Note: Descriptions are shown in the official language in which they were submitted.
~wos5129765 21 8~99 P.,l/~ 7
ROLL AND DIE COATINa ~T}~OD A~D AppARaTlJ6
WIT}I l~.~J . L.-J DIE 1IP
Tr r~TNTrAT FT~rn
The present invention relates to coating
methods. More particularly, the present invention
relates to coating methods using a die.
RA~ K~ OF THE INVENTION
U.S. Patent No. 2,681,294 discloses a vacuum
method for stabilizing the coating bead for direct
extruslon and slide types of metered coating systems.
Such stAh; 1; z~Ation onhAnr-~c the coating cArAh; 1 i ty of
these systems. However, these coating systems lack
5--ff;r;ont overall cArAh;lity to provide the thin wet
layers, even at very low liquid viscosities, required
for some coated products.
U.S. Patent No. 4,445,458 f~;crlrseG an
extrusion type bead-coating die with a beveled draw-
down surf ace to impose a b/iUllda,L y f orce on the
~ .IlLLr~am side of the coating bead and to reduce the
amount of vacuum norocc:~ry to maintain the bead.
Reduction of the vacuum m;n;~i~oc chatter defects and
coating streaks. To improve coating quality, the
obtuse angle of the beveled surf ace with respect to
the slot axis, and the position along the slot axis of
the bevel toward the moving web (overhang) and away
from the moving web (underhang) must be optimized.
The optimization results in the high quality needed
for coating photosensitive - lci~nc~ However, the
thin-layer performance rAr~hi 1 ity needed for some
coated pLudu~;Ls is lacking.
Figure 1 shows a known coating die 10 with a
vacuum chamber 12 as part of a metered coating system.
A coating liquid 14 is precisely sllrplied by a pump
16 to the die lO for application to a moving web 18,
supported by a backup roller 20. Coating liquid is
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~"rPl~P'l through a channel 22 to a manifold 24 for
distribution through a slot 26 in the die and coating
onto the moving web 18. A6 shown in Figure 2, the
coating liquid passes through the slot 26 and forms a
5 c--nt;n~ C coating bead 28 between the U~LL~U die
lip 30 and the downstream die lip 32, and the web 18.
D~ -lrnc fl and f2, the width of the lips 30, 32
commonly range from O . 25 to O . 76 mm. The vacuum
chamber 12 applies a vacuum U~_~Le-llll of the bead to
10 stAh~ the bead . While this conf iguration works
adequately in many situations, there is a need for a
die coating method which i ,jv~:s the performance of
known methods.
15 srrMMARY OF ~rrF ~NVE N~ION
The present invention i5 a die coating
apparatus for coating fluid coating onto a surface.
The ~aLc.~us inrl~ c a die having an u~a~Le:alll bar
with an u~D~al~ lip and a downstream bar with a
20 d~ ~L~am lip. The u~ c.m lip is formed as a land
and the ~ LLe~llu lip is formed as a sharp edge. A
y runs through the die between the U~LL~Iu
and l ~IlDL~:cuu bars. The pAccA3 _y has a slot
defined by the U~ L~::alU and downstream lips, and
25 coating fluid exits the die from the slot to form a
rnnt~mlrnlc coating bead between the upstream die lip,
tha d .I,,LL-,~m die lip, and the surface being coated.
A metering roller removes excess coating fluid. The
bead does not significantly move into the space
30 between the land and the surface to be coated even as
vacuum is increased.
Alternatively the apparatus can include a
roller on which the coating f luid is initially coated
and which contacts the web . An excess coating f luid
35 remover removes excess coating fluid from the roller.
A die coats the coating f luid onto the roller. The
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remover can be a doctor blade or a metering roller and
the coating liquid on the roller can be kiss
trzmsferred to the web.
A method of die coating according to the
5 present invention in~ A-.~ passing coating fluid
through a slot; improving coating performance by
. rh~nq~ nq at least one of the relative orientationS of
the land and the sharp edge; removing excess coating
fluid from the surface to be coated using a metering
10 roller; s~lectinq the length of the land, the edge
angle of the A~ LL~ u bar, the die attack angle
between the 1 L . ~ bar 6urface of the coating slot
And a tangent plane through a line on the surface to
be coated parallel to, and directly opposite, the
15 sharp edge, and the coating gap distance between the
~harp edge and the surf ace to be coated in combination
with each other; and selecting the slot height, the
overbite, and the ~u..v~ly~:nce in combination with each
other .
RRTl;~ 'K I 1-,~ . OF THE l)RAWINGS
Figure 1 is a schematic, ~:LU5'; 3ec~ional
view of a. known coating die.
Figure 2 is an enlarged cross-sec~ n~ l view
of the slot and lip of the die of Figure 1.
Figure 3 is a ~:LOSS s~actional view of an
extrusion die of the present invention.
Figure 4 is an enlarged UL05;3 s~_Lional view
of the slot and lip of the die of Figure 4.
Figure 5 is a ~;Lo6F sectional view of the
slot and lip similar to that of Figure 4.
Figure 6 is a ~:Loss~ n~l view of an
alternative vacuum chamber arr~r~ L.
Figure 7 is a cross-sectl~n~l view of
another alternative vacuum chamber "LlC~ily~ .
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Figure 8 is a ~LO56 SP~' tt~n~l view of an
alternative extrusion die of the present invention.
Figures 9a and 9b are enlarged cross-
5~ tl~nAl views of the slot, face, and vacuum chamber
of the die of Figure 8.
Figures lOa and lOb are schematic views of
the die of Figure 8.
Figure 11 shows coating test results which
compare the performance of a known extrusion die and
an extrusion die of the present invention for a
coating liquid of 1. 8 centipoise viscosity.
Figure 12 shows _ ~.tive test results for
a coating liquid of 2 . 7 centipoise viscosity.
Figure 13 is a collection of data from
coating tests.
Figure 14 is a graph of constant G/Tw lines
for an extrusion coating die of the present invention
for nine di~ferent coating liquids.
Figure 15 is a schematic view of a three
roll reverse roll coater using the die of the present
invention .
Figure 16 is schematic view of a two roll
reverse roll coater using the die of the present
invention .
Figure 17 is a schematic view of a gravure
coater using the die of the present invention.
Figure 18 is a two roll extrusion coater
using the die of the present invention.
Figures l9a, l9b, and l9c are cross-
sectir~n~l views of a kiss coater using the die of the
present invention.
Figures 20a, 20b, and 20c are cross-
s~ctionAl views of a kiss coater using the die of the
present invention.
Figure 20d is a ~.LO55 se_l.ional view of a
kiss coater using the die of Figure l9c.
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TT.TCn nr.~
This invention i8 a die coating method and
ap~..Lus where the die in-~ t~c a charp edge and a
S land which are positioned to improve and optimize
perf ormance . The land is conf igured to match the
shape of the surface in the immediate area of coating
liquid application. The land can be curved to match a
web passing around a backup roller or the land can be
flat to match a free span of web between rollers.
Figure 3 shows the extrusion die 40 with a
vacuum chamber 4 2 Or the present invention . Coating
liquid 14 is supplied by a pump 46 to the die 40 for
application to a moving web 48, supported by a backup
roller 50. Coating liquid is supplied through a
channel 52 to a manifold 54 for distribution through a
slot 56 and coating onto the moving web 48. As shown
in Figure 4, the coating liquid 14 passes through the
slot 56 and forms a continuous coating bead 58 among
the u~LL~calll die lip 60, the l~ LLæ~n die lip 62,
~nd the web 48. The coating liquid can be one of
uus liquids or other fluids. The U~DLLe:~lU die
lip 60 is part of an upstream bar 64, and the
LL- am die 62 lip is part of a ~1~ LL~al~ bar 66.
The height of the slot 56 can be controlled by a U-
shaped shim which can be made of brass or st:~inl-~sc
steel and which can be deckled. The vacuum chamber 42
applies vacuum uyDLL~alu of the bead to stabilize the
coating bead.
As shown in Figure 5, the U,u-,LL~:alu lip 60 is
formed as a curved land 68 and the ~' ..,-LL-~am lip 62
is rormed as a sharp edge 70. This configuration
u~s overall perforr-nre over that Or known die-
type coaters. T, uied performance means permitting
35 operating at increased web speeds and increased
coating gaps, operating with higher coating liquid
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viscosities, and creating thinner wet coating layer
~h;. ~
The 6harp edge 70 should be clean and free
of nicks and burrs, and should be straight within
5 micron in 25 cm of length. The edge radius should be
no greater than 10 microns. ~he radius of the curved
land 68 should be equal to the radius of the backup
roller 50 plus a minimal, and non-critical, 0.13 mm
~11. nre for coating gap and web thic-kn~cl~.
10 Alternatively, the radius of the curved land 68 can
exceed that of the backup roller 50 and shims can be
used to orient the land with respect to the web 48. A
given COIIveLye,l.Ce C achieved by a land with the same
radiu- as the backup roller can be achieved by a land
with a larger radius than the backup roller by
D~-n~rlllating the land with the shims.
Figure 5 also shows dimensions of geometric
operating parameters for single layer extrusion. The
length Ll o~ the curved land 68 on the upstream bar 64
2 0 can range f rom 1. 6 mm to 2 5 . 4 mm . The pref erred
length L1 is 12 . 7 mm. The edge angle Al of the
~ "..LL-aam bar 66 can range from 20 to 75, and is
preferably 60. The edge radius of the sharp edge 70
should be from about 2 microns to about 4 microns and
preferably le6s than 10 microns. The die attack angle
A2 between the downstream bar 66 surface of the
coating slot 56 and the tangent plane P through a line
on the web 48 surface parallel to, and directly
opposite, the sharp edge 70 can range from 60 to 120
and i5 prefer~bly 90-95, such as 93. The coating
gap G1 is the perpendicular distance between the sharp
edge 70 and the web 48. (The coating gap G1 is
measured at the sharp edge but is shown in some
Figures spaced from the sharp edge for drawing
3 5 clarity . Regardless of the location of Gl in the
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drawings - and due to the UU~ V~l~UL~ of the web the gap
lncreaDes aE~ one moves away from the sharp edge - the
gap i8 - :d at the sharp edge. )
Slot height H can range from 0. 076 mm to
5 3.175 mm. Overbite O is a positioning of the sharp
edge 70 of the ~ ..r,LL~:~m bar 66, with respect to the
., A~ ~L.~alll edge 72 of the curved land 68 on the
U~DLL~IIU bar 64, in a direction toward the web 48.
overbite also can be viewed a6 a retraction of the
10 ~ . ~IDLL-.~m edge 72 of the curved land 68 away from the
web 48, with respect to the sharp edge 70, for any
given coating gap Gl. Overbite can range from O mm to
O . 51 mm, and the settings at opposite ends of the die
slot should be within 2 . 5 microns of each other. A
15 precision mounting system for this coating system is
required, for example to accomplish precise overbite
uniformity. C~...vt~y~nce C is a counterclockwise, as
shown in Figure 5, angular positioning of the curved
land 68 away from a location parallel to (or
20 c~ .. ..l ~ lc with) the web 48, with the r' ....LLe~n edge
72 being the center of rotation. Cu..ve:Lyc:ilce can
range from 0 to 2.29, and the settings at opposite
ends of the die slot should be within o. 023 of each
other. The slot height, overbite, and c~ ry~ ~- e, as
25 well as the fluid properties such as viscosity affect
the performance of the die coating d~L~lLUS and
method.
From an overall performance s~r~nrlroint~ for
liquids within the viscosity range of 1,000 centipoise
30 and below, it is preferred that the slot height be
0.18 mm, the overbite be O . 076 mm, and the ;O~v-zly~ e
be O . 57. Performance levels using other slot heights
can be nearly the same. Performance advantages can
also be found at viscosities above 1,000 centipoise.
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Holding c~,..v~Ly~l~ce at 0.57, some other optimum slot
height and overbite combinationD are as ~ollows:
Slot Hei~ht Overbite
0.15 mm 0.071 mm
0. 20 mm 0 . 082 mm
0.31 mm 0.100 mm
0.51 mm 0.130 mm
10 In the liquid viscosity range noted above, and for any
given C~...v~Lyel~ce value, the optimum overbite value
Appears to be directly proportional to the square root
of the slot height value. Similarly, for any given
slot height value, the optimum overbite value appearD
15 to be inversely proportional to the square root of the
C~ .Lyt ..~;e value.
As shown in Figure 6, the vacuum chamber 42
can be an integral part of, or clamped to, the
u~D~.ec.-u bar 64 to allow precise, repeatable vacuum
20 system gas flow. The vacuum chamber 42 is formed
using a vacuum bar 74 and can be cnnnDrtecl through an
optional vacuum restrictor 76 and a vacuum manifold 78
to a vacuum source channel 80. A curved vacuum land
82 can be an integral part of the u~DLLealu bar 64, or
25 can be part of the vacuum bar 74, which is secured to
the U~DLL~:al~ bar 64. The vacuum land 82 has the same
radius of ~;ULVCI~ULe as the curved land 68. The curved
land 68 and the vacuum land 82 can be f inish-ground
together so they are "in line" with each other. The
30 vacuum land 82 and the curved land 68 then have the
same COllVeLY~I~Cê C with respect to the web 48.
The vacuum land gap G2 is the distance
between the vacuum land 82 and the web 48 at the lower
edge of the vacuum land and is the sum total of the
35 coating gap Gl, the overbite 0, and the t~ plA~ --L
cauDed by ~ ~JIlv~Lyellce C of the curved land 68.
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(Regardless of the location of G1 in the drawings the
gap is the perp--n~9; c~ r distance between the lower
edge of the vacuum land and the web. ) When the vacuum
land gap G2 i8 large, an excessive inrush of ambient
5 air to the vacuum chamber 42 occurs. Even though the
vacuum source may have suf f icient capacity to
~ e and maintain the specified vacuum ~L~5~UL~
level at the vacuum chamber 42, the inrush of air can
degrade coating performance.
In Figure 7, the vacuum land 82 i8 part of a
vacuum bar 74 which is attached to the U~DLL~IU bar
64. During fabrication, the curved land 68 i8
f inished with the C;~ v~L ~ e C "ground in . " The
vacuum bar 74 i5 then attached and the vacuum land 82
15 is finish ground, using a different grind center, such
that the vacuum land 82 is parallel to the web 48, and
the vacuum land gap G2 is equal to the coating gap G
when the dQsired overbite value is set. The vacuum
land length L2 may range from 6 . 35 mm to 25 . 4 mm. The
20 preferred length L2 is 12.7 mm. This ~mho~ L has
greater overall coating performance c~r~h;l~ty in
difficult coating situations than the: 'i L of
Figure 6, but it is always finish ground for one
specific set of operating conditions. So, as coating
25 gap G1 or overbite 0 are changed vacuum land gap G2 may
move away from its optimum value.
In Figures 8 and 9 the UyDl.Le:cllU bar 64 of
the die 40 is mounted on an u}JDLLedm bar positioner
84, and the vacuum bar 74 is mounted on a vacuum bar
30 positioner 86. The curved land 68 on the U~a~L~:-IIII bar
64 and the vacuum land 82 on the vacuum bar 74 are not
connected directly to each other. The vacuum chamber
42 is connected to its vacuum source through the
- vacuum bar 74 and the positioner 86. The mounting and
35 positioning for the vacuum bar 74 are separate from
those for the U~JD~L ~alll bar 64. This; ;)~_8
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perforr-nre of the die and allows precise, r~re~
vacuum system gas f low. Irhe robust conf iguration of
the vacuum bar system also aids in the ~ d
perf ormance as compared with known systems . Also,
5 this configuration for the vacuum bar 74 could improve
performance of other known coaters, such as slot,
~xtrusion, and slide coaters. A flexible vacuum seal
strip 88 seal6 between the upstream bar 64 and the
vacuum bar 7 4 .
The gap G2 between the vacuum land 82 and
the web 48 is not affected by coating gap Gl, overbite
0, or .;~..vcL~nC6 C changes, and may be held at its
optimum value continuously, during coating. The
vacuum land gap G2 may be set within the range f rom
o . 076 mm to O . 508 mm. The preferrea value for the gap
G2 is 0.15 mm. The preferred angular position for the
vacuum land 82 is parallel to the web 48.
During coating, the vacuum level is adjusted
to produce the best quality coated layer. A typical
vacuum level, when coating a 2 centipoise coating
liquid at 6 microns wet layer thirkn~ and 30.5 m/min
web speed, is 51 mm H20. Decreasing wet layer
th;rkn~C, increasing viscosity, or increasing web
speed could require higher vacuum levels ~Yr--eA; ng 150
2 5 mm H20 . Dies of this invention exhibit lower
satisfactory minimum vacuum levels and higher
satisfactory maximum vacuum levels than known systems,
and in some situations can operate with ZQro vacuum
where known systems cannot.
Figures lOa and lOb show some positioning
adJuL~ Ls and the vacuum chamber closurQ. Overbite
ad~ translates the ~ LL aul bar 66 with
respect to the upstream bar 64 such that the sharp
edge 70 moves toward or away from the web 48 with
respect to the ~ LLacl~u edge 72 o~ the curved land
68. Adjusting c.,.,ve Ly_l~ce rotates the upstream bar 64
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and the ' L- an, bar 66 together around an axis
running through the ~ ..,LL~am edge 72, such that the
curved land 68 moves from the position shown in Figure
10, ~way from parallel to the web 48, or back toward
5 parallel. Coating gap adju~,i L translates the
U~,~LL. a~o bar 64 and the ~ LL~a~ bar 66 together to
change the distance between the sharp edge 7 0 and the
web 48, while the vacuum bar remains stationary on its
mount 86, and the vacuum seal strip 88 flexes to
10 prevent air leakage during adjustments. Air leakage
at the ends of the die into the vacuum chamber 42 is
m;n;m;~od by end plates 90 attached to the ends of the
vacuum bar 7 4 which overlap the ends of the u~ L, e cllU
bar 64. The vacuum bar 74 is 0.10 mm to 0.15 _m
15 longer than the upstream bar 64, so, in a centered
condition, the clearance between each end plate 90 and
the upstream bar 64 will range from 0 . 050 mm to 0. 075
mm.
one -~l e -~cl operating characteristic has
20 been obs~L~-d during coating. The bead does not move
significantly into the space between the curved land
68 and the moving web 48, even as vacuum is increased.
This allows using higher vacuum levels than is
pos$;hlP with known extrusion coaters, and provides a
25 cv~ ;n~ly higher performance level. Even where
little or no vacuum is required, the invention
exhibits ; vv~d perf ormance over known systems .
That the bead does not move signif icantly into the
space between the curved land 68 and the web 48 also
30 means that the effect of "runout" in the backup roller
50 on ~ .LL~a-,~ coating weight does not differ from
that for known extrusion coaters.
Figure 11 graphs results of coating tests
which compare the perf ormance of a known extrusion die
35 with an extrusion die of this invention. In the
tests, the 1.8 centipoise coating liquid containing an
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organic solvent was applied to a plain polyester f ilm
web. The performance criterion was minimum wet layer
th~rlrn-~c~ at four different coating gap levels for
each of the two coating systems, over the 6peed range
5 Or 15 to 60 m/min. Curves A, B, C, and D use the
known, prior art die and were performed with coating
gaps of 0.254 mm, 0.203 mm, 0.152 mm, and 0.127 mm,
respectively. Curves E, F, G, and H use a die
according to this invention at the same respective
10 coating gaps. The lower wet th;rl~naCc levels for this
invention, ~d to the prior art die, are easily
visible. Figure 12 shows _ ~ tive test results for
a similar coating liquid of 2 . 7 centipoise viscosity,
at the same coating gaps. Once again, the performance
15 a~v~.l,Lc-ge for this invention is clearly visible.
Figure 13 is a collection of data from
coating tests where liquids at seven different
viscosities, and containing different organic
solvents, were applied to plain polyester film webs.
20 The results compare performance of the prior art
extrusion coater (PRIOR) and this invention (NEW).
The perf ormance criteria are mixed . Perf ormance
advc.l~tages ~or this invention can be f ound in web
speed (Vw), wet layer thirl-n~cc (Tw), coating gap,
25 vacuum level, or a combination of these.
One measure of coater performance is the
ratio of coating gap to wet layer thi rl-n~cc (G/Tw),
ror n particular coating liquid and web speed. Figure
14 shows a series of cv.v-La,,L G/Tw lines and viscosity
30 values of an extrusion die of this invention, for nine
different coating liquids. The liquids were coated on
plain polyester film base at a web speed of 30. 5
m/min. A few viscosity values appear to be out of
order, due to the effect of other coatability factors.
35 Four additional performance lines have been added
after calculating the G/Tw values for 30.5 m/min web
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~peed from Figures 11 and 12. From top to bottom, the
solid performance lines are the G/Tw for liquids o~
2 . 7 centipoise and 1. 8 centipoise coated by a known
extrusion die and the G/Tw for liquids of 2 . 7
5 centipoise and 1. 8 centipoise coated by an extrusion
die of this invention. The lines for of this
invention rt~Las~ l greater G/Tw values than the lines
for o~ the prior art coating die. In addition, the
lines for this invention are close to being lines of
~.. ,.,~1 ,Inl G/Tw, averaging 18 . 8 and 16 . 8, respectively.
The lines of the known coater show conQid-o~ably more
G/Tw variation over their length. This invention has
a much i vv_d operating characteristic for
~-;ntA~nin~ a coating bead at low wet th;~kn~ s
values, over known systems.
Coating dies of this invention can be used
as high performance liquid feed devices for roll and
kiss coaters. Figure 15 shows a three roll reverse
roll coater using an extrusion die 40 to feed coating
liquid 14 to a casting roller 330. Because the
surface of the casting roller 330 passes the die 40 in
a ~ -~l direction, the die 40 is inverted and the
vacuum chamber 42 is above the slot and the coating
bead . This does not af f ect coating perf ormance . A
metering roller 332 removes excess coating liquid,
leaving a precise layer on the casting roller 330. A
doctor blade 334 removes the excess coating liquid
from the metering roller 332 and drops it into a
liquid return pan 336 for recirculation.
M~An~hil~, a bead-splitting action transfers
part of the coating liquid from the casting roller 330
to the web 48 moving around the backup roller 50.
After the bead splits, a second doctor blade 338
cleans the r~ ;n~n J coating liquid from the casting
roller 330 and runs it into the recirculation pan 336.
Alternatively, the backup roller 50 can be rubber
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covered 60 the castinq roller 330 can contact the web
and tr~ns~er all of the coating liquid in this area to
the web. The second doctor blade 338 would then clean
any liquid from the casting roller 330 which i6
outside of the web width.
Figure 16 shows a two roll reverse roll
coater using an extru6ion die 40 to feed coating
liguid to the surface of the web 48 moving around the
backup roller 14, which is a wrapped casting roller.
The metering roller 332 removes excess coating liquid
from the surface of the web 48, leaving the desired,
precise wet coated layer. The doctor blade 334 cleans
the excess coating liquid from the metering roller 332
and runs it into the recirculation pan 336. Use of
this system in one example increased the vacuum window
from 5 . 08 mm to over 254 mm H20, and increased the
liquid feed coating gap from 0 .10 mm to 0 . 36 mm,
thereby improving stability and practically
eliminating streaking.
Figure 17 shows a gravure coater using an
extrusion die 40 to feed coating liquid to the surface
of a knurled roller 340. The die 40 has its vacuum
chamber 42 above its coating slot. A doctor blade 342
removes excess coating liquid from the knurl pattern
~o that the desired amount transfers to the web 48
moving around the rubber-~uve:~d backup roller 314.
The excess coating liquid recirculates through the pan
336. This method of feeding coating liquid to the
surface of a knurled roller can also be used for other
forms of gravure coating such as reverse, offset, and
dif f erential .
Figure 18 shows a two roll extrusion coater
using an extrusion die 40 to feed ccating liquid to
the surface of the casting roller 330, with stability
from the vacuum chamber 42. The layer of coating
liquid is thin and precise 80 that a metering roll is
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21 8789q
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not required. The bead split takes place directly to
the web 48 moving around the backup roller 314. A
doctor blade 338 remove6 the coating excess liquid
rrom the casting roller 330 and recirculates it
-~ 5 through the pan 336. Alternatively, the backup roller
50 can be rubber covered 80 the casting roller 330 can
contact the web and transfer all of the coating liquid
in this area to the web. The second doctor blade 338
would then clean any liquid from the casting roller
330 which is outside of the web width.
Figure l9a shows a kiss coater where an
extrusion die 40 feeds coating liquid through a
manifold 54 and a slot 56 to a transfer roller 344
such as a spindle having a ~;~ tQr ranging from 25.4
mm to 50.8 mm. The coating bead is st2~hili7od by the
vacuum chamber 42. The coating liguid on the transfer
roller 344 is kiss transferred to form the coated
layer on the web 48. The small 1;: Qr transfer
roller 344 has a small kiss transfer area, and
~ ~ve 8 web stability over that with a larger
transfer roller by reducing web flutter and cross
tension marks. The surface of the transfer roller 344
can be, for example, smooth, polished, medium grind,
grit blasted, or knurled.
Figure l9b shows a ki6s coater where the
extrusion die 40 with a vacuum chamber 42 feeds
coating liquid to the surface of a kiss transfer
roller 344. The roller 344 haB a larger rli2 - than
the spindle of Figure l9a. The coating liguid is kiss
transferred to form the coated layer on the web 48.
Figure l9c shows a kiss coater where a slide
coating die 310 feed2-2 coating liquid to the surface of
a kiss transfer roller 344. The coating liquid is
kiss transferred to form the coated layer on the web
48.
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Figure 20a shows a kiss coater where n dual-
layer extrusion die lOo reeds two coating liquids 116,
124 through ~hAnn~ 118, 126 to the 6urface of a
spindle, such as a transfer roller 344 having a
1l~ tt:L ranging from 25.4 mm to 50.8 mm. The two
coating liquids on the transfer roller 344 are
transferred to form two coated layers on the web 48.
~igure 20b shows a kiss coatQr where a dual-
layer extrusion die 100 feeds coating liquid to a kiss
transfer roller. The roller 344 has a larger rl~ ~r
than the roller of Figure 20a. Two coating liquids
116, 124 are fed through two separate manifolds and
two separate slots to meet at the coating bead. The
two coating liquids are transferred to the web forming
wet coated layers.
Figure 20c shows a kiss coater where a dual-
layer extrusion die 100 feeds coating liquid to a kis6
transfer roller 344. The two coating liquids 116, 124
are fed through two manifolds, but only one slot,
meeting inside the die. The two coating liquids on
the surface of the transfer roller 344 are transferred
to form the two coated layers on the web 48.
Figure 20d shows a kiss coater where a
multiple layer coating version of the die 220 of
Figure l9c feed6 four coating liquids onto the surface
of the tran~fer roller 344. Four liquids 116, 124,
346, 348 are fed through the die 100, down slide
surfaces 236 to form four layers on the surface of the
transfer roller 344. These layers are transferred to
~o ~onn ~our ~o~t~ I l=yer- or the web ib.
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