3 4
under the multilayer antireflective coating. In a variation, the FIGS. 1 and 2 are schematic, not-to-scale cross-sectional
electrical conductivity can be imparted to this antireflection views of plastic substrates carrying antireflective coatings of
layer in the form of a separate conductive layer, typically this invention.
made of a high refractive index material and of similar nG 3 fa a schematic ^agram of a magnetron sputtering
thickness to the first and second layers just recited. 3 unit useM for forming me anm-eflective coatings of this
Thus, in one preferred embodiment this invention pro- invention
vides a polymer having antireflection properties. This mate- ^ ^ fl ^ Qf ^ ...
rial has a solid polymer substrate presenting one or more when a ! rfc subs1rate (poly^myleneterphthalate)) is
surfaces sought to be antireflected. A multilayer antireflec- ... £>m antireflective ^ J m m£ention as set
tion coating is adhered to these surfaces and includes one io ■ c„ i i
_ B., ^ c, , , .. , forth in Example 1.
and preferably two or more pairs of layers, each of which ^
having, in order, a first layer, closest to the polymer n& 5 is j» diagram of the reflection achieved when
substrate, of sputter-deposited light transmissive. electri- hardcoated PET is treated as set forth m Example 2.
cally conductive inorganic material having an index of FIG. 6 is a diagram of the reflection achieved when PET
refraction of from 1.7 to 2.6 and a thickness of from about is is treated as set forth in Example 3.
50 to 3000 angstroms, and a second layer of sputter- FIG. 7 is a diagram of the reflection achieved when PET
deposited light transmissive inorganic material having an is treated as set forth in Example 4.
index of refraction of from 1.29 to 1.7 and a thickness of pi(j. 8 is a diagram of the reflection achieved when
from 50 to 3000 angstroms, followed by a lubricating layer hardcoated PET is treated as set forth in Example 5.
having a surface energy not greater man 40 dynes/cm on top 20 nG 9 is a ^ of ^ reflection achieved when
of fte multilayer antireflection coating. In variations on this hardcoated pEr is ^d as xt forth ^ & le 6
embodiment, the antireflected polymer additionally com
prising and/or a hardcoat layer on the polymer substrate and mG-10 is a dia8ram of me reflection achieved when glass
between the substrate and the multilayer antireflection coat- is freated as set forth m Example 7.
ing a hardcoat and/or a primer layer made up of an oxidiz- 25 DESCRIPTION OF PREFERRED
able metal under the multilayer antireflective coating. EMBODIMENTS
In a more preferred embodiment this antireflected polymer product has a polyester substrate and one or more, but The present invention provides an antireflection coating usually one, antireflective coatings with two pairs of layers, for substrates such as polymers. Turning to FIG. 1, an the first pair having, in order, a first layer, closest to the 30 antireflection-coated product 1 of this invention is illuspolyester substrate, of sputter-deposited, electrically trated. Product 1 includes a substrate 10. The substrates conductive, light transmissive inorganic material having an which benefit from the antireflective coating and process of index of refraction of from 1.88 to 2.15 and a thickness of this invention can include light transmissive inorganic matefrom 150 to 500 angstroms, and a second layer of sputter- rials such as glass, quartz, magnesium fluoride, calcium deposited, light-transmissive inorganic oxide having an 35 fluoride, zinc selenide, various crystals and the like. More index of refraction of from 1.4 to 1.6 and a thickness of from typically, however, the substrates are polymers, in particular 150 to 500 angstroms, and the second pair having a first carbon-based materials. They include classic organic polylayer of sputter-deposited conductive transparent inorganic mers sucn as polyesters and polycarbonates and fluorocarmaterial having an index of refraction of from 1.88 to 2.15 boD and fluorohydrocarbon materials as well. These mateand a thickness of from 500 to 1500 angstroms, and a second <to rials have indices of refraction of from about 1.2 to about 1.7 layer of sputter-deposited transparent inorganic oxide hav- and especially about 1.4 to about 1.7. Representative organic inganindexof refraction of from 1.4 to 1.6 and a thickness polymers include polyesters such as poly of from 150 to 1500 angstroms, followed by the lubrication (ethyleneterephthalate) ("PET"), polycarbonates, polyacrylayer and. again, with or without the hardcoat and primer lates and methacrylates such as poly(methylmethacrylate) layers. 45 (PMMA), poly(methacrylate). poly(ethylacrylate) and
In another aspect this invention provides a process for copolymers such as poly(methylmethacrylate-coirnparting antireflection properties to a light transmissive ethylacrylate). Fluorocarbon polymers such as TEFLON, substrate such as a polymer substrate. This process involves which is sold under a federally registered trademark of E. I the serial steps of (a) sputter-depositing a first layer, closest du Pont de Nemours and Company can be used as well, to the substrate, of transparent inorganic material having an *> Other polymers which have indices of refraction below that indexofrefractionoffroml.7to2.6andathicknessoffrom of antireflection coatings may be used, if desired, about 50 to 3000 angstroms, (b) sputter-depositing onto said Although not a limitation to the application of this invention, first layer a second layer of transparent inorganic material clear- light-transmissive, plastic materials (i.e.. plastic having an index of refraction of from 1.29 to 1.7 and a shects- 01 bodies having integrated transmissions over thickness of from 50 to 3000 angstroms, (c) repeating steps 55 the visual wavelengths of at least about 20%. i.e.. from about (a) and (b) and thereafter applying a layer of solvent-soluble 25% t0 about *>% without absorption or reflection lubricant such as a soluble fluoropolymer to provide a Peaks in ^ raaSe) yield particularly attractive final prodsurface energy not greater than 40 dynes/cm on top of the ucts- The materials (without the antireflection coatings of multilayer conductive inorganic antireflection coating stack. invention) commonly have from 5 to about 20% reflec
In additionally preferred aspects, this process can include « tion over the visual wavelengths. For example, PET reflect
a preglow step preceding one or more of these sputter 12-15% of me visible li^ght (two sided reflection). Although
depositing steps and can include the application of a lubri- nc* a requirement of the invention, this substrate may be
cation layer over the antireflection coating. colored OT ti°te4 ]* some aPPhcauons such coloring or
tinting can offer advantages such as by improving display
BRIEF DESCRIPTION OF THE DRAWINGS 65 contrast or eliminating backlighting problems or the like.
This invention will be described with reference to the The various inorganic and polymer substrates themselves
attached drawings. In these drawings, are commercially available or can be prepared by various
