Strength enhancers

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Only the strong survive. Resins traveling through the circular economy face challenges from enduring multiple heat cycles. To ease their journeys, companies recently have introduced additives that prevent degradation and buttress qualities such as strength and color. Among the companies offering additives for polyolefins and polyethylene (PE) are Baerlocher USA, GreenMantra Technologies and Nexam Chemical AB.

Baerlocher USA

Baerlocher USA, Cincinnati, part of the Baerlocher Group, Lingen, Germany, has introduced Baeropol DRS 6812 for processors recycling polyolefins.

The product is the latest addition to the company’s Baeropol RST (Resin Stabilization Technology) line. It delivers improvements in melt stability, polymer color and antioxidant solubility, all of which are critical elements for recycling and stabilizing resins. It can be used as a 1-to-1 replacement for most secondary phosphite antioxidants, according to the company.

“The rapidly growing polyolefin market, including the circular recycling economy, requires new stabilization technologies that can solve the challenges facing traditional phosphite additives, such as limited solubility that can lead to processing issues,” says Robert Sherman, technical director for Baerlocher USA’s Special Additives Division.

However, many of the most commonly used phosphite additives can separate from the polymer, resulting in the appearance of a white powdery substance on processing equipment and finished parts, a condition known as plate-out.

“The purpose of these products is to enhance the processability and reduce losing more physical properties in the final application coming from extrusion.” – Lars Öhrn, Nexam Chemical

“If you’ve got a brightly colored part like a detergent bottle, you don’t want to see this white powder on it,” Andersen says.

DRS 6812 delivers solubility and optimizes hydrolytic stability for consistent performance, he says. Unlike some of the products it replaces, it does not react with moisture in the atmosphere.

“On the recycling side, it has some particular advantages because the RST component is an antacid as well as a lubricant,” Andersen says. “When you are looking at recycle streams, they typically can have a variety of contaminants, including PVC (polyvinyl chloride), which, when you reheat those mixtures of polymers, they tend to be a little acidic. So, it is important to have antacids present when you are reprocessing polymers.”

Baerlocher developed the additive to address growing demand from processors of recycled plastic, company representatives say. The company predicts continued growth in demand for this type of product.

“Polyolefin manufacturers in North America really are going through a renaissance,” Andersen says. “We’ll probably see a 30-35 percent expansion in the volume of polyolefins produced in North America over the next three to five years. It’s a pretty significant growth.” 

GreenMantra Technologies

GreenMantra’s Ceranovus A120 PE wax is an additive for processing virgin or recycled plastics. One of its key markets is for the recycling of PE.

“You can use the product for 100-percent-recycled streams, blended recycled and virgin streams or just for virgin—it really depends on the customer’s application,” says Domenic Di Mondo, vice president of technology and business development for GreenMantra.

The Brantford, Ontario, company developed a patented manufacturing process for converting scrap plastics into high-value waxes and polymers that can be used as plastics additives. The products are sold under the Ceranovus brand name.

Ceranovus A120 PE wax, introduced last year, is a PE wax. It is produced from postindustrial plastic scrap and post- consumer recycled plastics, such as bags, film, yogurt containers and bottle caps.

When used as a processing aid, it acts as a lubricant. It reduces back pressure in an extruder, preventing equipment wear and tear and lowering energy consumption. It also can improve throughput. When used in processing PE, it enhances performance.

“When customers are processing polyethylene streams, we’re able to improve the performance of the finished product while also increasing throughput,” Di Mondo says. “Typically, we improve the melt flow of the plastic. We also improve the physical performance. You get better elongation. You are able to stretch that material more before you get a failure. That tends to help you with your blow molding or extrusion molded parts.

“When customers are processing polyethylene streams, we’re able to improve the performance of the finished product while also increasing throughput.” – Domenic Di Mondo, GreenMantra

“The other piece for us is, when we are working with polyethylene, our product allows you to get a better blending of the polymer,” he continues. “If you are working with a recycled plastics stream where you have a lot of variability of the plastics being mixed together, you tend to get a better, true mixing of those polyethylene polymers together.”

One of the uses of Ceranovus A120 PE wax is in compounding postconsumer recycled high-density polyethylene (HDPE). It improves the physical properties of composites and allows for higher recycled or filler content, according to the company. The result is an overall cost savings and an increase in the recycled content of finished parts.

GreenMantra officials cite tests by a third-party lab that added the wax at concentrations of 2 percent and 4 percent to postconsumer recycled HDPE. The compounding tests were conducted with a steady extruder screw speed of 125 rpm and a feed rate of 290 pounds per hour.

The results showed the addition of Ceranovus A120 PE wax increased the melt flow by 30 percent to 40 percent and reduced back pressure by 10 percent. The wax also reduced average energy requirements by about 20 percent, even as the machine maintained constant throughput.

In another test, postconsumer recycled HDPE pellets with 2 percent and 4 percent Ceranovus A120 PE wax were extruded and injection molded into bottles. The results were compared with a control sample that contained only postconsumer recycled HDPE without any A120 PE wax. The test results demonstrated melt flow rates of pellets with the wax were 58 percent faster than the control sample, and the part melt flow rate increased by 39 percent. With the addition of the wax at 2 percent and 4 percent concentrations, elongation improved 19 percent and 62 percent, respectively. When made with plastics containing either concentration of wax, the rate of bottle breakage in testing was reduced by more than 50 percent, according to the company.

Nexam Chemical AB

Nexam Chemical, Lomma, Sweden, is offering several new functional masterbatches to improve the properties of recycled PE used in pipe and film extrusion.

“The purpose of these products is to enhance the processability and reduce losing more physical properties in the final application coming from extrusion,” Nexam Chemical Chief Marketing Officer Lars Öhrn says. “For us, this is a new product line.”

The new products are Nexamite M480502, M480504, PE0180 and PE0191.

“Depending on the challenge the converter has processing recycled PE, we have four tools that can be used stand-alone or combined,” Öhrn says. “These tools are highly effective processing aids that help processing the plastic, so it flows easier, leaving less deposits and die buildups [and] protects the PE from further deterioration and reactive products that can rebuild PE chains.”

The M-series materials contain a long-chain branching component that connects PE molecules. These materials improve melt strength and other properties in recycled PE for pipe and film.

The other masterbatches—PE0180 and PE0191—contain different antioxidant and polyphthalamide (PPA) combinations that assist in protecting PE during extrusion and aid in processing.

“We have focused on extrusion applications like film and pipe,” Öhrn says. “Which product works best depends on the challenge the converter has. Do they need to stop production frequently due to die buildup? Then a product like PE0191 is a good start. Are they not having enough melt strength to run at the right speed or thickness? Then Nexamite M480502 and M480504 [are good starting points].”

Nexam introduced Nexamite M480502 and M480504 in the beginning of this year. The company acquired some products, including PE0180 and PE0191, when it bought Plasticolor Sweden AB, a manufacturer of masterbatch products, in December 2017.

Nexam Chemical normally sells these products as masterbatches, but the company can supply some of the active components in neat powder form.

The author is the senior staff reporter for Plastics Machinery Magazine. He can be contacted at bgeiselman@plasticsmachinerymagazine.com.