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Copolymers deliver design solutions for demanding applications

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Sabic Innovative Plastics' mission to help customers drive down system costs while achieving  exceptional performance with high-end thermoplastics has led to another industry game-changer – Lexan XHT clear, high-temperature polycarbonate (PC) copolymers. This innovative family of advanced PC resins features new polymer chemistry with an optimal balance of high heat resistance and high flow, enabling it to offer greatly expanded design options for molding thin-wall parts such as medical devices and electrical fuses. Lexan XHT copolymers also offer excellent clarity and colorability, making them top choices for applications like consumer and industrial lighting and heat shields. They are part of Sabic Innovative Plastics' growing Lexan copolymers portfolio built on the technology foundation laid by Lexan PC resin's 50-year track record.

"With Lexan XHT copolymers, Sabic Innovative Plastics is delivering on a previously unmet market need for a true high-heat resin technology with a near perfect balance of properties vs. other clear, high-heat materials," said Bala Ambravaneswaran, product marketing director, Lexan Copolymers & Special Effects, Sabic Innovative Plastics. "These innovative materials give our customers the high-tech yet practical solutions they need to succeed in new high-performance applications. Following the success of Lexan XHT copolymers in automotive lighting, we are quickly moving into diverse and equally challenging application areas."

Clear Resin Delivers Highest Performance for Extreme Heat Conditions
Lexan XHT copolymers address the need for PC-based materials with end-use temperatures in the range of 140C to 195C. They deliver an industry-leading relative thermal index (RTI) Underwriters Laboratories (UL) rating of 150C, surpassing polyarylate (PAR), polymethyl methacrylimide (PMMI) and other high-heat polycarbonates (HHPC). This exceptional high-temperature performance is achieved through proprietary chemistry that alters the polymer backbone by incorporating specialized monomers. Copolymers offer higher performance than compounds, blends and additives, which are not chemically integrated.

Lexan XHT copolymers surpass competitive high-heat materials in other key areas:

  • Lower color shift on ultraviolet (UV) weathering vs. PAR
  • Better color stability under heat aging vs. HHPC
  • Improved tensile and impact strength retention after heat aging vs. HHPC
  • Better resistance to cracks and haze after metallization than HHPC
  • Improved flame retardancy vs. PC, PMMI and HHPC. Compliance with eco protocols and UL94 capability down to V0 at 1mm and 5VA at 3mm in clear and opaque colors
  • Electrical properties suitable for high-heat film applications

Comparable alternate materials show marked yellowing and haze after extended exposure to heat and UV light, impacting the appearance of the application. In contrast, Lexan XHT copolymers minimize color shift and retain clarity over a long lifespan. The high-heat color stability and clarity of Lexan XHT copolymers make them an excellent candidate for applications including aesthetic and functional enclosures for industrial and commercial lighting, consumer products such as heat resistant helmets and heat shields, electrical components such as fuses, and non-biocompatible healthcare devices that must undergo autoclaving.

These materials have already been proven in automotive applications including bezels, reflectors and lens covers where they enable direct metallization, which eliminates the costs and environmental impact from pre-coating the part with paint or lacquer. When vacuum-metalized, parts made from Lexan XHT copolymers can withstand temperatures of up to 175C without blistering, hazing, delaminating or losing their brilliant luster.

Lexan XHT resins are available in a variety of colors with a clear or opaque base. Special visual effects such as diffusion, metallic and sparkle for custom needs, in challenging applications such as industrial lighting, and glass replacement are also available.

Up to 30 Percent Higher Flow and Less Scrap Reduce System Costs
To help designers reduce size, mass and weight, and create thinner-walled flame-retardant parts such as housings for consumer electronics, Lexan XHT copolymer grades offer improved flow characteristics for injection molding. These materials deliver a 30 percent longer flow length and better mold release than competitive high-heat materials, which help decrease melt temperatures and cooling requirements and cut cycle times by as much as 25 percent. In a heat-critical thin wall battery cover application, Lexan XHT resin was able to fill a part with 0.7mm nominal wall thickness.

Further, Lexan XHT copolymers can be recycled, allowing scrap to be reused in molding to raise yield and lower net costs. For example, because these materials can be direct-metalized without lacquering, scrap can be reused in the molding process. These properties can significantly reduce system costs, enabling a competitive advantage for customers.

For additional information on Sabic Innovative Plastics' portfolio of Lexan copolymers offering high heat resistance, high flow and ductility, flame/smoke/toxicity performance, ultimate scratch resistance, extreme impact resistance and UV weathering performance, go to www.sabic-ip.com

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