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Injection Moulding

Injection Moulding Liquid wood and more… Fig. 1: Green Lantern, Romolo Stanco by Lars Ziegler Jürgen Pfitzer Helmut Nägele Benjamin Porter Tecnaro GmbH Ilsfeld-Auenstein, Germany Founded in 1998, TECNARO GmbH develops, produces and markets bio-based and biodegradable compounds. Focusing on thermoplastic compounds made from renewable resources like lignin, cellulose, natural fibres, PLA, PHB, Bio-PE, Bio-PA and others, Tecnaro has been developing solutions for injection moulding, compression moulding, extrusion, calendaring, blow molding or thermoforming into moulded parts, semi-finished products, sheets, films or profiles. One of the raw materials mentioned is lignin, which is the second most abundant natural polymer after cellulose. More than 20 billion tonnes of lignin are generated naturally by photosynthesis per year. Lignin can be obtained as a by-product of the pulp and paper industry and the volume arising worldwide is about 50 to 60 million tonnes per year. Lignin can be extracted also from wood bark or straw. Mixing lignin with natural fibres like e. g. flax, hemp, wood or others and natural additives results in thermoplastic composites. These granules made from 100% renewable resources are named ARBOFORM ® (arbor, Latin = the tree) and protected with various patent families. Besides Arboform , Tecnaro´s business is focused on two other compound categories: Biopolymer compounds ARBOBLEND ® and natural fibre reinforced plastic composites ARBOFILL ® . ARBOFORM Arboform is sustainable, independent from crude oil, reduces environmental impacts and offers new markets for agriculture and forestry business. It combines two big industrial sectors: Wood industry can provide three dimensional parts in an economic way and plastics processors can substitute their materials by an ecological alternative. It can be considered as liquid wood. ARBOFILL The compounds are made from plastics and natural fibers like wood, hemp, flex, sisal, bagasse from sugarcane, bamboo, coir fibre from coconut husk, etc. This combination offers sustainable and aesthetical materials with good mechanical and thermal properties at very competitive costs. 22 bioplastics MAGAZINE [03/13] Vol. 8

Injection Moulding Fig. 2: Bios line: Household series made from Arbofill with FDA approval, COZA ARBOBLEND Arboblend can be 100% biodegradable or durable. It consists – depending on the grade - of biopolymers like the wood constituent lignin or of lignin derivatives and/or other biopolymers like polylactic acid, polyhydroxyalkanoates, starch, natural resins and waxes, cellulose, but also grades with sugar based Polyethylene and plant oil based Polyamides are available. The scope of material properties covers bio-compounds for injection moulding with very low up to very high Young‘s moduli of 100 to 16,000 MPa and high tensile strengths up to 100 MPa. Heat deflection temperatures (HDT-B) higher than 150°C are possible and impact strength can be modified to non-break (Charpy unnotched). New Arboblend grades include Thermoplastic Elastomers (TPEs) which can have biobased carbon contents of more than 90%. Compounds with following properties are already available: • hardness in a range from 65 to 95 Shore A • compression set below 45% • tensile strength up to 8 MPa • elongation at break up to 800% Processing and Application Tecnaro´s approach as a specialized compounder is the optimal choice of polymers, fibres, fillers, processing aids and additives preferably from renewable and natural resources in order to achieve the required material properties and processability at lowest possible cost and environmental impact. Additives allow special functionalities and properties like flame resistance, UV stability and high impact strength. High heat deflection temperatures and impact properties can also be achieved by blending, fibre reinforcement and processing adaptations. Today’s series applications can be found in a wide range of products like e.g. household, toys, automotive, furniture, electronics, music instruments, packaging, stationary, building and construction industries as well as in funeral business, agriculture and forestry. Until today, more than 200 series products have been realized so far. Due to free form geometries excellent designs can be achieved with Arboform. Low shrinkage grades allow precise tolerances in general without sink marks and very low warpage as well as a broad variation in wall thicknesses including thick-wall applications. Natural fibers are incorporated for reinforcement and sustainability reasons but also for special aesthetical designs: Injection moulded Arboform F results in surface appearances similar to root wood (see Fig 1). Arboform L and Arbofill have a regular visible fibre surface structure (see picture 2) which can be injection moulded without cloudiness or other typical moulding defects. Arboblend and Arbofill include grades which can be injection moulded into products with film hinges. Special Arboblend grades are available with Melt Volume Rates higher than 80 cm 3 /10 min. These are suitable for extreme thin-wall applications. Due to their low shrinkage and good bondage behavior several grades from all Tecnaro material families are suitable for Inmould Decoration IMD by back-filling of polymer and metal films as well as genuine wood veneers. According to a Tecnaro patent the latter can be moulded with overlap and therefore perfect intarsia can be realized without minimal gaps. Tecnaro´s bio-compounds can be chosen from an existing data base of already more than 2,000 formulations. For existing products and moulds the foreseen shrinkage and demoulding behavior as well as compatibility with hot runner systems, needle valves, etc. are taken into consideration. In case existing data seems not adequate for a new enquiry, modifications and new developments can be a suitable approach. Processing guidelines for each compound and technical assistance are provided for a successful start-up of serial production. bioplastics MAGAZINE [03/13] Vol. 8 23

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