticized Mechanical Recycled PLA Films Reinforced with Microbial Cellulose Particles Obtained from Kombucha Fermented in Yerba Mate Waste," Polymers (Basel), vol. 15, no. 2, Jan. 2023, doi: 10.3390 / POLYM15020285.

[0022] The publication of patent specification US 20220080701 discloses a method and design for producing biodegradable and ecological fabrics made of PLA fibres and / or yarns. These fabrics have one- or two- way filtration properties and / or humidity management properties with controlled porosity and a smooth or textured surface.

[0023] The applications of plant fibres in the manufacture of materials used for 3D printing are described in Potential for Natural Fiber Reinforcement in PLA Polymer Filaments for Fused Deposition Modeling (FDM) Additive Manufacturing: A Review (https: / / doi.org / 10.3390 / polyml3091407). This review highlights the potential of natural fibres such as kenaf fibres as reinforcements for PLA composite filaments for FDM 3D printing technology. The description of the utility model CN202450227U indicates a flexible material formed from a combination of PLA fibres and natural wool. The material is biodegradable and environmentally friendly and has unique properties such as high strength, gloss, good hygroscopic properties, fast drying, high flexibility, and UV resistance. A flexible fabric made of a blend of PLA and wool fibres, interwoven with warp and parallel forms, is described and the warp adopts bifilar yarn of PLA and wool fibres. The aforementioned parallel adopts two types of yarns. Only material in the form of yarn for making clothes is described. The disclosed material is not in the form of pellets or strings, which can take the form of a filament. Only two strands of PLA and wool, which are interwoven with each other, are described. Thus, the presented composition of the invention does not allow to obtain a material in a form that can be readily used for 3D printing or for use in injection moulding technology.

[0024] Therefore, new methods and PLA-based compositions with additives are still being sought to improve the mechanical, thermal, chemical, biological or optical properties of PLA, increasing its strength, stability, biodegradability. The aim was to develop a composition so as to provide an improvement in the indicated properties, but also to obtain the desired form of pellets - ground grains, a string, thread, preferably filament, for use in injection moulding technology or 3D printing. Another aim was to develop a method for obtaining composites in a simpler way and one that would produce a composite / material with the most homogeneous fibre dispersion.

[0025] The additive proposed by the inventors of the present invention for PLA is wool, which is a natural fibre of animal origin, recycled or virgin or a mixture of both, preferably obtained from sheep or other animals. According to the invention, recycled fibre as well as virgin fibre or a mixture of both is used.

[0026] The invention therefore relates to a PLA-based composite material with the addition of wool - wool fibres of animal origin, which combines the advantages of both components.

[0027] According to the invention, in the composite material, wool of virgin and / or recycled type is present in an amount of l%-60% by weight with respect to the composite. Wool in such quantities gives the material many advantages, such as high strength, abrasion resistance, thermal insulation, hygroscopicity, biodegradability or antibacterial activity. Wool can also be dyed in a variety of colours, adding aesthetic value, and the use of recycled wool provides an additional benefit to the final material obtained. Preferably, the composite material is in the form of a filament and / or pellets.

[0028] Preferably, in the PLA+wool composition material, the wool is present in an amount of 5 to 15% by weight with respect to the two-component material. Preferably, an amount of 5-10% is used.

[0029] The invention also refers to a method of producing a composite material containing in its composition PLA with the addition of wool of virgin and / or recycled type. According to the invention, PLA is combined with wool of animal origin of virgin and / or recycled type present in an amount of 1% to 60%, preferably 5-15%, most preferably 5-10%, by weight with respect to the two-component composite using extrusion. Extrusion consists in thermoplastic extruding a material that has first been subjected to a mechanical treatment. Extrusion is primarily a process of processing starch raw materials under the influence of heat, e.g. 120-200 °C, humidity and in high-pressure conditions. Extrusion in the used amount of the two-component composition allows to easily obtain especially a filament, but also pellets.

[0030] The following beneficial extrusion options were developed. Based on the guidelines below, a person skilled in the art will carry out the method using known techniques and selecting appropriate amounts of the composite. Depending on the temperature used and the type of the equipment, a different form of the composite material is obtained - a string, thread, filament, pellets. Preferably, a filament is obtained.

[0031] METHOD 1: Preferably, the extrusion is carried out from PLA pellets with the addition of wool fibres added during the loading process of the extruder.

[0032] METHOD 2: Preferably, the extrusion is carried out from a blend of PLA pellets with the addition of wool fibres previously combined by grinding them together.

[0033] METHOD 3: Preferably, the extrusion is carried out by directly placing PLA fibre fleece and wool fibre fleece in the extruder.

[0034] METHOD 4: Preferably, the extrusion is carried out from a blend produced by previously pressing PLA fibre fleece and wool fibre fleece (in a thermal press).

[0035] METHOD 5: Preferably, the extrusion is carried out from a mixture / blend prepared by pressing PLA pellets with wool fibre fleece (in a thermal press).

[0036] METHOD 6: Preferably, the extrusion is carried out from a blend prepared by pressing a film made of PLA pellets together with wool fibre fleece.

[0037] Then, a string, filament or pellets are obtained by a known method, selecting the temperature of the equipment accordingly.

[0038] In order to obtain the pellets according to the invention, instead of winding the material / filament onto a spool during the method, the material is fed directly into the pelletiser, where it is fragmented into pellets.

[0039] The invention relates to the use of the composite material in the form of, in particular, a filament or a string or thread, pellets, preferably a filament with a diameter of 1 to 5 mm. The material can be used in 3D techniques in the form of a filament to prepare various spatial forms, including in medicine, and processed into pellets used for loading injection moulding machines in 3D techniques or for use in injection moulding technology. The use according to the invention relates to both pellet form as well as a string, thread and filament form prepared from the pellets.

[0040] The invention in the form of a filament (a line with a diameter of 1 to 5 mm) as well as pellets is applicable in the production of a material using thermoplastic techniques / screw extrusion using PLA poly(lactic acid) polymer material with a specified quantity of virgin and / or recycled wool fibre admixture. The use of the material according to the invention relates to 3D printing techniques using the material in the form of a filament to prepare various spatial forms, including in medicine, but also in a form processed by a known technique into pellets used for loading injection moulding machines in 3D printing techniques and for use in injection moulding technology.

[0041] The invention has many benefits, including:

[0042] • The resulting composite material has very good mechanical, thermal, chemical, biological, and optical properties, increasing its strength, stability, biodegradability. Based on research, it has been determined that using from 1 to 15% of wool fibres of animal origin of virgin and / or recycled type improves mechanical properties the most, thermal - from 20 to 40%, optical - 40 to 60%.

[0043] • The resulting material in the form of a filament can be readily used in 3D techniques to obtain various spatial forms, including in medicine, and in the form of pellets, it can be used for loading injection moulding machines / for use in injection moulding technology.

[0044] • Possibility to obtain a filament and / or pellets from the composite material - Environmental protection: PLA with wool is environmentally friendly as it does not contain harmful substances such as bisphenol A, phthalates or heavy metals. In addition, PLA with wool is biodegradable under composting conditions, reducing waste and greenhouse gas emissions.

[0045] • Cost savings: PLA with wool is cheaper to produce than traditional plastics because it uses renewable raw material sources such as plant starch and wool. In addition, PLA with wool has lower disposal costs as it does not require special processing or storage.

[0046] • Enhancing competitiveness: PLA with wool can be used for the production of a variety of products such as packaging, textiles, toys, utensils or medical components. PLA with wool has good mechanical, thermal, barrier and antimicrobial properties, making it attractive to consumers who are looking for eco-friendly and high-quality alternatives to traditional plastics. According to the invention, several methods have been developed for preparing a composite material with an effective combination of PLA and wool fibres - as indicated above.

[0047] The preparation of the composite material is carried out using the following methods:

[0048] • METHOD 1. Extrusion from PLA pellets with the addition of wool fibres added during the loading process of the extruder.

[0049] • METHOD 2. Extrusion of a filament from PLA pellets with the addition of wool fibres combined by grinding them together.

[0050] • METHOD 3. Extrusion of a filament directly from PLA fibre fleece and wool fibre fleece.

[0051] • METHOD 4. Extrusion of a filament of a blend produced by previously pressing PLA fibre fleece and wool fibre fleece (in a thermal press).

[0052] • METHOD 5. Extrusion of a filament from a blend prepared by pressing PLA pellets with wool fibre fleece (in a thermal press). METHOD 6. Extrusion of a filament from a blend prepared by pressing a film made of PLA pellets together with wool fibre fleece.

[0053] The invention is further described in embodiments and in a drawing, where: Fig. 1 shows an exemplary extruder, Fig. 2 - an exemplary set of samples (Examples 1-6), Fig. 3 - process steps for preparing wool and / or PLA fibre fleece - Examples 3, 4, 5, 6, Fig. 4 - process steps described in Example 6, i.e. A, Preparation of a film from PLA pellets, B) Obtained film, C) Laying the prepared fleece on adhesive paper in the mould for pressing, C) Laying the PLA film on the fleece, D-E) Pressing in a press, 5N pressure, F) Fragmentation after pressing, G) Fragmenting the strips using a pelletiser, obtaining a blend for filament production. Fig. 5 - obtained pellets and filament, with 40:60 ratio of recycled wool to PLA, Fig. 6 - obtained pellets and filament with 5:95 ratio of wool to PLA.

[0054] Examples describe the conditions used in the methods for preparing PLA-wool composition and provide the composition. Wool fibre fleece of animal origin is used in the method according to Examples 3, 4, 5, 6. Using mathematical calculation, a person skilled in the art will determine an exemplary composition - based on the developed weight range of wool fibres in the composite, i.e. from 1 to 60 wt% with respect to the composite material according to the described composition of the invention.

[0055] Table 1 shows the properties of an exemplary material obtained in Example 6 with the ratio of 20% wool and 80% PLA.

[0056] The term "pellets" used in the specification means a solid plastic / composite produced by extrusion of a material (in the form of a line) with a constant diameter (1-5 mm) cut into fragments of 2 to 10 mm in length, that can be used in 3D printing technology e.g. FGF, and / or injection moulding technology; The filaments take the form of a thin, long (even several-hundred-meter-long) fibre / line wound onto a spool and can be used in 3D printing technology, e.g. FDM and / or FFF technology. The term "pellets" is an English term corresponding to a Polish term meaning granulated substance and is also used in Polish as a loan-word. A fleece is the result of a unidirectional arrangement of the fibres after manual or mechanical carding of the wool.

[0057] The term "sandwich" refers to a multilayer / alternate arrangement of different structures on each other, which are then pressed using force and temperature.

[0058] Example 1 - First method

[0059] Extrusion from PLA pellets with the addition of wool fibres added during the loading process of the extruder.

[0060] The production of the material consists in loading the extruder with a blend of pellets with (virgin and / or recycled) wool fibres - in this example these fibres were recycled, i.e. from hand- or machine- made clothes - in this example, the mixing was performed manually in a container with PLA pellets and pre-cut / chopped wool fibres. The percentage composition by weight of the blend thus prepared was assumed to be 10% by weight of the fibre, i.e. 90 grams of PLA pellets and 10 grams of recycled wool fibres were used. The prepared blend was loaded into a screw-extruder feeder - speed parameters: RPM - 30; pressure of 4 bar; Melting temperature 165-175 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 1.75 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory properties, especially mechanical properties, as well as visual aspect.

[0061] A similar method as described above was used to obtain a composite material, wherein 5 grams of recycled fibres and 95 grams of PLA were used. The prepared blend was loaded into a screw-extruder feeder - with parameters as described above, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 1.75 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised especially by satisfactory mechanical properties as well as visual aspect.

[0062] A similar method as described above was used to obtain a composite material, wherein 60 grams of recycled wool fibres and 40 grams of PLA were used. The prepared blend was loaded into a screwextruder feeder - 50 RPM; pressure of 4 bar; temperature 165-210 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The composite material produced in the form of a filament is characterised especially by satisfactory thermal, mechanical properties as well as visual aspect.

[0063] Using a similar method as described above, a process was carried out to obtain pellets, except that instead of the material / filament being wound onto a spool, it was fed directly into a pelletiser, where the material was fragmented into pellets with a diameter of 3 mm and a length of 5 mm. The properties of each mixture were checked and it was found that for this range of PLA fibres used, a material with good mechanical and thermal properties was obtained. This was determined by making samples from the produced filament using 3D printing technology for strength testing in accordance with PN-EN ISO 178 and 527-2. Moreover, critical temperature points were determined using DSC technology.

[0064] The following examples describe the use of a similar extruder and parameters.

[0065] Example 2 - Second method

[0066] Extrusion of a filament from PLA pellets with the addition of wool fibres combined by grinding them together.

[0067] The production of the PLA+wool blend consisted in grinding PLA pellets with the addition of wool fibres. Grinding was conducted in 15-second cycles with 20-second intervals. Grinding was conducted until the mixture looked homogeneous, with an average of 5 cycles.

[0068] The assumed percentage composition by weight was 3%, i.e. 3 grams of virgin wool fibres were used for 97 grams of PLA. The prepared blend was loaded into a screw-extruder feeder - parameters in the same order as described in the previous example RPM - 50; 4 bar; 160-175 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 2.00 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0069] A similar method as described above was used to obtain a composite material, wherein 60 grams of wool fibres and 40 grams of PLA were used. The prepared blend was loaded into a screw-extruder feeder - RPM - 40; 4 bar; 165-190 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 2.85 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised especially by satisfactory mechanical properties as well as visual aspect. A similar method as the one above was carried out to obtain pellets, except that instead of the material / filament being wound onto a spool, it was fed directly into a pelletiser, where the material was fragmented into pellets with a diameter of 2.85 mm and a length of 3 mm.

[0070] The properties of each mixture were checked and it was found that for this range of PLA fibres used, a material characterised by good mechanical and thermal strength was obtained. This was determined by making samples from the produced filament using 3D printing technology for strength testing in accordance with PN-EN ISO 178 and 527-2. Moreover, critical temperature points were determined using DSC technology.

[0071] Example 3 - Third method

[0072] Extrusion of a filament directly from PLA fibre fleece and wool fibre fleece.

[0073] Preparation of the blend consisted in directly feeding the extruder with a non-needle-punched, nonwoven fleece with a percentage composition by weight of 50 / 50, i.e. 50 grams of recycled wool fibres were used for 50 grams of PLA. The prepared blend was loaded into a screw-extruder feeder - RPM - 70; 4 bar; 165-195 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 4.95 mm + / - 0.05 mm and was fed directly into the pelletiser, where the material was fragmented into pellets with a diameter of 4.95 mm and a length of 3 mm + / - 0.05 mm.

[0074] The composite material produced in the form of a filament is characterised especially by satisfactory mechanical properties as well as visual aspect.

[0075] A similar method as described above was used to obtain a composite material, wherein 10 grams of wool fibres and 90 grams of PLA were used. The prepared blend was loaded into a screw-extruder feeder - RPM - 90; 4 bar; 165-185 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 1.50 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0076] The properties of each mixture were checked and it was found that for this range of PLA fibres used, a material with good mechanical and thermal properties was obtained. This was determined by making samples from the produced filament using 3D printing technology for strength testing in accordance with PN-EN ISO 178 and 527-2. Moreover, critical temperature points were determined using DSC technology. Example 4 - Fourth method

[0077] Extrusion of a filament from a blend produced by previously pressing PLA fibre fleece and wool fibre fleece (in a thermal press). The blend was made by pressing a non-needle-punched fleece with a ratio of 40:60 (PLA / wool), i.e. for 40 grams of PLA, 60 grams of recycled wool fibres were used in a press, using 50 kN pressure for 5 min at 200 °C.

[0078] The resulting structure was fragmented into pieces of max. 3 mm x 5 mm. The prepared blend was loaded into a screw-extruder feeder - RPM - 80; 4 bar; 165-195 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 3.55 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0079] A similar method as described above was used to obtain a composite material, wherein 2 grams of wool fibres and 98 grams of PLA were used. The prepared blend was loaded into a screw-extruder feeder - RPM - 90; 4 bar; 165-175 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 2.85 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0080] Using a similar method as the one above, a process was carried out to obtain pellets, except that instead of the material / filament being wound onto a spool, it was fed directly into a pelletiser, where the material was fragmented into pellets with a diameter of 2.85 mm and a length of 5 mm + / - 0.05 mm.

[0081] The properties of each mixture were checked and it was found that for this range of PLA fibres used, a material with good mechanical and thermal properties was obtained. This was determined by making samples from the produced filament using 3D printing technology for strength testing in accordance with PN-EN ISO 178 and 527-2. Moreover, critical temperature points were determined using DSC technology.

[0082] Fig. 3 shows the steps of the method.

[0083] Example 5 - Fifth method

[0084] Extrusion of a filament from a blend prepared by pressing PLA pellets with wool fibre fleece (in a thermal press). A layer of coated paper with a heat resistance of up to 260°C was placed on the bottom of the mould. The pellets were then poured over the fibres. The percentage composition by weight was 15% wool and 85% PLA, respectively. Heat treatment was carried out at 200 °C. The samples were subjected to two cycles of 3 min each. For the first sample, there were three cycles. Initially, a pressure of 0 kN was applied to the mould, which was then increased to 15 kN. The samples thus obtained were then fragmented and the resulting blend was fed into the extruder. The prepared blend was loaded into a screw-extruder feeder - RPM - 60; 4 bar; 165-185 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 1.2 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0085] A similar method as described above was used to obtain a composite material, wherein 5 grams of wool fibres and 95 grams of PLA were used. The prepared blend was loaded into a screw-extruder feeder - RPM - 90; 4 bar; 165-175 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 2.85 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0086] Using a similar method as the one above, a process was carried out to obtain pellets, except that instead of the material / filament being wound onto a spool, it was fed directly into a pelletiser, where the material was fragmented into pellets with a diameter of 2.85 mm and a length of 3 mm + / - 0.05 mm.

[0087] The properties of each mixture were checked and it was found that for this range of PLA fibres used, a material with good mechanical and thermal properties was obtained. This was determined by making samples from the produced filament using 3D printing technology for strength testing in accordance with PN-EN ISO 178 and 527-2. Moreover, critical temperature points were determined using DSC technology.

[0088] Example 6 - Sixth method

[0089] Extrusion of a filament from a blend prepared by pressing a film made of PLA pellets together with wool fibre fleece.

[0090] As a result, the following sequence of actions was established. In the first step, a film was made (a thin layer of previously pressed 20 grams of PLA pellets). The mould which was used was made of a system of three steel plates, stacked flat on top of each other, with the middle plate, having a cavity inside, acting as a spacer. The first solid steel plate was the base and on top of it, the second plate was placed and within its cavity, a thickTeflon foil was placed, on which PLA pellets were in turn placed. The pellets were covered with another layer of Teflon foil and everything was covered with the third steel plate.

[0091] The system thus prepared was placed in a press heated to 200 °C for 5 min. No pressure was applied to the system, the press was only closed. The film thus produced was then placed on 80 grams of wool fibre fleece inserted into a brass mould. Both the bottom and the top of the mould had been insulated with coated paper so that the sandwich system would not stick to the mould.

[0092] The closed mould was inserted into the press and heated at 220 °C under 15 kN pressure for 5 min. The pressure welded materials obtained were fragmented and the resulting ground grains were then loaded into an extruder RPM - 80; 4 bar; 165-185 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 2.85 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised by satisfactory mechanical properties as well as visual aspect.

[0093] Using a similar method as the one above, a process was carried out to obtain pellets, except that instead of the material / filament being wound onto a spool, it was fed directly into a pelletiser, where the material was fragmented into pellets with a diameter of 2.85 mm and a length of 3 mm + / - 0.05 mm.

[0094] A similar method as described above was used to obtain a composite material, wherein 60 grams of wool fibres and 40 grams of PLA were used. The prepared blend was loaded into a screw-extruder feeder - RPM - 60; 4 bar; 165-190 °C, and the extrusion process was carried out until the depletion of the loaded material, using air cooling to cool the extruded material. The extruded material had a diameter of 4.00 mm + / - 0.05 mm and was wound directly using an automatic winding machine. The composite material produced in the form of a filament is characterised especially by satisfactory mechanical properties, as well as visual aspect.

[0095] Using a similar method as the one above, a process was carried out to obtain pellets, except that instead of the material / filament being wound onto a spool, it was fed directly into a pelletiser, where the material was fragmented into pellets with a diameter of 4.00 mm and a length of 2.5 mm + / - 0.05 mm.

[0096] The properties of each mixture were checked and it was found that for this range of PLA fibres used, a material characterised especially by high / good mechanical and thermal properties was obtained. This was determined by making samples from the produced filament using 3D printing technology for strength testing in accordance with PN-EN ISO 178 and 527-2. Moreover, critical temperature points were determined using DSC technology.

[0097] Examples of the obtained properties of the composite material in the form of a filament obtained according to Examples 1-6.

[0098] The table presents the average values for the Banding test, which was carried out in the X axis and the Y axis on a series of samples printed from the obtained material. Based on the tests carried out, the standard deviation and mean values for the samples were calculated.

[0099] Table 1 20% wool / 80 PLA, EXAMPLE 6

[0100] The steps of the process described in the examp e are shown in Fig. 4.

[0101] Figs. 5 and 6 show the material prepared in Examples 1-6.

Claims

Claims1. A PLA-based composite material characterised in that it contains wool of animal origin of virgin and / or recycled type in an amount of 1% to 60% by weight with respect to the two-component composite.

2. The material according to claim ^characterised in that the wool is present in an amount of 5-15% by weight.

3. The material according to claim ^characterised in that the wool is present in an amount of 5-10% by weight.

4. The material according to claim ^characterised in that it is in the form of a filament.

5. The material according to claim ^characterised in that it is in the form of pellets.

6. A method for producing a PLA-based composite material, characterized in that PLA is combined with wool of animal origin of virgin and / or recycled type present in an amount of 1% to 60%, preferably 5 to 10%, by weight with respect to the blend using extrusion.

7. The method according to claim 6, characterised in that the extrusion is carried from PLA pellets with the addition of wool fibres added during the loading process of the extruder.

8. The method according to claim 6, characterised in that the extrusion is carried out from a mixture of PLA pellets with the addition of wool fibres previously combined by grinding them together.

9. The method according to claim 6, characterised in that the extrusion is carried out by directly placing PLA fibre fleece and wool fibre fleece in the extruder.

10. The method according to claim 6, characterised in that the extrusion is carried out from a mixture produced by previously pressing PLA fibre fleece and wool fibre fleece, preferably in a thermal press.

11. The method according to claim 6, characterised in that the extrusion is carried out from a mixture prepared by pressing PLA pellets with wool fibre fleece, preferably in a thermal press.

12. The method according to claim 6, characterised in that the extrusion is carried out from a mixture prepared by previously pressing a film made of PLA pellets together with wool fibre fleece.

13. The method according to claims 6-12, characterised in that an elevated temperature of 160 to 210 °C is used during the extrusion.

14. The method according to claims 6-13, characterised in that the resulting material is fed directly into a pelletiser to prepare pellets.

15. The method according to claims 6-14, characterised in that during the method, the material is wound onto a spool to prepare a filament.

16. Use of the PLA-based composite material described in claim 1-3, characterized in that the material is in the form of pellets or a filament, preferably having a diameter of 1 to 5 mm.

17. The use according to claim 16, characterised in that the filament is used to prepare spatial forms prepared from the composite material.

18. The use according to claim 16, characterised in that the material in the form of a filament is used in additive manufacturing to prepare various spatial forms.

19. The use according to claim 16 characterised in that the material is used as pellets for loading injection moulding machines or for use in injection moulding technology.

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