Materials Make Manufacturing Go ‘Round

Kudos to materials manufacturers for continually developing more innovative, and increasingly, green products. For instance, SABIC Innovative Plastics recently launched a new Lexan polycarbonate (PC) film – Lexan EFR – that makes non-brominated, non-chlorinated flame retardance (FR) at thinner gauges than flame-retardant polypropylene (FRPP). This new material lets electrical/electronics (E/E) OEMs create flatter, lighter-weight notebook computers and other electronic devices while reducing material costs. The film helps global E/E manufacturers to go beyond current environmental directives by voluntarily eliminating halogenated additives in their products.

Adaptor-made-from-Lexan-EFR-Film
An adaptor made from Lexan EFR Film

The product is flame retardant without using brominated or chlorinated additives thus meeting the requirements of the European Union’s Restriction of Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE 2006) directives. These new materials have a full listing in the Underwriters Laboratory (UL) yellow card system.

Compared to FRPP, the new film shrinks less by a factor of three, is more puncture resistant, and has higher tensile strength. These properties make it possible to use thin gauges of Lexan EFR film to replace thicker FRPP film. Not only do thinner gauges help create slimmer and lighter-weight consumer electronics, but down-gauging also lowers total costs by reducing the amount of material required. The new film also provides low moisture absorption, high thermal performance (glass transition temperature of 170ºC), and dielectric strength. Target applications for this material include insulation for printed circuits, printed circuit boards, disk drives, keyboards, inverters and adaptors, die-cut spacers, labels, and overlays.

Electromagnetic interference/radio frequency interference (EMI/RFI) shielding is another benefit provided by Lexan EFR film. As US and European regulatory agencies continue to tighten restrictions on EMI/RFI emissions, electronic device manufacturers are looking for new shielding products to replace metal boxes, conductive paints, plating, metal chassis, and conductive polymers that add weight and cost. Lexan EFR film is a low-cost, lightweight solution for both primary and secondary shielding, while maintaining UL recognition. The film can be fabricated using thermoforming, embossing, clean-edge die cutting, scoring, and bending. The product is available in matte/polish and velvet/matte finishes and various gauges between 100 and 762 microns.


The KEG-2005 silicone materials are ideally suited for the medical industry. They are tear resistant and prevent cracks in devices and equipment.

Silicones
Shin-Etsu Silicones of America recently launched its KEG-2005 silicone series that are well suited for the healthcare industry. All of the products in this series are tested to meet medical device biocompatibility standards including ISO 10993/USP Class VI/CFR 177.2600.

The products are engineered to resist tear propagation. The material properties offer better toughness for applications such as baby bottle nipples and peristaltic pump tubes for dispensing food products and pharmaceutical nutrients. The high tear strength LSR rubber material is formulated to prevent cracks through the silicone. This phenomenon is called “knotty tear” which is harder to pull apart and results in high tear resistance values.

The KEG-2005 series was tested against other leading materials to determine how it tears under tensile force. The results were measured in force (lb) per meter; with a straight crack representing the lowest values, a curved crack rating better, and a vertical crack rating best. The series higher tear strength combined with good release properties, it also allows for demolding parts – particularly those with thin wall thicknesses – without tearing or creating scrap. KEG-2005 is used in Europe and will be introduced to the US in 2010.


Fire retardant compounds
A new portfolio of wire and cable products for optical fibers was recently launched by PolyOne. The product family includes several grades of ECCOH and ECCOH PF low smoke and fume, zero halogen (LSFOH) compounds and OnColor and OnCap colorant and additive products. These materials are formulated for a group of optical fiber applications known as FTTs, or fiber to the x, denoting all optical fiber used in telecommunications.

In the past, optical fiber cables were primarily used for outdoors and did not require flame retardant sheathing materials. Increasingly, however, bandwidth providers are bringing fiber optics into buildings – known as FTTB, or Fiber To The Building and to individual living units – called FTTH, or Fiber To The Home. These cables must be flame retardant and contain materials that are low-smoke, low-fume, and non-halogenated (also called LSF0H, for Low Smoke and Fume, Zero Halogen).

fiber-optic-cabling
Fiber optic cabling is now being routed into homes and buildings where the sheathing and insulation must be flame retardant. PolyOne formulated ECCOH and ECCOH PF low smoke and fume, zero halogen (LSFOH) compounds for these applications with non-halogenated flame retardants for increased safety.

In addition to good flame retardance, these materials offer low smoke and low toxicity benefits, and include the following features:

• ECCOH compounds offer low corrosion, low shrinkage (less than 1%), good mechanical strength to prevent fiber breakage, and low memory retention to ensure good attenuation properties.
• Mini-ducts: ECCOH PF grades are recommended for mini-ducts through which fiber is routed. Used mainly in multi-dwelling units, these compounds are highly flame retardant, while their inherent stiffness allows easy installation and provides bend radius control.
• OnCap Anti-static compound for use as an inner layer for mini-tubes enables optical fibers to be blown further. This compound can be co-extruded as an internal layer 0.5mm thick.

Each ECCOH compound can also be provided with suitable OnColor color concentrates to match specific requirements, with master batches available for other materials such as high-density polyethylene (HDPE), polybutylene terephthalate (PBT), and thermoplastic polyurethane (TPU).

Polymer meets medical specs
A leading medical device OEM recently contracted with Kaysun Corporation, a custom plastic injection molder, to help design a new handheld device. The Kaysun engineering team narrowed down a list of potential medical-grade materials. They were tasked to identify those that were chemical and flame resistant and had high impact strength. The OEM provided a list of common cleaning agents used in medical environments.

Sabic-Cycoloy
Sabic Cycoloy is a polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS) high impact amorphous thermoplastic that combines ease of processing with low-temperature ductility. Cycoloy resin blends are a good design choice when both appearance and durability are important. (photo courtesy of Sabic Innovative Plastics)

For the main housing, Kaysun selected a polycarbonate/ABS blend because a polycarbonate alone did not meet chemical resistance requirements. The Sabic Cycoloy CX 2244ME met all the requirements and offered good moldability. The resin is a flame retardant PC/ABS blend featuring excellent balance of flow and impact resistance together with UL-94 V0 rating at < 1mm. The material also higher chemical resistance to general hospital cleaners.

kaysun-polycarbonate_abs-blend
Kaysun chose a polycarbonate/ABS blend for the main housing components of a new handheld patient monitoring device to withstand the chemical cleaners used in healthcare, provide impact resistance, and meet the V2 UL flammability standard required for its battery power source. The company also used a polycarbonate for the device window because it met these requirements while retaining its clarity.

For the device window, the team selected the Sabic Lexan 945A polycarbonate because it will not fog for a long time. The resin is a non-filled, injection moldable grade. This non-chlorinated, non-brominated flame retardant PC has an UL-94 V0 rating and is available in transparent and tinted color options.

Sabic-Lexan-polycarbonate-resin
Sabic Lexan polycarbonate resin is an amorphous engineering thermoplastic, characterized by good mechanical, optical, electrical, and thermal properties. (photo courtesy of Sabic Innovative Plastics)

Polyurethanes
Eco-friendly hotel bathtubs can be made to last longer by applying the polyurethane spray system Multitec Advanced Foam from Bay Systems. The Coral Suites & Spa Hotel on the island of Tenerife fitted 120 bathtubs with the material. Bathtub manufacturer BSB (Bañera sobre Bañera) and its supplier Handcrafted Industrial Projects developed and produced the bathtubs with the Spanish BaySystems, a division of Bayer MaterialScience.

Traditionally, bathtub shapes were created by thermoforming a polymethyl methacrylate (PMMA) or acrylonitrile-butadiene-styrene (ABS) thermoplastic film. To ensure that the molded part has the necessary stability, the reverse side of the thermoformed film has to be reinforced. Until now, this has been done in many cases using a time-intensive manual process that involved laminating the film with unsaturated polyesters and cut glass fibers. Other drawbacks are the use of styrene as a solvent and co-reactant, and the need for annealing during the curing phase.

In contrast, Multitec Advanced Foam is applied just like a coating. No plasticizers or solvents are required and it is processed without glass fibers or fillers on high- or low-pressure equipment. The high reactivity and easy handling ensure cost-efficient reinforcement of the films. There is no need for annealing. The bathtubs also demonstrate their ecological credentials when in use by absorbing both heat and sound. Since they are long-lasting, the tubs also help to reduce waste at disposal sites. Hotel chains want to ensure their furnishings and fittings are eco-friendly and sustainable.

Discuss this on the Engineering Exchange:

Sabic Innovative Plastics
www.sabic-ip.com

Shin-Etsu Silicones of America
www.shinetsusilicones.com

PolyOne
www.polyone.com

Bayer MaterialScience
www.bayermaterialscience.com

Bay Systems
www.bayer-baysystems.com

Kaysun Corporation
www.kaysun.com

::Design World::