When Brazilian appliance maker Suggar Eletrodomésticos (www.suggar.com.br) started using transparent top doors on some of its washing machine models, customers responded positively and sales increased. However, the company quickly found that the styrene acrylonitrile (SAN) resin it was using was not providing the impact resistance needed to withstand the rough handling of the door.
The design challenge was finding a durable material that provided the clarity of SAN. The answer was Luzz 730 grade polypropylene (PP) from Quattor Petroquímica (formerly Nova Petroquímica) enhanced with Millad NX8000 additive from Milliken Chemical. "We had been looking for a solution that could give our thick washing machine doors both impact resistance and high transparency," Marcelo Emrich Soares, director for Suggar, tells APPLIANCE. "That was exactly what Milliken and Quattor offered us in this project, which was started in late 2007."
According to Rafi Green, international specialist in the development of new materials for Suggar, the enhanced PP provided the company with several advantages over SAN. "It is durable, has good scratch and impact resistance, which, along with its unique optical properties, made this project possible," Green says.
The PP was also easier to work with. "Not only due to the high injection molding speeds, but also because we are able to enjoy a very robust process," Green explains. "Not to mention it results into a considerably lower downtime of our equipment. We had no adaptation cost to use this new product." In fact, the material's lower density is said to make its cost equivalent to the SAN resin.
The PP's aesthetic benefits are due its clarifier, which is said to offer a 50% reduction in haze compared to the current industry standard. For an upscale, sophisticated look, Suggar colors the clear resin with a smoke tint before injection-molding the parts.
To establish the proper parameters and conditions for manufacturing the parts, a team from Milliken and Quattor Petroquímica ran molding trials initially at Quattor's Innovation Center in São Paulo, Brazil, and later at Suggar’s facilities in Belo Horizonte. When formulating the new material, Soares says that special attention was put in to mold finish, processing conditions, and optimal formulation. "As a matter of fact, we at Suggar have developed a mold with a unique design for our new washers in an effort to add even more value to this project," he says.
The resulting material has been such a success that Soares says Suggar is using the PP in two other washing machine models. "We intend to use the same concept of utilizing this resin in other appliances we currently make, or even brand new ones we want to start producing in our facilities before year ends," he says.