Recycling of Battery Housings and Multilayer Films

TAGS:  Sustainability / Natural Solutions      Additives for Packaging    

What does a starter battery and a PET bottle have in common?

Typically, when polymers reach their end of use a large amount doesn’t end up in landfills and incinerators (thankfully). Rather, it finds its way back to be used another time through recycling.

Recycling can be quite easy when the waste is pre-sorted well. This is the connection between a PET bottle and a starter battery: both are collected and recycled after their use.

However, more often, recycling can be challenging. Multilayer films combine different layers of polar and unpolar polymers, which cannot be separated mechanically. Yet, to reduce environmental waste, recycling battery housings and multilayer films are useful and can be achieved by using additives.

Recycling

Sustainability is a key trend in many end use markets driven by legislation, society, non-governmental organizations and more. Subtrends, such as source reduction, lightweight, bio-degradable materials, and less hazardous chemicals aim to create an environmentally friendly economy around the plastic market. One part of it is recycling. More and more products are developed utilizing an increased number of reused polymers.

However, the nearly unlimited amount of varying polymer combinations, fillers, and other ingredients as well as the different applications seem to lead to a similar endless number of problems.

Overcoming these challenges requires a whole toolbox of solutions with a multi-level approach to reach the desired properties including: the use of modern polymerization technology, clever product design allowing better reusability, and innovative machinery for collecting, washing, and sorting waste streams and of course, for compounding and converting recycled materials.

Additionally, overcoming these challenges requires additives to enable and ensure the necessary material quality and functionality.

At the beginning of the first cycle of use, thermoplastics are equipped with a variety of raw materials and additives to prepare them for their intended use. These include, for example, UV stabilizers or additives to increase mechanical and thermal strength. During their use, their effectiveness can decrease over time. In addition, later during recycling, impurities, pigment residues and high or incorrect filler loads can further reduce performance. The compounds obtained are often only suitable for the production of cost-effective and low-quality products. But that doesn’t have to be the case.

Recycling of Battery Housings

Another special application example is the recycling of used battery housings. Through a take-back system, batteries from automobiles are collected by manufacturers or contract companies with a very high return rate and recycled there.

Even in electric vehicles, 12 V batteries continue to be used in addition to the high-voltage battery for the drive, as the main battery is disconnected from the vehicle network when switched off.

The polymers used for the housings (in this case PP) are exposed to aggressive substances during their time of use, meaning the recyclates obtained may still contain acid and metal residues despite cleaning. Direct reuse would significantly accelerate the aging of the plastic. For this reason, the use of special additives, such as RECYCLOBYK products, is necessary for restabilization.



For testing, specimens are subjected to accelerated artificial heat aging conditions at 135°C or 155°C and the time to embrittlement is measured. Without additives, the accelerated heat aging lifetime in the example shown is less than 250 hours for the unstabilized compound. By using 0.2-1.0 % RECYCLOBYK, this time can be extended to more than 2000 hours, significantly exceeding a standard stabilizer package (1250 hours) (G. 07).



The improved performance is evident in terms of elongation, tensile strength, and modulus, as well as Charpy impact strength.

The results show the combined relative performance in terms of elongation, tensile strength, and tensile modulus, as well as Charpy impact strength compared to the nonstabilized control sample (= 100 %). The use of a standard stabilizer package improves the aging properties, but even at 1 %, it only achieves around the same performance as 0.2 % RECYCLOBYK.

Multilayer Film Compatibilization

A particularly challenging area of application is the recycling of multi-layer films. These typically combine the unique properties of different polymers to achieve the required performance. The main focus is on extending the shelf life of food products by providing a good barrier against oxygen and moisture. One polymer combination commonly used for this purpose is polyamide and LLDPE.

The good barrier properties and the high strength of a polyamide complement the advantages of LLDPE, such as high impact and puncture resistance.

The separation of the two polymer layers is currently not possible during reprocessing on an industrial scale, since the less dominant phase (PA in this case) forms large polymer spheres in the LLDPE matrix during regranulation due to the different surface energies.

This deteriorates the optical properties (especially transparency) of the material. The insufficient compatibility of the two polymers also leads to low mechanical resistances, especially in terms of elongation and impact strength. Compatibilization by using a highly functionalized SCONA modifier makes it possible to make the non-polar LLDPE compatible with the polar PA.



The use of the modifier leads to better bonding of the polyamide to the polyolefin phase and thus to finer distribution. This improves the mechanical and optical properties. The best possible distribution is achieved by using a twin-screw extruder.

Mechanical and Optical Properties of PA/LLDPE Blends


1.) PA/LLDPE 30/70: Inhomogeneous material with poor compatibility, poor optical properties, and low mechanical resistance.




2.) With SCONA modifier: With a highly functionalized SCONA modifier for excellent compatibility and improved mechanical and optical properties.

View SCONA^® Range by BYK

View a full range of SCONA® thermoplastics modifiers by BYK, analyze technical data of each product, get technical assistance or request samples.

BYK – A Leading Chemical Supplier

BYK is now a global leader in key parts of the additive manufacturing industry. Within the industry, our reinforced composites and PVC plastisols are highly regarded. They are noted for their exceptional processing capabilities and simplicity of application, in addition to their mechanical and aesthetic advantages. The RECYCLOBYK® 4371 surpasses the antioxidant package B -2 which provided 1250 hours at 1%. BYK additives are the perfect way to restabilize your products and increase sales. The company has developed a perfect additive for your multi files and named it SCONA® TPPE 1102 PALL/SCONA® TSPOE 1002 GBLL. With a wide variety of additives available, you can find the perfect one for your product. BYK has been in the business of additive manufacturing for years, so you know that you’re getting quality products and services. Contact us today to learn more about our additives and how they can help stabilize your product and increase sales.