U.S. patent application number 15/084025 was filed with the patent office on 2016-07-21 for methods of making lamination transfer films for forming antireflective structures.
The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Olester Benson, Jr., Terry O. Collier, Michael Benton Free, Mieczyslaw H. Mazurek, Justin P. Meyer, Evan L. Schwartz, Martin B. Wolk.
Application Number | 20160208385 15/084025 |
Document ID | / |
Family ID | 53544016 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160208385 |
Kind Code |
A1 |
Free; Michael Benton ; et
al. |
July 21, 2016 |
METHODS OF MAKING LAMINATION TRANSFER FILMS FOR FORMING
ANTIREFLECTIVE STRUCTURES
Abstract
Transfer films, articles made therewith, and methods of making
and using transfer films that include antireflective structures are
disclosed.
Inventors: |
Free; Michael Benton; (St.
Paul, MN) ; Meyer; Justin P.; (Oakdale, MN) ;
Benson, Jr.; Olester; (Woodbury, MN) ; Collier; Terry
O.; (Woodbury, MN) ; Mazurek; Mieczyslaw H.;
(Roseville, MN) ; Schwartz; Evan L.; (Vadnais
Heights, MN) ; Wolk; Martin B.; (Woodbury,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
St. Paul |
MN |
US |
|
|
Family ID: |
53544016 |
Appl. No.: |
15/084025 |
Filed: |
March 29, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14159253 |
Jan 20, 2014 |
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15084025 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 2037/243 20130101;
B32B 2551/00 20130101; C03C 2217/732 20130101; B32B 2307/40
20130101; C03C 17/30 20130101; C23C 16/50 20130101; C03C 17/28
20130101; B32B 37/025 20130101; Y10T 156/10 20150115; G02B 1/02
20130101; Y10T 428/24355 20150115; C03C 2217/77 20130101; C23C
16/0236 20130101; G02B 1/118 20130101; B32B 38/10 20130101 |
International
Class: |
C23C 16/50 20060101
C23C016/50; C23C 16/02 20060101 C23C016/02 |
Claims
1. A method of forming a transfer film, comprising: reactive ion
etching a layer of sacrificial material to form antireflective
nanostructure template features; coating a thermally stable
backfill material on the antireflective nanostructure template
features to form a thermally stable backfill layer having a first
surface conforming to the antireflective nanostructure template
features and an opposing planar second surface, forming a
lamination transfer film; and disposing the layer of sacrificial
material on a release surface of a carrier film before the reactive
ion etching step.
2. The method according to claim 1, wherein the reactive ion
etching step comprises applying a discontinuous random masking
layer on a first surface of the layer of sacrificial material and
reactive ion etching portion of the layer of sacrificial material
not protected by the masking layer to form the antireflective
nanostructure template features.
3. The method according to claim 1, wherein the antireflective
nanostructure template features comprise nanoscale features having
a height to width ratio of about 5:1 or greater.
4. The method according to claim 1, wherein the thermally stable
backfill layer comprises an organosilicon polymer.
5. The method according to claim 1, wherein the thermally stable
backfill layer comprises silsesquioxanes of bridge or
ladder-type.
6. The method according to claim 1, wherein the thermally stable
backfill layer comprises zirconia, titania, alumina, boron carbide,
or silicon carbide nanoparticles.
Description
BACKGROUND
[0001] Nanostructures and microstructures on glass substrates are
used for a variety of applications in display, lighting,
architecture and photovoltaic devices. In display devices the
structures can be used for light extraction or light distribution.
In lighting devices the structures can be used for light
extraction, light distribution, and decorative effects. In
photovoltaic devices the structures can be used for solar
concentration and antireflection. Patterning or otherwise forming
nanostructures and microstructures on large glass substrates can be
difficult and cost-ineffective.
SUMMARY
[0002] The present disclosure relates to lamination transfer films
for forming articles with antireflective structures and method of
forming these lamination transfer films.
[0003] In one aspect, a transfer film includes a carrier film, a
sacrificial template layer disposed on the carrier film and having
antireflective nanostructure template features, and a thermally
stable backfill layer having a first surface conforming to the
antireflective nanostructure template features and an opposing
planar second surface.
[0004] In another aspect, a method includes laminating the planar
second surface of the transfer film described herein to a receptor
substrate and baking out the sacrificial template layer to form a
thermally stable backfill layer having antireflective nanostructure
features.
[0005] In another aspect, a method of forming a transfer film
includes reactive ion etching a layer of sacrificial material to
form antireflective nanostructure template features and coating a
thermally stable backfill material on the antireflective
nanostructure template features, forming a thermally stable
backfill layer having a first surface conforming to the
antireflective nanostructure template features and an opposing
planar second surface. The method forming a lamination transfer
film.
[0006] In another aspect, a method of forming a transfer film
includes depositing sacrificial material template layer having
antireflective nanowhisker template features on a release surface
of a carrier film and coating a thermally stable backfill material
on the antireflective nanowhisker template features to form a
thermally stable backfill layer having a first surface conforming
to the antireflective nanowhisker template features and an opposing
planar second surface. The method forming a lamination transfer
film.
[0007] In a further aspect, an optical article includes a layer of
sapphire material and a thermally stable backfill layer having
antireflective nanostructure features fixed to the layer of
sapphire material.
[0008] These and various other features and advantages will be
apparent from a reading of the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The disclosure may be more completely understood in
consideration of the following detailed description of various
embodiments of the disclosure in connection with the accompanying
drawings, in which:
[0010] FIG. 1 is a schematic process flow diagram of an
illustrative sputter/etch method of forming the transfer film and
resulting final AR structure;
[0011] FIG. 2 is a schematic process flow diagram of an
illustrative nanowhisker method of forming the transfer film and
resulting final AR structure;
[0012] FIG. 3A is a schematic process flow diagram of an
illustrative sputter/etch method of forming a hierarchical
structured transfer film and resulting final AR structure;
[0013] FIG. 3B is an enlargement of the reentrant template
structure with hierarchical structure of FIG. 3A;
[0014] FIG. 3C is an enlargement of the reentrant structure with
hierarchical structure of FIG. 3A;
[0015] FIG. 4 is a top view SEM micrograph of a perylene whisker
sacrificial film of Example 1;
[0016] FIG. 5 is a top view SEM micrograph of the thermally stable
perylene whisker formed AR structure on glass of Example 1;
[0017] FIG. 6 is a side view SEM micrograph of the thermally stable
perylene whisker formed AR structure on glass of Example 1;
[0018] FIG. 7 is a top view SEM micrograph of a perylene whisker
sacrificial film of Example 2;
[0019] FIG. 8 is a side view SEM micrograph of the resulting
inorganic hierarchical nanostructure on glass of Example 2;
[0020] FIG. 9A is a top view SEM micrograph of AR sacrificial
template sample 2 of Example 3;
[0021] FIG. 9B is a top view SEM micrograph of AR sacrificial
template sample 7 of Example 3;
[0022] FIG. 9C is a top view SEM micrograph of AR sacrificial
template sample 15 of Example 3;
[0023] FIG. 10A-1 illustrates a top view on the left and FIG. 10A-2
illustrates a side view on the right of baked out AR nanostructures
for sample 2;
[0024] FIG. 10B-1 illustrates a top view on the left and FIG. 10B-2
illustrates a side view on the right of baked out AR nanostructures
for sample 7;
[0025] FIG. 10C-1 illustrates a top view on the left and FIG. 10C-2
illustrates a side view on the right of baked out AR nanostructures
for sample 15;
[0026] FIG. 11A is a top view of view SEM micrograph of AR
sacrificial template sample A of Example 4;
[0027] FIG. 11B is a top view of view SEM micrograph of AR
sacrificial template sample B of Example 4;
[0028] FIG. 11C is a top view of view SEM micrograph of AR
sacrificial template sample C of Example 4;
[0029] FIG. 12A is a top view of view SEM micrograph of resulting
clean inorganic AR nanostructure of Sample A of Example 4;
[0030] FIG. 12B is a top view of view SEM micrograph of resulting
clean inorganic AR nanostructure of Sample B of Example 4;
[0031] FIG. 12C is a top view of view SEM micrograph of resulting
clean inorganic AR nanostructure of Sample C of Example 4;
[0032] FIG. 13 is a is a top view of view SEM micrograph of
resulting clean inorganic AR nanostructure on sapphire of Example
5;
[0033] FIG. 14A is a top view SEM micrograph of the resulting
inorganic hierarchical AR nanostructure of Example 6;
[0034] FIG. 14B is a side view SEM micrograph of the resulting
inorganic hierarchical AR nanostructure of Example 6;
[0035] FIG. 15A is a top view SEM micrograph of the resulting
inorganic hierarchical AR nanostructure of Example 7;
[0036] FIG. 15B is a side view SEM micrograph of the resulting
inorganic hierarchical AR nanostructure of Example 7; and
[0037] FIG. 15C is a magnified side view SEM micrograph of the
resulting inorganic hierarchical AR nanostructure of Example 7.
DETAILED DESCRIPTION
[0038] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which are
shown by way of illustration several specific embodiments. It is to
be understood that other embodiments are contemplated and may be
made without departing from the scope or spirit of the present
disclosure. The following detailed description, therefore, is not
to be taken in a limiting sense.
[0039] All scientific and technical terms used herein have meanings
commonly used in the art unless otherwise specified. The
definitions provided herein are to facilitate understanding of
certain terms used frequently herein and are not meant to limit the
scope of the present disclosure.
[0040] Unless otherwise indicated, all numbers expressing feature
sizes, amounts, and physical properties used in the specification
and claims are to be understood as being modified in all instances
by the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in the foregoing specification
and attached claims are approximations that can vary depending upon
the properties sought to be obtained by those skilled in the art
utilizing the teachings disclosed herein.
[0041] The recitation of numerical ranges by endpoints includes all
numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2,
2.75, 3, 3.80, 4, and 5) and any range within that range.
[0042] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" encompass embodiments having
plural referents, unless the content clearly dictates
otherwise.
[0043] As used in this specification and the appended claims, the
term "or" is generally employed in its sense including "and/or"
unless the content clearly dictates otherwise.
[0044] As used herein, "have", "having", "include", "including",
"comprise", "comprising" or the like are used in their open ended
sense, and generally mean "including, but not limited to". It will
be understood that "consisting essentially of", "consisting of",
and the like are subsumed in "comprising," and the like.
[0045] In this disclosure:
[0046] "backfill materials" or "backfill layers" refers to layers
of materials that fill in irregular or structured surfaces to
produce a new surface that may be used as a base to build
additional layered elements and is thermally stable;
[0047] "bake-out" refers to the process of substantially removing
sacrificial material present in a layer by pyrolysis, combustion,
sublimation, or vaporization while leaving thermally stable
materials substantially intact (backfill, substrate);
[0048] "bake-out temperature" refers to the maximum temperature
reached during the process of substantially removing sacrificial
materials in a layer by pyrolysis or combustion while leaving
thermally stable materials substantially intact (backfill,
substrate);
[0049] "combust" or "combustion" refers to a process of heating a
layer that comprises organic materials in an oxidizing atmosphere
so that organic materials undergo a chemical reaction with the
oxidant;
[0050] "nanostructures" refers to features that range from about 1
nm to about 2000 nm in their longest dimension and includes
microstructures;
[0051] "pyrolyze" or "pyrolysis" refers to a process of heating a
sacrificial layer in an inert atmosphere so that organic materials
in the article decompose;
[0052] "structured surface" refers to a surface that includes
periodic, quasi-periodic or random engineered microstructures,
nanostructures, and/or hierarchical structures that can be in a
regular pattern or random across the surface;
[0053] "thermally stable" refers to materials that remain
substantially intact during the removal of sacrificial
materials;
[0054] "polysiloxanes" refers to highly branched oligomeric or
polymeric organosilicon compounds and may include carbon-carbon
and/or carbon-hydrogen bonds while still being considered as
inorganic compounds;
[0055] "anisotropic" refers to having a height to width (that is,
average width) ratio of about 1.5:1 or greater (preferably, 2:1 or
greater, or %:1 or greater).
[0056] The present disclosure relates to lamination transfer films
for forming articles with antireflective structures and method of
forming these lamination transfer films. These transfer films can
be laminated to a desired substrate (like glass) and "baked out" to
reveal unique antireflective structures. The antireflective
nanostructured articles made by the methods described herein can
exhibit one or more desirable properties such as antireflective
properties, light absorbing properties, antifogging properties,
improved adhesion, durability, hydrophobic and hydrophilic
properties. For example, in some embodiments, the surface
reflectivity of the nanostructured anisotropic surface is about
75%, preferable about 50%, or more preferably about 25% of the
surface reflectivity of an untreated surface. The antireflective
structures can be from template antireflective structures created
by either reactive ion etching or nanowhisker deposition (using
perylene red), for example. A thermally stable backfill material
conforms to the template antireflective structures and remains on a
receptor substrate following bake out of the sacrificial template
antireflective structures. These thermally stable antireflective
structures provided by the transfer films can create filmless
broadband antireflection structures on receptor substrates such as
glass and sapphire surfaces. Hierarchical structured surfaces can
be formed that utilize the antireflective structures. While the
present disclosure is not so limited, an appreciation of various
aspects of the disclosure will be gained through a discussion of
the examples provided below.
[0057] As used herein with respect to comparison of surface
properties, the term "untreated surface" means the surface of an
article comprising the same material (as the nanostructured surface
of the disclosure to which it is being compared) but without a
nanostructured anisotropic surface. In some embodiments, the
percent reflection of the nanostructured anisotropic surface can be
less than about 2% (typically, less than about 1%) as measured
using the "Measurement of Average % Reflection" method described
below. Likewise, in some embodiments, the percent transmission of
the nanostructured anisotropic surface can be about 2% or more than
the percent transmission of an untreated surface as measured using
the "Measurement of Average % Transmission" method described
below.
[0058] FIG. 1 is a schematic process flow diagram 10 of an
illustrative sputter/etch method of forming the transfer film 30
and resulting final antireflective (AR) structure 50. This method
includes forming a transfer film 30 by reactive ion etching a layer
of sacrificial material 12 to form antireflective nanostructure
template features 14 and coating a thermally stable backfill
material 22 on the antireflective nanostructure template features
14, forming a thermally stable backfill layer 22 having a first
surface 15 conforming to the antireflective nanostructure template
features 14 and an opposing planar second surface 16, and forming a
lamination transfer film 30.
[0059] The thermally stable backfill solution can be coated onto
the antireflective nanostructure template features 14 and any
solvent or portion of solvent removed and optionally cured to form
the thermally stable backfill layer 22. Preferably, after removal
of solvent and curing, the thermally stable material substantially
planarizes the sacrificial template layer. Substantial
planarization means that the amount of planarization (P %), as
defined by Equation 1, is greater than 50%, or greater than 75%, or
preferably greater than 90%.
P %=(1-(t.sub.1/h.sub.1))*100 (1)
where t.sub.1 is the relief height of a surface layer and h.sub.1
is the feature height of features covered by the surface layer, as
further disclosed in P. Chiniwalla, IEEE Trans. Adv. Packaging
24(1), 2001, 41.
[0060] The sacrificial template layer 12 can be on a carrier layer
11 (i.e., liner) having a releasable surface. In other embodiments,
a carrier layer 11 is not present. The liner or carrier layer 11
can be implemented with a thermally stable flexible film providing
mechanical support for the other layers. The liner 11 has a
releasable surface, meaning the liner 11 allows for release of a
material applied to the releasable surface. The carrier layer 11
should be thermally stable above 70.degree. C., or alternatively
above 120.degree. C., without adversely affecting either the
sacrificial layer or the backfill layer. One example of a carrier
film is polyethylene terephthalate (PET).
[0061] The support substrate or carrier layer (described herein)
can be embodied as a flexible film providing mechanical support for
the other layers. One example of a carrier film is polyethylene
terephthalate (PET). Various polymeric film substrates comprised of
various thermosetting or thermoplastic polymers are suitable for
use as the support substrate. The carrier may be a single layer or
multi-layer film. Illustrative examples of polymers that may be
employed as the carrier layer film include (1) fluorinated polymers
such as poly(chlorotrifluoroethylene),
poly(tetrafluoroethylene-cohexafluoropropylene),
poly(tetrafluoroethylene-co-perfluoro(alkyl)vinylether),
poly(vinylidene fluoride-cohexafluoropropylene); (2) ionomeric
ethylene copolymers poly(ethylene-co-methacrylic acid) with sodium
or zinc ions such as SURLYN-8920 Brand and SURLYN-9910 Brand
available from E. I. duPont Nemours, Wilmington, Del.; (3) low
density polyethylenes such as low density polyethylene; linear low
density polyethylene; and very low density polyethylene;
plasticized vinyl halide polymers such as plasticized
poly(vinychloride); (4) polyethylene copolymers including acid
functional polymers such as poly(ethylene-co-acrylic acid) "EAA",
poly(ethylene-co-methacrylic acid) "EMA", poly(ethylene-co-maleic
acid), and poly(ethylene-co-fumaric acid); acrylic functional
polymers such as poly(ethylene-co-alkylacrylates) where the alkyl
group is methyl, ethyl, propyl, butyl, et cetera, or CH3 (CH2)n-
where n is 0 to 12, and poly(ethylene-co-vinylacetate) "EVA"; and
(5) (e.g.) aliphatic polyurethanes. The carrier layer can be an
olefinic polymeric material, typically comprising at least 50 wt %
of an alkylene having 2 to 8 carbon atoms with ethylene and
propylene being most commonly employed. Other carrier layers
include for example poly(ethylene naphthalate), polycarbonate,
poly(meth)acrylate (e.g., polymethyl methacrylate or "PMMA"),
polyolefins (e.g., polypropylene or "PP"), polyesters (e.g.,
polyethylene terephthalate or "PET"), polyamides, polyimides,
phenolic resins, cellulose diacetate, cellulose triacetate (TAC),
polystyrene, styrene-acrylonitrile copolymers, cyclic olefin
copolymers, epoxies, and the like. In some embodiments, the carrier
layer can include paper, release-coated paper, non-wovens, wovens
(fabric), metal films, and metal foils. In some embodiments, the
carrier layer can include sacrificial materials that can remain on
the transfer film during the bake out process. For example, the
carrier film can include a PET layer on a PMMA release layer where
the release layer remains on the transfer film following release
from the PET layer. Sacrificial materials (such as the PMMA release
layer), can be pyrolyzed by subjecting them to thermal conditions
that can vaporize substantially all of the organic material present
in the sacrificial layers. These sacrificial layers can also be
subjected to combustion to burn out all of the organic material
present in the sacrificial layer. Typically, a clear, high-purity
polymer, such as poly(methyl methacrylate), poly(ethyl
acrylate-co-methyl methacrylate), can be used as the sacrificial
material. Useful sacrificial materials leave very low organic
residuals (ash) after pyrolysis or combustion at the bake out
temperature.
[0062] The antireflective nanostructure template features 14 are
formed by a sputter/etch or reactive ion etching process described
in one or more of: WO2013148031 entitled "NANOSTRUCTURED MATERIAL
AND METHOD OF MAKING THE SAME"; WO201325614 entitled
"NANOSTRUCTURED ARTICLES AND METHODS TO MAKE THE SAME";
US20130344290 entitled "NANOSTRUCTURED ARTICLES"; US20140004304
entitled "MULTILAYER NANOSTRUCTURED ARTICLES"; US20130038949
entitled "METHOD OF MAKING A NANOSTRUCTURE"; US20120328829 entitled
"COMPOSITE WITH NANO-STRUCTURED LAYER"; US20110281068 entitled
"NANOSTRUCTURED ARTICLES AND METHODS OF MAKING NANOSTRUCTURED
ARTICLES"; US20120012557 entitled "METHOD FOR MAKING NANOSTRUCTURED
SURFACES"; US20090263668 entitled "DURABLE COATING OF AN OLIGOMER
AND METHODS OF APPLYING"; or US20100239783 entitled "METHODS OF
FORMING MOLDS AND METHODS OF FORMING ARTICLES USING SAID
MOLDS".
[0063] In many embodiments, the sputter/etch or reactive ion
etching process includes applying a thin, random, discontinuous
masking layer 17 to a major surface of the sacrificial template
layer using plasma chemical vapor deposition. The major surface of
the sacrificial template layer can be a planar surface or a
microstructured surface. The random, discontinuous masking layer is
the reaction product of plasma chemical vapor deposition using a
reactant gas that can include a compound selected from
organosilicon compounds, metal alkyls, metal isopropoxides, metal
acetylacetonates and metal halides. In other embodiments the mask
can be formed using surface nanoparticle mask, a bulk nanoparticle
mask, a sputtered mask, or a simultaneous sputter/etch mask.
[0064] Plasma chemical vapor deposition (or plasma-enhanced
chemical vapor deposition) is a process by which plasmas, typically
generated by radio-frequency discharge, are formed in the space
between two electrodes when that space is filled with a reacting
gas or gases. Plasma chemical vapor deposition is done under vacuum
to reduce side reactions from unwanted species being present in the
reacting chamber. The reacting gas or gases typically deposit thin
solid films on a substrate. In the provided method, a random,
discontinuous masking layer is formed on the sacrificial template
layer using plasma chemical vapor deposition. When small amounts of
the product produced by plasma chemical vapor deposition initially
deposit on the sacrificial template layer they tend to group
together in small islands that are initially in a random,
discontinuous pattern. In the provided method, reaction conditions
are adjusted (web speed, plasma discharge energy, time of substrate
exposure, etc.) so as to halt the deposition before any coalescence
occurs. The masking layer thus deposited is random and
discontinuous. In many embodiments the individual islands have
average lateral dimensions of less than about 400 nm, less than
about 200 nm, less than about 100 nm, less than about 50 nm or even
less than about 20 nm.
[0065] This method includes etching portions of the major surface
not protected by the masking layer 17 to form a nanostructure 14 on
the sacrificial template layer 12. Typically, reactive ion etching
is used for the etching. In one embodiment, the provided method can
be carried out using a continuous roll-to-roll process referred to
as "cylindrical reactive ion etching" (cylindrical RIE).
Cylindrical RIE utilizes a rotating cylindrical electrode to
provide anisotropically etched nanostructures on the surface of a
substrate or article. In general, cylindrical RIE can be described
as follows. A rotatable cylindrical electrode ("drum electrode")
powered by radio-frequency (RF) and a grounded counter-electrode
are provided inside a vacuum vessel. The counter-electrode can
comprise the vacuum vessel itself. An etchant gas is fed into the
vacuum vessel, and a plasma is ignited and sustained between the
drum electrode and the grounded counter-electrode.
[0066] A continuous substrate including the sacrificial template
layer and the optional carrier layer and having a random,
discontinuous masking layer can then be wrapped around the
circumference of the drum and the substrate can be etched in the
direction normal to the plane of the substrate. The exposure time
of the substrate can be controlled to obtain a predetermined etch
depth of the resulting nanostructure. The process can be carried
out at an operating pressure of approximately 10 mTorr. Cylindrical
RIE is disclosed, for example, in PCT Pat. App. No. US/2009/069662
(David et al.).
[0067] The antireflective nanostructure template features 14 made
by the sputter/etch or reactive ion etching process and the
corresponding antireflective nanostructure features 52 of the
thermally stable backfill layer 50 can have a nanostructured
anisotropic surface. The antireflective nanostructure template
features 14 can comprise nanoscale features having a height to
width ratio of about 2:1 or greater; preferably about 5:1 or
greater. In some embodiments, the height to width ratio can even be
50:1 or greater, 100:1 or greater, or 200:1 or greater. The
antireflective nanostructure template features 14 can comprise
nanofeatures such as, for example, nano-pillars or nano-columns, or
continuous nano-walls comprising nano-pillars or nano-columns.
Typically, the nanofeatures have steep side walls that are
substantially perpendicular to the substrate. In some embodiments,
the majority of the nanofeatures can be capped with mask
material.
[0068] The antireflective nanostructure template features 14 are
the inverse of the antireflective nanostructure features 52. For
example, the height to width ratio of the antireflective
nanostructure template peaks correspond to the height to width
ratio of the antireflective nanostructure valleys.
[0069] In some embodiments the sacrificial template layer 12
includes the thermally stable molecular species and/or inorganic
materials such as, for example, inorganic nanomaterials. The
inorganic nanomaterials can be present in a sacrificial layer 12
and the sacrificial material can be cleanly baked out leaving a
densified layer of nanomaterials. In some embodiments, the
densified layer of nanomaterials can completely or partially fuse
into a glass-like material. The densified layer of nanomaterials
can have substantial void volume. The densified layer of
nanomaterials can be transparent and can have a high index of
refraction compared to surrounding layers of the disclosed transfer
films. Inorganic nanoparticles can be present in one or more
embedded layers, each layer having a different index of refraction
influenced by the type and concentration of nanoparticles present
in the layer.
[0070] The lamination transfer film 30 can be laminated to a
receptor substrate 40 and exposed to a heating or baking out
process to remove the sacrificial template layer 12 and to form
antireflective nanostructure features 52 of the thermally stable
backfill layer 50. In some embodiments, an optional sacrificial
adhesive layer (not shown) is applied to the backfill layer 22 or
to receptor substrate 40, prior to lamination.
[0071] Examples of receptor substrates 40 include glass such as
display mother glass (e.g., backplane mother glass), display cover
glass, lighting mother glass, architectural glass, roll glass, and
flexible glass. An example of flexible roll glass is commercially
available under the trade designation WILLOW glass from Corning
Incorporated. Other examples of receptor substrates include metals
such as metal parts, sheets and foils. Yet other examples of
receptor substrates include sapphire, silicon, silica, and silicon
carbide.
[0072] Display backplane mother glass receptor substrates can
optionally include a buffer layer on a side of the receptor
substrate to which a lamination transfer film is applied. Examples
of buffer layers are described in U.S. Pat. No. 6,396,079, which is
incorporated herein by reference as if fully set forth. One type of
buffer layer is a thin layer of SiO.sub.2, as described in K.
Kondoh et al., J. of Non-Crystalline Solids 178 (1994) 189-98 and
T-K. Kim et al., Mat. Res. Soc. Symp. Proc. Vol. 448 (1997) 419-23,
both of which are incorporated herein by reference as if fully set
forth.
[0073] A particular advantage of the transfer films and methods
described herein is the ability to impart antireflective
nanostructure features to receptor surfaces with large surfaces,
such as display mother glass or architectural glass. Semiconductor
patterning methods exist for creating nanopatterns that can be
complex, however these methods are generally slow, complicated,
expensive, and limited to the size of a single wafer (e.g., around
300 mm diameter). Step and repeat stamping methods such as
nanoimprint lithography has been used to produce nanopatterns over
larger areas than semiconductor patterning methods, however these
methods are still generally slow, expensive, and complicated, often
requiring several conventional photolithographic process steps such
as resist coating, reactive ion etching, and resist stripping.
[0074] The transfer films and method described herein overcomes the
above mentioned size constraints and complexity by utilizing
roll-to-roll processing. The transfer films described herein have
large enough dimensions to be used to impart nanostructures over,
at least, entire large digital display substrates (e.g., a 55 inch
diagonal AMOLED HDTV, with dimensions of 52 inches wide by 31.4
inches tall), for example.
[0075] The sacrificial template layer 12 can be cleanly baked out
leaving antireflective nanostructure features 52 of the thermally
stable backfill layer 50. FIG. 10A-C illustrate SEM micrographs of
the antireflective nanostructure features 52 of the thermally
stable backfill layer 50 formed by this process and described in
Example 3 below. These figures illustrate that the sacrificial
template layer 12 is capable of being baked out while leaving
antireflective nanostructure features 52 of the thermally stable
backfill layer 50.
[0076] FIG. 2 is a schematic process flow diagram 100 of an
illustrative nanowhisker method of forming the transfer film 130
and resulting final AR structure 152. This method includes forming
a transfer film 130 by depositing sacrificial material template
layer having antireflective nanowhisker template features 114 on a
release surface 13 of a carrier film 11 (described above) and
coating a thermally stable backfill material 22 on the
antireflective nanowhisker template features 114 to form a
thermally stable backfill layer 22 having a first surface 15
conforming to the antireflective nanowhisker template features 114
and an opposing planar second surface 16.
[0077] The thermally stable backfill solution can be coated onto
the antireflective nanostructure sacrificial template features 114
and any solvent or portion of solvent removed and optionally cured
to form the thermally stable backfill layer 22. Preferably, after
removal of solvent and curing, the thermally stable material
substantially planarizes the sacrificial template layer as
described above.
[0078] The antireflective nanowhisker sacrificial template features
114 can be formed by any useful process and use materials as
described in U.S. Pat. No. 5,039,561 entitled "METHOD FOR PREPARING
AN ARTICLE HAVING SURFACE LAYER OF UNIFORMLY ORIENTED, CRYSTALLINE,
ORGANIC MICROSTRUCTURES". This references describes forming
nanostructured anisotropic nanofeatures or nanowhiskers of the dye
perylene red by vacuum deposition of a smooth layer of the dye
followed by annealing to promote self-assembly of the dye molecules
into whisker elements as illustrated in FIG. 4 and described in
Example 1 below.
[0079] The lamination transfer film 130 can be laminated to a
receptor substrate 40 (described above) and exposed to a heating or
baking out process to remove the antireflective nanowhisker
sacrificial template features 114 and to form antireflective
nanostructure features 152 of the thermally stable backfill layer
150. In some embodiments, an optional sacrificial adhesive layer
(not shown) is applied to the backfill layer 22 or to receptor
substrate 40, prior to lamination.
[0080] The antireflective nanowhisker sacrificial template features
114 can be cleanly baked out leaving antireflective nanostructure
features 152 of the thermally stable backfill layer 150. FIG. 5-6
illustrate SEM micrographs of the antireflective nanostructure
features 152 of the thermally stable backfill layer 150 formed by
this process. These figures illustrate that the antireflective
nanowhisker sacrificial template features 114 is capable of being
baked out while leaving antireflective nanostructure features 152
of the thermally stable backfill layer 150.
[0081] FIG. 3A is a schematic process flow diagram 200 of an
illustrative method of forming a hierarchical structured transfer
film 230 and resulting final AR structure 250. This method includes
forming a transfer film 230 by depositing sacrificial material
template layer 12, having antireflective template features 14 on
microstructure 9, (illustrated in FIG. 3B as a magnified view) on a
release surface 13 of a carrier film 11 (described above) and
coating a thermally stable backfill material 22 on the
antireflective template features 14 to form a thermally stable
backfill layer 22 having a first surface conforming to the
antireflective template features 14 with the masking layer 17 and
an opposing planar second surface.
[0082] The thermally stable backfill solution can be coated onto
the microstructure 9 and antireflective nanostructure template
features 14 and any solvent or portion of solvent removed and
optionally cured to form the thermally stable backfill layer 22.
Preferably, after removal of solvent and curing, the thermally
stable material substantially planarizes the sacrificial template
layer as described above.
[0083] The antireflective template features 14 can be formed by any
useful process, such as those described above. The microstructure 9
can be formed by any useful process such as a continuous cast and
cure process or embossed to produce the microstructure 9.
[0084] The lamination transfer film 230 can be laminated to a
receptor substrate 40 (described above) and exposed to a heating or
baking out process to remove the sacrificial template layer 12 and
to form antireflective nanostructure features 252 (illustrated in
FIG. 3C as a magnified view) of the thermally stable backfill layer
250. In some embodiments, an optional sacrificial adhesive layer
(not shown) is applied to the backfill layer 22 or to receptor
substrate 40, prior to lamination.
[0085] The sacrificial template layer 12 and/or antireflective
nanowhisker template features 114 can be cleanly baked out leaving
antireflective nanostructure features 252 of the thermally stable
backfill layer 250. FIGS. 7, 8 14A, 14B, 15A and 15B illustrate SEM
micrographs of the antireflective nanostructure features 252 of the
thermally stable backfill layer 250 formed by this process. These
figures illustrate that the sacrificial template layer 12 and/or
antireflective nanowhisker template features 114 are capable of
being baked out while leaving antireflective nanostructure features
252 of the thermally stable backfill layer 250.
Thermally Stable Material
[0086] A thermally stable material is utilized to form the
thermally stable backfill layer of the transfer film. The thermally
stable material includes thermally stable molecular species. It is
understood that the thermally stable material and the thermally
stable molecular species includes precursor materials that either
are or transform into materials that remain substantially intact
during the removal of sacrificial materials, such as during "bake
out" or pyrolysis.
[0087] Materials that may be used for the backfill include
polysiloxane resins, polysilazanes, polyimides, silsesquioxanes of
bridge or ladder-type, silicones, and silicone hybrid materials and
many others. Exemplary polysiloxane resins are available under the
trade designation PERMANEW 6000, available from California
Hardcoating Company, Chula Vista, Calif. These molecules typically
have an inorganic component which leads to high dimensional
stability, mechanical strength, and chemical resistance, and an
organic component that helps with solubility and reactivity.
[0088] In many embodiments the thermally stable molecular species
includes silicon, hafnium, strontium, titanium or zirconium. In
some embodiments the thermally stable molecular species includes a
metal, metal oxide or metal oxide precursor. Metal oxide precursors
may be used in order to act as an amorphous "binder" for inorganic
nanoparticles, or they may be used alone.
[0089] In many embodiments, the materials useful in the current
invention belong to a class of the highly branched organosilicon
oligomers and polymers of a general formula (as below) which can be
further reacted to form crosslinked networks by homo-condensation
of Si--OH groups, hetero-condensation with the remaining
hydrolyzable groups (e.g. alkoxy), and/or by reactions of the
functional organic groups (e.g. ethylenically unsaturated). This
class of materials is derived primarily from organosilanes of a
general formula:
R.sub.xSiZ.sub.4-x,
wherein
[0090] R is selected from hydrogen, substituted or unsubstituted
C.sub.1-C.sub.20 alkyl, substituted or unsubstituted
C.sub.2-C.sub.10 alkylene, substituted or unsubstituted
C.sub.2-C.sub.20 alkenylene, C.sub.2-C.sub.20 alkynylene,
substituted or unsubstituted C.sub.3-C.sub.20 cycloalkyl,
substituted or unsubstituted C.sub.6-C.sub.20 aryl, substituted or
unsubstituted C.sub.6-C.sub.20 arylene, a substituted or
unsubstituted C.sub.7 to C.sub.20 arylalkyl group, a substituted or
unsubstituted C.sub.1 to C.sub.20 heteroalkyl group, a substituted
or unsubstituted. C.sub.2 to C.sub.20 heterocycloalkyl group,
and/or combinations of these.
[0091] Z is a hydrolyzable group, such as halogen (containing the
elements F, Br, Cl, or I), C.sub.1-C.sub.20 alkoxy,
C.sub.5-C.sub.20 aryloxy, and/or combinations of these.
[0092] The majority of the composition may consist of RSiO.sub.3/2
units thus the class of materials is often called silsesquioxanes
(or T-resins), however they may also contain
mono-(R.sub.3Si--O.sub.1/2), di-(R.sub.2SiO.sub.2/2) and
tetrafunctional groups (Si--O.sub.4/2). Organically-modified
disilanes of the formula:
Z.sub.3-nR.sub.nSi--Y--Si R.sub.nZ.sub.3-n
are often used in the hydrolyzable compostions to further modify
the properties of the materials (to form the so-called bridged
silsesquioxanes), the R and Z groups are defined above. The
materials can be further formulated and reacted with metal
alkoxides (M(OR)m) to form metallo-silsesquioxanes.
[0093] In many embodiments the highly branched organosilicon
oligomers and polymers of a general formula:
##STR00001##
[0094] R.sub.1 is selected from hydrogen, substituted or
unsubstituted C.sub.1-C.sub.20 alkyl, substituted or unsubstituted
C.sub.2-C.sub.10 alkylene, substituted or unsubstituted
C.sub.2-C.sub.20 alkenylene, C.sub.2-C.sub.20 alkynylene,
substituted or unsubstituted C.sub.3-C.sub.20 cycloalkyl,
substituted or unsubstituted C.sub.6-C.sub.20 aryl, substituted or
unsubstituted C.sub.6-C.sub.20 arylene, a substituted or
unsubstituted C.sub.7 to C.sub.20 arylalkyl group, a substituted or
unsubstituted C.sub.1 to C.sub.20 heteroalkyl group, a substituted
or unsubstituted C.sub.2 to C.sub.20 heterocycloalkyl group, and/or
combinations of these;
[0095] R.sub.2 is selected from hydrogen, substituted or
unsubstituted C.sub.1-C.sub.20 alkyl, substituted or unsubstituted
C.sub.2-C.sub.10 alkylene, substituted or unsubstituted
C.sub.2-C.sub.20 alkenylene, C.sub.2-C.sub.20 alkynylene,
substituted or unsubstituted C.sub.3-C.sub.20 cycloalkyl,
substituted or unsubstituted C.sub.6-C.sub.20 aryl, substituted or
unsubstituted C.sub.6-C.sub.20 arylene, a substituted or
unsubstituted C.sub.7 to C.sub.20 arylalkyl group, a substituted or
unsubstituted C.sub.1 to C.sub.20 heteroalkyl group, a substituted
or unsubstituted C.sub.2 to C.sub.20 heterocycloalkyl group, and/or
combinations of these;
[0096] R.sub.3 is selected from hydrogen, substituted or
unsubstituted C.sub.1-C.sub.20 alkyl, substituted or unsubstituted
C.sub.2-C.sub.10 alkylene, substituted or unsubstituted
C.sub.2-C.sub.20 alkenylene, C.sub.2-C.sub.20 alkynylene,
substituted or unsubstituted C.sub.3-C.sub.20 cycloalkyl,
substituted or unsubstituted C.sub.6-C.sub.20 aryl, substituted or
unsubstituted C.sub.6-C.sub.20 arylene, a substituted or
unsubstituted C.sub.7 to C.sub.20 arylalkyl group, a substituted or
unsubstituted C.sub.1 to C.sub.20 heteroalkyl group, a substituted
or unsubstituted C.sub.2 to C.sub.20 heterocycloalkyl group, and/or
combinations of these;
[0097] R.sub.4 is selected from hydrogen, substituted or
unsubstituted C.sub.1-C.sub.20 alkyl, substituted or unsubstituted
C.sub.2-C.sub.10 alkylene, substituted or unsubstituted
C.sub.2-C.sub.20 alkenylene, C.sub.2-C.sub.20 alkynylene,
substituted or unsubstituted C.sub.3-C.sub.20 cycloalkyl,
substituted or unsubstituted C.sub.6-C.sub.20 aryl, substituted or
unsubstituted C.sub.6-C.sub.20 arylene, a substituted or
unsubstituted C.sub.7 to C.sub.20 arylalkyl group, a substituted or
unsubstituted C.sub.1 to C.sub.20 heteroalkyl group, a substituted
or unsubstituted C.sub.2 to C.sub.20 heterocycloalkyl group, and/or
combinations of these;
[0098] R.sub.5 is selected from hydrogen, substituted or
unsubstituted C.sub.1-C.sub.20 alkyl, substituted or unsubstituted
C.sub.2-C.sub.10 alkylene, substituted or unsubstituted
C.sub.2-C.sub.20 alkenylene, C.sub.2-C.sub.20 alkynylene,
substituted or unsubstituted C.sub.3-C.sub.20 cycloalkyl,
substituted or unsubstituted C.sub.6-C.sub.20 aryl, substituted or
unsubstituted C.sub.6-C.sub.20 arylene, a substituted or
unsubstituted C.sub.7 to C.sub.20 arylalkyl group, a substituted or
unsubstituted C.sub.1 to C.sub.20 heteroalkyl group, a substituted
or unsubstituted C.sub.2 to C.sub.20 heterocycloalkyl group, and/or
combinations of these;
[0099] Z is a hydrolyzable group, such as halogen (containing the
elements F, Br, Cl, or I), C.sub.1-C.sub.20 alkoxy, C-C.sub.20
aryloxy, and/or combinations of these.
[0100] m is an integer from 0 to 500;
[0101] n is an integer from 1 to 500;
[0102] p is an integer from 0 to 500;
[0103] q is an integer from 0 to 100.
[0104] As used herein, the term "substituted" refers to one
substituted with at least a substituent selected from the group
consisting of a halogen (containing the elements F, Br, Cl, or I),
a hydroxy group, an alkoxy group, a nitro group, a cyano group, an
amino group, an azido group, an amidino group, a hydrazino group, a
hydrazono group, a carbonyl group, a carbamyl group, a thiol group,
an ester group, a carboxyl group or a salt thereof, a sulfonic acid
group or a salt thereof, a phosphoric acid group or a salt thereof,
alkyl group, a C.sub.2 to C.sub.20 alkenyl group, a C.sub.2 to
C.sub.20 alkynyl group, C.sub.6 to C.sub.30 aryl group, a C.sub.7
to C.sub.13 arylalkyl group, a C.sub.1 to C.sub.4 oxyalkyl group, a
C.sub.1 to C.sub.20 heteroalkyl group, a C.sub.3 to C.sub.20
heteroarylalkyl group, a C.sub.3 to C.sub.30 cycloalkyl group, a
C.sub.3 to C.sub.15 cycloalkenyl group, a C.sub.6 to C.sub.15
cycloalkynyl group, a heterocycloalkyl group, and a combination
thereof, instead of hydrogen of a compound.
[0105] The resulting highly branched organosilicon polymer has a
molecular weight in a range from 150 to 300,000 Da or preferably in
a range from 150 to 30,000 Da.
[0106] Preferably, the thermally stable backfill contains the
reaction product of the hydrolysis and condensation of a
methyltriethoxysilane precursor in a polar solvent. After
synthesis, the resulting polymer preferably has a molecular weight
of nominally less than 30,000 Da. The thermally stable backfill
solution also preferably includes less than fifty percent by weight
silica nanoparticles nominally of a size between 10-50
nanometers.
[0107] The thermally stable compositions described herein
preferably comprise inorganic nanoparticles. These nanoparticles
can be of various sizes and shapes. The nanoparticles can have an
average particle diameter less than about 1000 nm, less than about
100 nm, less than about 50 nm, or less than about 35 nm. The
nanoparticles can have an average particle diameter from about 3 nm
to about 50 nm, or from about 3 nm to about 35 nm, or from about 5
nm to about 25 nm. If the nanoparticles are aggregated, the maximum
cross sectional dimension of the aggregated particle can be within
any of these ranges, and can also be greater than about 100 nm.
"Fumed" nanoparticles, such as silica and alumina, with primary
size less than about 50 nm, may also be used, such as CAB-OSPERSE
PG 002 fumed silicas, CAB-O-SPERSE 2017A fumed silicas, and
CAB-OSPERSE PG 003 fumed alumina, available from Cabot Co. Boston,
Mass. Their measurements can be based on transmission electron
microscopy (TEM). Nanoparticles can be substantially fully
condensed. Fully condensed nanoparticles, such as the colloidal
silica, typically have substantially no hydroxyls in their
interiors. Non-silica containing fully condensed nanoparticles
typically have a degree of crystallinity (measured as isolated
particles) greater than 55%, preferably greater than 60%, and more
preferably greater than 70%. For example, the degree of
crystallinity can range up to about 86% or greater. The degree of
crystallinity can be determined by X-ray diffraction techniques.
Condensed crystalline (e.g. zirconia) nanoparticles have a high
refractive index whereas amorphous nanoparticles typically have a
lower refractive index. Various shapes of the inorganic or organic
nanoparticles may be used, such as sphere, rod, sheet, tube, wire,
cube, cone, tetrahedron, and the like.
[0108] The size of the particles is generally chosen to avoid
significant visible light scattering in the final article. The
nanomaterial selected can impart various optical properties (i.e
refractive index, birefringence), electrical properties (e.g
conductivity), mechanical properties (e.g toughness, pencil
hardness, scratch resistance) or a combination of these properties.
It may be desirable to use a mix of organic and inorganic oxide
particle types to optimize an optical or material property and to
lower total composition cost.
[0109] Examples of suitable inorganic nanoparticles include metal
nanoparticles or their respective oxides, including the elements
zirconium or zirconia (Zr), titanium or titania (Ti), hafnium (Hf),
aluminum or alumina (Al), iron (Fe), vanadium (V), antimony (Sb),
tin (Sn), gold (Au), copper (Cu), gallium (Ga), indium (In),
chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn),
yttrium (Y), niobium (Nb), molybdenum (Mo), technetium (Te),
ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium
(Cd), lanthanum (La), tantalum (Ta), tungsten (W), rhenium (Rh),
osmium (Os), iridium (Ir), platinum (Pt), and any combinations
thereof.
[0110] In a preferred embodiment, nanoparticles of zirconium oxide
(zirconia) are used. Zirconia nanoparticles can have a particle
size from approximately 5 nm to 50 nm, or 5 nm to 15 nm, or 10 nm.
Zirconia nanoparticles can be present in the durable article or
optical element in an amount from 10 to 70 wt %, or 30 to 50 wt %.
Zirconias for use in materials of the invention are commercially
available from Nalco Chemical Co. (Naperville, Ill.) under the
product designation NALCO OOSSOO8 and from Buhler AG Uzwil, 20
Switzerland under the trade designation "Buhler zirconia Z-WO sol".
Zirconia nanoparticle can also be prepared such as described in
U.S. Pat. No. 7,241,437 (Davidson et al.) and U.S. Pat. No.
6,376,590 (Kolb et al.). Titania, antimony oxides, alumina, tin
oxides, and/or mixed metal oxide nanoparticles can be present in
the durable article or optical element in an amount from 10 to 70
wt %, or 30 to 50 wt %. Densified ceramic oxide layers may be
formed via a "sol-gel" process, in which ceramic oxide particles
are incorporated into a gelled dispersion with a precursor of at
least one modifying component followed by dehydration and firing,
as described in U.S. Pat. No. 5,453,104 (Schwabel). Mixed metal
oxide for use in materials of the invention are commercially
available from Catalysts & Chemical Industries Corp.,
(Kawasaki, Japan) under the product designation OPTOLAKE.
[0111] Other examples of suitable inorganic nanoparticles include
elements and alloys known as semiconductors and their respective
oxides such as silicon (Si), germanium (Ge), silicon carbide (SiC),
silicon germanide (SiGe), aluminium nitride (AlN), aluminium
phosphide (AlP), boron nitride (BN), boron carbide (B.sub.4C),
gallium antimonide (GaSb), indium phosphide (InP), gallium arsenide
nitride (GaAsN), gallium arsenide phosphide (GaAsP), indium
aluminum arsenide nitride (InAlAsN), zinc oxide (ZnO), zinc
selenide (ZnSe), zinc sulfide (ZnS), zinc telluride (ZnTe), mercury
zinc selenide (HgZnSe), lead sulfide (PbS), lead telluride (PbTe),
tin sulfide (SnS), lead tin telluride (PbSnTe), thallium tin
telluride (Tl.sub.2SnTe.sub.5), zinc phosphide (Zn.sub.3P.sub.2),
zinc arsenide (Zn.sub.3As.sub.2), zinc antimonide
(Zn.sub.3Sb.sub.2), lead(II) iodide (PbI.sub.2), copper(I) oxide
(Cu.sub.2O).
[0112] Silicon dioxide (silica) nanoparticles can have a particle
size from 5 nm to 75 nm or 10 nm to 30 nm or 20 nm. Silica
nanoparticles are typically in an amount from 10 to 60 wt.-%.
Typically the amount of silica is less than 40 wt %. Suitable
silicas are commercially available from Nalco Chemical Co.
(Naperville, Ill.) under the trade designation NALCO COLLOIDAL
SILICAS. For example, silicas 10 include NALCO trade designations
1040, 1042, 1050, 1060, 2327 and 2329. the organosilica under the
product name IPA-ST-MS, IPA-ST-L, IPA-ST, IPA-ST-UP, MA-ST-M, and
MAST sols from Nissan Chemical America Co. Houston, Tex. and the
SNOWTEX ST-40, ST-50, ST-20L, ST-C, ST-N, ST-O, ST-OL, ST-ZL,
ST-UP, and ST-OUP, also from Nissan Chemical America Co. Houston,
Tex. Suitable fumed silicas include for example, products sold
under the tradename, AEROSIL series OX-50, -130, -150, and -200
available from DeGussa AG, (Hanau, Germany), and CAB-O-SPERSE 2095,
CAB-O-SPERSE A105, CAB-O-SIL M5 available from Cabot Corp.
(Tuscola, Ill.). The weight ratio of polymerizable material to
nanoparticles can range from about 30:70, 40:60, 50:50, 55:45,
60:40, 70:30, 80:20 or 90:10 or more. The preferred ranges of
weight percent of nanoparticles range from about 10 wt % to about
60% by weight, and can depend on the density and size of the
nanoparticle used.
[0113] In many embodiments, the thermally stable backfill layer
includes zirconia, titania, alumina, boron carbide, or silicon
carbide nanoparticles. In some embodiments, the thermally stable
backfill layer includes zirconia. In some embodiments, the
thermally stable backfill layer includes titania. In some
embodiments, the thermally stable backfill layer includes alumina.
In some embodiments, the thermally stable backfill layer includes
boron carbide. In some embodiments, the thermally stable backfill
layer includes silicon carbide.
[0114] Within the class of semiconductors include nanoparticles
known as "quantum dots," which have interesting electronic and
optical properties that can be used in a range of applications.
Quantum dots can be produced from binary alloys such as cadmium
selenide, cadmium sulfide, indium arsenide, and indium phosphide,
or from ternary alloys such as cadmium selenide sulfide, and the
like. Companies that sell quantum dots include Nanoco Technologies
(Manchester, UK) and Nanosys (Palo Alto, Calif.).
[0115] Examples of suitable inorganic nanoparticles include
elements known as rare earth elements and their oxides, such as
lanthanum (La), cerium (CeO.sub.2), praseodymium
(Pr.sub.6O.sub.11), neodymium (Nd.sub.2O.sub.3), samarium
(Sm.sub.2O.sub.3), europium (Eu.sub.2O.sub.3), gadolinium
(Gd.sub.2O.sub.3), terbium (Tb.sub.4O.sub.7), dysprosium
(Dy.sub.2O.sub.3), holmium (Ho.sub.2O.sub.3), erbium
(Er.sub.2O.sub.3), thulium (Tm.sub.2O.sub.3), ytterbium
(Yb.sub.2O.sub.3) and lutetium (Lu.sub.2O.sub.3). Additionally,
phosphorecent materials known as "phosphors" may be included in the
thermally stable backfill material. These may include calcium
sulfide with strontium sulfide with bismuth as an activator
(CaxSr)S: Bi, Zinc sulfide with copper "GS phosphor", mixtures of
zinc sulfide and cadmium sulfide, strontium aluminate activated by
Europium (SrAl.sub.2O.sub.4:Eu(II):Dy(III)),
BaMgAl.sub.10O.sub.17:Eu.sup.2+ (BAM), Y.sub.2O.sub.3:Eu, doped
ortho-silicates, Yttrium aluminium garnet (YAG) and Lutetium
aluminium garnet (LuAG) containing materials, any combinations
thereof, and the like. A commercial example a phosphor may include
one of the ISIPHOR.TM. inorganic phosphors (available from Merck
KGaA, Darmstadt, Germany).
[0116] The nanoparticles are typically treated with a surface
treatment agent. Surface-treating the nano-sized particles can
provide a stable dispersion in the polymeric resin. Preferably, the
surface-treatment stabilizes the nanoparticles so that the
particles will be well dispersed in a substantially homogeneous
composition. Furthermore, the nanoparticles can be modified over at
least a portion of its surface with a surface treatment agent so
that the stabilized particle can copolymerize or react with the
parts of the composition during curing. In general, a surface
treatment agent has a first end that will attach to the particle
surface (covalently, ionically or through strong physisorption) and
a second end that imparts compatibility of the particle with the
composition and/or reacts with resin during curing. Examples of
surface treatment agents include alcohols, amines, carboxylic
acids, sulfonic acids, phospohonic acids, silanes and titanates.
The preferred type of treatment agent is determined, in part, by
the chemical nature of the metal oxide surface. Silanes are
preferred for silica and other for siliceous fillers. Silanes and
carboxylic acids are preferred for metal oxides such as zirconia.
The surface modification can be done either subsequent to mixing
with the monomers or after mixing. It is preferred in the case of
silanes to react the silanes with the particle or nanoparticle
surface before incorporation into the composition. The required
amount of surface modifier is dependent upon several factors such
particle size, particle type, modifier molecular weight, and
modifier type. In general it is preferred that approximately a
monolayer of modifier is attached to the surface of the particle.
The attachment procedure or reaction conditions required also
depend on the surface modifier used. For silanes, it is preferred
to surface treat at elevated temperatures under acidic or basic
conditions for from 1-24 hr approximately. Surface treatment agents
such as carboxylic acids may not require elevated temperatures or
extended time.
[0117] Representative embodiments of surface treatment agents
suitable for the compositions include compounds such as, for
example, isooctyl trimethoxy-silane, N-(3-triethoxysilylpropyl)
methoxyethoxyethoxyethyl carbamate (PEG.sub.3TES),
N-(3-triethoxysilylpropyl) methoxyethoxyethoxyethyl carbamate
(PEG.sub.2TES), 3-(methacryloyloxy)propyltrimethoxysilane,
3-acryloxypropyltrimethoxysilane,
3-(methacryloyloxy)propyltriethoxysilane, 3-(methacryloyloxy)
propylmethyldimethoxysilane,
3-(acryloyloxypropyl)methyldimethoxysilane,
3-(methacryloyloxy)propyldimethylethoxysilane, 3-(methacryloyloxy)
propyldimethylethoxysilane, vinyldimethylethoxysilane,
phenyltrimethoxysilane, n-octyltrimethoxysilane,
dodecyltrimethoxysilane, octadecyltrimethoxysilane,
propyltrimethoxysilane, hexyltrimethoxysilane,
vinylmethyldiacetoxysilane, vinylmethyldiethoxysilane,
vinyltriacetoxysilane, vinyltriethoxysilane,
vinyltriisopropoxysilane, vinyltrimethoxysilane,
vinyltriphenoxysilane, vinyltri-t-butoxysilane,
vinyltris-isobutoxysilane, vinyltrii sopropenoxysilane,
vinyltris(2-methoxyethoxy) silane, styrylethyltrimethoxysilane,
mercaptopropyltrimethoxysilane, 3-5
glycidoxypropyltrimethoxysilane, acrylic acid, methacrylic acid,
oleic acid, stearic acid, dodecanoic acid,
2-[2-(2-methoxyethoxy)ethoxy]acetic acid (MEEAA),
beta-carboxyethylacrylate, 2-(2-methoxyethoxy)acetic acid,
methoxyphenyl acetic acid, and mixtures thereof. Further, a
proprietary silane surface modifier, commercially available from
OSI Specialties, Crompton South Charleston, W. Va. under the trade
designation "Silquest Al230", has been found particularly
suitable.
[0118] In some embodiments the thermally stable molecular species
includes a metal, metal oxide or metal oxide precursor. Metal oxide
precursors may be used in order to act as an amorphous "binder" for
inorganic nanoparticles, or they may be used alone. Sol-gel
techniques may be used to react these precursors in order to cure
the material into a solid mass and are known to those skilled in
the art. Suitable metal oxide precursors include alkyl titanates
such as titanium (IV) butoxide, n-propyl titanate, titanium
triethanolamine, titanium phosphate glycol, 2-ethylhexyl titanate,
titanium (IV) ethoxide, titanium (IV) isopropoxide, and the like.
These are commercially available under the "TYZOR" trade name owned
by Dorf-Ketal Inc. (Houston, Tex.). Also suitable metal oxide
precursors include zirconium chloride or zirconium(IV) alkoxides
such as zirconium (IV) acrylate, zirconium(IV) tetraisopropoxide,
zirconium(IV) tetraethoxide, zirconium(IV) tetrabutoxide, and the
like, all available from Aldrich (St. Louis, Mo.). Also suitable
metal oxide precursors include hafnium(IV) chloride or hafnium
alkoxides such as hafnium(IV) carboxyethyl acrylate, hafnium(IV)
tetraisopropoxide, hafnium(IV) tert-butoxide, hafnium(IV)
n-butoxide, also available from Aldrich (St. Louis, Mo.). These
materials can also be used as inorganic nanomaterials in the
sacrificial template layer in order to form the bridging layer.
Sacrificial Materials
[0119] The sacrificial layer is a material capable of being baked
out or otherwise removed while leaving the structured surface layer
and the bridging layer, substantially intact. The sacrificial layer
includes, for example, the sacrificial template layer and the
optional sacrificial releasable layer, depending upon a
construction of the transfer film.
[0120] The sacrificial layer can have the antireflective
nanostructure template features alone or in addition to a
microstructured surface. The antireflective nanostructure template
features can be formed as described above. The microstructure can
be formed through embossing, a replication process, extrusion,
casting, or surface structuring, for example. The structured
surface can include nanostructures, microstructures, or
hierarchical structures. Nanostructures comprise features having at
least one dimension (e.g., height, width, or length) less than or
equal to 2 micrometers. Microstructures comprise features having at
least one dimension (e.g., height, width, or length) less than or
equal to one millimeter. Hierarchical structures are combinations
of nanostructures and microstructures.
[0121] The sacrificial layer can comprise any material as long as
the desired properties are obtained. Preferably, the sacrificial
layer is made from a polymerizable composition comprising polymers
having number average molecular weights of about 1,000 Da or less
(e.g., monomers and oligomers). Particularly suitable monomers or
oligomers have molecular weights of about 500 Da or less, and even
more particularly suitable polymerizable molecules have molecular
weights of about 200 Da or less. Said polymerizable compositions
are typically cured using actinic radiation, e.g., visible light,
ultraviolet radiation, electron beam radiation, heat and
combinations thereof, or any of a variety of conventional anionic,
cationic, free radical or other polymerization techniques, which
can be photochemically or thermally initiated.
[0122] Useful polymerizable compositions comprise curable
functional groups known in the art, such as epoxide groups,
allyloxy groups, (meth)acrylate groups, epoxide, vinyl, hydroxyl,
acetoxy, carboxylic acid, amino, phenolic, aldehyde, cinnamate,
alkene, alkyne, ethylenically unsaturated groups, vinyl ether
groups, and any derivatives and any chemically compatible
combinations thereof.
[0123] The polymerizable composition used to prepare the
sacrificial template layer may be monofunctional or multifunctional
(e.g, di-, tri-, and tetra-) in terms of radiation curable
moieties. Examples of suitable monofunctional polymerizable
precursors include styrene, alpha-methylstyrene, substituted
styrene, vinyl esters, vinyl ethers, octyl (meth)acrylate,
nonylphenol ethoxylate (meth)acrylate, isobornyl (meth)acrylate,
isononyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate,
2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate,
beta-carboxyethyl (meth)acrylate, isobutyl (meth)acrylate,
cycloaliphatic epoxide, alpha-epoxide, 2-hydroxyethyl
(meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate,
n-butyl (meth)acrylate, methyl (meth)acrylate, hexyl
(meth)acrylate, (meth)acrylic acid, N-vinylcaprolactam, stearyl
(meth)acrylate, hydroxyl functional caprolactone ester
(meth)acrylate, isooctyl (meth)acrylate, hydroxyethyl
(meth)acrylate, hydroxypropyl (meth)acrylate, hydroxyisopropyl
(meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyisobutyl
(meth)acrylate, tetrahydrofuryl (meth)acrylate, and any
combinations thereof.
[0124] Examples of suitable multifunctional polymerizable
precursors include ethyl glycol di(meth)acrylate, hexanediol
di(meth)acrylate, triethylene glycol di(meth)acrylate,
tetraethylene glycol di(meth)acrylate, trimethylolpropane
tri(meth)acrylate, trimethylolpropanepropane tri(meth)acrylate,
glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate,
pentaerythritol tetra(meth)acrylate, neopentyl glycol
di(meth)acrylate, bisphenol A di(meth)acrylate,
poly(1,4-butanediol) di(meth)acrylate, any substituted, ethoxylated
or propoxylated versions of the materials listed above, or any
combinations thereof
[0125] The polymerization reactions generally lead to the formation
of a three-dimensional "crosslinked" macromolecular network and are
also known in the art as negative-tone photoresists, as reviewed by
Shaw et al., "Negative photoresists for optical lithography," IBM
Journal of Research and Development (1997) 41, 81-94. The formation
of the network may occur through either covalent, ionic, or
hydrogen bonding, or through physical crosslinking mechanisms such
as chain entanglement. The reactions can also be initiated through
one or more intermediate species, such as free-radical generating
photoinitiators, photosensitizers, photoacid generators, photobase
generators, or thermal acid generators. The type of curing agent
used depends on the polymerizable precursor used and on the
wavelength of the radiation used to cure the polymerizable
precursor. Examples of suitable commercially available free-radical
generating photoinitiators include benzophenone, benzoin ether, and
acylphosphine photoinitiators, such as those sold under the trade
designations "IRGACURE" and "DAROCUR" from Ciba Specialty
Chemicals, Tarrytown, N.Y. Other exemplary photoinitiators include
2,2-dimethoxy-2-phenylacetophenone (DMPAP),
2,2-dimethoxyacetophenone (DMAP), xanthone, and thioxanthone.
[0126] Co-initiators and amine synergists may also be included to
improve curing rates. Suitable concentrations of the curing agent
in the crosslinking matrix range from about 1 wt. % to about 10 wt.
%, with particularly suitable concentrations ranging from about 1
wt. % to about 5 wt. %, based on the entire weight of the
polymerizable precursor. The polymerizable precursor may also
include optional additives, such as heat stabilizers, ultraviolet
light stabilizers, free-radical scavengers, and combinations
thereof. Examples of suitable commercially available ultraviolet
light stabilizers include benzophenone-type ultraviolet absorbers,
which are available under the trade designation "UVINOL 400" from
BASF Corp., Parsippany, N.J.; under the trade designation "CYASORB
UV-1164" from Cytec Industries, West Patterson, N.J.; and under the
trade designations "TINUVIN 900," "TINUVIN 123" and "TINUVIN 1130"
from Ciba Specialty chemicals, Tarrytown, N.Y. Examples of suitable
concentrations of ultraviolet light stabilizers in the
polymerizable precursor range from about 0.1 wt. % to about 10 wt.
%, with particularly suitable total concentrations ranging from
about 1 wt. % to about 5 wt. %, relative to the entire weight of
the polymerizable precursor.
[0127] Examples of suitable free-radical scavengers include
hindered amine light stabilizer (HALS) compounds, hydroxylamines,
sterically hindered phenols, and combinations thereof. Examples of
suitable commercially available HALS compounds include the trade
designated "TINUVIN 292" from Ciba Specialty Chemicals, Tarrytown,
N.Y., and the trade designated "CYASORB UV-24" from Cytec
Industries, West Patterson, N.J. Examples of suitable
concentrations of free radical scavengers in the polymerizable
precursor range from about 0.05 wt. % to about 0.25 wt. %.
[0128] Patterned structured template layers can be formed by
depositing a layer of a radiation curable composition onto one
surface of a radiation transmissive carrier to provide a layer
having an exposed surface, contacting a master with a preformed
surface bearing a pattern capable of imparting a three-dimensional
structure of precisely shaped and located interactive functional
discontinuities including distal surface portions and adjacent
depressed surface portions into the exposed surface of the layer of
radiation curable composition on said carrier under sufficient
contact pressure to impart said pattern into said layer, exposing
said curable composition to a sufficient level of radiation through
the carrier to cure said composition while the layer of radiation
curable composition is in contact with the patterned surface of the
master. This cast and cure process can be done in a continuous (3C)
manner using a roll of carrier, depositing a layer of curable
material onto the carrier, laminating the curable material against
a master and curing the curable material using actinic radiation.
The resulting roll of carrier with a patterned, structured template
disposed thereon can then be rolled up. This method is disclosed,
for example, in U.S. Pat. No. 6,858,253 (Williams et al.).
[0129] Other materials that may be used for the sacrificial layer
include, polyvinyl alcohol (PVA), ethylcellulose, methylcellulose,
polynorbornes, poly(methylmethacrylate (PMMA), poly(vinylbutyral),
poly(cyclohexene carbonate), poly(cyclohexene propylene) carbonate,
poly(ethylene carbonate) poly(propylene carbonate) and other
aliphatic polycarbonates, and any copolymer or blend thereof, and
other materials described in chapter 2, section 2.4 "Binders" of R.
E. Mistler, E. R. Twiname, Tape Casting: Theory and Practice,
American Ceramic Society, 2000. There are many commercial sources
for these materials. These materials are typically easy to remove
via dissolution or thermal decomposition via pyrolysis or
combustion. Thermal heating is typically part of many manufacturing
processes and thus removal of the sacrificial material may be
accomplished during an existing heating step. For this reason,
thermal decomposition via pyrolysis or combustion is a more
preferred method of removal.
[0130] There are several properties that are preferred in the
sacrificial materials. The material should be capable of being
coated onto a substrate via extrusion, knife coating, solvent
coating, cast and cure, or other typical coating methods. It is
preferred that the material be a solid at room temperature. For
thermoplastic sacrificial materials, it is preferred that the glass
transition temperature (Tg) is low enough to allow it to be
embossed by a heated tool. Thus, it is preferred that the
sacrificial material have a Tg above 25.degree. C., more preferred
above 40.degree. C. and most preferred above 90.degree. C.
[0131] Another material property that is desired for the
sacrificial material is that its decomposition temperature be above
the curing temperature of the backfill material(s). Once the
backfill material is cured, the structured layer is permanently
formed and the sacrificial template layer can be removed via any
one of the methods listed above. Materials that thermally decompose
with low ash or low total residue are preferred over those that
have higher residuals. Residue left behind on a substrate may
adversely impact electrical and/or optical properties such as
conductivity, transparency or color of the final product. Since it
is desirable to minimize any changes to these properties in the
final product, residual levels of less than 1000 ppm are preferred.
Residuals levels of less than 500 ppm are more preferred and
residual level below 50 ppm are most preferred.
[0132] The term "cleanly baked out" means that the sacrificial
layer can be removed by pyrolysis, combustion, sublimation or
vaporization without leaving a substantial amount of residual
material such as ash. Examples of preferred residual levels are
provided above, although different residual levels can be used
depending upon a particular application.
Sacrificial Adhesive Layer
[0133] The sacrificial adhesive layer can be implemented with any
material enhancing adhesion of the transfer film to the receptor
substrate without substantially adversely affecting the performance
of the transfer film. This layer can also be described as an
adhesion promoting layer. The sacrificial adhesive layer appears to
facilitate the final permanent bond between the receptor substrate
and the baked-out thermally stable structure. The sacrificial
adhesive layer is capable of being cleanly baked out during the
methods described herein.
[0134] Objects and advantages of this disclosure are further
illustrated by the following examples, but the particular materials
and amounts thereof recited in these examples, as well as other
conditions and details, should not be construed to unduly limit
this disclosure.
EXAMPLES
[0135] All parts, percentages, ratios, etc. in the examples are by
weight, unless noted otherwise. Solvents and other reagents used
are obtained from Sigma-Aldrich Corp., St. Louis, Mo. unless
specified differently.
[0136] The Reflectance (Average Reflection % or % R) of a plasma
treated surface was measured using BYK Gardner color guide sphere.
One sample of each film was prepared by applying Yamato Black Vinyl
Tape #200-38 (obtained from Yamato International Corporation,
Woodhaven, Mich.) to the backside of the sample. A clear glass
slide of which transmission and reflection from both sides were
predetermined was utilized to establish the % reflection from the
black tape. The black tape was laminated to the backside of the
sample using a roller to ensure there were no air bubbles trapped
between the black tape and the sample. To measure the front surface
total Reflectance (% R, specular and diffuse) by an integrating
sphere detector, the sample was placed in the machine so that the
non-tape side was against the aperture. The Reflectance (% R) was
measured at a 10.degree. incident angle and average Reflectance (%
R) was calculated by subtracting the Reflectance (% R) of the black
tape for the wavelength range of 400-700 nm.
Example 1
Unstructured Perylene Whisker AR
Perylene Coating
[0137] The base film was an unprimed 2-mil Kapton H. Samples were
placed in a batch coater with a starting base pressure of
7.times.10-7 Torr. Perylene red pigment (PV Fast Red B,
CAS#4948-15-6) was vapor deposited onto the surface of the supplied
sheets at a rate of .about.6 .ANG./sec to achieve a total perylene
thickness of 2000 .ANG. (200 nm). The batch coater was then vented
and the samples were placed into a batch oven that was slowly
heated up to a maximum temperature of 268.degree. C. (6 hours) at
.about.18 mTorr and then turned off and slowly cooled to RT before
being vented and removed. The perylene whiskers are shown in FIG.
4.
Backfill Coating
[0138] A section of the perylene coated film was attached to a 2
in.times.3 in microscope slide with tape. PermaNew 6000 (available
from California Hardcoating Company, Chula Vista, Calif.) was
diluted to 15% w/w in 80:20 IPA/butanol, brought to room
temperature, and filtered through a 1.0 um filter. The sample of
the treated film was coated with the PermaNew solution, which was
applied to the film sample by spin coating on a Cee 200X Precision
spin coater (Brewer Science, Inc. Rolla, Mo.). The spin parameters
were 500 rpm for 3 seconds (solution application), and 2000 rpm for
30 seconds, then 500 rpm for 10 seconds. Approximately 5
milliliters of the PermaNew solution was applied to the replicated
film during the solution application step of the spin cycle. The
coated sample was placed in a oven at 80.degree. C. for four hours
to cure the PermaNew coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0139] Glass slides, 2 in.times.3 in, were cleaned with IPA and a
lint free cloth. The slide was mounted on the vacuum chuck of a
spin coater. The spin coater was programmed for 500 RPM for 5
seconds (coating application step) then 1500 RPM for 10 sec (spin
step), then 500 RPM for 60 seconds (dry step).
[0140] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the glass slide during the coating application portion
of the spin cycle. The slide was then removed from the spin coater
and allowed to dry.
Lamination
[0141] The film was laminated at 180.degree. F. (PermaNew coating
side toward the sacrificial adhesive layer) to the IOA/AA coated
glass slide using a thermal film laminator (GBC Catena 35, GBC
Document Finishing, Lincolnshire, Ill.). The laminated sample was
removed from the laminator and allowed cool to room
temperature.
Bake-Out
[0142] After lamination, the Kapton support was separated from the
laminated layers, leaving the Perma-New, Perylene, and IOA/AA
layers adhered to the glass slide. The sample was placed on a
hotplate 300.degree. C. at a rate of approximately 10.degree.
C./min. The hotplate was held at 300.degree. C. for approximately
ten minutes, then heated to 370.degree. C. at a rate of
approximately 10.degree. C./min and held for approximately 10
minutes. A propane torch was used to gently heat the sample above
370.degree. C. until the Perylene coating was removed from the
surface. The hotplate and sample were then to cool down to ambient
temperature. The resulting clean inorganic nanostructure is shown
in FIG. 5 and FIG. 6.
Measurement of Average Reflectance at Near Normal Incidence
[0143] Each sample was prepared by applying a black vinyl tape
(obtained from Yamato International Corporation, Woodhaven, Mich.
under the trade designation "#200-38") to the backside of the
sample. The black tape was applied using a roller to ensure there
are no air bubbles trapped between the black tape and the sample.
The same black vinyl tape was similarly applied to an uncoated
glass slide of which reflection from both sides are predetermined
in order to have a control sample to establish the % reflection
from the black vinyl tape in isolation. The non-taped side of first
the taped sample and then the control was then placed against the
aperture of BYK Gardner color guide sphere (obtained from
BYK-Gardner of Columbia, Md. under the trade designation
SPECTRO-GUIDE) to measure the front surface total % reflection
(specular and diffuse). The % reflection was then measured at a
10.degree. incident angle for the wavelength range of 400-700 nm,
and average % reflection was calculated by subtracting out the %
reflection of the control, creating the average corrected %
reflection. The results of the average % reflection and average
corrected % reflection are shown in Table 1.
TABLE-US-00001 TABLE 1 Average % reflection and average corrected %
reflection for the unstructured perylene whisker AR on glass.
Average Average Corrected Sample % Reflection % Reflection Perylene
Whiskers 2.0 1.20
Example 2
600 nm Structured Perylene Whisker AR
Structured Template
[0144] The substrate was a primed 0.002 inch (0.051 mm) thick PET.
The replicating resin was a 75/25 blend of SR 399 and SR238 (both
available from Sartomer USA, Exton, Pa.) with a photoinitator
package comprising 1% Darocur 1173 (Available from Ciba, Tarrytown,
N.Y.), 1.9% triethanolamine (available from Sigma-Aldrich, St.
Louis, Mo.), and 0.5% OMAN071 (available from Gelest, Inc.
Morrisville, Pa.). Replication of the resin was conducted at 20
ft/min (6.1 m/min) with the replication tool temperature at 137 deg
F. (58 deg C.). Radiation from a Fusion "D" lamp operating at 600
W/in was transmitted through the film to cure the resin while in
contact with the tool. The replication tool was patterned with a
600 nm pitch linear sawtooth groove.
[0145] The replicated template film was primed in a plasma chamber
using argon gas at a flow rate of 250 standard cc/min (SCCM) at a
pressure of 25 mTorr and RF power of 1000 Watts for 30 seconds.
Subsequently, a release coated tool surface was prepared by
subjecting the samples to a tetramethylsilane (TMS) plasma at a TMS
flow rate of 150 SCCM but no added oxygen, which corresponded to an
atomic ratio of oxygen to silicon of about 0. The pressure in the
plasma chamber was 25 mTorr, and the RF power of 1000 Watts was
used for 10 seconds.
Sacrificial Template Coating
[0146] The base film was an unprimed 2-mil Kapton H. The
replicating resin was ethoxylated bisphenol A dimethacrylate
(SR540, available from Sartomer Company, Exton, Pa.) with a
photoinitator package comprising 0.5% Darocur 1173 and 0.1% TPO.
The resin was coated between the base film and a tool film in a nip
with a fixed closed gap and a pressure of 80 psi. The laminate was
cured with radiation from a Fusion "D" lamp operating at 600 W/in
was transmitted through the film to cure the resin while in contact
with the tool. The tool film was then removed from the sample,
resulting in a structured resin coating on polyimide.
Perylene Coating
[0147] Samples were placed in a batch coater with a starting base
pressure of 7.times.10-7 Torr. Perylene red pigment (PV Fast Red B,
CAS#4948-15-6) was vapor deposited onto the surface of the supplied
sheets at a rate of .about.6 .ANG./sec to achieve a total perylene
thickness of 2000 .ANG. (200 nm). The batch coater was then vented
and the samples were placed into a batch oven that was slowly
heated up to a maximum temperature of 268.degree. C. (6 hours) at
.about.18 mTorr and then turned off and slowly cooled to RT before
being vented and removed. The resulting perylene structure on the
sawtooth structured surface is shown in FIG. 7.
Backfill Coating
[0148] A section of the perylene coated structured film was
attached to a 2 in.times.3 in microscope slide with tape. PermaNew
6000 (available from California Hardcoating Company, Chula Vista,
Calif.) was diluted to 15% w/w in 80:20 IPA/butanol, and brought to
room temperature, and filtered through a 1.0 um filter. The sample
of the treated film was coated with the PermaNew solution, which
was applied to the film sample by spin coating on a Cee 200X
Precision spin coater (Brewer Science, Inc. Rolla, Mo.). The spin
parameters were 500 rpm/3 sec (solution application), and 2000
rpm/30 sec, then 500 rpm for 10 seconds. Approximately 5
milliliters of the PermaNew solution was applied to the replicated
film during the solution application step of the spin cycle. The
coated sample was placed in a oven at 80.degree. C. for four hours
to cure the PermaNew coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0149] Glass slides, 2 in.times.3 in, were cleaned with IPA and a
lint free cloth. The slide was mounted on the vacuum chuck of a
spin coater. The spin coater was programmed for 500 RPM for 5
seconds (coating application step) then 1500 RPM for 10 sec (spin
step), then 500 RPM for 60 seconds (dry step).
[0150] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the glass slide during the coating application portion
of the spin cycle. The slide was then removed from the spin coater
and allowed to dry.
Lamination
[0151] The film was laminated at 180.degree. F. (PermaNew coating
side toward the sacrificial adhesive layer) to the IOA/AA coated
glass slide using a thermal film laminator (GBC Catena 35, GBC
Document Finishing, Lincolnshire, Ill.). The laminated sample was
removed from the laminator and allowed cool to room
temperature.
Bake-Out
[0152] After lamination, the Kapton supporting the film stack was
separated from the laminated structure, leaving the Perma-New,
Perylene, SR540, and IOA/AA layers adhered to the glass slide. The
sample was placed on a hotplate 300.degree. C. at a rate of
approximately 10.degree. C./min. The hotplate was held at
300.degree. C. for approximately ten minutes to decompose the
IOA/AA, then heated to 370.degree. C. at a rate of approximately
10.degree. C./min and held for approximately 10 minutes to
decompose the SR540. A propane torch was used to gently heat the
sample above 370.degree. C. until the Perylene coating was removed
from the surface. The hotplate and sample were then allowed to cool
down to ambient temperature. A side view of the resulting inorganic
hierarchical nanostructure on glass is shown in FIG. 8.
Example 3
Unstructured QPAC AR
Sacrificial Material Layer Coating
[0153] A 5 wt % solution of QPAC 100 (poly(alkylene
carbonate)copolymer, Empower Materials, Inc., New Castle, Del.) in
1,3-dioxolane was delivered at a rate of 30 cm.sup.3/min to a 10.2
cm (4 inch) wide slot-type coating die in continuous film coating
apparatus. The solution was coated on the backside of a release
liner (Release Liner, 50 microns thick, commercially available from
CP Films, Fieldale, Va. as "T50"). The coated web travelled
approximately 2.4 m (8 ft) before entering a 9.1 m (30 ft)
conventional air floatation drier with all 3 zones set at
65.5.degree. C. (150.degree. F.). The substrate was moving at a
speed of 3.05 m/min (10 ft/min) to achieve a wet coating thickness
of about 80 micrometers.
Sputtered-Etch AR Coatings
[0154] The samples were sputter etched with the following
conditions, and selected samples are shown in Table 2.
TABLE-US-00002 TABLE 2 Process conditions for sputter etch samples.
TMS Flow O.sub.2 Flow Pressure Power Speed Sample sccm sccm mTorr
watts Ft/min Control 2 30 500 5.6 6000 6 7 20 500 8 6000 4 15 10
500 7.3 6000 4
[0155] FIG. 9A-C are top view SEMs of QPAC sacrificial template AR
samples for three sputter etch conditions: sample 2 (9A), sample 7
(9B), and sample 15 (9C).
Backfill Coating
[0156] A section of the sputter etch film was attached to a 2 in
.times.3 in microscope slide with tape. PermaNew 6000 (available
from California Hardcoating Company, Chula Vista, Calif.) was
diluted to 15% w/w in 80:20 IPA/butanol, brought to room
temperature, and filtered through a 1.0 um filter. The sample of
the treated film was coated with the PermaNew solution, which was
applied to the film sample by spin coating on a Cee 200X Precision
spin coater (Brewer Science, Inc. Rolla, Mo.). The spin parameters
were 500 rpm for 3 sec (solution application), and 2000 rpm for 30
sec, then 500 rpm for 10 seconds. Approximately 5 milliliters of
the PermaNew solution was applied to the replicated film during the
solution application step of the spin cycle. The coated sample was
placed in a oven at 80.degree. C. for four hours to cure the
PermaNew coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0157] Glass slides, 2 in.times.3 in, were cleaned with IPA and a
lint free cloth. A slide was mounted on the vacuum chuck of a spin
coater. The spin coater was programmed for 500 RPM for 5 seconds
(coating application step) then 1500 RPM for 10 sec (spin step),
then 500 RPM for 60 seconds (dry step).
[0158] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the glass slide during the coating application portion
of the spin cycle. The slide was then removed from the spin coater
and allowed to dry.
Lamination
[0159] The film was laminated at 180.degree. F. (PermaNew coating
side toward the sacrificial adhesive layer, to the IOA/AA coated
glass slide using a thermal film laminator (GBC Catena 35, GBC
Document Finishing, Lincolnshire, Ill.). The laminated sample was
removed from the laminator and allowed cool to room
temperature.
Bake-Out
[0160] After lamination, the PET support was separated from the
laminated layers, leaving the Perma-New, QPAC, and IOA/AA layers
adhered to the glass slide. The sample was placed in a box furnace
(Lindberg Blue M box furnace model BF51732PC-1, Asheville N.C.,
USA) and brought from 25.degree. C. to 300.degree. C. at a rate of
approximately 10.degree. C./min. The furnace was held at
300.degree. C. for thirty minutes, then heated to 500.degree. C. at
a rate of approximately 10.degree. C./min and held for one hour to
decompose the IOA/AA and the QPAC. The furnace and sample are then
allowed to cool down to ambient temperature. The resulting clean
inorganic nanostructure was shown in FIG. 10A-C illustrating a top
view on the left and a side view on the right of baked out AR
nanostructures for sample 2 (10A), sample 7 (10B) and sample 15
(10C).
Measurement of Average Reflectance at Near Normal Incidence
[0161] The average % reflection average corrected % reflection were
measured as described in Example 1. The results of the average %
reflection and average corrected % reflection are shown in Table
3.
TABLE-US-00003 TABLE 3 % reflection and corrected % reflection for
unstructured QPAC AR on glass Average Average Corrected Sample %
Reflection % Reflection QPAC AR 2 3.61 2.81 QPAC AR 7 1.50 0.70
QPAC AR 15 3.15 2.35
Example 4
Unstructured SR540 AR
Template
[0162] The substrate film was an 2 mil unprimed PET film coated
with 8 micron thick PMMA copolymer (75 wt. %
polymethylmethacrylate, 25 wt. % polyethyl acrylate, "PRD510-A",
Altuglas Inc.) using a roll-to-roll web coating process. The
replicating resin was ethoxylated bisphenol A dimethacrylate
(SR540, available from Sartomer Company, Exton, Pa.) with a
photoinitator package comprising 0.5% Darocur 1173 and 0.1% TPO.
Flat sacrificial films were prepared by coating the substrate film,
at a web speed of 10 ft/min (about 3 meters/min.), and the coated
web was pressed against unprimed PET using a nip heated to
90.degree. F. (43.degree. C.) and a pressure of 30 psi. The resin
was then cured using two banks of FUSION high intensity UV D-bulb
lamps (obtained from Fusion Systems, Rockville, Md.), one set at
600 watt/2.5 cm (100% power setting), and the other set at 360
watt/2.5 cm (60% power setting). The cured resin was then separated
from the unprimed PET and wound into a roll.
Sputtered-Etch AR Coatings
[0163] The samples were sputter etched with the following
conditions outlined in Table 4, and selected samples top view SEM
photos are shown in FIG. 11A (sample A[6]), FIG. 11B (sample B[18])
and FIG. 11C (sample C[57]).
TABLE-US-00004 TABLE 4 Process conditions for sputter etch samples.
TMS Flow O.sub.2 Flow Pressure Power Time Sample Sccm sccm mTorr
watts seconds Sample A[6] 20 500 5 6000 15.58 Sample B[18] 20 500 5
6000 46.75 Sample C[57] 20 500 5 6000 148.05
Backfill Coating
[0164] A section of the sputter etch film was attached to a 2
in.times.3 in microscope slide with tape. PermaNew 6000 (available
from California Hardcoating Company, Chula Vista, Calif.) was
diluted to 15% w/w in 80:20 IPA/butanol, brought to room
temperature, and filtered through a 1.0 um filter. The sample of
the treated film was coated with the PermaNew solution, which was
applied to the film sample by spin coating on a Cee 200X Precision
spin coater (Brewer Science, Inc. Rolla, Mo.). The spin parameters
were 500 rpm for 3 sec (solution application), and 2000 rpm for 30
sec, then 500 rpm for 10 seconds. Approximately 5 milliliters of
the PermaNew solution was applied to the replicated film during the
solution application step of the spin cycle. The coated sample was
placed in an oven at 80.degree. C. for four hours to cure the
PermaNew coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0165] Glass slides, 2 in.times.3 in, were cleaned with IPA and a
lint free cloth. The slide was mounted on the vacuum chuck of a
spin coater. The spin coater was programmed for 500 RPM for 5
seconds (coating application step) then 1500 RPM for 10 sec (spin
step), then 500 RPM for 60 seconds (dry step).
[0166] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the glass slide during the coating application portion
of the spin cycle. The slide was then removed from the spin coater
and allowed to dry.
Lamination
[0167] The film was laminated at 180.degree. F. (PermaNew coating
side toward the sacrificial adhesive layer) to the IOA/AA coated
glass slide using a thermal film laminator (GBC Catena 35, GBC
Document Finishing, Lincolnshire, Ill.). The laminated sample was
removed from the laminator and allowed cool to room
temperature.
Bake-Out
[0168] After lamination, the PET support was separated from the
laminated layers, leaving the Perma-New, SR540, co-PMMA, and IOA/AA
layers adhered to the glass slide. The sample was placed in a box
furnace (Lindberg Blue M box furnace model BF51732PC-1, Asheville
N.C., USA) and brought from 25.degree. C. to 300.degree. C. at a
rate of approximately 10.degree. C./min. The furnace was held at
300.degree. C. for thirty minutes, then heated to 500.degree. C. at
a rate of approximately 10.degree. C./min and held for one hour to
decompose the IOA/AA, PMMA copolymer and the SR540. The furnace and
sample were then allowed to cool down to ambient temperature.
[0169] The resulting clean inorganic nanostructure samples top view
SEM photos are shown in FIG. 12A (sample A), FIG. 12B (sample B)
and FIG. 12C (sample C).
Measurement of Average Reflectance at Near Normal Incidence
[0170] The average % reflection average corrected % reflection were
measured as described in Example 1. The results of the average %
reflection and average corrected % reflection are shown in Table
5.
TABLE-US-00005 TABLE 5 Average % reflection and average corrected %
reflection for the unstructured SR540 AR on glass Average Average
Corrected Sample % Reflection % Reflection A 4.18 3.38 B 4.48 3.68
C 1.56 0.76
Example 5
Unstructured SR540 AR on Sapphire
Template
[0171] The substrate film was an 2 mil unprimed PET film coated
with 8 micron thick PMMA copolymer (75 wt. %
polymethylmethacrylate, 25 wt. % polyethyl acrylate, "PRD510-A",
Altuglas Inc.) using a roll-to-roll web coating process. The
replicating resin was ethoxylated bisphenol A dimethacrylate
(SR540, available from Sartomer Company, Exton, Pa.) with a
photoinitator package comprising 0.5% Darocur 1173 and 0.1% TPO.
Flat sacrificial films were prepared by coating the substrate film,
at a web speed of 10 ft/min (about 3 meters/min.), and the coated
web was pressed against unprimed PET using a nip heated to
90.degree. F. (43.degree. C.) and a pressure of 30 psi. The resin
was then cured using two banks of FUSION high intensity UV D-bulb
lamps (obtained from Fusion Systems, Rockville, Md.), one set at
600 watt/2.5 cm (100% power setting), and the other set at 360
watt/2.5 cm (60% power setting). The cured resin was then separated
from the unprimed PET and wound into a roll.
Sputtered-Etch AR Coatings
[0172] The samples are sputter etched with the following conditions
shown in Table 6.
TABLE-US-00006 TABLE 6 Process conditions for sputter etch Sample
A(27). TMS Flow O.sub.2 Flow Pressure Power Time Sample Sccm sccm
mTorr watts seconds Sample A(27) 20 500 5 6000 70.12
Synthesis of Backfill Material
[0173] A 500 ml 3-neck round bottom flask was charged with 175.0
grams of a 45.4 wt % solids dispersion of 10 nm zirconia particles
(prepared as described in U.S. Pat. No. 7,241,437 and U.S. Pat. No.
6,376,590). Next, the flask was equipped with a stir bar, stir
plate, condenser, heating mantle, thermocouple and temperature
controller. With the batch mixing, 78.8 grams
methyltriethoxysilane, MTES, (Alfa Aesar, Ward Hill, Mass.) and
80.0 grams anhydrous alcohol (95/5 v/v ethanol/2-propanol, Avantor
Performance Materials Inc, Center Valley, Pa.) were added to the
batch. The batch was held for 1 hour at room temperature with
mixing. After 1 hour, the batch heated to 70.degree. C. and held at
70.degree. C. for 4 hours with mixing. After the 4 hour hold, the
batch was allowed to cool to room temperature. This dispersion was
filtered through a 1 micron 37 mm syringe filter (Pall Life
Sciences, Ann Arbor, Mich.) into a 32 ounce glass bottle. The final
sample was a low viscosity, slightly hazy, translucent dispersion
and was measured to be 32.9 wt % solids.
Backfill Coating
[0174] A section of the sputter etch film was attached to a 2
in.times.3 in microscope slide with tape. The backfill material
synthesized above was diluted to 7.5% w/w in butanol, brought to
room temperature, and filtered through a 1.0 um filter. The sample
of the treated film was coated with the backfill material, which
was applied to the film sample by spin coating on a Cee 200X
Precision spin coater (Brewer Science, Inc. Rolla, Mo.). The spin
parameters were 500 rpm for 3 sec (solution application), and 5000
rpm for 30 sec, then 500 rpm for 10 seconds. Approximately 5
milliliters of the backfill solution was applied to the replicated
film during the solution application step of the spin cycle. The
coated sample was placed in an oven at 80.degree. C. for four hours
to cure the backfill coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0175] Sapphire substrates were cleaned with IPA and a lint free
cloth. The substrate was mounted on the vacuum chuck of a spin
coater. The spin coater as programmed for 500 RPM for 5 seconds
(coating application step) then 1500 RPM for 10 sec (spin step),
then 500 RPM for 60 seconds (dry step).
[0176] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the sapphire substrate during the coating application
portion of the spin cycle. The substrate was then removed from the
spin coater and allowed to dry.
Lamination
[0177] The film was laminated at 180.degree. F. (backfill coating
toward the sacrificial adhesive layer) to the IOA/AA coated
sapphire substrate using a thermal film laminator (GBC Catena 35,
GBC Document Finishing, Lincolnshire, Ill.). The laminated sample
was removed from the laminator and allowed cool to room
temperature.
Bake-Out
[0178] After lamination, the PET support was separated from the
laminated layers, leaving the backfill, SR540, co-PMMA, and IOA/AA
layers adhered to the sapphire substrate. The sample was placed in
a box furnace (Lindberg Blue M box furnace model BF51732PC-1,
Asheville N.C., USA) and brought from 25.degree. C. to 300.degree.
C. at a rate of approximately 10.degree. C./min. The furnace was
held at 300.degree. C. for thirty minutes, then heated to
500.degree. C. at a rate of approximately 10.degree. C./min and
held for one hour to decompose the IOA/AA, PMMA copolymer and the
SR540. The furnace and sample were then to cool down to ambient
temperature. The resulting clean inorganic nanostructure on
sapphire is shown in FIG. 13.
Measurement of Average Reflectance at Near Normal Incidence
[0179] The average % reflection average corrected % reflection were
measured as described in Example 1. The results of the average %
reflection and average corrected % reflection are shown in Table
7.
TABLE-US-00007 TABLE 7 Average % reflection and average corrected %
reflection for the unstructured SR540 AR on Sapphire. Average
Average Corrected Sample % Reflection % Reflection SR 540 27
Sapphire AR 6.62 5.25
Example 6
600 nm Structured SR540 AR
Structured Template
[0180] The substrate used was a primed 0.002 inch (0.051 mm) thick
PET. The replicating resin was a 75/25 blend of SR 399 and SR238
(both available from Sartomer USA, Exton, Pa.) with a photoinitator
package comprising 1% Darocur 1173 (Available from Ciba, Tarrytown,
N.Y.), 1.9% triethanolamine (available from Sigma-Aldrich, St.
Louis, Mo.), and 0.5% OMAN071 (available from Gelest, Inc.
Morrisville, Pa.). Replication of the resin was conducted at 20
ft/min (6.1 m/min) with the replication tool temperature at 137 deg
F. (58 deg C.). Radiation from a Fusion "D" lamp operating at 600
W/in was transmitted through the film to cure the resin while in
contact with the tool. The replication tool was patterned with a
600 nm pitch linear sawtooth groove.
[0181] The replicated template film was primed in a plasma chamber
using argon gas at a flow rate of 250 standard cc/min (SCCM), and a
pressure of 25 mTorr and RF power of 1000 Watts for 30 seconds.
Subsequently, a release coated tool surface was prepared by
subjecting the samples to a tetramethylsilane (TMS) plasma at a TMS
flow rate of 150 SCCM but no added oxygen, which corresponded to an
atomic ratio of oxygen to silicon of about 0. The pressure in the
plasma chamber was 25 mTorr, and the RF power of 1000 Watts was
used for 10 seconds.
[0182] The substrate film was an 2 mil unprimed PET film coated
with 8 micron thick PMMA copolymer (75 wt. %
polymethylmethacrylate, 25 wt. % polyethyl acrylate, "PRD510-A",
Altuglas Inc.) using a roll-to-roll web coating process. The
replicating resin was ethoxylated bisphenol A dimethacrylate
(SR540, available from Sartomer Company, Exton, Pa.) with a
photoinitator package comprising 0.5% Darocur 1173 and 0.1%
TPO.
[0183] Structured sacrificial films were prepared by coating the
substrate film, at a web speed of 10 ft/min (about 3 meters/min.),
and the coated web was pressed against the release coated,
replicated template film using a nip heated to 90.degree. F.
(43.degree. C.) and a pressure of 30 psi. The structured resin was
then cured using two banks of FUSION high intensity UV D-bulb lamps
(obtained from Fusion Systems, Rockville, Md.), one set at 600
watt/2.5 cm (100% power setting), and the other set at 360 watt/2.5
cm (60% power setting). The cured, structured resin was then
separated from the polymer tool and wound into a roll. The
resulting structured film had prisms of 540 nm height with a
periodicity of 600 nm.
Sputtered-Etch AR Coatings
[0184] The samples are sputter etched with the conditions shown for
Sample D in Table 8.
TABLE-US-00008 TABLE 8 Process conditions for sputter etch Sample
D. TMS Flow O.sub.2 Flow Pressure Power Speed Sample Sccm sccm
mTorr watts Feet/min Sample D 20 500 6 6000 2.43
Backfill Coating
[0185] A section of the sputter etch film was attached to a 2
in.times.3 in microscope slide with tape. PermaNew 6000 (available
from California Hardcoating Company, Chula Vista, Calif.) was
diluted to 15% w/w in 80:20 IPA/butanol, brought to room
temperature, and filtered through a 1.0 um filter. The sample of
the treated film was coated with the PermaNew solution, which was
applied to the film sample by spin coating on a Cee 200X Precision
spin coater (Brewer Science, Inc. Rolla, Mo.). The spin parameters
are 500 rpm for 3 sec (solution application), and 2000 rpm for 30
sec, then 500 rpm for 10 seconds. Approximately 5 milliliters of
the PermaNew solution was applied to the replicated film during the
solution application step of the spin cycle. The coated sample was
placed in an oven at 80.degree. C. for four hours to cure the
PermaNew coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0186] Glass slides, 2 in.times.3 in, were cleaned with IPA and a
lint free cloth. A slide was mounted on the vacuum chuck of a spin
coater. The spin coater was programmed for 500 RPM for 5 seconds
(coating application step) then 1500 RPM for 10 sec (spin step),
then 500 RPM for 60 seconds (dry step).
[0187] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the glass slide during the coating application portion
of the spin cycle. The slide was then removed from the spin coater
and allowed to dry.
Lamination
[0188] The film was laminated at 180.degree. F., PermaNew coating
side down, to the IOA/AA coated glass slide using a thermal film
laminator (GBC Catena 35, GBC Document Finishing, Lincolnshire,
Ill.). The laminated sample was removed from the laminator and
allowed cool to room temperature.
Bake-Out
[0189] After lamination, the PET support was separated from the
laminated layers, leaving the Perma-New, SR540, co-PMMA, and IOA/AA
layers adhered to the glass slide. The sample was placed in a box
furnace (Lindberg Blue M box furnace model BF51732PC-1, Asheville
N.C., USA) and brought from 25.degree. C. to 300.degree. C. at a
rate of approximately 10.degree. C./min. The furnace was held at
300.degree. C. for thirty minutes, then heated to 500.degree. C. at
a rate of approximately 10.degree. C./min and held for one hour to
decompose the IOA/AA, PMMA copolymer and the SR540. The furnace and
sample were then to cool down to ambient temperature. The resulting
clean inorganic nanostructure is shown in FIG. 14A (top view) and
FIG. 14B (side view).
Example 7
3 Micrometer Structured SR540 AR
Structured Template
[0190] The substrate used was a primed 0.002 inch (0.051 mm) thick
PET. The replicating resin was a 75/25 blend of SR 399 and SR238
(both available from Sartomer USA, Exton, Pa.) with a photoinitator
package comprising 1% Darocur 1173 (Available from Ciba, Tarrytown,
N.Y.), 1.9% triethanolamine (available from Sigma-Aldrich, St.
Louis, Mo.), and 0.5% OMAN071 (available from Gelest, Inc.
Morrisville, Pa.). Replication of the resin was conducted at 20
ft/min (6.1 m/min) with the replication tool temperature at 137 deg
F. (58 deg C.). Radiation from a Fusion "D" lamp operating at 600
W/in was transmitted through the film to cure the resin while in
contact with the tool. The replication tool was patterned with a 3
micron pitch linear sawtooth groove.
[0191] The replicated template film was primed in a plasma chamber
using argon gas at a flow rate of 250 standard cc/min (SCCM), a
pressure of 25 mTorr and RF power of 1000 Watts for 30 seconds.
Subsequently, a release coated tool surface was prepared by
subjecting the samples to a tetramethylsilane (TMS) plasma at a TMS
flow rate of 150 SCCM but no added oxygen, which corresponded to an
atomic ratio of oxygen to silicon of about 0. The pressure in the
plasma chamber was 25 mTorr, and the RF power of 1000 Watts was
used for 10 seconds.
Sacrificial Template Coating
[0192] The substrate film was an 2 mil unprimed PET film coated
with 8 micron thick PMMA copolymer (75 wt. %
polymethylmethacrylate, 25 wt. % polyethyl acrylate, "PRD510-A",
Altuglas Inc.) using a roll-to-roll web coating process. The
replicating resin was ethoxylated bisphenol A dimethacrylate
(SR540, available from Sartomer Company, Exton, Pa.) with a
photoinitator package comprising 0.5% Darocur 1173 and 0.1% TPO.
The resin was coated between the base film and a tool film in a nip
with a fixed gap of 0 mil. The laminate was cured with radiation
from a Fusion "D" lamp operating at 600 W/in as transmitted through
the film to cure the resin while in contact with the tool. The tool
film was then removed from the sample, resulting in a structured
resin coating on PET.
Sputtered-Etch AR Coatings
[0193] The samples are sputter etched with the conditions shown for
Sample E in Table 9.
TABLE-US-00009 TABLE 9 Process conditions for sputter etch Sample
E. TMS Flow O.sub.2 Flow Pressure Power Speed Sample Sccm sccm
mTorr watts Feet/min Sample E 20 500 6 6000 2.43
Backfill Coating
[0194] A section of the sputter etch film was attached to a 2
in.times.3 in microscope slide with tape. PermaNew 6000 (available
from California Hardcoating Company, Chula Vista, Calif.) was
diluted to 15% w/w in 80:20 IPA/butanol, brought to room
temperature, and filtered through a 1.0 um filter. The sample of
the treated film was coated with the PermaNew solution, which was
applied to the film sample by spin coating on a Cee 200X Precision
spin coater (Brewer Science, Inc. Rolla, Mo.). The spin parameters
were 500 rpm for 3 sec (solution application), and 2000 rpm for 30
sec, then 500 rpm for 10 seconds. Approximately 5 milliliters of
the PermaNew solution was applied to the replicated film during the
solution application step of the spin cycle. The coated sample was
placed in a oven at 80.degree. C. for four hours to cure the
PermaNew coating, then cooled to room temperature.
Sacrificial Adhesive Layer Coating
[0195] Glass slides, 2 in.times.3 in, were cleaned with IPA and a
lint free cloth. A slide was mounted on the vacuum chuck of a spin
coater. The spin coater was programmed for 500 RPM for 5 seconds
(coating application step) then 1500 RPM for 10 sec (spin step),
then 500 RPM for 60 seconds (dry step).
[0196] A solution of IOA/AA Optically Clear Adhesive (90%
isooctylacrylate, 10% acrylic acid, as described in US reexam
patent 24,906 (Ulrich) was diluted to 5 wt % in 66:33 ethyl
acetate/heptane. Approximately 1-2 mL of the IOA/AA solution was
applied to the glass slide during the coating application portion
of the spin cycle. The slide was then removed from the spin coater
and allowed to dry.
Lamination
[0197] The film was laminated at 180.degree. F. (PermaNew coating
side toward the sacrificial adhesive layer) to the IOA/AA coated
glass slide using a thermal film laminator (GBC Catena 35, GBC
Document Finishing, Lincolnshire, Ill.). The laminated sample was
removed from the laminator and allowed cool to room
temperature.
Bake-Out
[0198] After lamination, the PET support was separated from the
laminated layers, leaving the Perma-New, SR540, co-PMMA, and IOA/AA
layers adhered to the glass slide. The sample was placed in a box
furnace (Lindberg Blue M box furnace model BF51732PC-1, Asheville
N.C., USA) and brought from 25.degree. C. to 300.degree. C. at a
rate of approximately 10.degree. C./min. The furnace was held at
300.degree. C. for thirty minutes, then heated to 500.degree. C. at
a rate of approximately 10.degree. C./min and held for one hour to
decompose the IOA/AA, PMMA copolymer and the SR540. The furnace and
sample were then to cool down to ambient temperature. The resulting
clean inorganic nanostructure is shown in FIG. 15A (top view) and
FIG. 15B (side view) and FIG. 15C (magnified side view).
[0199] Thus, embodiments of LAMINATION TRANSFER FILMS FOR FORMING
ARTICLES WITH ANTIREFLECTIVE STRUCTURES are disclosed.
[0200] All references and publications cited herein are expressly
incorporated herein by reference in their entirety into this
disclosure, except to the extent they may directly contradict this
disclosure. Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that a variety of alternate and/or equivalent
implementations can be substituted for the specific embodiments
shown and described without departing from the scope of the present
disclosure. This application is intended to cover any adaptations
or variations of the specific embodiments discussed herein.
Therefore, it is intended that this disclosure be limited only by
the claims and the equivalents thereof. The disclosed embodiments
are presented for purposes of illustration and not limitation.
* * * * *