RTP Company: The Global Leader in Specialty Compounding

New Specialty Polycarbonate/Acrylic Compounds Offer Superior Impact Properties

A recently devised specialty alloy combines acrylic, polycarbonate (PC), and specialty additives to produce an impact-resistant material with very unique properties. While other polycarbonate-acrylic alloy resins are already available in the marketplace, this new formulation from Winona, MN-based RTP Company called 1800 A Series PC/Acrylic, provides manufacturers and designers with new application and design options by incorporating wear additives, flame retardants, and/or PermaStat® permanent anti-static protection. These additives enhance a PC/Acrylic compound's properties to meet a diversity of requirements.

Processes Like Acrylic, Tougher Than Polycarbonate

After compounding, the resulting 1800 A Series PC/Acrylic compound displays greater impact strength than PC, while maintaining the excellent processing characteristics associated with acrylic. The PC/Acrylic compound can also be processed at lower temperatures than PC, thereby decreasing cooling and cycle times during the injection molding process for increased efficiency.

Impact Resistant For Tough Applications

The innovative PC/Acrylic alloy is used for many items, such as housings for handheld devices, lighted signs, appliances, security system control panels, luggage, and medical diagnostic devices. "The PC/Acrylic alloy is best utilized when impact resistance is important, especially in places where the item might drop or get hit," states Kevin Marshall, Product Manager at RTP Company.

There are numerous applications requiring impact resistance over a wide range of temperatures. One example is using PC/Acrylic for snowboard bindings. "PC/Acrylic has very good cold temperature properties and will maintain its impact resistance," says Marshall. Its cold temperature impact resistant properties enable it to withstand the forces and poundings that a snowboarder endures during a day on the slopes. To appeal to a consumer, PC/Acrylic's natural opaque white color provides an excellent base for a wide range of colors and visual effects.

Flame Retardant In Thin Wall Applications

PC/Acrylic compounds are a versatile product family and can be modified with various additives to provide a broad range of performance. PC/Acrylic with flame retardants see frequent use in housing and control panel applications. Its combination of excellent impact properties at various temperatures, along with UL yellow card flammability ratings of V-0 @ 1.5mm and 5-VA @ 2.2mm, allow this product to outperform FR grades of PC and PC/ABS in critical applications.

The outstanding properties of PC/Acrylic with flame retardants (RTP 1800A FR) let manufacturers meet strict UL and other regulatory agency standards for critical electrical and electronic applications. With a 5-VA @ 2.2mm rating, PC/Acrylic with flame retardants can be used in product housings with thin wall sections. Designers and manufacturers can be confident of the flame protection at thinner wall section without sacrificing toughness. This contributes to favorable economics for processors producing PC/Acrylic parts compared with traditional materials, such as FR grades of PC and PC/ABS.

ESD Protection And Metal Replacement

Also used for computer components and business machines where manufacturers need electrostatic dissipative (ESD) protection, PC/Acrylic compounds offer characteristics that most other polymers and alloys cannot. "Because of the excellent flow characteristics, injection molders can mold long thin parts that may have perforated holes in the part design, enabling them to completely fill the mold," states Marshall. Conductive PC/Acrylic compounds have successfully replaced metal components by offering lower cost, weight reduction, and parts consolidation.

PC/Acrylic was specified for the shutter actuator used on Lexmark International Inc.'s (Lexington, KY) printer toner cartridges. Lexmark was using acetal for molding its printer cartridges but switched to PC/Acrylic alloy to reduce material and processing costs. The specialty alloy flowed well into its four-cavity molds, which included small gates. Lexmark experienced good dimensional stability characteristics, and even found it to be economically priced in relation to the acetal.

The actuator holds the shutter open during printing and must sustain its dimensions and resist bending for long periods of time. There are two small snap details on the part, one that automatically locks into the shutter and the other into the housing of the printer cartridge. Without the impact strength of the PC/Acrylic the part would experience significant breakage. Lexmark has performed extensive drop testing on the product (eight drops from 36 inches) with the toner still in its package. The parts have yet to fail a test.

Lubrication And Soft-Touch Add Value For Consumers

The addition of lubricants to PC/Acrylic compounds reduces surface wear and squeaking without sacrificing a part's color or appearance. Thanks to the wear resistance and dimensional stability of PC/Acrylic compounds, cell phone belt clips and pager holsters easily release a portable electronic device without scratching the surfaces. The PC/Acrylic's impact resistance and toughness maintains part performance under a wide variety of consumer environments.

Another growth area is PC/Acrylic's use as a rigid substrate for thermoplastic elastomers. Elastomers can be over-molded onto PC/Acrylic providing an ergonomic, soft touch feel to a finished product. "Thermoplastic elastomer compounds combine the performance and properties of conventional thermoset rubbers with the processability of thermoplastics. The combination of PC/Acrylic and elastomers give designers new flexibility in applications that require both impact resistance and soft touch," states Marshall.

Cost And Performance

Even though its physical and impact properties are similar or better, PC/Acrylic prices are comparable to those made with PC/ABS. "Our PC/Acrylic compounds process better than PC or PC/ABS compounds, and they offer exceptional impact properties," says Marshall. "In the world of plastics you have a lot of options. In PC/Acrylic compounds, our customers have found an acceptable balance of cost, performance, and processing."

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RTP Company is a privately owned specialty compounder, creating thousands of custom formulations each year from a variety of thermoplastic resins, additives, and fillers. For more information contact: RTP Company, 580 East Front Street, Winona, MN 55987; Tel: 507-454-6900 or 800-433-4787; Fax: 507-454-4629; or Web site http://www.rtpcompany.com/products/1800A/.