NXT® Plano Sunlenses | beyond limits | | | | | | NXT® is the most revolutionary innovation in the field of unbreakable optical filters: | The NXT® Project was born in the USA during the 1990’s, finding its first applications for military purposes. After several years of research and development, Intercast further optimized the NXT® technology for optical uses, launching the first material, which has become the new standard for the next generation of premium sun, sport, and fashion eyewear.
NXT® is an optical polymer unlike any other, having innovative technical and performance characteristics that overcome the limitations of other lens materials currently available. NXT® is unbreakable, lightweight, durable, and easily drilled and processed without cracking. NXT® opens new horizons in style and design freedom. Thanks to its versatility, designers can finally develop innovative shapes for fashion and sport sunglasses, discovering new technical applications never seen before. NXT® is compatible with all plastic and metal frame materials, enabling manufacturers to improve manufacturing processes, and reduce costs and rejects.
The NXT® lifetime guarantee of unbreakability, not only provides safety and protection to the end user, but also sets a new standard of quality and reliability.
This certificate of guarantee is offered in the NXT® brochures and hang tags, which accompany sunglasses fitted with lenses made from NXT®.
| | MAIN ADVANTAGES
Lightweight
NXT® is about 16% lighter than CR-39® and 10% lighter than polycarbonate. Impact Resistance Higher than Polycarbonate NXT®’s impact resistance is higher than polycarbonate and passes all impact resistance standards.
No Stress Cracking or Crazing
Unlike polycarbonate and other materials, NXT® is not sensitive to stress cracking, so it does not craze or break when subjected to mechanical strains.
Excellent Workability
Unlike CR-39® , polycarbonate and polyamide, NXT® can be easily drilled without brittleness or stress cracking problems.
Processed by Casting
Lenses in NXT® are made by casting, which ensures low internal stress, high optical homogeneity, thermal and mechanical stability. Such properties make NXT® the material ideally suited for high quality unbreakable polarized lenses.
Excellent Optical Properties
NXT® has lower refractive index, internal stress, and chromatic dispersion (Abbe number) than polycarbonate, resulting in lower surface reflection and “rainbow effect”, higher definition and sharper images.
High Chemical Resistance
Unlike polycarbonate and polyamide, NXT® is not attacked by common chemicals or solvents (i.e. acetone and methyl alcohol).
High thermal stability
NXT® polymer has high thermal stability and is not subject to optical or mechanical distortions, even when exposed to temperatures in excess of 80°C.
NXT® VARIA® Lenses (photochromic lenses)
Unlike polycarbonate and CR-39®, photochromic molecules can be formulated in the mass of NXT®, providing greater stability and efficiency.
Thanks to the unique properties of NXT® high quality, impact-resistant lenses offering excellent photochromic performance are finally available, both in solid and gradient colors, ideally suited for active sports. It also opens the door to photochromic rimless eyewear having lenses guaranteed not to crack or break.
NXT® POLAR Lenses
Polarized lenses are now available in NXT®, bringing the ultimate strength, optical performance, and reliability to the growing premium polarized market. Unlike injected polycarbonate polarized lenses, cast NXT® is free of stress - the cause of birefringence that reduces polarization and causes distraction stress patterns.
NXT® POLAR VARIA® Lenses
The newest lenses in NXT®, Polar Varia®, combine the benefits of both polarization and photochromic technologies, offering the ultimate combination of properties, ideally suited for high performance sport sunglasses. | | | MATERIALS COMPARISON TABLE | Properties | CR-39® | polycarbonate | | High Impact
Resistance Test (1) | fail | pass | Pass | | Specific Gravity | 1.32 | 1.22 | 1.11 | | Refractive Index (2) | 1.50 | 1.59 | 1.53 | Abbe Number
(chromatic dispersion) | 58 | 29 | 45 | Internal Stress/
Birefringence (3) | low | high | low | | Chemical Resistance | good | poor | goof | | Stress Cracking | brittle | sensitive | not sensitive | (1) ANSI Z-87.1 Impact Resistance Standard and High Speed Impact Test, EN 166 standard.
(2) For sun lenses lower value means better optical quality.
(3) NXT®, like CR-39 is produced by casting, while polycarbonate is injected moulded with high stress. | | | | A special anti-static, anti-scratch Quarz® coating is applied on lenses in NXT®, making them highly compatible with available treatments including antifog, hydrophobic, mirror, and special multilayer anti-reflection coatings. | STRESS CRACKING | | | Stress cracking is caused over time by an overload of permanent internal tensions that exceed the elasticity limit. Stress cracking results in crazing of the lenses, haze and loss of mechanical strength. NXT® is not sensitive to stress cracking. | | | TO AVOID STRESS CRACKING YOU NEED TO:
| | with polycarbonate: | with NXT® | | Symmetric bevel | Not needed | The frame must have the same curvature than the lens.
The difference of curvature in the two perpendicular directions shall not be higher than 0.25 diopters for metal frames and 0.50 diopters for plastic frames. | Not needed | The lens shall not be fitted too tight.
Control contact points between the frame and the lens under a polarized light, to check that the dimension of the lens in not too big compared to the frame.
| Not needed | Adopt a lens shape that holds the lens between top and bottom. | Not needed | Do not overheat the material locally.
Use tungsten carbide or polycrystalline drills. Adopt a 1500 to 2000 RPM speed. | Not needed | Avoid localized stress due to contact with metal
The drilling diameter shall be bigger than the screw. The tightening of the screw shall not be done directly on the lens. Use Nylon or silicon discs and tubes to interpose a soft material between the lens and the screw. A soft tightening can also be adopted and use glue or screw locking glue without solvent. | Not needed | The information and statements presented herein are based on the results of tests and evaluations known to INTERCAST EUROPE. They are not to be taken as representations or warranties of performance or results.
Should a customer require any warranty for product performance a written request must be addressed to us. Subject to change without notice. |
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