Note: Descriptions are shown in the official language in which they were submitted.
CA 02833843 2013-11-19
SWITCHABLE ARTICLES AND METHODS OF MAKING SAME
TECHNICAL FIELD
[0001] The present disclosure relates to switchable articles, and methods of
making switchable
articles.
BACKGROUND
[0002] Glass is an excellent material for transparent articles such as
architectural and vehicle
glazings, lenses, opthalmic devices and the like, but brings with it several
drawbacks in terms of
weight and a potential cause of significant injury in the case of impact or
breakage. Introduction
of tempered and laminated glass has had a positive impact on the safety aspect
of using glass, but
the issue of weight remains. As vehicle components are redesigned to reduce
weight (in an
effort to reduce fuel consumption, cost and improve safety), plastic glazing
becomes attractive.
Similarly, use of plastic visors and lenses, in masks, helmets, goggles and
other eyewear reduces
weight, and may allow for greater variety in shape and configuration, as
plastics can be more
readily molded.
[0003] Many plastics and polymers that provide the desired transparency for
use in vehicle and
automotive glazings are challenged by degradation and instability over time
(yellowing), and the
ease of surface marking by abrasion incurred with normal use. Various UV
blocking and
abrasion resistant coating systems have been developed to overcome these
disadvantages. Such
plastics may be colored or tinted, or have colored layers applied to them (in
part to disguise the
yellowing and make abrasions less apparent), but these static layers do not
provide a user with
the ability to adjust the transmitted light.
[0004] Some electrochromic materials ("light valves" e.g. suspended particle
devices US
7361252) may be suitable for preparing as a flexible film or layer, but may
not tolerate
temperatures necessary for thermoforming or injection molding (US 7361252).
Other
electrochromic materials may be tolerant of elevated temperatures, but their
manufacture may
not be amenable to application to a flexible film or moldable surface. Some
electrochromic
materials applied to a glass layer (e.g. those of SAGE Electrochromics) may
employ specialized
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coating processes such as sputtering or chemical vapor deposition, and the
fine layers formed in
this manner may be cracked or disrupted when molded or shaped.
SUMMARY
[0005] In accordance with one aspect, there is provided a switchable article,
comprising: a
transparent plastic layer; a switchable film; and optionally, a heat-
attenuating layer. The
switchable article may be prepared by any suitable method including
thermoforming, vacuum
forming, injection molding or the like.
[0006] In accordance with another aspect, there is provided an injection-
molded switchable
article comprising a transparent plastic layer, a switchable film and an
adhesive layer.
[0007] In accordance with another aspect, there is provided a thermoformed,
switchable article,
comprising a transparent plastic layer and a switchable film. The thermoformed
switchable
article may further comprise an adhesive layer.
[0008] In accordance with another aspect, there is provided a method of
preparing a switchable
article comprising: providing a switchable film; optionally, disposing a heat
attenuating layer on
a side of the switchable film; and molding a transparent plastic layer in
contact with the heat
attenuating layer. The step of molding may be preceded by a step of placing
the switchable film
in an injection mold, with the heat attenuation layer facing the interior of
the injection mold.
[0009] The switchable film may comprise a switching material disposed between
a first and a
second substantially transparent substrates, each substrate having disposed
thereon a transparent
conductive layer, the transparent conductive layers each in contact with the
switching material.
The switching material may comprise one or more compounds having
electrochromic and
photochromic properties.
[0010] In accordance with another aspect, the switchable article is an
architectural glazing, a
vehicle glazing, or an opthalmic device such as a lens, visor, goggle, etc.
[0011] In accordance with another aspect, the switchable article is a vehicle
glazing.
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[0012] In accordance with another aspect, there is provided an article as
described herein, with
reference to the Figures.
[0013] This summary does not necessarily describe the entire scope of all
aspects. Other
aspects, features and advantages will become apparent to those of ordinary
skill in the art upon
review of the following description of specific embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] These and other features will become more apparent from the following
description.
[0015] Figure 1 shows a top view of a switchable article according to an
embodiment.
[0016] Figure 2 shows a cross-sectional schematic diagram of a switchable
article along line Y-
Y.
[0017] Figure 3 shows a flowchart of steps of a method for producing a
switchable article,
according to an embodiment.
[0018] Figure 4a shows a cross sectional schematic diagram of a portion of a
switchable article
in a mold, according to an embodiment.
[0019] Figure 4b shows a cross sectional schematic diagram of a switchable
article in a mold,
according to an embodiment.
[0020] Figure 5 shows a schematic diagram of electrical leads and a controller
of a switchable
article, according to an embodiment.
[0021] Figure 6 shows a top view schematic of a switchable film, according to
an embodiment.
[0022] Figure 7 shows a cross-sectional diagram of the switchable film, along
line Z-Z.
DETAILED DESCRIPTION
[0023] The disclosure provides, in part, a switchable article, comprising: a
transparent plastic
layer; a switchable film; and optionally a heat-attenuating layer. The
disclosure further provide,
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in part, a method of preparing a switchable article comprising: providing a
switchable film;
optionally disposing a heat attenuating layer on a side of the switchable
film; and molding a
transparent plastic layer in contact with the heat attenuating layer. A
switchable article may be an
architectural or vehicle glazing, lens, goggle, visor, or other transparent or
partially transparent
article where it is desired to alter the transmitted light.
[0024] Switchable glazing may be incorporated into vehicles (automobiles,
trains, planes, water-
going vessels or the like) or architectural installations (buildings, houses
or the like). A
switchable glazing may be configured for appropriate size and location for
mounting in a vehicle
as a 'sunroof' or window (rear, side, windshield etc). The glazing may be
transparent, or
substantially, with or without tinting or coloration. The glazing may be
opaque, or substantially
opaque, as desired. The vehicle or architectural installation may further
include a controller, or
components for accessing a controller, to control the degree of transparency
or opacity of the
glazing, as may be desired. The controller may be controlled by a user, or
controlled in an
automated manner (e.g. in response to the environment or pre-programmed
criteria), or a
combination of the two. The glazing may have markings or decorations on a
portion of the area.
While some embodiments may refer to a glazing, it will be apparent that the
methods and
properties addressed may be applicable to other switchable articles.
[0025] Inclusion of a UV blocking component in the switchable article may
enhance weathering
performance of the article, and may be protective of the interior of the
vehicle or building where
the article is installed by reducing the amount, and wavelength range, of UV
light that reaches
the interior. Inclusion of an infrared (IR) blocking component in the
switchable article may be
useful in controlling the temperature of the article (dependent in part on the
positioning of the
infrared blocking component in the article layers), and may also be useful in
reducing the heat
gain of the interior of the vehicle or building where the article is installed
by reducing the
amount of infrared radiation reaching the interior. Where the infrared
blocking component is
positioned behind the switchable film (relative to the incident light), the
article may accumulate
heat, which may serve to increase the temperature of the switchable film.
[0026] Referring to Figure 1, a view of a switchable glazing according to one
embodiment is
shown generally at 20. The glazing 22 is substantially transparent with
electrical lead 24
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(comprising leads 142 and 144) connecting the switchable film of the glazing
to the poles of a
power source (not shown), via a controller 26. In the embodiment shown, the
glazing may have a
solid circumferential band 30 with an adjacent, patterned band 28 adjacent,
around the periphery
of the glazing. The bands may be applied with ink to the glazing during
manufacture, or after the
glazing is constructed.
[0027] Referring to Figure 2, a cross sectional schematic diagram of a
switchable glazing
according to one embodiment is shown generally at 10. A heat-attenuating layer
12 is disposed
between a switchable film 14, and a transparent plastic layer 16, providing a
switchable glazing
having exposed sides A and B. Side A, side B or both sides A and B may further
have applied
thereto one or more layers comprising a coating system. The coating system may
comprise one
or more of an abrasion resistant layer, a weathering protective layer or the
like, and may further
include a primer layer.
[0028] Switchable film
[0029] . A switchable film comprises a first and a second substrate, a first
and a second electrode
disposed on the surface of at least one of the substrates and a switching
material disposed
between first and second substrates and in contact with the switching
material. The switching
material may comprise one or more compounds having electrochromic and
photochromic
properties. The switchable film may be capable of transitioning from a light
state to a dark state
on exposure to UV radiation and from a dark state to alight state with
exposure to visible light, or
application of an electric voltage.
[0030] Examples of switchable films ("optical filter") are described in
W02010/142019, and
methods of constructing a switchable film are also addressed generally herein.
Substrates may
be colorless or colored, transparent or reflective. The color may be selected
to be
complementary to that of the switching material in a dark state, light state
or dark state and light
state, and/or complementary to the color of the site where the switchable
article is or will be
used, or installed. For example, the switchable film may be of a color
complementary to a
vehicle or building envelope, frame of an opthalmic device or helmet or mask.
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[0031] Substrates: A substrate may be glass or plastic ("organic glass") -
float glass, tempered
glass, toughened, or chemically -strengthened glass, an organic glass or the
like. A substrate
may be flexible (e.g. plastic film, glass film, or glass microsheet) or rigid.
An organic glass is an
amorphous, solid glasslike material made of transparent plastic. Organic glass
may provide
advantages such as toughness, reduced weight, improved thermal insulation,
ease of colour
modification (incorporation of colorants in the plastic when molding) or the
like. Examples of
organic glasses or plastics include polycarbonate, acrylonitrile butadiene
styrene, polyesters
(polyethylene terephthalate (PET), modified PET), acrylics (polymethyl
methacrylate) or
modified acrylics (e.g. imidized, rubber toughened, stretched or the like),
polyester carbonate,
allyl diglycol carbonate, polyether imide, polyether sulfone (polysulfone,
PSU), cellulose
acetate, cellulose butyrate, cellulose propionate, polymethyl pentene,
polyolefins, nylon,
polyphenylsulfone, polyarylate, polystyrene, polycarbonate, polysulfone,
polyurethane,
polyvinyl chloride, styrene acrylonitrile , ethylene vinyl acetates, or the
like. Where the one or
more glass is a rigid or flexible plastic, one or more of the components of
the switching material
may be selected to be immiscible, or insoluble, with one or more of the
components of the
substrate, to prevent diffusion into the substrate. For example, a solvent or
plasticizer used in
some embodiments described herein may be immiscible, or insoluble, with a
plasticizer used in
an organic glass. Combinations of substrates and switching material materials
with one or more
immiscible components may be selected in this way. In some embodiments, a
layer of plastic
(e.g. PET film) may be included between the substrate and the switching
material, to prevent
diffusion of plasticizers or other components into the substrate. Substrates
may independently be
of any suitable thickness. Substrates may independently be coated with, or
comprise anti-scratch
layers, security films, heat or infrared reflecting or absorbing materials, or
UV reflecting or
absorbing materials or the like. A substrate may be tinted or may comprise
coatings or additives
to block some wavelengths of light (e.g. portions of UV, VIS, IR incident
light or the like)..
Color and depth of coloration of tinted glass may be selected to achieve
certain levels of light
transmission (visible, UV or IR), or to harmonize with the site of
installation e.g. exterior
automotive paint, building envelope, or to harmonize with other components of
a laminated
glass. Glass color may be described with reference to colour values L*a* and
b*, and/or light
transmittance (LTA).
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[0032] The substrate may be of uniform or varying thickness, and of any
suitable dimension.
For example, the substrate may have a thickness from about 0.01 mm to about 10
mm, or any
amount or range therebetween, for example 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7,
8, 9 or 10 mm, or
from about 0.012 mm to about 10 mm, or from about 0.5 mm to 10 mm, or from
about 1 mm to 5
mm, or from about 0.024 mm to about 0.6 mm, or from about 0.051 mm (2 mil) to
about 0.178
mm (7 mil). In some embodiments, the thickness and/or material of a first
substrate differs from
the thickness and/or material of a second substrate.
[0033] Conductive coatings may include a transparent conducting oxide (TCO)
such as
indium tin oxide (ITO), fluorine tin oxide (FTO) or the like, metal or metal
oxide coatings (e.g.
silver, gold or the like), transparent conducting polymers, or other
substantially transparent
conductive coatings. Examples of transparent substrates with conductive
coatings include ITO-
coated glass, or FTO-coated glass (e.g. TEC glass from Pilkington). For
embodiments
comprising co-planar electrodes, the electrode pattern (e.g. interdigitated
electrodes such as that
illustrated in Figure 3c) may be etched into a conductive coating on the
substrate, or printed on a
substrate. In some embodiments, a substrate with a conductive layer may be ITO-
coated glass,
or ITO-coated PET.
[0034] In some embodiments, both first and second electrodes may be disposed
on one
substrate. First and second coplanar electrodes may be etched into the
conductive coating or
printed on the surface of the substrate in a suitable pattern e.g., a
discontinuous conductive
coating providing first and second electrodes on the same substrate. In such
embodiments, a
second substrate may lack a conductive coating, and first and second busbars
and electrical
connectors may be disposed on the first and second electrodes of the first
substrate. PCT
publication W02012/079159 describes coplanar electrode configurations that may
be useful in
some embodiments.
[0035] Switching material: examples of switching material and methods for
preparing are
described in PCT/CA2013/000522, with a priority claim to US 61/652,466 filed
May 29, 2012;
and PCT/CA2013/000339, with a priority claim to US 61/706,001 filed September
26, 2012. In
some embodiments, the switching material may be disposed upon a first
substrate, or
'sandwiched' between a first substrate and a second substrate. The switching
material may be a
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liquid, a gel, a solid or a semi-solid, and may be formed in a layer of
suitable thickness. Suitable
thickness of a switchable film may be dependent on one or more of a desired
light transmission
in a dark state, a faded state or both a dark state and a faded state; a
desired optical clarity (haze),
or a desired thickness of a finished switchable film or switchable article.
Examples of thickness
ranges include from about 0.1 micron (micrometer, gm) to about 100 microns, or
any amount or
range therebetween, for example from about 10 microns to about microns, or
from about 0.1
micron to about 10 microns, or from about 0.5 micron to about 5 microns, or
from about 0.5
micron to about 2.5 micron or any amount or range therebetween. In some
embodiments, the
layer of switching material is of uniform, or substantially uniform,
thickness. In some
embodiments, the layer of switching material is of non-uniform thickness.
[0036] A switchable film, or switchable article comprising a switchable film,
may have a
switching time (to transition from a dark state to a light state, or from a
light state to a dark state)
of from about 10 seconds to about 5 minutes, or any amount or range
therebetween. Switching
time may be altered by varying one or more of thickness of switching material
or composition of
the switching material.
[0037] A switching material may comprise a compound having both electrochromic
and
photochromic properties. With such compounds present, the switching material
may darken (e.g.
reach a 'dark state') when exposed to of light in the UV and/or VIS range
(e.g. from about 350 to
about 450 nm), and may lighten ("fade", achieve a 'light state") when exposed
to a voltage, or
when exposed to light that excludes wavelengths below about 475 nm. Such a
switching material
may be alternately described as an auto-darkening material. In some
embodiments, the switching
material may fade upon exposure to selected wavelengths of visible (VIS)
light, without sacrifice
of the ability to be electrofaded when restored to a darkened state. In some
embodiments, the
switching material may darken when exposed to light comprising wavelengths
from about 350
nm to about 450 nm, or any amount or range therebetween, and may lighten when
a voltage is
applied. The switching material may be substantially optically clear, or
demonstrate no more
than 1%, no more than 2% or no more than 3% haze in both faded and dark
states.
[0038] A switching material may comprise (by weight percent) about 3 to about
20 parts
polymer or polymer matrix, about 60 to about 85 parts solvent, about 0.1 to
about 10 parts ionic
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material (e.g. salt or the like), about 0.1 to about 30 parts of a compound
having electrochromic
and photochromic properties. The polymer matrix may be formed from
crosslinking of a
crosslinkable polymer. Generally (without wishing to be bound by theory), a
switching material
comprising a greater proportion of chromophore, solvent and/or ionic material
may have a faster
switching time than a switching material with a lesser proportion of
chromophore, solvent and/or
ionic material. A thinner switchable material may have a faster switching time
than a thicker one.
A switching material with a higher degree of cross-linking may have a slower
switching time
than one with a lesser degree of cross-linking. A switching material with a
greater proportion of
crosslinkable polymer, rheology modifier, or crosslinkable polymer and
rheology modifier may
have a slower switching time than one with a lesser proportion of thermoset
polymer, rheology
modifier, or thermoset polymer and rheology modifier. A switching material may
be applied to a
substrate using roll-to-roll coating, as is known in the art, and a second
substrate attached thereto,
to provide a variable transmittance filter.
[0039] Solvents, ionic components, polymers, rheology modifiers, crosslinking
agents,
crosslinking systems and/or other components of switchable films are addressed
in the indicated
patents and applications. A switching material may further comprise one or
more other additives,
such as dyes, UV light stabilizers, antioxidants, salts, surfactants, adhesion
promoters, charge
carriers, charge compensators or the like.
[0040] Compounds: Examples of compounds having electrochromic and photochromic
properties ("chromophores") include some diarylethenes. Examples of such
diarylethenes are
described in PCT/CA2012/000910 filed September 21, 2012, US 7,777,055 and
W02010/142019, and include1,2-diaryl cyclopentene compounds. The chromophore
comprises
two isomers, a ring-open, or open, isomer and a ring-closed, or closed,
isomer. These
chromophores are reversibly convertible between open and closed forms with the
application of
voltage or light.
[0041] Oxidation of the chromophore to convert a ring-closed form to a ring-
open form may be
induced by application of a voltage to a switching material comprising the
chromophore, and
may be independent of the polarity of the applied voltage. The chromophore may
be an anodic
species, that is, the electrochromic colour change occurs primarily at the
anode of an
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electrochromic film or device. The amount of chromophore that may be
incorporated in the
switching material can be an amount sufficient to provide the desired light
transmission in dark
state, faded state or both dark and faded states, and in any case less than or
equal to a solubility
limit of the chromophore in the switching material. The switching material,
when prepared, may
be substantially free of undissolved components, including undissolved
chromophore,
undissolved polymers, undissolved ionic materials or the like. A suitable
amount of chromophore
may provide a switchable film, article comprising a switchable film or a
switchable article with a
desired level of light transmission or absorption in a dark state, a faded
state or a dark state and a
faded state. In some embodiments, a suitable amount of chromophore may be
selected to
complement the level of light transmission when combined with a static filter,
such that the light
absorption of the switching material in the dark state, faded state or dark
state and faded state
combined with the light transmission of the static filter provides the desired
light transmission. A
static filter may be a non-switching layer or component of the film or
article.
[0042] For example, one or more chromophores may be present in a switching
material in an
amount (% weight) of about 0.05% to about 30%, or any amount or range
therebetween, for
example about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18,
19, 20, 21, 22, 23, 24, 25,
26, 27, 28 or 29%. Examples of such chromophores include, but are not limited
to, the
following:
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CA 02833843 2013-11-19
,
F F
F F
F Ill F
s / \ / \ S
\/ S S \ /
o . . oF F F
F
? F e F
(0 S /\ /\ S
c? c \ / ...oz Ss \ /
\ /
? f>I
r
,
/0 0\i .
\ . 0
, 0 1
F F
F F
F 111 F
\ /
0 0
# *
[0043] Generally, a switching material may be coated at a suitable thickness
onto a conductive
coating of a substrate. A second layer may be applied on the switching
material ¨ the second
layer may be a transparent conductive layer, or a substrate comprising a
transparent conductive
material (e.g. ITO coated PET). The step of laminating may be preceded by, or
followed by, a
step of crosslinking or curing of the switching material. The step of curing
may comprise heating
the composition to a temperature suitable for crosslinking (e.g. about 50 to
about 90 C, or any
amount or range therebetween. The step of disposing may be preceded by a step
of filtration of
the composition.
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100441 Examples of substrates include polymer films such as PET, and may
further comprise a
conductive coating, such as ITO; the substrate may be a moving web. The first
and/or second
substrates may be independently opaque or transparent, or substantially
transparent. The
substrate may be optically clear. In some embodiments, when the switching
material is disposed
upon, or sandwiched between the substrate(s), the switching material is
optically clear (e.g.
demonstrating a haze of less than about 5%, less than about 4%, less than
about 3%, less than
about 2% or less than about 1%). Haze may be measured using methods known in
the art, for
example use of an XL-211 Hazemeter from BYK-Gardner, according to
manufacturer's
instructions.
[0045] The switching material may have a high viscosity at room temperature
and may be made
into a lower-viscosity liquid by heating to allow it to be applied or coated
onto the substrate. In
one embodiment, the switching material is heated to about 100 C and pressed
between the
substrates. Alternately, the switching material may be cast as a liquid and
then further treated to
increase the viscosity of the material to form a gel ¨ the switching material
may be dried
(evaporation of a co-solvent), or a switching material comprising a
crosslinkable resin may be
cured to increase the viscosity to form a gel. Curing the switching material
may be accomplished
with chemical crosslinking, temperature or UV light; other methods may be
suitable with
different formulations. One skilled in the art will appreciate that this
polymerization and/or
cross-linking can be initiated by chemical-, thermal-, or photo-type
initiators. The switching
material may then adhere to conductive layers on first and second substrates
to form an integral
structure. In some embodiments, components of the switching material or
composition may be
combined in particular order, or in particular subcombinations ('parts'), with
the parts combined
at a later point. Preparation of first, second and/or third parts may be
advantageous to solubilize
one or more components of a composition, prevent side reactions, or to prevent
initiation of
crosslinking ('curing') before the formulation is complete or ready for
casting or coating. For
example, a switching material for coating on a substrate may be prepared
according to the steps
of: providing a first part comprising a crosslinkable polymer, a chromophore,
an ionic material
and a first portion of a solvent; providing a second part comprising an
optional hardener, a
crosslinking agent and a second portion of the solvent; providing an
accelerant and an optional
co-solvent (e.g. MEK, THF or the like, which may be removed before laminating
the second
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substrate); combining the first part and the second part; and combining the
third part with the
combined first and second parts. Disposition of the switching material may be
performed in an
environment of reduced oxygen (e.g. less than 100 ppm) and/or reduced humidity
(e.g. less than
100 ppm relative humidity)
[0046] A suitable thickness may be selected such that the composition is of
the desired thickness
once the co-solvent is evaporated (if the switching material comprises a co-
solvent), or the final
layer is of the desired thickness following cooling and/or crosslinking of the
coated switching
material. For example, to obtain a final thickness of about 50 microns, a
switching material with
co-solvent may be applied to the substrate in a layer of about 100 to about
120 microns.
[00471 Once the filter has been made, it may further be cut to size, and/or
sealed around the
perimeter. Electrical connections may be made to the electrodes (transparent
conductive layers).
The electrical connection can be made by applying bus bars onto the substrates
in contact with
the transparent conductive coating. In some embodiments, busbars may be
applied on the
substrate before disposition of the switching material, or before lamination
of the substrate to the
switching material. Electrical leads (electrical connectors, connectors) can
then be attached to the
bus bars.
100481 Switching materials and optical filters as referenced herein may be
particularly suitable
for use with thermoforming, injection molding or other plastic-shaping methods
involving the
application of heat, as the components of the switching material, in
particular the chromophores,
are tolerant of elevated temperatures ¨ from about 80 C to about 140 C or any
amount or range
therebetween for a suitable period of time. To allow conformation of the
switchable film to the
mold or form, and forming or injecting the transparent plastic layer. Examples
of suitable times
may range from a few seconds or minutes, to an hour or more.
100491 Heat-attenuating layer
[0050] A switchable article may include a heat attenuating layer between the
switching material
and the injection molded or thermoformed plastic. Inclusion of a heat-
attenuating layer between
the switchable film and the transparent plastic layer provides insulation from
the melted or
heated plastic, and further protection of the switching material may be
provided by rapidly
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cooling the transparent plastic once molded or shaped. The heat attenuating
layer may be
transparent, or substantially transparent. The heat attenuating layer may have
a low thermal
conductivity. The heat attenuating layer may have a heat transfer coefficient
less than that of the
molten plastic injected into the mold cavity. The heat attenuating layer may
be infrared radiation
reflective. "Heat" includes infrared radiation from a heat source; a heat
source may include
incident light on the article, or may include heat from the transparent
plastic layer in a forming,
molding or casting process involved in producing a switchable article, or in
laminating a
switchable article. The heat attenuating layer, when positioned between the
switchable film and
the transparent plastic layer during production of the article may, in part,
mitigate the heat to
which the switchable film is exposed during production of a switchable
article.
[0051] The heat attenuating layer may be applied directly to one side of the
switchable film by
laminating, spraying, coating, dipping, sputter coating, magnetron sputtering,
electron beam
evaporation, ion beam sputtering, plasma enhanced chemical vapor deposition,
or the like. In
some embodiments, the heat attenuating layer may be applied to a substantially
transparent
plastic film (e.g. PET), and the film in turn laminated to the switchable film
with a substantially
transparent adhesive. In some embodiments the heat attenuating layer comprises
indium tin
oxide (ITO), and is an infrared blocking layer. The ITO layer may be of any
suitable thickness
providing sufficient transparency is maintained, e.g. from about 1000 to about
3000 angstroms
thick. In some embodiments, one of the transparent conductive layers may be a
heat attenuating
layer.
[0052] A heat attenuating layer may be a heat-activated adhesive. In some
embodiments, a layer
of heat-activated adhesive may be applied to an outer surface of a switchable
film before
thermoforming the switchable film adjacent to, or between transparent plastic
layers.
[0053] Transparent plastic layer
[0054] A transparent plastic layer may comprise polycarbonate, acrylonitrile
butadiene styrene
(ABS), polyesters (PET, PETG), acrylics (polymethyl methacrylate, PMMA) or
modified
acrylics (imidized, rubber toughened, stretched or the like), polyester
carbonate, allyl diglycol
carbonate, polyether imide, polyether sulfone (polysulfone, PSU), cellulose
acetate, cellulose
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butyrate, cellulose propionate, polymethyl pentene, polyolefins, nylon,
polyphenylsulfone,
polyarylate, polystyrene, polycarbonate, polysulfone, polyurethane, polyvinyl
chloride, styrene
acrylonitrile (SAN), EVA, or the like. The transparent plastic may comprise
additives such as
colorants, mold release agents, adhesion promoting agents, antioxidants, UV
absorbing agents or
the like. In some embodiments, it may be advantageous to include a layer of
plastic (e.g. PET
film) between the switchable film and the transparent plastic layer to prevent
diffusion of
plasticizers or other components of the switchable film into the transparent
plastic. This plastic
film may be, or be a vehicle for, a heat attenuating layer.
[0055] In some embodiments, a decorative ink may be applied to the surface of
the heat
attenuating layer, or to a surface of the switchable film, before the
transparent plastic layer is
applied, thereby encapsulating the ink layer in the interior of the switchable
article. Figure 1
shows an example of such an ink application. Other patterns may include labels
or manufacturer
information, or the like. The ink may be of any suitable type, comprising
polycarbonate resins,
polyester resins or combinations thereof. The ink may be applied by screen
printing, mask or
spray jet, pad printing or the like.
100561 Making a switchable article
[0057] The transparent plastic layer may be formed by any suitable technique,
including
molding, which includes injection molding, blow molding, injection molding,
compression
molding, injection-compression molding, thermoforming, vacuum forming, film
insert molding
or the like, or a combination thereof. In some embodiments, techniques may be
combined, such
as forming the switchable film with heat attenuating layer into the desired
shape (e.g. the inside
of a mold), and molding the transparent plastic layer onto the switchable film
with heat
attenuating layer.
[0058] In accordance with another aspect, there is provided a method of
preparing a switchable
article comprising: providing a switchable film; disposing a heat attenuating
layer on a side of
the switchable film; and molding a transparent plastic layer in contact with
the heat attenuating
layer.
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[0059] In accordance with another aspect, there is provided a method of
preparing a switchable
glazing comprising: providing a switchable film; disposing a heat attenuating
layer on a side of
the switchable film; and laminating a transparent plastic layer in contact
with the heat attenuating
layer.
[0060] In accordance with another aspect, there is provided a method of
preparing a switchable
article comprising: providing a switchable film; disposing a heat attenuating
layer on a side of
the switchable film; inserting the switchable film with heat attenuating layer
into a mold;
trimming the switchable film with heat attenuating layer to fit the mold; and
injecting a molten
transparent plastic resin into the mold cavity, the transparent plastic resin
contacting the heat
attenuating layer and adhering thereto; cooling the transparent plastic resin
and removing the
molded switchable article from the mold. Adhesion of the transparent plastic
resin to the heat
attenuating layer may be by melt-fusion, or may be by activation of a heat-
activated adhesive
applied to a surface of the switchable film, the heat attenuating layer, or a
combination thereof
[0061] Referring to Figure 3, steps for a method of preparing a switchable
glazing are set out
generally at 50. A first step 52 provides a switchable film. A heat
attenuating layer is disposed
on a side of the switchable film (54), and a transparent plastic layer is
molded in contact with the
heat attenuating layer (56). The transparent plastic layer may be applied by
any of several
methods including dip or spray molding, vacuum forming or injection molding or
injection-
compression molding. Where the transparent plastic layer is injection molded,
the step of
molding may be preceded by a step of placing the switchable film in an
injection mold, with the
heat attenuation layer facing the cavity of the injection mold. Step 54 may be
preceded by a step
of preheating one or both portions of the mold. In some embodiments, a step of
molding may be
preceded by a step of trimming the switchable film to fit the mold, and/or a
step of applying
decorative ink to the switchable film.
[0062] Figure 4 shows generally at 40 a switchable film 14 with a heat
attenuating layer 12
applied to one side, positioned against a portion 42 of a mold for injection
molding of a plastic
article, according to one embodiment. The switchable film 14 may be held in
position on the
mold portion 42 by any suitable method ¨ for example, by vacuum or static, or
by gravity, if the
mold is positioned suitably, or a combination thereof. The profiles of
portions 42 and 44 of the
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mold define a cavity 46 into which the transparent plastic injected via
injection ports in platen 47
and mold 42, and compressed with pressure applied to the mold portions by
platens 47, 48 to
form the transparent plastic layer 16 of the switchable article, melt-fused to
the switchable film
and heat attenuating layer. The mold is opened, and the switchable article
removed. A mold or
form may be made of any suitable material for withstanding the conditions for
forming or
molding. In some embodiments, the mold portions may be heated or cooled
independently to
suitable temperatures, as desired. For example, both portion 42 and 44 may be
heated to a
temperature that the switchable film will tolerate (without damage or loss of
function) - this
temperature may be below that of the melted plastic for injection into the
cavity. Where the
temperature of the melted plastic is greater than a temperature that the
switchable film will
tolerate, the heat attenuating layer may provide sufficient thermal insulation
to reduce the heat
transferred from the melted plastic to the switchable film.
[0063] In some embodiments, the switchable film may have electrical leads
attached before
incorporation into the switchable article by film in mold injection molding.
The switchable film
may be positioned against the mold portion and anchored as described, with the
electrical leads
folded behind the switchable film, between the film and the mold portion. The
mold may be
closed and the plastic injected. In other embodiments, a switchable film with
busbars is
incorporated into a switchable article, and electrical connectors added after
the molded,
switchable article is removed from the mold. Some mechanical systems for
connecting an
electrical connector to a busbar are described in PCT publication
W02008/134669. For
example, a compressive edge clip may be provided to secure an electrical
connector to a bus bar;
the compressive edge clip may have protrusions (tabs, or teeth) that penetrate
the substrate of the
switchable film to contact the busbar.
[0064] Polycarbonate is available from several suppliers (e.g. SABIC, Bayer,
Styron, Teijin or
others), with a variety of properties. Selection of the polycarbonate, or
other transparent plastic,
will be dependent on the intended use of the switchable article. For example,
polycarbonate for
use in an automotive glazing (window or sunroof) will need to meet safety
testing and other
performance objectives - an example of a polycarbonate material suitable for a
vehicle glazing is
MakrolonTM (Bayer).
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[0065] Preheating one or both portions of the mold may provide additional
flexibility to the
switchable film and/or heat attenuating layer, allowing the film to conform to
the surface of the
mold more easily. Resin may be injected under pressure as a single shot
through one or several
injection ports. Further compression of the layers may be provided by
application of pressure by
the platens 47, 48 to which the molds 42, 44 are attached Cooling of the
melted plastic once
injected into the mold may be controlled by water or air cooling of the mold
portions. The rate
of cooling may be controlled so as to minimize or prevent the development of
molding artefacts,
shrinkage or temperature related defects in the transparent plastic layer, and
to minimize the time
the article components are exposed to the temperature of the melted plastic. .
[0066] To thermoform a switchable film, the film is laid over a form, and heat
applied to the
film; a vacuum may also be applied to draw the switchable film over the form
to attain the
desired shape, and the form may be preheated, or not. Alternately, the film
may be placed
between positive and negative forms (e.g. two halves of a mold), and heat and
pressure
(sufficient to shape the film) applied by the first and second negative forms
to the film
therebetween, to attain the desired shape. The film is allowed to cool below
the plastic point of
the substrates, and removed from the form(s). A transparent plastic layer of
the corresponding
shape is also prepared by injection molding, thermoforming, vacuum forming or
other suitable
method. To prepare the switchable article, the formed switchable film and
formed plastic layer
are mated, and affixed with an adhesive layer between them. The adhesive layer
may be a
pressure sensitive or a heat sensitive adhesive, and the film and plastic
layer may be affixed with
further heat and/or pressure to form the article.
[0067] The switchable article may be of any suitable thickness. For example,
an architectural or
vehicle glazing may be from about 3mm to about 6mm in thickness overall,
[0068] Coating system
[0069] After forming the switchable article, one or more abrasion resistant
layers, weathering
protection layers or the like may be applied to surface A, surface B or both,
of the switchable
article. A weathering layer may include a polyurethane or acrylate coating, or
a top-coat with a
primer. A primer may comprise a UV absorbing component in a compatible polymer
and
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solvent system for application to a surface of the switchable article. A
topcoat may be applied
over the primer, providing abrasion resistance and additional UV resistance.
Examples of
weathering layers and coating systems, and methods of applying the layers and
components are
described in, for example, US Patent Publication Nos. US 2007/0026235, US
2007/0104956.
Weathering layers and coating systems may be applied to the switchable article
by any technique
known in the art, for example spray coating, curtain coating, dip coating,
spin coating, flow
coating, sputter coating, magnetron sputtering, electron beam evaporation, ion
beam sputtering,
plasma enhanced chemical vapor deposition, or the like.
[0070] Anti-scratch: an abrasion-resistant coating may be applied to the
switchable article to
prevent distortion or surface damage, and preserve optical clarity; anti-
scratch coatings may be
particularly beneficial for use with transparent plastics. An example of an
abrasion-resistant
coating may be a polysiloxane coating (e.g. Momentive AS5400, AS4700
polysiloxane wet-coat
system)
[0071] Security coating: A security coating may be applied to the switchable
article to prevent
release of particles during breakage. Examples of such materials include
PVB/PET composites
or hard-coated PET films (e.g. SPALLSHIELDTM (DuPont).
[0072] UV-blocking: One or more layers may comprise a UV blocking component.
Adhesive
layers such as PVB may have additives that block UV (e.g. US 6627318); some
transparent
plastics, or some substrates may be made of a material that has been treated
with a UV blocking
material (e.g. UV-blocking PET), or have a UV blocking layer applied thereto.
It may be cost
effective to incorporate into the variable transmittance optical filter a
substrate that blocks UV ¨
this may be advantageous in protecting the switching material from some
incident UV light.
Surprisingly, the switchable films will still switch even when a UV blocking
substrate that
blocks a substantial portion of incident UV light of 380 nm or greater, and
all UV light below
about 375 nm.
[0073] Sound insulation: Multiple layers of materials with different
properties may diffuse
sound or vibration, reducing the amount of sound or vibration transmitted
through the article.
Sound insulation may be provided by the layers of the switchable article as
described herein,
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and/or by inclusion of an additional acoustic layer. Acoustic PVB may be known
by trade names
such as SAFLEXTM or VANCEVATM. US 5190826 describes composition comprising two
or
more layers of resins of differing polyvinyl acetals; the acoustic layer may
be in the range of 0.2
to 1.6 mm. US 6821629 describes an acoustic layer comprising an acrylic
polymer layer and
polyester film layer. Acoustic layers comprising PVC, modified PVC,
polyurethane or the like
may also be used.
[0074] Self-cleaning coating: a self-cleaning coating may be applied to an
outboard surface of
the switchable article. Several examples of such coatings, and methods of
applying them are
known ¨ examples include hydrophilic coatings based on TiO2 (e.g. Pilkington
ACTIVTm) and
hydrophobic coatings (e.g. AQUACLEANTM or BIOCLEANTm).
[0075] IR Reflecting: Examples of such films include US 2004/0032658 and US
4368945.
Alternately IR blocking materials may be incorporated into a layer of plastic,
or an adhesive
layer and applied to the switchable film. An IR blocking layer may reflect or
absorb IR light.
Reflection of IR may reduce the solar heat gain of the interior space, whereas
absorption of IR
may increase the temperature of the switchable article, which may be
advantageous in increasing
the switching speed of the switchable article.
[0076] Coatings or treatments applied to the inboard or outboard surfaces of
transparent
switchable articles are generally optically clear. Other examples of coatings
or treatments may
include antiglare or anti-reflective coatings.
[0077] Borders: It may be desirable for some switchable articles such as
vehicle or automotive
glazings to have a border (opaque, partially opaque or faded, for example) to
provide esthetic
enhancement, or mask wires ,busbars, connectors or other components of, or
used with, a
switchable article, or mask one or more antennas embedded in the glazing.
[0078] Identification marks: Identification marks may be necessary for some
switchable
articles ¨ it may be a manufacturing requirement for automotive or
architectural glazings or other
articles, for example, to be labeled with information pertaining to
manufacturer, testing standards
or other regulatory or required information. It may also be desired to
'personalize' a switchable
article with a name, logo, diagram or other esthetic element. Inks or pigments
used for borders or
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identification markings need to adhere to the surface to which they are
applied (e.g. a part of the
switchable film insert), and be suitably durable to withstand testing and
handling of the article
during manufacture and installation, and during normal use. US Publication No.
2008/0085415
provides some examples of polyester-polycarbonate inks that may be suitable.
100791 Controlling a switchable article
[0080] The switching material may be transitionable from a light state to a
dark state on
exposure to light, and further may be transitionable from a dark state to a
light state upon
application of a voltage. The light may have a wavelength from about 350 nm to
about 450 nm.
For application of the voltage, the switchable article may further comprise an
electrical connector
configured for electrically connecting each of the transparent conductive
layers to a voltage
source.
[0081] Referring to Figure 5, Electrical leads may connect the switchable
article to a control
circuit comprising a power source (voltage source) 146. A switch 148 may open
and close the
control circuit to control power to a switchable film of the switchable
article 10 based on input.
Switch 148 may be a two-way or three-way switch, or may be a multi-state
control device such
as a potentiostat, and allow selection of different states of the variable
transmittance layer. Input
may come from a user (e.g. operation of a switch), or some other input such as
a timer, pre-
existing instructions (e.g. programmed into a memory comprising part of the
control circuit) a
device monitoring the light transmittance of the switchable optical filter,
incident light, and may
be operable by a user, a preexisting program, timer or another component of
the control circuit.
[0082] Other components of a control circuit may include a DC-DC converter for
converting the
voltage from the power source to an appropriate voltage, a voltage regulator,
timer, light sensor,
voltage or resistance sensors or the like. Control circuits and systems that
may be used with
variable transmittance optical filters and layered compositions according to
various embodiment
are described in, for example, PCT publication W02010/142019, and
PCT/CA2013/000381,
with a priority claim to U.S. Provisional patent application 61/625,855 filed
April 18, 2012.
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[0083] Electrical leads 142, 144 may extend out one side of the laminated
glass (such as in
Figure 6), and layer. Molding of the switchable article may encapsulate
busbars 158 a, b and a
portion of the electrical leads 142, 144 contacting busbars 158 a, b, forming
a sealed unit.
[0084] Figure 6 and 7 shows a schematic diagram of a switchable film,
illustrating busbars and
electrical leads connected thereto. A switchable film comprising a layer of
switching material
152 between first 154 and second 156 substrates is electrically connected to
electrical leads 142,
144 via busbars 158a, b applied to a conductive coating 160a, 160b on
substrates 154, 156, in
contact with the switching material 152. The substrates of the switchable
optical filter have
opposing overhanging edges, cut to expose the conductive coating. Optional
peripheral seal 164
seals the cut edge of the switching material.
[0085] Busbars, electrical connectors and control circuits: Busbars may be
applied to a
portion of the conductive layer on opposing sides of the switching material,
so that a voltage
differential is created across the switching material to effect the switch.
The busbars may be of
any suitable material to provide a low-profile conductive area suitable for
attachment of an
electrical connector thereto. Examples of suitable materials include
conductive adhesive,
conductive ink, conductive epoxy, metal mesh or film or the like, comprising
at least one type of
metal such as aluminum, gold, silver, copper or the like. The conductive
material may be applied
to the conductive surface by any of several methods known in the art,
including printing,
painting, screenprinting ('silkscreening') or the like. Electrical connectors
or leads may be of any
suitable material and may be affixed to the busbar by any suitable methods,
including adhesion
(conductive adhesive or conductive epoxy), clips, rivets, conductive tape,
wire or the like. A
suitable electrical connector may be suitably durable or heat-resistant to
withstand temperatures
associated with thermoforming or injection molding of polycarbonate or other
plastics.
[0086] A control circuit can be used to switch the electrical voltage on or
off, based on input
from an automated or semi-automated device (e.g. an irradiance meter,
thermometer), a building
or vehicle environmental control system, a user or some other input, and can
also be used to
modulate the voltage to a predetermined level. A power source for may include
an AC line
voltage in a house or other building, a DC power source (e.g. a battery of a
vehicle, or in a
separate battery or power pack), an energy harvesting power source (e.g. solar
panel) or the like.
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CA 02833843 2013-11-19
The control circuit may comprise one or more switches (transistor, relay, or
electromechanical
switch) for opening and closing a circuit between the voltage regulators and
the optical filters, an
AC-DC and/or a DC-DC converter for converting the voltage from the power
source to an
appropriate voltage; the control circuit may comprise a DC-DC regulator for
regulation of the
voltage. The control circuit can also comprise a timer and/or other circuitry
elements for
applying electric voltage to the variable transmittance optical filter for a
fixed period of time
following the receipt of input.
[0087] Embodiments include switches that can be activated manually or
automatically in
response to predetermined conditions. For example, control electronics may
process information
such as time of day, ambient light levels detected using a light sensor, user
input, stored user
preferences, occupancy levels detected using a motion sensor, or the like, or
a combination
thereof, the control electronics configured to activate switches for applying
voltage to the optical
filter in response to processed information in accordance with predetermined
rules or conditions.
Where the multilayer composition according to various embodiments is part of
an automotive
article (window or sunroof, or the like), the article may be installed in the
vehicle and electrically
connected to the vehicle's electrical system, through wiring in the frame,
dash or roof, or
connected to rails or guide tracks as may be used for some automotive roof
applications.
[0088] In one embodiment, the control electronics comprises a user-activated
switch that passes
the DC voltage from the power source substantially directly to the variable
transmittance optical
filter. The user activated switch can be a normally-open push button, or
another type of switch. A
switch may be configured to remain closed for a predetermined amount of time
following
actuation, thereby facilitating application of voltage to the optical filter
for sufficient time to
effect a state transition.
[0089] The voltage to be applied for transitioning the optical filter may be
from about 0.1 V to
about 20 V, or any amount or range therebetween. In some embodiments, the
amount of voltage
applied is from about 0.1V to about 5V, or from about 1V to about 10 V, or
from about 1.0 V to
about 2.2 V, or from about 0.5V to about 3V, or from about 1.2V to about 2.5
V, or from about
1.8 V to about 2.1 V, or any amount or range therebetween. In some
embodiments, the voltage
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CA 02833843 2013-11-19
applied is less than about 12 V, or less than about 6 V, or less than about 3
V or less than about
2.5 V, or about 2 V.
[0090] The term "mil" as used herein, refers to the unit of length for 1/1000
of an inch (.001).
One (1) mil is about 25 microns; such dimensions may be used to describe the
thickness of an
optical filter or components of an optical filter, according to some
embodiments of the invention.
One of skill in the art is able to interconvert a dimension in `mil' to
microns, and vice versa.
[0091] "About" as used herein when referring to a measurable value such as an
amount, a
temporal duration, and the like, is meant to encompass variations of 20% or
10%, more
preferably 5%, even more preferably 1%, and still more preferably 0.1% from
the specified
value, as such variations are appropriate to perform the disclosed methods.
[0092] Other Embodiments
[0093] It is contemplated that any embodiment discussed in this specification
can be
implemented or combined with respect to any other embodiment, method,
composition or aspect,
and vice versa. Figures are not drawn to scale unless otherwise indicated.
[0094] The present invention has been described with regard to one or more
embodiments.
However, it will be apparent to persons skilled in the art that a number of
variations and
modifications can be made without departing from the scope of the invention as
defined in the
claims. Therefore, although various embodiments of the invention are disclosed
herein, many
adaptations and modifications may be made within the scope of the invention in
accordance with
the common general knowledge of those skilled in this art. Such modifications
include the
substitution of known equivalents for any aspect of the invention in order to
achieve the same
result in substantially the same way. Numeric ranges are inclusive of the
numbers defining the
range. In the specification, the word "comprising" is used as an open-ended
term, substantially
equivalent to the phrase "including, but not limited to," and the word
"comprises" has a
corresponding meaning. As used herein, the singular forms "a", "an" and "the"
include plural
referents unless the context clearly dictates otherwise. Citation of
references herein shall not be
construed as an admission that such references are prior art to the present
invention, nor as any
admission as to the contents or date of the references. All publications are
incorporated herein by
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reference as if each individual publication was specifically and individually
indicated to be
incorporated by reference herein and as though fully set forth herein. The
invention includes all
embodiments and variations substantially as hereinbefore described and with
reference to the
examples and drawings.
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