Nano-Composite Polymer Optical Coatings Vampire Optical Coatings, Inc. Tom Faris vampirecoatings@earthlink.net
Introdction What is a nano-composite polymer coating? Or Definition: A coating that has some volme fraction of inorganic nano-particles dispersed within the coating; sch that, the physical, optical and/or electrical properties are modified. Also known as a ceramer (i.e. a ceramic polymer) Types: Si0x modified coatings abrasion resistance improvement (2 to 3x) Antimony tin oxide/indim tin oxide modified coatings selective transmission/heat rejection coatings Electro-static dissipative coatings Zirconim oxide modified High refractive index coatings Index matching coatings
Introdction Reflectance Light transmission = LT Reflectance = R Comprised of speclar and diffse reflection R(%) = %R (speclar) + %R (diffse) Absorbance = Abs %LT = 100 - R(%) Abs(%) Fresnel Reflectance i.e. mirror like R(%) per side = ([(h d 1)/(h d +1)] 2 )*100 Diffse Reflectance Scattered Light (ASTM D1003)
Introdction Why does reflectance matter? Reflectance redces the contrast of a display Decease in readability of display Lower black level & higher backgrond noise Exacerbated as nmber of interfaces increases Interfacial Reflectance Happens every time refractive index changes Proportional to change in refractive index
Figre 1: Resistive Toch Panel Reflections R1 = 5.0% R2, R3 = 10 to 12% each R4 = 5.0 % R total = ~ 30 % of ambient light R1 R2 R3 R4R5 PET film ITO display
Introdction How is a display s s contrast improved? Anti-Glare film Comprised of an irreglar srface that scatters reflections Redces speclar reflectance Increases diffse reflectance Anti-Reflection Film Mlti-layer layer vacm deposited dielectric materials Destrctive interference of light Excellent performance, very expensive de to slow rates and ltra vacm reqirements Wet applied low reflectance coatings Good performance, lower cost (floro coatings) Index matching coatings (toch panels) Vacm deposited dielectric mlti-layers layers Redces R(%) & increases LT (%) Excellent performance, expensive de to slow rates and ltra vacm reqirements
Introdction Prodction techniqes Vacm deposited AR (Spttering, PVD, PECVD(?)) Reqires an ltra vacm Slow rate de to thick layers of inorganic oxides Reqires additional anti-smdge layer Sol-Gel dip deposited AR Large tanks with low sage rate Vibration sensitive Additional anti-smdge layer necessary Low refractive index floro monomer/polymer Atmospheric prodction sing traditional roll-to to-roll wet coating techniqes Anti-smdge layer inherent Adeqate performance with lower cost (~1/3 vacm)
Introdction What does this mean? Vacm deposition techniqes Provide excellent performance bt Have high costs de to low rates Is there another way to make and apply dielectric coatings? Coatings/coating techniqe shold: Allow versatile designs/mltiple applications Thin layers with high precision Have high prodction rates Compliment crrent prodction processes
Table 1: Nano-Particle Coating Dispersions & Properties Coating Wt% nano- particle* Metal Oxide Type Size (nm) Appearance Refractive index (550nm) VHx 80.0 Zr0 2 mixed 20 Dry coating is shiny & clear 1.7950 VHx-C 85.0 ATO 15 Clear gray/green 1.7455 VHx-S 55.0 Sb 2 0 5 30 Dry coating is shiny & clear 1.6835 IM002.15 25.0 Si0 2 20 Clear 1.485 IMESD07 70.0 ATO 15 Gray/Green 1.685 * Wt % nano-particles is given as the weight percentage in the final dry coating
Table 2: Film Strctre(s) A C 3.0 micron HC PET Film B ID A B C %LT %Haze %R(Y) %R avg(450 to 650nm) PET N/A N/A N/A 89 <1.00 >5.00 >5.00 1251S N/A IM002 (95nm) VHx (80nm) >93 <1.00 1.40 <1.75 751H MHC (95nm) Ti02 (18nm) VHx (102nm) >93 <1.00 0.80 <1.00 IMAR ITO (22nm) IM002 (45nm) VHx (75nm) >91 <1.00 N/A N/A LR N/A Floro (100nm) VHx (80nm) >93 1.00 1.50
Reslts & Discssion High Refractive Index Coatings (VHx) HybridAR coatings (VAR 751H): Design: Air/UV acrylate/ti0 2 /VHx/HC PET VHx acts as bffer layer in design Provides broad band AR with only 1 thin spttered dielectric layer (18nm Ti0 2 ) Eliminates several thick spttered layers Anti-fingerprint layer step eliminated High abrasion and chemical resistance Design can incorporate ITO for condctive AR film or other dielectric materials
% reflection 10 9 8 7 6 5 4 3 2 1 Reslts & Discssion Figre 2: HybridAR Performance Reflectance vs. wavelength HybridAR Mlti-layer AR 0 400 450 500 550 wavelength(nm) 600 650 700
Reslts & Discssion High Refractive Index Coatings (VHx) Index Matched ITO Coatings Design: Air/ITO/IM002/VHx/PET Light transmission is increased as compared to standard ITO coated film (>91.0% vs. mid 80 s) Comparable performance with vacm deposited index matching layers Several thick vacm deposited layers are eliminated Redced cost of prodction Versatile index matching
95 Reslts & Discssion Figre 3: ITO Index Matching Performance Light Transmission v. wavelength ITO PET vs. IMAR 92.5 % light transmission 90 87.5 85 82.5 80 77.5 75 400 450 500 550 600 650 700 wavelength(nm)
Figre 4: AR/Index matched Resistive Toch Panel Reflections R1 = 1.50 % R2, R3 = 3.0 % each R4 = 1.50 % R total = ~ 10 % of ambient light R1 R2 R3 R4R5 1251S PET film IMAR display
Reslts & Discssion High Refractive Index Coatings (VHx) Low Reflectance Coatings (VAR 1251S) Design: Air/IM002/VHx/HC PET High transmission Low reflectance (high reflected color) Excellent drability Simple constrction Sbstrates polycarbonate 188 micron to 640 micron AR-1 1 and AR-2 2 (lens materials) PET, PMMA and acetate films (>80 micron)
Reslts & Discssion Figre 5: Low Reflectance Coating Performance 6.00 Reflectance vs. wavelength 5.00 % Reflection 4.00 3.00 2.00 1251S 1.00 0.00 400 450 500 550 600 650 700 wavelength (nm)
Reslts & Discssion Low Refractive Index Coatings (IM002) Si0x (20 to 40 wt%) in dry coating UV crable Abrasion resistant coatings High clarity excellent abrasion resistance 2x to 3x UV acrylate coatings Low index coating for IMAR and 1251S Very thin layers possible High transmission, good niformity Tnable srface energy mlti-layer layer stacks possible AFP srface possible
Reslts & Discssion Other Coatings/Combinations Antimony Tin Oxide and/or Indim Tin Oxide Nano-Composites Infrared blocking filters/coatings Absorption based Mlti-layer layer reflective heat mirrors (65 % reflectance at 950nm) Electro-Static Dissipative Coatings (ESD) >10(7) Ohms/sqare High Abrasion resistance Permanent ESD
Conclsions Nano-Composite Polymer Coatings Are sefl as sbstittes for or as. Compliments to vacm deposited inorganic metal oxides Facilitates sbstantial prodctivity improvements Uses conventional roll-to to-roll wet coating eqipment Coated materials prodced exhibit excellent optical properties, mechanical properties and temperatre/hmidity resistance.
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