Materials | 2 MINUTE READ

Purging Compound R&D Ramps Up to Meet Specific Material & Processing Problems

The challenge for suppliers of purging compounds has shifted from educating processors about their benefits to researching new formulations to further increase those benefits. 


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“We’re growing every year…we are in an expansion mode and would consider acquisitions, capacity expansions, and further product development,” says Joseph Serell, v.p, of Sun Plastech, manufacturer of the Asaclean brand of purging compounds, adding that the company’s R&D operation currently has 10 full-time engineers on board. Indicative of this direction is the company’s 2015 acquisition of Novachem, which added a family of chemical purging agents to its arsenal of mechanical purging compounds. Visitors can find out more about both at Booth W3283

Serell gave Plastics Technology a quick glimpse of how things have changed in this industry: “The adoption of purging compounds each year becomes greater and greater. Twenty years ago, we aimed to educate processors and compounders as to why they ought to consider use of commercial purging compounds in terms of efficiency and cost benefits. This is no longer the case, as they (purging compounds) have become widely accepted. So, now we aim to address questions such as how much money we can save them or how to address specific problems.”  Many processors are doing far more color and material changes and many are specializing in shorter runs, making the need for a good commercial purging compound more crucial, he explains.

The company is addressing these trends and others, such as the frequent introduction of new specialty resin grades, including higher-heat engineering resins, for example. As such, the company has developed purging compounds that have heat resistance to 790 F.  Moreover, says Serell, Sun Plastech has seen the need to address other processes such as blown film and blow molding with new grades.

Until recently, blown film processors have not been big users of commercial purging compounds, owing to long runs with fewer material changes, according to Serell. He notes that the company is introducing new purging compounds of both varieties—mechanical and chemical—that meet the specific needs of this process. He explains that the key for these processors is not having to re-string the bubble. As such, film processors want a purging compound that holds the bubble, runs through quickly, with the new resin close behind. As an example, he cites a change from a colored to a clear resin. “This is more of a consultative sale in that we offer a consultation on how to solve a problem based on their process. We narrow down the problem and make our recommendation.”

In the case of blow molding, meanwhile, the company is focusing on its acquired N-Series of chemical purging compounds, as they excel in creating pressure and agitation. This is key in blow molding, Serell says. In blow molding, resin typically flows at low speeds and little pressure. “Part of the chemical reaction causes an expansion of the purging agent—expanding into areas where mechanical purging compounds might not be able to reach.”