Note: Descriptions are shown in the official language in which they were submitted.
21 87896
~WO 95129766 ~ C~
--1--
__ COATIN¢ PROCB88 POR
PRTdP7 PqT.~rMT~nT~ PT T~ F~ 8
RA~ r uu~d of the Invention
Field of the Invention
This invention relates to a coating process for
preparing polymerizable f ilms .
Descril~tiQn of the Related Art
The bead coating method of applying fluids to
substrates i5 known. According to this method, coating
fluid is fed via a metering pump to a die which
deposits the coating fluid on the surface of a moving
substrate as the substrate moves past the die. As the
15 coating fluid leaves the die it forms a continuous
coating bead between the upstream die lip, the
fl~: ..=,L.c:~.a die lip, and the web. The moving substrate
is wetted by the bead as the substrate moves past the
bead to create a layer of coating fluid on the
20 substrate. To improve the stability of the bead (and
thus reduce coating i nh~ ~ J - ities), a vacuum may be
applied to a vacuum chamber located upstream of the
coating bead.
r rv of the Invention
In general, the invention features a method of
coating the surface of a sub8trate with an ~:5--~t;A1 1Y
solvent-free (i.e., 100% solids1 polymerizable fluid by
passing the fluid through a die onto the surface of the
substrate as the substrate moves relative to the die.
The die includes a channel adapted to receive the
fluid and an adjustable width slot in communication
with the channel through which the f luid is passed .
The slot is formed between the C9 .~ L~ u bar 66 and
the U~JD~LC:OIU bar 64. The ~1 I.D~Leam bar lip is formed
35 as a sharp edge 70 and the ll~- ~L~ U bar lip is formed
as a land 68 which substAnt i A 1 1 Y corresponds in shape
WO95/29766 21 87896 P~J~ ~''0I1~ --
--2--
to the shape of the substrate in the immediate area of
coating fluid application. As used herein, "upstream"
and "d .~.Lr~ l" are relative to the direction of the
moving substrate.
In preferred ~ s, the edge radius of the
sharp edge (as defined in Fig. 3) measures no more than
about 10 microns, and more preferably ranges from about
2 to about 4 micron6. The edge angle Al of the sharp
edge (as defined in Fig. 3) preferably ranges from
about 20 to about 75 and preferably is about 50 -
60 .
The Cu~ve:Ly_.~Ce of the die C (as defined in Fig.
3) preferably ranges from about 0 to about 2.29, more
preferably from about 0 to about 1.5.
The 6harp edge and the land are pref erably
configured such that the sharp edge is displaced
towards the surface of the substrate relative to the
land. The degree of ~ pl~ L is referred to as
"overbite" 0. Preferably, the overbite i8 no greater
20 than about 0 . 64 mm.
The sharp edge is substantially straight. For
example, along a distance of about 25 cm measured
anywhere along the sharp edge, the straightness of the
edge does not vary by more than about 2 . 5 microns, and
25 pref erably no more than about 1 micron .
The rate at which the f luid passes through the die
and the rate at which the 6ubstrate moves relative to
the die are adjusted to provide a substantially uniform
caliper coating on the substrate.
The viscosity of the coating fluid is preferably
at least about 10 cps, and may be 100 cps or greater,
or even 1000 cps or greater. The method may be adapted
to apply both thin and thick coatings. During coating,
a vacuum may be applied to the upstream side of the die
35 to improve coating quality if desired. The sub8trate
may be a web.
~ WO ss/29766 2 ~ ~ 7~ ~ 6 ~ o l l ~
The invention enables the p~-:~aL~tion of solvent-
free coatings having uniform caliper in both the
downweb and uL~e- _b directions. Both thick and thin
films can be prc~aI6d. The invention i5 useful in a
5 variety of settings, ;nnl~ in~ the preparation of
optical quality thin films and adhesive films.
Other features and advantages of the invention
will be apparent from the following description of the
preferred ' ' i- -nts thereof, and from the claims .
Brief Descrit~tion of the Drawi n-~c
The invention will be more fully understood with
reference to the following drawings in which:
Figure 1 is a cross-sectional view of an extrusion
die of the present invention.
Figure 2 is an enlarged ~;Lo58 s~ ional view of
the slot and lip of the die of Figure 1.
Figure 3 is a ~iL uss-sectional view of the slot and
lip similar to that of Figure 2.
Figure 4 is a ~iLùss~ nt;nnAl view of an
20 alternative vacuum chamber alL , L.
Figure 5 is a cross-sectional view of another
alternative vacuum chamber aL~ y. ~.
Figure 6 is a ~iLOSS se.il irnAl view of an
alternative extrusion die of the present invention.
Figures 7A and 7B are enlarged ~:L~Sfi-C~ Li~n~l
views of the slot, face, and vacuum chamber of the die
of Figure 6.
Figures 8A and 8B are schematic views of the die
of Figure 6.
Descri~tion of the Preferred F~ i c
This invention is a die coating method for coating
polymerizable fluids onto substrates (e.g., webs) the
die includes an U~Lt:CUU die lip formed as a sharp edge
and a il .,D~L-:am die lip formed as a land. The shape
35 of the land substantially :~L' e:DpOIldS to the shape of
the substrate in the immediate area of coating f luid
Wo 95/29766 2 l 81 ~ 9 6 r~~
--4--
application. The 6hape of the ~iub~LL~te may be flat or
curved .
Figure 1 shows an extrusion die 40 with a vacuum
chamber 42 useful in the coating method according to
5 the present invention. Polymerizable fluid 44 is
supplied by a pump 46 to the die 40 for application to
a moving substrate 48, supported by a backup roll 50.
Polymerizable f luid 44 is supplied through a channel 52
to a manifold 54 for distribution through a slot 56 and
10 coating onto the moving substrate 48. The height and
width of slot 56 can be controlled by means of a U-
shaped 6him 41. The shim is typically made of brass or
stainless steel.
As shown in Figure 2, the polymerizable fluid 44
15 passes through the slot 56 and forms a continuous
coating bead 58 between the ' ...,LLeam edge 72 of land
68, the lip of d~ LL t ~llu bar 66, and the substrate 48 .
Vacuum chamber 42 (Figure 1) applies vacuum u~LLe:a~ of
the bead to s~hil i 7e the coating bead. If desired,
20 the ~ Lu~c: of both die 40 and backup roll 50 may
be controlled to improve coating rheology.
The polymerizable f luid can be one of ~u~
compositions. Polymerization may be th~-l ly induced
or radiation induced (e.g., ultraviolet radiation or
25 electron beam). r ~ of suitable polymerizable
f luids include epoxies, acrylates, methacrylates, vinyl
ethers, isocyanates, and mixtures thereof. The
resulting coatings are useful in a variety of
applications, ;n~ ;n~ adhesive6, optical quality
30 films (e.g., polymer dispersed liquid crystal or "PDLC"
films and optical adhesives), precision caliper films,
and vibration damping materials. The coatings are
particularly useful in applications reS~uiring thin
films with uniform caliper control.
The lip of the upstream bar 64 is formed as a
curved land 68 and the lip of the downstream bar 66 is
21 ~7~96
095129766 P~l/~ s lt~
--5--
formed a6 a sharp edge 70. Sharp edge 70 should be
clean and free of nicks and burrs, and should be
straight within 1 micron in 25 cm of length measured
anywhere along the edge. The edge radius should be no
5 greater than 10 microns. The radius of the curved land
68 should be egual to the radius of the backup roll 50
plus a minimal, and non-critical, 0.13 mm allowance for
coating gap and substrate th; rlrn~B5.
Figure 3 show6 dimensions of geometric operating
10 parameters f or single layer extrusion . The length L~ of
the curved land 68 on the u~:.LLe:all~ bar 64 can range
from 1. 6 mm to 25 . 4 mm. The preferred length L~ is 12 . 7
mm. The edge angle Al of the downstream bar 66 can
range from 20 to 75, and is preferably 50-60O. The
15 dle attack angle A2 between the downstream bar 66
surface of the coating slot 56 and the tangent plane P
through a line on the substrate 48 surface parallel to,
and directly opposite, the sharp edge 70 can range from
60 to 120 and is preferably 90 to 95. The coating
20 gap G~ is the distance between the sharp edge 70 and the
substrate 48.
Slot height H is the distance between u~JD~L~a~ bar
64 and ~ .DL~am bar 66, and is controlled by
controlling the thickness of shim 41 (shown in Figure
25 1). In general, the slot height ranges from 0.076 mm
to 1.27 mm.
overbite O is a positioning of the sharp edge 70
of the ~ all~ bar 66, with respect to the
;' IID~Le:alll edge 72 of the curved land 68 on the
30 U~DLLe:alll bar 64, in a direction toward the substrate
48. Overbite also can be viewed as a retraction of the
d~..llDLLC:am edge 72 of the curved land 68 away from the
substrate 48, with respect to the sharp edge 70, for
any given coating gap G~. Overbite can range from 0 mm
35 to 0.64 mm, and the set~;ng~ at opposite ends of the
die slot should be within 2 . 5 microns of each other.
WO 95/29766 2 ~ 8 7 8 9 6 P~"~
--6--
CGIIVeL~ Ce C is a counterclockwise, as shown in
Figure 3, positioning of the curved land 68 away from a
location parallel to the substrate 48, with the f
du...,~LL~ am edge 72 being the center of rotation.
5 Cvll~_ly~ e can range from oo to 2.29, and the
~ett;n~c at opposite ends of the die slot should be
within O . 023 of each other .
Overbite, slot height and ~;u~ y~l~. e together
affect the ability of the coating die to hold a steady
10 bead. The interaction between these variable6 depends
upon the rheology of the polymerizable coating;
accordingly, these variables, along with the substrate
speed, are adjusted based upon the particular
polymerizable coating being uaed.
Optimum coating quality is achieved when the die
coating ~l~aL~Lus is isolated from ambient sources of
vibration and/or other disrupting factors.
The vacuum chamber 4 2, as shown in Figure 4, can
be an integral part of, or clamped securely to, the
20 U~DLL~:~III bar 64 to allow precise, repeatable vacuum
system gas flow. The vacuum chamber 42 is formed using
a vacuum bar 74 and can be .:ul,,,c:uLed through a vacuum
restrictor 76 and a vacuum manifold 78 to a vacuum
source channel 80. As shown in Figure 4, a curved
25 vacuum land 82 is attached directly to the u~LLe:~uu bar
64. The vacuum land 82 has the same radius of
;ULV~LULa as the curved land 68. The curved land 68
and the vacuum land 82 can be f inish-ground together 80
they are "in line" with each other. The vacuum land 82
30 and the curved land 68 then have the same cu"veLyellce
with respect to the substrate 48.
The vacuum land gap G2 is the distance between the
vacuum land 82 and the substrate 48, and is the sum
total of the coating gap G~, the overbite, and the
35 displacement caused by the u"v~l4t:l~ce C of the curved
land. When the vacuum land gap G2 is large, an
~ 1 8~96
wog5/29766 r l~l a
_7
eYce6sive inrush of ambient air to the vacuum chamber
42 occurs. Even though the vacuum 60urce may have
6ufficient capacity to ~ Le and maintain the
specified vacuum ,ULe:~~ULe level at the vacuum chamber
5 42, the inrush of air can have undesirable effect6.
In Figure 5, the vacuum land 82 is part of a
vacuum bar 74 which is attached to the u~LLe~ bar 64.
During fabrication, the curved land 68 is finished with
the uC~v~ e "ground in. " The vacuum bar 74 i6 then
10 attached and the vacuum land 82 is fini6h ground, using
a different grind center, such that the vacuum land 82
i8 parallel to the 6ub6trate 48, and the vacuum land
gap G2 is equal to the coating gap G, for one
pre6elected value of the overbite. The vacuum land
15 length L2 may range from 6.35 mm to 25.4 mm. The
preferred length L2 i6 12.7 mm. This ~-~i L has
greater overall coating r~r~hi l ity in difficult coating
situations compared to the ' i r L of Figure 4, but
it is always finish ground for one specific set of
20 operating conditions. Consequently, as coating gap G~
or overbite 0 are changed vacuum land gap G2 may move
away from its optimum value.
In Figure6 6, 7A, and 7B, the die 40 is mounted on
an upstream bar positioner 84, and the vacuum bar 74 is
25 mounted on a vacuum bar positioner 86. The curved land
68 on the u~_LLe~m bar 64 and the vacuum land 82 on the
vacuum bar 74 are not cAnnPctP~l directly to each other.
The vacuum chamber 4 2 is connected to its vacuum source
through the vacuum bar 74 and the positioner 86. The
30 mounting and positioning for the vacuum bar 74 are
separate from those for the U~U~LL~:~IU bar 64. A
flexible vacuum seal strip 88 seals between the
U~.LLe~llll bar 64 and the vacuum bar 74.
The gap G2 between the vacuum land 82 and the
35 substrate 48 i8 not affected by coating gap G~,
overbite, or ullveL~ ce change6, and may be held at
Wog~/29766 2~87896 ~ tl~o ~
it6 optimum value continuously, during coating. The
vacuum land gap G2 may be set within the range from
0.076 mm to 0.508 mm. The preferred value for the gap
G2 is 0.15 mm. The ~L~fe:~L~d angular position for the
5 vacuum land is parallel to the substrate 48.
Figures 8A and 8B show some positioning
adjustments and the vacuum chamber closure. Overbite
adjustment OA translates the downstream bar 66 with
respect to the u~LL~z~lu bar 64 such that the sharp edge
10 70 moves toward or away from the substrate 48 with
respect to the ~ ",.~L-:am edge 72 of the curved land
68. C~llvc~yt~ adjustment CA rotates the upstream bar
64 and the ~ D~Leam bar 66 together around an axis
running through the d~...llDLLt:alU edge 72, such that the
15 curved land 68 moves counterclockwise from the position
shown in Figures 8A and 8B, away from parallel to the
substrate 48, or clockwise back toward parallel.
Coating gap adjustment CGA translates the upstream bar
64 and the ~ "~.LL~:a u bar 66 together to change the
20 distance between the sharp edge 70 and the DUL:~LLC~te
48, while the vacuum bar remains s tationary on its
mount 86, and the vacuum seal strip 88 flexes to
prevent air leakage during a-ljuDi L6. Air leakage at
the ends of the die into the vacuum chamber 42 is
25 m;n;m;7~-1 by end plates 90 attached to the ends of the
vacuum bar 74 which overlap the ends of the u~LLt:-llu
bar 64. The vacuum bar 74 is 0.10 mm to 0.15 mm longer
than the upstream bar 64, so, in a centered condition,
the clearance between each end plate 90 and the
30 U~ Le:~:lIU bar 64 will range from 0.050 mm to 0.075 mm.
The width of the coating yLvduced by a given die
is reduced where indicated by ~Ac.rlrl ;nq~ the die and
the vacuum chamber by ~ ;ULLC:llLly inc~,L~,L~-ting a)
shaped plugs to reduce the widths of the die cavity
35 manifold 54 and vacuum chamber 42 to the rl~rl~l; ng width
~W095/29766 2~878~ P~ s~ --
and b) a shim into the die that has a shim slot width
..u...,~ in~ to the ~rkl ing width.
During coating, it has been found that, as a
cc~nseyue:~U of the ,i~ U~LUL~ of die 40, bead 58 does
5 not move down to any appreciable extent into the space
between curved land 68 and the moving substrate 48,
even as vacuum is increased. This allows the use of
relatively high vacuum levels. M~ ,v~:., good results
are obtained even in the absence of vacuum. In
10 addition, the effect of "runout" in back-up roll 50 on
downweb coating weight i8 min1mi7~1.
The abu~ des.;.ibed die ~L~ U~ coupled with
careful control of (a) the rate at which the
polymerizable composition is delivered to the die
15 (through control of pump speed) and (b) the substrate
speed results in coatings having uniform caliper in
both the downweb and ~;L ~ directions .
For applications where optical ~eaLc.~.~e of the
article is critical, r~nt~minAtion resulting from
20 airborne particulates can be reduced by coating
substrate6 in a clean room environment.
The invention will now be more fully understood
with reference to the following examples which are not
to be construed as limiting the scope of the invention.
2 5 1! ~ANPLE8
Test P~ ,r~ A
The ele. L.~, ~,~Lical rPRp~n~PP: of the PDLC devices
were characterized using a computer-co~.L~ ~,lled test
stand consisting of an IBM personal computer interfaced
30 with Kepco 125-lKVA-3T power supply, a Dyn-Optics
Optical Nonitor 590, and a Valhalla Scientific 2300
Series Digital Power Analyzer. The optics of the Dyn-
optics Optical Monitor were adjusted such that the
~rec~ r tr~n~ fiit -l of photopically-filter light at
35 an approximate 6 collection half angle was measured
relative to an open beam.
Wos5ng766 2 l ~7 ~ r~.,, s 11~ ~
--10--
A sample of a PDLC film/electrode sandwich
measuring several square centimeters was attached to
the lead6 of the power supply using a cnnn~ctnr such as
that described in the aforementioned Engfer et al.
5 application. A 60 Hz voltage ranging from zero to 120
volts AC tVAC) was applied to the sample in 5 VAC
inUL- LE and the SrerlllAr tr~n-miccil~n recorded.
Test PL . .~. .1 . I e B
The haze of the powered tl20 VAC, 60 Hz) PDLC
10 devices was measured using a Pacif ic Scientif ic Gardner
XL-835 Colorimeter according to the manufacturer's
instructions .
A series of adhesives were prepared from
15 prepolymer syrups consisting of a mixture of 90 wt. %
lsooctyl acrylate and 10 wt. % acrylic acid tAldrich,
Nilwaukee, WI) containing 0 . 04 wt. % photoinitiator 2-
phenyl-2,2-~ii LLU"Y acetorhPnnn~ tK13-1, Sartomer, West
Chester, PA) as described in U.S. Pat. No. 4,330,590
tVesley), which is incuL~,Lc~ted herein by reference.
The syrups were partially photopolymerized to
viscosities of 360, 1950 and 5600 cps tas ~ ed on a
Brookf ield viscometer using a t4 spindle operating at
60 rpm) by varying the e~lJo~uLe times.
After the syrups had been advanced to the
indicated viscosities, an additional 0.1 wt.% RB-l
photoinitiator and 0 . 2 wt. % hPY~n~ ; Ol diacrylate
(Sartomer, West Chester, PA) were added to the syrups
and the mixtures agitated until ~ f luids were
3 o obtained. The resulting f luids were coated on the
substrates at the th; rlrn--cR~c indicated in Table 1
using a precision coating die as described above and
the lamination ~aL~.Lu~ described in Vesley et al.,
PCT International application No.
35 (Attorney's Docket No. 50777PCT7A) entitled "Lamination
Process for Coatings," filed u ul~uuLLellLly with the
~WO9s/29766 27~7~9~ P ~
--11--
present application and assigned to the 6ame assignee
as the present application.
During the coating operation, the first substrate
was unwound from a first unwind roll and passed over a
5 Ls~ e "hrrl in~, unheated steel backup roll 25.4 cm (10
inches) in d~ t~Pr where a 10.2 cm (4 inch) wide strip
of the prepolymer syrup, which was delivered to the
precision coating die using a precision gear pump
(available from Zenith Corp. ), was coated onto the
10 first surface of the first substrate using a 10.2 cm (4
inch) die with no vacuum applied to the vacuum chamber.
In EYamples 1-4, a coating die similar to that
illustrated in Figure 4 was configured with a 0 . 50 mm
(20 mil) shim, a 0 cu~velyt:nCe~ an overbite of 0.076
15 mm (3 mil), a coating land L~ of 12.7 mm, a vacuum land
L2 f 12 . 7 mm, and a die attack angle A2 of 90. In
Examples 5-6, a 20.3 cm (8 inch) wide strip of the
prepolymer syrup was coated onto the first surface of
the first substrate using a 20.3 cm (8 inch) die
20 similar to that used for Examples 1-4 except that it
was configured with a 0.048 mm (19 mil) shim and an
overbite Or 0.254 mm (10 mil). The coating gap was
adjusted as indicated in Table 1 along with the pump
speed and substrate speed to produce coatings having
25 the indicated th i rknPccPs . No vacuum was applied to the
vacuum chamber during the coating operation.
The second substrate was unwound f rom a second
unwind roll and passed around a 2 . 54 cm ( 1 inch)
diameter sintered metal laminator bar where it was
30 laminated to the coated face of the first sub6trate
according to the pl~,ceduLe: described in the
aforementioned Vesley et al. application. The
laminator bar was located approximately 12 cm (4.7
inches) ~ Lr ~ from the backup roll such that the
35 coated substrate was not in contact with the backup
roll or other idler or takeup roll at the point of
Wog~tt9766 21 8789~ 1~1,1 5 ~l6~ ~
--12--
lamination, and positioned 80 that the uncoated first
substrate was d~ aDsed approximately 3.8 mm (150 mils)
below the plane def ined by the f irst substrate as it
passed between the backup roll and the idler roll; the
5 extent of depression is hereinafter referred to as
"interference. " Air ~JL~DnULe: (approximately 2 . l bar)
through the sintered metal bar was adjusted to provide
a cushion of air between the laminator bar and the
second substrate.
The thus ~Lulu~.ed uncured laminate construction
was cured to a high per~ormance ~LaDauLa sensitive
adhe6ive by passing the construction under a bank of
fluuL_6ce.,~ black lights lamps (F20T12-350BL, available
from Osram Sylvania, Danvers, MA). The laminate
15 .ullDLLuuLion was exposed to 360 mJ/cm2 of irradiation as
- .:d with a WIRAD radiometer (model number
UR365C~3, available from Electronic InDLLI Ltltion and
Technology, Inc., Sterling, VA) equipped with a glass
filter responsive between 300 and 400 nm, with a
20 maximum tr~n-~i C-cion at 365 nm. The average light
intensity in the curing zone was about 2 . 3 mW/cm2.
Coating speeds were controlled by a vacuum pull roll
positioned at the end of the cûating line and were
maintained at approximately 5.5 m/min. (11 feet/min).
Table 1 shows typical coating variations for
various coating thi 1~ ~p~6ec and viscosities. The cured
adhesives of examples 5 and 6 adhered to the polyester
when the laminated collDLL ... Lion was peeled apart.
Adhesive and shear properties of the cured polymer
30 syrupS of r 1PC 5-6 were consistent with the
properties obtained from similar formulations cured
under the conditions described in U. S . Pat. No.
4,330,590.
~ Wo 95K9766 2 J 8 7 8 9 6
--13--
T~bl-- 1
First Socoud Viscosily Contin~ Co-tiug
E~mple Subst~te Substnte (cps)~ G-p (mm) Ibicl~ness
(mm)
5 IPETI PETQ 365 0.175 0.223 i 0.004
2PET2 PET~ 365 0.175 0.154iO.003
3PET2 PET2 1,950 0.175 0.116iO.001
4PEI~ PET2 1,950 0.175 0.221iO.001
SRdense PElq 5,600 0127 O.150iO.OOI
P pa'
10 6 Rde~so PET2 5,600 0.05 0.93io 08
P~lpe~
1. Measured on a Brookfield vLacometer u~ing A ~4 ~pindle
operating at 60 rpm.
2. Bia~ lly oriented PET ~ilm, 51 mLcrona (2 mila) thick.
15 3. Polyethyl _u.lLe~ p~per provided with ~ ailicone rele~ae
co~tinq .
Ex~m~l~ 7
A PDLC device was ~Leua~ed from a fluid cmnt I;n;n~
(a) 55 parts of a mixture consisting of 30.0 wt.% RCC-
15C curable matrix mixture obtained without initiator
and with 50% less thiol (W.R. Grace, Atlanta, GA), 7.5
wt.9c acrylic acid, 30.0 wt.% isooctyl acrylate, 15.0
wt.~6 2~phel1u~LyeL11yl acrylate (Sartomer, West Chester,
PA), 15 . 0 wt. % divinyl ether of triethylene glycol
(International Specialty Products, Wayne, NJ), and 2.5
wt. % KB-l photoinitiator, and (b) 45 parts BL036 liquid
crystal mixture (EN Industries, Hav L1.u...e, NY) having a
30 solution viscosity of 42 cps (measured on a Brookfield
viscometer using a t3 spindle operating at 60 rpm).
The fluid, which was d~ s~d under vacuum for
- approximately 2 minutes at ambient t~ ~lLULe, wa6
applied as a 15 . 2 cm ( 6 inch) wide strip to the
35 electrode surface of an ITO-coated polyester film
(90/lO indium/tin oxide ratio, 80 ohms/square, 51
microns (2 mil) thick PET, available from Southwall
Technologies, Palo Alto, CA) at a rate of approximately
w0 95/29766 2 ~ 8 7 ~ 9 ~ P ~ s ~
--14--
152.4 cm/min (5 ft/minute) using the precision coating
process described in r , ~ 6 eYcept that a 88 . 9 cm
die similar to that illustrated in Figure 7a was used.
This die was deckled to produce a narrower coating and
5 configured with a 152 micron shim, a coating land
having a length (L~) of 12.7 mm, a vacuum land having a
length L2 f 12.7 mm, a 0.57 cvl~c,Lg~llce~ a 33 micron
overbite, a vacuum land gap G~ of 0.152 mm, a die attack
angle A2 Of 95, and a coatlng gap G~ of 102 microns.
10 The cv.lv_L~ ce of the vacuum bar was o and no vacuum
was applied to the vacuum chamber during coating. Both
the die and back-up roll were temperature controlled at
21C. A ~LeS~UL~ of 1.7 bar was maintained to the
sintered metal bar during lamination and the lamination
15 bar was adjusted to provide an interference of 3 . 6 mm.
The uncured laminate vll~u~ LiOn was cured by
passing the CVI-~ U- ~ion through a cooled curing
chamber cvl-=,LLu~ed of ultraviolet transparent
AcrylitelM OP-4 (available from Cyro Industries, Nt.
20 Arlington, NJ), extending approximately 61 cm (2 feet)
into a cure chamber equipped with two banks of
fluvL~sce,.l~ black lights (F20T12-350BL, available from
osram Sylvania, Danvers, NA), one bank positioned on
each side of the laminate. Air temperature in the
25 cooling chamber wa~ monitored by a Ule ~_ le mounted
in the chamber under the second fluvLesc~ bulb and
controlled at the indicated tl _ ~oLuL~a by ill-Lvdu~ ing
temperature controlled air. Each side of the laminate
uv~LLu~;Lion was exposed to approximately 530 mJ/cm2 of
30 radiation calculated from light intensities of 1.1
mW/cm2 as measured through the conductive electrode used
in the PDLC device by means of a uvl~S~ll~; r~ c.r
(model number UBM365M0, available from Electronic
In_LL, Lcltion and Technology, Inc., Sterling, VA)
35 equipped with a glass filter responsive between 300 and
400 nm, with a maximum tr~n~ on at 365 nm. The
~ W095/29766 ;~l 81l~9~; r~l~u. ~
--15--
radiometer was specially calibrated to read in absolute
lntensity .
The backup roll 50 was a pacer roll driven by a
Torquer T~ Pr precision motor (available from
5 Inland Motor Division, Bradford, VA).
The cured coating th;~ knPGG of the resulting PDLC
film was 24+1 microns. The PDLC device had on- and
off-state ~rAn^~;CCions of 73.1% and 1.2%,
respectively, and a haze of 5. 8% .
r l-- 8
A PDLC device was prepared as described in Example
7 except that the coating fluid had the following
composition: (a) 5û parts of a mixture consisting of
20.0 wt.% Vectomer 2020 tAllied-Signal, Inc.,
15 Norri6town, NJ), 5.0 wt.% acrylic acid, 25.0 wt.%
isooctyl acrylate, 15.0 wt.% 2-phel.o..yéL~.yl acrylate,
10 wt.% trimethylolpropane tris(3 ~ pLopropionate)
(Aldrich, Nilwaukee, WI), 22.5 wt.% cy--]nhPvlnp
dimethanol divinyl ether (International Specialty
20 Products, Wayne, NJ) and 2.5 wt.9~ Escacure RB-1, and
(b) 50 parts BL036 liquid crystal mixture. The
viscosity of the coating fluid was 134 cps (measured on
a Brookfield vis~ Pr using a ~3 spindle operating at
60 rpm). The coating t~ ~LuLe was 21C and during
25 lamination an air ples:~uLe of 2.4 bar was maintained to
the laminator bar which was adjusted to provide an
interference of 3 . 8 mm. The fluid was applied as a
15.2 cm (6 inch) wide strip to the electrode surface of
an IT0-coated polyester f ilm at a rate of approximately
30 152.4 cm/min (5 ft/minute) using the precision coating
process described in Example 7 except that the die was
configured with a 46 micron overbite, a coating gap of
102 microns, and a vacuum of 1.9 mm Hg (1 inch of
water) was used to apply the solution at 22C. The film
35 was cured at 21C by PYposin~ each side to approximately
W09~l29766 ~ ~ 1 ~7~ P l/~ 5 ~ ~ ~
--16--
530 mJ/cm2 at an intensity of 1. 0 mW/cm2 to produce a
PDLC film with a thicknes6 of 23+1 microns.
The PDLC device had on- and off-state
transmissions of 71.9% and 1.1%, respectively, and a
5 haze of 4 . 8% .
1~ 9
A PDLC device was prepared as described in Example
7 except that the fluid contained 500 parts of BL036
liquid crystal mixture and 333 parts of a mixture
10 having the composition of 2 . 5 wt . % Esacure KB-1
photoinitiator, 7.5 wt.% acrylic acid, 30.0 wt.%
isooctyl acrylate, 15 . O wt. % 2~ph~ ye ~l~yl acrylate
15.0 wt.% Uralac 3004-102 (DSM Resins, U.s., Inc.,
Elgin, IL), and 30.0 wt.% Uralac 3004-300 (DSN Resins,
15 U.S., Inc., Elgin, IL). The 88.9 cm wide die was
configured with a slot width of 88.9 cm, an overbite of
43 microns, a vacuum land gap G2 Of 24.5 mm and a vacuum
of 1. 9 mm Hg was applied to the vacuum chamber during
coating. The IT0-coated polyester film used for the
20 ele~ LL~,des was approximately 130 microns (5 mils)
thick. An air ~La5r UL~: of 3.4 bar wa6 maintained to
the laminator bar which was adjusted to provide an
interference of 6.35 mm. The resulting laminate was
exposed W light having an average intensity of
approximately 1. 68 mW/cm2 at about 23 C to produce a
PDLC f ilm approximately 18 microns thick .
The PDLC device had on- and of f -state
trAnr~ sion~ of 73.4% and 1.7%, respectively, and a
haze of 5 3%
lSx~mpl-t 10
A PDLC device was prepared as described in Example
7 except that a fluid containing (a) 57.5 parts of a
mixture consisting of 13 . 7 wt . % lauryl methacrylate
(Rhom Tech, Inc., Malden, MA), 3.9 wt.% methacrylic
acid (Aldrich, Iqilwaukee, WI), 80 . 4 wt. % RCC-15C
obtained without initiator (W.R. Grace, Atlanta, GA),
~woss/29766 2 1 8 78 ~6 r~ r 1~
~nd 2 wt.~6 photoinitiator KB-l, and (b) 42.5 parts of
BL036 liquid crystal mixture, with a solution viscosity
of 210 Cp5 ~measured on a Brookfield viscometer using a
#4 spindle operating at 60 rpm~, was used. The die was
5 conf igured with a 152 mm shim having a slot width of
88 . 9 cm, a 76 micron coating gap, and a 51 micron
overbite . The coating was applied as a 88 . 9 cm wide
strip of the uncured matrix on the IT0 coated PET film
at a substrate speed of 0.91 m/minute (3 feet/minute).
10 During coating, a 3.7 mm Hg (2 inches water) vacuum was
applied to the vacuum chamber. During lamination, an
interference of 3 . 8 mm was used. The laminate
co~ L-u~;~ion was exposed to 330 mJ/cm2 of W light
having an average intensity of 1. 7 mW/cm2.
The thickness of the cured coating was 21+0 . 6
microns. The PDLC device had on- and off-state
tr~n~ n~ of 74% and 2.7%, respectively, and a haze
of 4 . 59~ .
r lo 11
A PDLC device was ~ d as described in Example
7 except that a fluid containing (a) 45 parts of a
mixture consisting of 2 . 5 wt. % KB-l photoinitiator,
20 . O wt. 96 9460 allyl aliphatic urethane (Monomer
Polymer & Dajac, Trevose, PA), 35.0 wt.% isooctyl
25 acrylate, 7.5 wt.% acrylic acid, 20 wt.~ 2 pllelloy~LII2~1
acrylate, and 15.0 wt.% Uralac 3004-102, and (b) 55
parts of BL036 liquid crystal mixture, with a solution
viscosity of 64 cps (- ~ d on a Brookfield
viscometer using a #3 spindle operating at 60 rpm), was
3 o used . The die was conf igured with a 152 micron shim
having a slot width of 88.9 cm, an overbite of 30
microns and the coating applied to the IT0 coated PET
substrate at a rate of 3 m/min. at 20C with a vacuum
of 2 . 8 mm Hg applied to the vacuum chamber. An air
35 ~Lesc,u-e of 3.4 bar was maintained to the lamination
bar which was adjusted to provide an interference of
W0 9s/29766 2 1 8 7 8 9 ~ "~( ~
--18--
3.8 mm. The laminate col.DL~u~Lion was exposed to 303
mJ/cm2 of W light having an average intensity of 1. 6
mW/cm~ .
The cured coating th;~l-no~6 was 17.4+0.6 microns.
5 The PDLC device had on- and off-state transmissions of
70.0% and 0.8%, respectively, and a haze of 8.6~.
E 1~ 12
An adhesive composition was prepared as described
in Example 5 except that the prepolymer syrup was
10 prepared from a solution containing 90 wt.% isooctyl
acrylate, 10 wt.9~ acrylic acid, and 0.04 wt.% KB-1
photoinitiator that had been advanced to a viscosity of
430 cps (measured on a Brookfield viscometer using a
4 spindle operating at 60 rpm) and to which an
15 additional 0.1 wt. % KB-1 had been added was used as the
coating fluid. The die was configured with a 0.25 mm
shim, an overbite of 76 microns and a coating gap of 76
microns. The polymer syrup was cured in a N~ a~ re
without a second substrate being applied to the coating
20 by ~ ODUL,2 to UV lights having an average intensity of
1.2 mW/cm~ to produce a IJ~-sssuL~ sensitive adhesive
having a th1~ 1rnP~fi of 21.5+0.5 microns.
