Plastics for a modern world

In this special feature, Karen Stretch reviews pioneering developments designed to uphold product integrity without compromising consumers or the environment.

Superior performance additives

Developing high-performance additives for specialised plastics products is all part of the service at Masterbatch SA.

Included in its world-class masterbatch and pigment lines, Masterbatch SA (MBSA) supplies an extensive range of additives to plastics converters.

Additives impart properties that enhance functionality and performance characteristics, allowing plastics to be used in a myriad modern applications. With its ‘open-lab’ policy, MBSA’s technical experts ensure a full understanding of each customer’s requirements and can advise on the most suitable additive for the intended application.

Economic forces are driving demand for extended shelf life packaging and a masterbatch containing antimicrobials – or Mastermicrobials (MBSA’s trademarked brand name) – are now at the technological forefront.

Antimicrobials provide protection from food-related bacteria and provide odour control. Engineering and technological advances at the molecular level (nano technology) have now made integration of prohibitively-expensive raw materials economically feasible.

Silver, renowned for its antimicrobial properties, is used in masterbatch applications to prevent bacterial and fungal growth that may cause food decay. Antimicrobial requirements vary from product to product and are usually dependent on moisture content – for example, fruits, vegetables or meats. Mastermicrobials can be a cost-effective addition to packaging – and can be added into monolayer films as coextruded barrier films are not a requirement for producing extended shelf life packaging.

Enhancing recycling

As steady growth of recycling engages an increasing number of stakeholders, competitiveness and legislative obligations require exceptional quality control for suppliers of recycled materials and recycled finished goods. Moisture, a critical control parameter, needs to be actively addressed and controlled. Here, MBSA supplies desiccant masterbatch to remove excess moisture and volatiles in raw material, enhancing the processability of regrind polymers.

Among latest developments, an odour-absorbing masterbatch neutralises the typical recycling smell and peroxide initiators alter the melt flow index (MFI) of recycled polypropylene (PP).

To illustrate, an economical source of recycled PP of a certain MFI is discarded garden furniture. End-use application of recyclate may require a significantly high MFI, which, through the addition of a peroxide initiator, shortens the PP chains, thus increasing MFI.

Laser marking technology

Turning to the topic of laser marking, Ane de Heus, MBSA’s technical manager, explains: ‘Today’s consumers demand “intelligent packaging” and laser marking on plastics is becoming more common. Applications include direct printing of promotional and legislative information – for example, expiry dates on beverage closures.’

Most plastics cannot be economically marked without the addition of laser-sensitive additives, typically having an aluminium base. During the laser marking process, heat causes the additive base to react, inducing a colour change in the polymer itself. Different laser marking technologies operate in the ultra-violet (UV) or infrared (IR) range of the electromagnetic spectrum. Laser marking (YAG printers) in the UV range causes a photochemical reaction with the polymer. Technologies operating in the IR range cause a thermochemical reaction.

The complex process of matching laser marking technologies with laser marking additives, without compromising colour integrity, is a specialist capability at MBSA.

Complex requests

‘Requests for seemingly conflicting properties are becoming more prevalent,’ continues MBSA MD, Anthony van Niekerk. ‘For example, we’re the only local manufacturer to engineer a solution to meet both flame retardant and UV properties for stadium chair applications.’

Commonly used additives that improve performance of a final product include UV stabilisers to slow down degradation through sunlight; flame retardants to reduce a product’s tendency to burn; and anti-oxidants to reduce degradation through exposure to heat and oxygen.

Additives used to improve the function of the final product are anti-static to minimise static electricity build-up, anti-block to reduce adhesion and anti-fog to reduce condensation – important factors for films and closures. The addition of processing aids also improves the handling and processability of certain polymers.

Compliance and safety matters

MBSA’S strictly-controlled restrictive substance list and tightly-monitored production and testing procedures, which drive its ISO 22000:2005 food safety compliance, ensure products that are safe for direct food contact.

MBSA is also ISO 9001:2008; ISO 14 001:2004 and OHSAS 18 001:2007 compliant for quality, environment and health & safety management systems.

‘We’ve earned our colours by owning our knowledge,’ affirms Anthony. ‘To achieve this, we invest significantly in R&D at all levels, from science and chemistry to people, processes and raw materials. Our passion for plastics ensures that this knowledge manifests itself in our products and service levels. This is the only true competitive edge a company has and the only true sustainable value proposition for customers,’ he concludes.