Toys Cracking the code
Toys Cracking the code of durable Over the past 50 years, thermoplastics have largely replaced metal and wood as the preferred materials used for toy manufacturing. Amongst all commodity thermoplastics, ABS is one of the most commonly selected resins for high-end toy applications that demand long-term durability. Although ABS has been developed, refined and optimized over several decades to meet the performance requirements of the toy market, it has remained a fully fossil fuel-based material and includes a number of additives that have been identified as potentially harmful to human health and the environment (as defined by California’s Proposition 65 [1]). And then, enter Solegear Bioplastic Technologies who has focused its attention on developing bioplastics with maximum bio-based content for high performance markets like toys and other ABS applications. The company’s most recent research and development has led to the successful development of a new generation of durable biopolymers with over 95% bio-based content and performance characteristics that make it a real contender as a bio-based replacement for ABS. ABS or Acrylonitrile-butadiene-styrene is a ter-polymer in which each of the three polymers brings unique characteristics on their own and also in synergy with one another. Acrylonitrile (A) delivers mainly hardness and gloss, butadiene (B) creates impact resistance, and styrene (S) brings heat resistance, gloss and lowers the overall material cost. There are also significant differences in the ratio of each polymer and additive used in ABS formulations, depending on their end-market uses (such as water drainage tubing, interior and exterior automotive parts, computer and printer housings, electrical and electronics casings, toys, – to name just a few). Formulations designed for plastic toys are in the upper spectrum of all ABS formulations, as high-end toys are expected to retain their gloss, mechanical and chemical resistance, as well as show no significant signs of aging over time. This is quite important, as toys are well known to retain sentimental value and be passed down from generation to generation. Bioplastic producers around world have grappled with the challenges of replicating the durability and synergistic properties of ABS using bio-based materials, but Canada’s Solegear Bioplastic Technologies embarked on this quest several years ago in response to demands from manufacturers for materials made with fewer chemicals of concern and more renewable resources. Earlier last year, the world-leading toy manufacturer, LEGO ® , announced a longterm initiative to address the issue (cf. p. 31). The Danish company announced an investment of 1 billion DKK to boost search for more sustainable materials replacing ABS and others plastics by 2030 [2]. Similarly did Italy-based Bio-on Laboratories (cf. p. 26) who recently kicked off a contest to formulate products using their naturally biodegradable PHA. In late 2015 the “Minerv PHA Supertoys project was launched by Bio-on Laboratories with no commercial goals” [3]. Table 1: Properties for Novadur 650 (Lanxess Engineering Chemistry, Styrenics Resins Asia Pacific - Product Range and Reference Data (2006).) Figure 1: Comparison of properties of SGB XD1000, XD1010 and ABS Novadur 650 Property Testing methods Values Specific gravity ISO 1183 1.04 Tensile strength at break (MPa) ISO 527 33 Elongation at yield, at break (%) ISO 527 20 Tensile modulus (MPa) ISO 527 2,250 Flexural strength (MPa) ISO 178 68 Flexural modulus (MPa) ISO 178 2,200 Notched IZOD Impact 23 °C (KJ/m 2 ) ISO 180 22 Heat distortion Temperature 1.80 MPa (°C) ISO 75 91 Heat deflection (°C) Flexural modulus (GPa) Flexural strength (MPa) Tensile modulus (GPa) Impact izod notched (J/m) Ultimate tensile strength (MPa) Elongation @ yield (%) Elongation @ break (%) XD1000 XD1010 ABS 32 bioplastics MAGAZINE [04/16] Vol. 11
Toys bioplastics for the toy market Adding to the challenges are the perceptions that bioplastics by their very nature are designed to be disposable. As a research model, Solegear focuses on developing bioplastic formulations using existing, readily available biopolymer building blocks and combining them with appropriate additives and fillers to meet certain performance characteristics, all the while maintaining the highest possible biobased content, no chemicals of concern and low CO 2 footprints. In 2014 when Solegear turned its attention to developing a material replacement for a typical ABS used in toys like building bricks or figurines, the Company used the Lanxess Novadur 650 as the baseline reference material for targeted properties (see Table 1). A rigorous screening process was started that would deliver strong sustainability benefits, but also prioritize the long-time durability of the bioplastic material. An extradurable formulation was the main objective. An ambitious Design of Experiments (DOE) plan was developed for a wide discovery phase that would combine a variety of biopolymers and polymers with some additives. As expected, combinations of several different types of (bio) polymers delivered both miscible and non-miscible options. Over 100 different formulations were individually compounded, molded and tested in laboratories using an iterative process. With each iteration, biopolymers could be accepted or rejected to narrow the search based on targeted specifications. The formulations in development were all compounded using twin-screw extruders; however, processing pellets into testing specimens, including tensile bars and molded parts, presented a somewhat different challenge. Where needed, twin–screw reactive extrusion was the preferred method for compounding pellets of each formulation. From these pellets, different testing bars were injected. Tensile, flexural and IZOD impact were the principal properties evaluated according to ASTM standards. Regardless of academic or small-scale lab research throughout the process, scaling-up using industrial equipment is always extremely challenging. After successful lab-scale results, selected formulations were run and tested on a small industrial line, with only minor processing adjustments being made along the way. The final successful formulations have now been commercialized under the name of Traverse ® XD1000 series. The principal mechanical and thermal properties have been compared with those of Novadur ® 650 as shown in Figure 1. Traverse XD formulations deliver similar impact values, higher stiffness (rigidity) and an important increase in ductility (typically over 250% elongation at break vs approximately 20%). One particular formulation exceeded the expectations of the R&D team to deliver what has been affectionately nicknamed super tough, with high strength, high impact resistance and high ductility all combined. Some differences have been noted regarding shrinkage rate, which is slightly By: Michel Labonté Solegear Bioplastic Technologies Inc. Vancouver, BC, Canada Both photos provided for illustrative purposes only, not actual Solegear products bioplastics MAGAZINE [04/16] Vol. 11 33
