Meeting growing  demand for recycled PP

There is a growing demand for recycled plastics across a wide range of industries. Recent research estimates that US demand alone for post-consumer recycled plastic will rise 6.5% yearly to 3.5 billion pounds in 2016.

Recycled plastics are also helping support growth in other markets around the world. The predicted growth rate of the Indian plastics industry is one of the highest in the world, with plastics consumption growing at 16% a year (compared to 10% in China and around 2.5% in the UK). Some 47% of Indian plastics are recycled. In contrast, a study by WRAP and Valpack found that only half a million tons of the 1.6 million tons of recyclable plastics that enter the UK household waste and recycling system a year, are recovered. China is reporting double-digit growth of its plastics recycling sector.

The automotive sector, which is using increasing quantities of plastics, in order to reduce weight and cost, is an essential part of the plastics recycling ecosystem. Over the past few years automotive plastics have contributed to reducing the weight of automobiles by 500 to 750 pounds. A 10% reduction in weight on average improves gas mileage by about 6%. The use of around 257 lbs of plastics in a modern vehicle has therefore significantly improved mileage. Greenhouse gas emissions over the total life of the vehicle are reduced because over 85% of the energy consumed during the life of a vehicle occurs during its useful life (gas, oil, maintenance). Automotive plastics make up about 0.5% by weight of a landfill. Despite this low percentage, automotive and plastic companies are striving to reduce that amount.

Opel, which is part of the General Motors Group, is setting new benchmarks for the use of recycled polypropylene with its Insignia model. According to the Insignia website, “The cornerstones of our recycling policy are the recycling oriented design and the recovery concept for end of life vehicles (ELVs). It means your car is made using more recycled materials and wasting fewer resources than ever. And when it comes to disposing of an old Opel, we make sure almost nothing goes to waste.

According to the website, Opel has a long tradition of using recycled materials, also known as recyclates. More than 130 plastic recyclate types have been specified and approved for use in production. In comparison to new resources, recyclates must fulfil all the same technical specifications and be produced at a lower cost. Where these two criteria are met, recycled materials are preferred, but quality is never compromised. Our recycling team takes every effort to maintain high quality look and feel, mechanical and thermal durability, along with performance standards. “In fact, because our recycled materials are of such a high standard and quality, they can now be used for visible parts as well as hidden parts of Opel cars,” says the company.

One of the additives being used to ensure the quality of the recycled plastics is SONGNOX® 3001-2, a stabilizer blend from Songwon, which meets requirements in terms of improved long term heat stability. The product is certified for use in automotive interior applications, according to the company. Songwon is the second largest manufacturer of polymer stabilizers in the world. Automotive Industries (AI) asked Thomas Schmutz, Leader Global Technical Service & Application Development, BU Polymer Stabilizers, Songwon Industrial Group, about the key breakthroughs in the development of plastic stabilizers.

Schmutz: In 2014, we broadened our portfolio with new experimental stabilizer solutions. Based on our SONGXTEND® 2121, SONGXTEND® 2122 and SONGXTEND® 2123, they have similar features and address fogging and odor issues in car interiors. The new stabilizers are being tested for:

• The talc-filled automotive compounding market, to provide better long-term thermal stability (XP 2041, XP 2042 and XP 2037 experimental stabilizers)
• The glass fiber (GF) re-enforced PP market for both short- or long-glass fiber PP

(XP 2035 and XP 1080 experimental stabilizers)

Currently, there is a trend in the market for GF-PP to meet 3000h at 150oC and possibly replace polyamide compounds for automotive under the hood applications.

AI: What are the main challenges in the use of recycled polypropylene?

Schmutz: Polypropylene is very sensitive to thermo-oxidative degradation. Without stabilizers, severe degradation during melt conversion occurs. This reduces the useful life of the plastic – the Long-Term Thermal Stability or LTTS.

AI: What is the most suitable light stabilizer solution for an automotive interior application that complies with the more stringent requirements of the automotive industry on VOC / FOG and total carbon emission?

Schmutz: Our newly-developed UV systems, SABO®STAB UV 210 and SABO®STAB UV 228 50PP light stabilizers, are gaining commercial momentum in the market. Representing the synergistic use of light stabilizers, they outperform standard UV stabilizers in polyolefin substrates in terms of color protection, gloss retention, and surface protection. They also show superior solubility and compatibility with polyolefins resulting in less blooming issues in relation to other low molecular weight HALS.

Our SABO®STAB UV 210 light stabilizer is best suited to exterior automotive applications, such as bumpers or side trims. It is a 100% active product and therefore very cost efficient. SABO®STAB UV 228 50PP light stabilizer, is ideal for interior automotive applications such as dashboards and door panels, and is meeting the more stringent requirements of the automotive industry on VOC/FOG and total carbon emission. Its concentrate form provides easy handling, low dust build up, and free flowing behavior for accurate dosing in polymer processing operations.

AI: Where do you see main growth in the use of recycled PP by the automotive industry?

Schmutz: The main growth in recycled PP use should come from the “visible” parts in the car interior and exterior applications.

AI: What are the main constraints?

Schmutz: For interior applications, the main constraints are the recycling resin odors and for the exterior, the challenge is achieving the required light stability

AI: How can they be overcome?

Schmutz: Recycled PP out of the post-consumer waste stream is the biggest obstacle, because food contaminants on the plastic’s surface or odorants in detergent or softener bottles are a major source of the final odor in the recycled PP. There are companies on the market that are trying to overcome this problem. One of them is Quality Circular Polymers.

AI: What do you expect the next major technological breakthrough from a Songwon perspective to be?

Schmutz: Songwon is constantly monitoring the trends in the automotive market and looking for new opportunities. For example, if the new emission standards like Euro 6, or other automotive standards, require changes in polymer stabilization, then Songwon will definitely focus on this type of opportunity.