Chemical-, hydrolysis-resistant resin for plastic-over-metal molding of consumer electronics applications:

Plastics are still preferred because they offer better design freedom, are easier to make into complex shapes, and cost less, the answer to this engineering challenge is a plastic-metal hybrid.

Pittsburgh – October 9, 2008 – Smaller, sleeker and lighter – these are the goals of designers seeking to create the latest products for the consumer electronics market. Finding the right material to give designers the freedom to feed consumers’ demand for compact, elegant devices that can stand up to the abuses of everyday life is a challenge Bayer MaterialScience LLC (BMS) faced head-on with the introduction of its new Makroblend® UT5205 polycarbonate / polyester resin.

“The trend in the consumer electronics market is for thinner and smaller devices, which can lead to extensive manufacturing challenges,” said Gerald DiBattista, market segment leader, IT, Electrical/Electronics Polycarbonates, BMS. “Generally, as devices become thinner, they become less rigid. This has forced designers to either work with very expensive, light and strong metals like aluminum or magnesium, or to work with thinner plastic materials and deal with the loss in stiffness which can result in an inferior-looking product. Since plastics are still preferred because they offer better design freedom, are easier to make into complex shapes, and cost less, the answer to this engineering challenge is a plastic-metal hybrid.”

The hybrid DiBattista refers to is achieved through metal insert molding, a process that utilizes a simple metal frame with plastic injection-molded around it. The metal provides the stiffness required for the part, while the plastic provides durability, as well as a high-gloss finish or other desired aesthetic effects such as contours, which are difficult and expensive to produce in metal. BMS’ Makroblend UT5205 resin was specifically designed to address the engineering challenges associated with metal insert molding.

Metal and plastic have different thermal coefficients of linear expansion, as plastic expands and contracts more than metal. Therefore, the metal insert molding process itself adds stresses to the part as the plastic shrinks around the metal during cooling. Makroblend UT5205 resin is specifically formulated to reduce these stresses during the molding process as well as in everyday heating and cooling cycles (such as when a device is left in a hot or frigid car) to ensure the finished part will be able to stand up to typical day-to-day abuses.

In addition to the stresses associated with the metal insert molding process, everyday elements and items that come into contact with consumer electronic devices – such as heat, moisture, foods and personal care chemicals – can amplify these stresses and cause a metal insert molded part to crack or fail.

“Makroblend UT5205 is a special formulation made to offer exceptional resistance to chemicals such as lotions as well as improved hydrolysis resistance compared with typical thermoplastic blends that tend to degrade in heat and humidity. This is particularly important when molding ultra-thin electronics like cell phones and MP3 players, which consumers expect to be able to take with them wherever they go,” explained Nick Sunderland, senior associate scientist, Product Applications Development Group, BMS. “For example, everyday substances your MP3 player could come into contact with during a day at the beach, like sun block, are comprised of substances that can break down plastic. So we developed Makroblend UT5205 with exceptional chemical resistance so the consumer can focus on having fun.”

Metal insert molding is also a simpler, more cost-effective manufacturing process than alternatives like die-casting, which requires the use of costly metal and die-cast parts, or glass-filled plastics, which are prone to fracturing and can result in poor surface finish.

“This is just the beginning for metal insert molding using Makroblend UT5205 resin,” said Sunderland. “Right now we’re focusing on the consumer electronics market, but this formulation could be used in any application where there’s a need for metal/plastic parts that stand up to chemicals and stresses.”

About Bayer MaterialScience
Effective March 1, 2007, Bayer MaterialScience has combined its entire global polyurethane systems business under the umbrella brand of BaySystems™. This change affects not only existing product brands in this segment – including Bayflex® – but also the global network of polyurethane systems houses. More information about BaySystems™ can be found at www.bayer-baysystems.com.

Bayer MaterialScience LLC is one of the leading producers of polymers and high-performance plastics in North America and is part of the global Bayer MaterialScience business with nearly 15,400 employees at 30 sites around the world and 2007 sales of 10.4 billion euros. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction, medical, and sports and leisure industries. Our inorganic basic chemicals unit produces chlorine and related essential products for the chemicals industry. Let us give life to your vision. Bayer MaterialScience – Where VisionWorks.

Bayer Corporation, headquartered in Pittsburgh, is a subsidiary of Bayer AG, an international health care, nutrition and high-tech materials group based in Leverkusen, Germany. In North America, Bayer had 2007 net sales of 8.1 billion euros and employed 16,800 at year end. Bayer’s three subgroups, Bayer HealthCare, Bayer CropScience and Bayer MaterialScience, improve people’s lives through a broad range of essential products that help diagnose, prevent and treat diseases; protect crops and enhance yields; and advance automobile safety and durability.