By Joel Johnson With lab owners and managers looking for ways to increase profits and reduce processing costs, many labs are looking to spin coating costs and performance. When researching a scratch resistant coating the following parameters are necessary to make the right decision for your business, fabricating process, and your customers’ needs. Stability of a coating is crucial and the length of time a coating remains viscous in a coating system can be critical to success. Most coatings when new, will have a coating thickness of 4.5-6 microns, (50 microns is the average thickness of a strand of hair). With some coating brands viscosity will double within 24 to 48 hours of being added to the coating machinery. As viscosity rises the coating become...
Part 1: Environment Control Effective process control starts with monitoring and controlling the fabricating environment. All systems involved with ophthalmic laboratory processing are influenced by environmental conditions and variations. Environmental parameters must be optimized to achieve maximum yield, optimized product performance and minimal breakage. This includes the Backside Coating unit and its ultimate performance. We will review the following environmental conditions: Cleanliness Climate control System Air System Water LAB CLEANLINESS – The very name “laboratory” suggests an extremely clean environment. Historically the typical Ophthalmic Laboratory has been anything but extremely clean. In fact some Labs...
For many years ophthalmic coatings with the best abrasion resistance have been thermal cured coatings containing solvent. These coatings were generally based on polysiloxanes with nano particles of silicon dioxide dispersed in the mix. The polysiloxanes were produced from epoxy functional silanes, with varying percentages of other silanes to modify the properties to give the best balance of abrasion resistance, adhesion, and AR compatibility. Advantage’s of a coating containing polysiloxane is superior abrasion resistance and enhance adhesion between the hard coat and the first layer of the AR stack. This is due in part to a chemical bond between the hard coat and the first layer of the AR stack. It is well documented that polysiloxanes typically provide superior adhesion to m...
AST-1TM Coating Solution Testimonials “The AST-1 coating has improved the adhesion of our ARC in the spin coating process. Due to AST-1’s thickness it now allows lens flexibility without cracking or stressing. And finally, the AST-1 is crisp, crystal clear with more transparency, and better adhesion giving the patient lens a longer lifetime performance of the ARC.” Italo Billau, HB Optical Laboratories “Vision-Ease Lens tested almost every, if not every, UV curable backside coating available on the ophthalmic lens market. No coating has been able to pass our adhesion testing that we require for our Thindex 1.70 lens that will always be AR coated until Ultra-Optics released a coating called AST-1 in 20...
SCRATCH-RESISTANT COATINGS AND AR Posted from a submission in Optical Lab Products (OLP), a publication of First Vision Media Group An AR coating is only as good as the hardcoat that it adheres to, but a brief history of polysiloxane can help explain the chemistry. Jim Grootegoed Look up scratch-resistant coating on Wikipedia and you'll find: "An anti-scratch or scratch-resistant coating... film or coating that can be applied to optical surfaces, such as the faces of a lens... (acting)... as a protective layer thus making the lenses more durable." The hardcoat performs an equally important function providing a sort of "primer" layer for anti-reflective (AR) e...