U.S. patent application number 12/057220 was filed with the patent office on 2008-10-02 for web transport apparatus and solution casting process.
Invention is credited to Takatoshi HORIKAWA, Hidekazu Yamazaki.
Application Number | 20080237289 12/057220 |
Document ID | / |
Family ID | 39792501 |
Filed Date | 2008-10-02 |
United States Patent
Application |
20080237289 |
Kind Code |
A1 |
HORIKAWA; Takatoshi ; et
al. |
October 2, 2008 |
WEB TRANSPORT APPARATUS AND SOLUTION CASTING PROCESS
Abstract
A pin tentering apparatus as web transport apparatus includes a
tentering mechanism for transporting self-supporting cast film by
retaining web edge portions of the cast film. A gas flow device
blows evaporative gas to the cast film being transported, to float
the cast film. A static pressure adjuster lowers static pressure of
the evaporative gas to a web middle portion with respect to a web
width direction of the cast film, to regularize distribution of the
static pressure in the web width direction. In the gas flow device,
a blower duct introduces the evaporative gas. A nozzle plate is
positioned at a front end of the duct, and has nozzles which blow
the evaporative gas. Preferably, the static pressure adjuster
includes an exhaust device, disposed to face the web middle portion
between the plural nozzles, for exhausting the evaporative gas.
Inventors: |
HORIKAWA; Takatoshi;
(Kanagawa, JP) ; Yamazaki; Hidekazu; (Kanagawa,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
39792501 |
Appl. No.: |
12/057220 |
Filed: |
March 27, 2008 |
Current U.S.
Class: |
226/97.4 |
Current CPC
Class: |
B65H 2701/1752 20130101;
B65H 2301/517 20130101; B65H 23/24 20130101; B65H 20/20 20130101;
B65H 2701/1719 20130101; B65H 2406/112 20130101; B65H 2406/1132
20130101; B65H 2301/5114 20130101 |
Class at
Publication: |
226/97.4 |
International
Class: |
B65H 20/14 20060101
B65H020/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2007 |
JP |
2007-088141 |
Claims
1. A web transport apparatus comprising: a transport mechanism for
transporting web by retaining web edge portions of said web; a gas
flow device for blowing gaseous medium to said web being
transported, to float said web; and a static pressure adjuster for
lowering static pressure of said gaseous medium to a web middle
portion of said web with respect to a web width direction thereof,
to regularize distribution of said static pressure in said web
width direction.
2. A web transport apparatus as defined in claim 1, wherein said
gas flow device includes: a duct for introducing said gaseous
medium; and a nozzle plate, positioned at a front end of said duct,
having a nozzle, for blowing said gaseous medium through said
nozzle.
3. A web transport apparatus as defined in claim 2, wherein said
static pressure adjuster limits said distribution of said static
pressure to a value equal to or more than -200% and equal to or
less than +200% per unit area of said web.
4. A web transport apparatus as defined in claim 3, wherein said
gaseous medium is evaporative gas, and said transport mechanism is
constituted by a tentering mechanism.
5. A web transport apparatus as defined in claim 3, wherein said
static pressure adjuster controls a flow rate of said gaseous
medium in said gas flow device with respect to said web width
direction.
6. A web transport apparatus as defined in claim 3, wherein said
nozzle is constituted by plural nozzles; said static pressure
adjuster includes an exhaust device, disposed to face said web
middle portion between said plural nozzles, for exhausting said
gaseous medium.
7. A web transport apparatus as defined in claim 6, wherein said
exhaust device is so constructed that a flow rate of exhausting
said gaseous medium is variable.
5. A web transport apparatus as defined in claim 6, wherein said
plural nozzles include: a first nozzle group of nozzles opposed to
said web edge portions; and a second nozzle group of nozzles,
opposed to said web middle portion, and offset from said exhaust
device.
9. A web transport apparatus as defined in claim 3, wherein said
static pressure adjuster includes a recess, formed in said nozzle
plate, and opposed to said web middle portion.
10. A web transport apparatus as defined in claim 3, wherein said
nozzle is constituted by plural nozzles including: a first nozzle
group of nozzles opposed to said web edge portions; a second nozzle
group of nozzles, opposed to said web middle portion, for operating
at a smaller flow rate of said gaseous medium than a flow rate of
said gaseous medium of said first nozzle group, to constitute said
static pressure adjuster.
11. A web transport apparatus as defined in claim 10, wherein said
duct includes: a first duct section for introducing said gaseous
medium to said first nozzle group; a second duct section for
introducing said gaseous medium to said second nozzle group; said
static pressure adjuster controls said duct by setting said flow
rate smaller for said second duct section than for said first duct
section.
12. A web transport apparatus as defined in claim 10, wherein a
total aperture area of said second nozzle group is smaller than a
total aperture area of said first nozzle group.
13. A web transport apparatus as defined in claim 10, wherein a
number of said nozzles in said second nozzle group is smaller than
a number of said nozzles in said first nozzle group.
14. A web transport apparatus as defined in claim 3, wherein said
nozzle plate is constituted by plural nozzle plates, arranged in a
transport direction of said web at a regular interval, disposed
respectively to extend in said web width direction, for blowing
said gaseous medium; said static pressure adjuster includes a
movable plate portion disposed between said nozzle plates, a
distance of said movable plate portion from said web being
variable.
15. A web transport apparatus as defined in claim 14, wherein said
movable plate portion is set farther from said web than said nozzle
plates.
16. A web transport apparatus as defined in claim 14, further
comprising an exhaust device, disposed through said movable plate
portion, for exhausting said gaseous medium.
17. A web transport apparatus as defined in claim 3, wherein said
transport mechanism includes: first and second tenter pin groups,
disposed to face respectively said web edge portions, respectively
including plural tenter pins for piecing said web edge portions; a
moving device for endlessly moving said first and second tenter pin
groups along said web edge portions, to transport said web.
18. A web transport apparatus as defined in claim 17, wherein said
web is cast film, formed by casting cellulose ester solution
containing cellulose ester and solvent, and having a
self-supporting property.
19. A web transport apparatus as defined in claim 18, wherein
content of said solvent contained in said cast film is equal to or
more than 130 wt. %.
20. A solution casting process comprising steps of: casting
cellulose ester solution on to an endlessly traveling support, to
form cast film; stripping said cast film from said support;
transporting said cast film by retaining web edge portions of said
cast film; blowing gaseous medium to said cast film being transport
for flotation; and lowering static pressure of said gaseous medium
to a web middle portion of said cast film with respect to a web
width direction thereof, to regularize distribution of said static
pressure in said web width direction.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a web transport apparatus
and solution casting system. More particularly, the present
invention relates to a web transport apparatus and solution casting
system in which web or cast film produced continuously can be
prevented from protrusion with a curve even in application of
gaseous medium to the web.
[0003] 2. Description Related to the Prior Art
[0004] Polymer film is widely used as optical functional film
because of high transparency, flexibility and possibility for
lightweight feature and reduction of the thickness. Among various
examples of polymer films, cellulose ester film produced from
cellulose acylate or other cellulose esters is characterized in
high performance with rigidity and low birefringence. The cellulose
ester film is used as photosensitive material for photography, and
also as protective film, optical compensation film and the like for
a panel shaped polarizer element as a constituent of a liquid
crystal display device (LCD).
[0005] Solution casting is a typically used method of producing the
cellulose ester film. At first, viscous solution or dope containing
cellulose ester and solvent is prepared, and cast from a casting
die on to a casting support. Cast film is formed. When the cast
film comes to have a self-supporting property, a self-supporting
cast film is stripped from the casting support. A tentering machine
is supplied with the self-supporting cast film, clamps web edges of
the self-supporting cast film to transport the same, which is dried
and becomes the cellulose ester film. A web edge slitter slits web
edges portions of the cellulose ester film, which is dried finally
by a dryer and wound by a winder.
[0006] JP-A 2003-260741 discloses a tentering machine, specifically
a pin tentering machine for use with the self-supporting cast film
having a high solvent amount. A duct is disposed lower or higher
than the cellulose ester film and blows evaporative gas to the
self-supporting cast film. The self-supporting cast film is
transported and dried at the same time.
[0007] If the self-supporting cast film is transported in flotation
by the duct, force of gas to a web middle portion as viewed in a
web width direction. The web middle portion is likely to protrude
convexly while the self-supporting cast film is transported.
Although there is a social requirement of a large area type of
liquid crystal display panel, no known technique is effective in
preventing incidental protrusion of the web middle portion of which
a web width may be considerably great. Specifically, a solution
casting system should be suitable for a great width structure.
Distribution of the static pressure of the atmosphere under the
self-supporting cast film is still wider than that according to the
widely used tentering machine, the distribution corresponding to
that of the force of floating of the self-supporting cast film in
the tension drying. However, it is impossible in known techniques
to solve problems of instability of transport of the
self-supporting cast film and degradation of the self-supporting
cast film as product.
SUMMARY OF THE INVENTION
[0008] In view of the foregoing problems, an object of the present
invention is to provide a web transport apparatus and solution
casting system in which web or cast film produced continuously can
be prevented from protrusion with a curve even in application of
gaseous medium to the web.
[0009] In order to achieve the above and other objects and
advantages of this invention, a web transport apparatus includes a
transport mechanism for transporting web by retaining web edge
portions of the web. A gas flow device blows gaseous medium to the
web being transported, to float the web. A static pressure adjuster
lowers static pressure of the gaseous medium to a web middle
portion of the web with respect to a web width direction thereof,
to regularize distribution of the static pressure in the web width
direction.
[0010] The gas flow device includes a duct for introducing the
gaseous medium. A nozzle plate is positioned at a front end of the
duct, has a nozzle, for blowing the gaseous medium through the
nozzle.
[0011] The static pressure adjuster limits the distribution of the
static pressure to a value equal to or more than -200% and equal to
or less than +200% per unit area of said web.
[0012] The gaseous medium is evaporative gas, and the transport
mechanism is constituted by a tentering mechanism.
[0013] The static pressure adjuster controls a flow rate of the
gaseous medium in the gas flow device with respect to the web width
direction.
[0014] The nozzle is constituted by plural nozzles. The static
pressure adjuster includes an exhaust device, disposed to face the
web middle portion between the plural nozzles, for exhausting the
gaseous medium.
[0015] The exhaust device is so constructed that a flow rate of
exhausting the gaseous medium is variable.
[0016] The plural nozzles include a first nozzle group of nozzles
opposed to the web edge portions. A second nozzle group of nozzles
is opposed to the web middle portion, and offset from the exhaust
device.
[0017] The static pressure adjuster includes a recess, formed in
the nozzle plate, and opposed to the web middle portion.
[0018] The nozzle is constituted by plural nozzles including a
first nozzle group of nozzles opposed to the web edge portions. A
second nozzle group of nozzles is opposed to the web middle
portion, for operating at a smaller flow rate of the gaseous medium
than a flow rate of the gaseous medium of the first nozzle group,
to constitute the static pressure adjuster.
[0019] The duct includes a first duct section for introducing the
gaseous medium to the first nozzle group. A second duct section
introduces the gaseous medium to the second nozzle group. The
static pressure adjuster controls the duct by setting the flow rate
smaller for the second duct section than for the first duct
section.
[0020] In a preferred embodiment, a total aperture area of the
second nozzle group is smaller than a total aperture area of the
first nozzle group.
[0021] In another preferred embodiment, a number of the nozzles in
the second nozzle group is smaller than a number of the nozzles in
the first nozzle group.
[0022] The nozzle plate is constituted by plural nozzle plates,
arranged in a transport direction of the web at a regular interval,
disposed respectively to extend in the web width direction, for
blowing the gaseous medium. The static pressure adjuster includes a
movable plate portion disposed between the nozzle plates, a
distance of the movable plate portion from the web being
variable.
[0023] The movable plate portion is set farther from the web than
the nozzle plates.
[0024] Furthermore, an exhaust device is disposed through the
movable plate portion, for exhausting the gaseous medium.
[0025] The transport mechanism includes first and second tenter pin
groups, disposed to face respectively the web edge portions,
respectively including plural tenter pins for piecing the web edge
portions. A moving device endlessly moves the first and second
tenter pin groups along the web edge portions, to transport the
web.
[0026] The web is cast film, formed by casting cellulose ester
solution containing cellulose ester and solvent, and having a
self-supporting property.
[0027] A content of the solvent contained in the cast film is equal
to or more than 130 wt. %.
[0028] According to another aspect of the invention, a solution
casting process includes a step of casting cellulose ester solution
on to an endlessly traveling support, to form cast film. The cast
film is stripped from the support. The cast film is transported by
retaining web edge portions of the cast film. Gaseous medium is
blown to the cast film being transport for flotation. Static
pressure of the gaseous medium to a web middle portion of the cast
film is lowered with respect to a web width direction thereof, to
regularize distribution of the static pressure in the web width
direction.
[0029] Accordingly, web or cast film produced continuously can be
prevented from protrusion with a curve even in application of
gaseous medium to the web, because the static pressure of gaseous
medium at the web middle portion is lowered.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The above objects and advantages of the present invention
will become more apparent from the following detailed description
when read in connection with the accompanying drawings, in
which:
[0031] FIG. 1 is an explanatory view in side elevation illustrating
a solution casting system;
[0032] FIG. 2 is a cross section illustrating one preferred gas
flow device having an exhaust conduit;
[0033] FIG. 3 is a perspective view illustrating the gas flow
device of FIG. 2;
[0034] FIG. 4 is a cross section illustrating one preferred gas
flow device having a static pressure adjusting recess;
[0035] FIG. 5 is a perspective view illustrating the gas flow
device of FIG. 4;
[0036] FIG. 6 is a cross section illustrating one preferred gas
flow device having plural controllable duct sections;
[0037] FIG. 7 is a perspective view illustrating the gas flow
device of FIG. 6;
[0038] FIG. 8 is a perspective view illustrating one preferred gas
flow device having movable plate portions;
[0039] FIG. 9 is a cross section illustrating the gas flow device
of FIG. 8.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) OF THE PRESENT
INVENTION
[0040] In FIG. 1, a solution casting system 10 of the invention is
illustrated. The solution casting system 10 includes a casting
chamber 11, a transition region 12, a pin tentering machine 13, a
clip tentering machine 14, web edge slitters 15a and 15b, a dryer
16, a cooler 17 and a winder 18.
[0041] The casting chamber 11 includes a feed block 22, a casting
support drum 23, a casting die 24, a stripping roller 26, a solvent
condenser 27 and a solvent recovery device 28. The feed block 22 is
supplied by a dope producing apparatus 20 with dope or viscous
solution. The casting die 24 is adapted to casting the dope on to
the casting support drum 23. The stripping roller 26 strips cast
film 25 of cellulose ester from the casting support drum 23 to
deliver self-supporting cast film 25a as web. The solvent condenser
27 condenses and liquefies solvent gas evaporated from the cast
film 25. The solvent recovery device 28 recovers the liquefied
solvent. A heat exchange medium circulator (not shown) is connected
with the casting support drum 23, and conditions the surface
temperature of the casting support drum 23 at a predetermined level
by flow of heat exchange medium through its conduit. A temperature
adjuster 30 is associated with the casting chamber 11 for
conditioning its inner temperature.
[0042] A flow conduit is formed in the feed block 22 for dope. The
form of the flow conduit can be modified to adjust the structure of
the cast film 25. A decompressor 32 with a decompression chamber is
associated with the casting die 24. A rear side or upstream side of
the bead of the dope is decompressed by the decompressor 32, the
bead flowing from the ejection slot down to the casting support
drum 23. This is for stabilizing the contact of the bead with the
casting support drum 23. A jacket (not shown) is associated with
the decompressor 32 for adjusting the inner temperature with heat
exchange medium.
[0043] The casting support drum 23 is a continuously rotatable drum
of a stainless steel. A surface of the casting support drum 23 is
finished by polishing. This is effective in forming the cast film
25 with high flatness on the casting support drum 23. Note that a
casting support element may be a different form other than the
casting support drum 23. For example, a casting support may be an
endless belt, which can be turned about by two driving rollers. A
preferable width of the casting support drum 23 can be 1.1-2.0
times as much as a casting width of the dope. The material of the
casting support drum 23 is preferably has sufficient strength and
resistance to corrosion, for example, stainless steel or other
materials.
[0044] The shape, material, size and the like of the casting die 24
are not limited. A coat hanger type of die is preferable for the
casting die 24 so a casting width of the dope can be kept at a
predetermined size. A preferable size of the slot in the casting
width direction is 1.1-2.0 times as long as the casting width of
the dope. A preferable material of the casting die 24 can be
stainless steel of a type of precipitation hardening owing to the
durability, heat resistance and the like. Also, the material of the
casting die 24 has the corrosion resistance sufficient for
prevention of pitting on the gas-liquid interface even after
dipping in a liquid mixture of dichloromethane, methanol and water
for three (3) months. Desirably, a corrosion resistance of the
material should be equal to that of SUS 316 steel according to
forced corrosion test in electrolytic aqueous solution. In view of
heat resistance, the material can have a coefficient of thermal
expansion of 2.times.10.sup.-5 (/deg. C.) or less.
[0045] A hardened layer or case can be preferably formed on the end
of the slot lip of the casting die 24. Various methods for forming
the hardened layer or case can be used, including application of a
ceramic coating, a hard chromium plating, and processing of
nitriding. In case of using the ceramic coating, the material of
the ceramic coating should have suitability for grinding, low
porosity, low fragility, high resistance to corrosion, suitability
for adhesion to the casting die 24, and property of small adhesion
to the dope. Specifically, WC (tungsten carbide), Al.sub.2O.sub.3,
TiN, Cr.sub.2O.sub.3 and the like can be used, among which WC is
particularly preferable. A thermal spray process can be used for
applying a WC coating.
[0046] A contact surface of the casting die 24 for the dope is
preferably a polished or abraded surface for high smoothness to
form the cast film 25 with high flatness. An absorption device (not
shown) is preferably connected to a slot edge portion of the
casting die 24, and absorbs air at an edge flow rate of 1-100
liters per minute. Thus, it is possible to reduce an air flow which
might cause unevenness on surfaces of the bead.
[0047] A great number of transport rollers 35 are arranged in the
transition region 12 and transport the self-supporting cast film
25a to the pin tentering machine 13 after stripping from the
casting support drum 23. A fan or blower 36 is disposed higher than
a path of the self-supporting cast film 25a, and blows evaporative
gas to reduce the contained solvent from the self-supporting cast
film 25a by drying.
[0048] In FIG. 2, the pin tentering machine 13 includes an endless
chain 40, a tenter pin plate 42, and tenter pins 43 in two tenter
pin groups, those being included in a transport mechanism. Each one
of rails 39 support the endless chain 40 for endless traveling in a
circulating manner. The tenter pin plate 42 is fastened on the
endless chain 40. The tenter pins 43 are disposed to project from
the tenter pin plate 42. When the self-supporting cast film 25a
from the transition region 12 enters the pin tentering machine 13,
the tenter pins 43 are pierced in web edge portions 45 of the
self-supporting cast film 25a, which is transported in a transport
direction X according to the endless chain 40 and the tenter pin
plate 42. A shifting mechanism 44 operates to shift the rails 39 in
a web width direction Y of the self-supporting cast film 25a. Thus,
the width of the self-supporting cast film 25a is adjustable
according to drying.
[0049] In FIGS. 2 and 3, a gas flow device 48 for drying is
included in the pin tentering machine 13 and disposed under a path
for the self-supporting cast film 25a. The gas flow device 48
includes a blower duct 50, a gas source 52, apertures of an exhaust
device 53 as static pressure adjuster, and an exhaust flow rate
control unit 54. In a lower surface 55 of the duct 50, an inlet
opening 55a for inlet fitting is formed. Gaseous medium 56 or
evaporative gas is supplied by the gas source 52, and enters the
duct 50 through the inlet opening 55a. A nozzle plate 57 is
positioned on a top of the duct 50 in the gas flow device 48.
Plural nozzles 57a are formed in the nozzle plate 57, are disposed
at a regular interval, and blow out the gaseous medium 56. Note
that the self-supporting cast film 25a in the pin tentering machine
13 has a volatile content or residual solvent content which is, for
example, equal to or more than 130 wt. %.
[0050] The exhaust device 53 is positioned at the center of the
duct 50 relative to the width direction, and extends from the
nozzle plate 57 to the lower surface 55. Plural exhaust conduits
53a in the exhaust device 53 are arranged in the direction X at a
regular interval. The exhaust conduits 53a are disposed in the
nozzle plate 57 of the duct 50 and opposed to the web middle
portion of the self-supporting cast film 25a as viewed in the width
direction. Gaseous medium 56a or evaporative gas, included in the
gaseous medium 56 under the self-supporting cast film 25a, is
exhausted by the exhaust conduits 53a in the exhaust device 53.
Also, the exhaust device 53 includes an exhaust opening 53b. The
exhaust opening 53b is formed in the lower surface 55 of the duct
50, and passes the gaseous medium 56a toward the outside. The
exhaust flow rate control unit 54 controls an exhaust flow rate of
the gaseous medium 56a from the exhaust opening 53b. Note that
indication of reference numerals in FIG. 3 is simplified for
convenience, for example, the exhaust device 53, the exhaust
conduits 53a, the gaseous medium 56 and 56a and the nozzles
57a.
[0051] Thus, the static pressure of the portion opposed to the web
middle portion of the self-supporting cast film 25a in the lower
space can be lowered by exhausting the gaseous medium 56a through
the exhaust conduits 53a which are positioned to face the web
middle portion. The distribution of the static pressure under the
self-supporting cast film 25a can be limited to a range from -200%
to +200% of the weight per area of the self-supporting cast film
25a, because the static pressure of the web middle portion is set
equal to the static pressure of other portions. Note that the use
of the unit of the weight per area of the self-supporting cast film
25a for the distribution of the static pressure is because of the
finding in that the static pressure of flotation required for
transport with floating should be the weight of the self-supporting
cast film 25a.
[0052] The distribution of the static pressure can be regularized
under the self-supporting cast film 25a. It is possible to prevent
the self-supporting cast film 25a from protruding convexly upwards
in the pin tentering machine 13. Quality of the cellulose ester
film will be kept high.
[0053] An aperture of the exhaust conduits 53a may not be
quadrilateral. For example, the aperture of the exhaust conduits
53a may be elliptical. Also, an exhaust conduit can be formed with
a nozzle-shaped circular aperture, and can be disposed regularly
and opposed to the web middle portion of the self-supporting cast
film 25a. In the embodiment, the lower surface 55 of the duct 50 is
formed similarly to the nozzle plate 57. However, the nozzle plate
57 may be formed with an area larger than an area of the lower
surface 55. For this structure, the exhaust device 53 is shaped
with a larger area of the exhaust conduits 53a than an area of the
exhaust opening 53b. Furthermore, an area adjusting mechanism can
be added for adjusting an aperture area of the exhaust conduits
53a. The static pressure distribution under the self-supporting
cast film 25a may be regularized by lowering the static pressure
under the web middle portion.
[0054] In the embodiment, the gas flow device 48 is disposed under
the path of the self-supporting cast film 25a. However, an upper
gas flow device for drying with a blower duct can be disposed
higher than the path of the self-supporting cast film 25a, and blow
evaporative gas down to the same.
[0055] In FIG. 1, the clip tentering machine 14 is positioned
downstream from the pin tentering machine 13, clamps and transports
the web edge portions 45 of the self-supporting cast film 25a, and
also dries the same. Thus, cellulose ester film 37 is obtained. The
web edge slitter 15a is disposed between the pin tentering machine
13 and the clip tentering machine 14, and slits the web edge
portions 45 of the cellulose ester film 37 exited from the pin
tentering machine 13. The web edge slitter 15b is disposed between
the clip tentering machine 14 and the dryer 16, and slits the web
edge portions 45 from the cellulose ester film 37 exited from the
clip tentering machine 14. A film crusher 65 is connected with the
web edge slitters 15a and 15b, and grinds the web edge portions 45
into chips. The cellulose ester film 37 being slitted is moved to
the dryer 16. A great number of rollers 67 are contained in the
dryer 16, and transport the cellulose ester film 37 which is dried
at the same time. The cellulose ester film 37 from the dryer 16 is
transported to the cooler 17, and cooled down to approximately the
room temperature.
[0056] An adsorption solvent recovery device 69 is connected with
various elements which are the transition region 12, the pin
tentering machine 13, the clip tentering machine 14 and the dryer
16. The adsorption solvent recovery device 69 recovers gaseous
solvent from those elements by adsorption. The recovered solvent is
reused as raw material for the dope.
[0057] A winding roller 70 is included in the winder 18, and winds
the cellulose ester film 37 from the cooler 17 in a form of a roll.
Also, a press roller 71 in the winder 18 controls tension exerted
in the cellulose ester film 37 during the winding on to the winding
roller 70.
[0058] Finally, the cellulose ester film 37 with high flatness is
obtained stably and rapidly. A web width of the cellulose ester
film 37 is preferably equal to or more than 1,400 mm and equal to
or less than 2,500 mm. The feature of the invention is effective
also if the width is over 2,500 mm. A thickness of the cellulose
ester film 37 as product is equal to or more than 20 microns and
equal to or less than 100 microns, and preferably equal to or more
than 20 microns and equal to or less than 80 microns, and desirably
equal to or more than 30 microns and equal to or less than 80
microns.
[0059] Another preferred embodiment is hereinafter described.
Elements similar to those of the above embodiment are designated
with identical reference numerals. In FIGS. 4 and 5, a gas flow
device 75 for drying is disposed under a path for the
self-supporting cast film 25a in the pin tentering machine 13. The
gas flow device 75 includes a blower duct 76 and a gas source 78 in
the gas flow device, which supplies gaseous medium 77 or
evaporative gas to the duct 76. A nozzle plate 80 is an element
positioned at the top of the duct 76. A static pressure adjusting
recess 82 is formed in the nozzle plate 80, opposed to the web
middle portion of the self-supporting cast film 25a, and extends in
the transport direction X. Nozzles 82a are formed in the static
pressure adjusting recess 82, and blow the gaseous medium 77.
Nozzles 80a are formed in portions of the nozzle plate 80 except
for the static pressure adjusting recess 82 in the duct 76, are
positioned regularly, and blow the gaseous medium 77. There is a
lower surface 83 of the duct 76. An inlet opening 83a for inlet
fitting is formed in the lower surface 83 for supply of the gaseous
medium 77 from the gas source 78.
[0060] The static pressure adjusting recess 82 is formed in the
nozzle plate 80 and extends in the X direction of the duct 76. The
nozzles 82a are formed in the portion of the static pressure
adjusting recess 82. Thus, a distance from the nozzles 82a to the
self-supporting cast film 25a is longer than that from the nozzles
80a to the same. A space on the nozzle plate 80 opposed to the web
middle portion of the self-supporting cast film 25a is defined
larger, so that a static pressure at the web middle portion of the
self-supporting cast film 25a can be lower. Thus, the static
pressure of the web middle portion becomes approximately equal to
the static pressure of the web edge portions. The static pressure
distribution of the atmosphere under the self-supporting cast film
25a is regulated in a range from -200% to +200% of the weight per
area of the self-supporting cast film 25a. Therefore, the web
middle portion of the self-supporting cast film 25a in the pin
tentering machine 13 is reliably prevented from protruding convexly
upwards in the transport. Note that indication of reference
numerals in FIG. 5 is simplified for convenience, for example, the
gaseous medium 77 and the nozzles 80a and 82a.
[0061] The static pressure adjusting recess 82, as viewed in the
section, is formed in the V shape in FIGS. 4 and 5, but may be
formed in another suitable shape, such as a semi-circular shape, a
quadrilateral shape and the like. Also, it is possible instead of
the static pressure adjusting recess 82 to use modified forms of
nozzles opposed to the web middle portion for the purpose of
lowering the static pressure in the middle. To modify the nozzles,
their arrangement, shapes, and the like may be suitably changed.
Specifically, the number of the nozzles in the portion opposed to
the web middle portion can be set smaller than the number of the
nozzles in portions opposed to the web edge portions. Also, a total
area of openness of the nozzles in the portion opposed to the web
middle portion can be set smaller than a total area of openness of
the nozzles in portions opposed to the web edge portions.
Furthermore, a depth adjusting mechanism may be added to adjust the
depth of the static pressure adjusting recess 82, so as to change
the volume of the space under the web middle portion of the
self-supporting cast film 25a. This is effective in regularizing
the distribution of the static pressure.
[0062] Also, one or more projections may be formed on a nozzle
plate of an upper gas flow device directed downwards, in place of
the static pressure adjusting recess 82 in the nozzle plate 80 of
the duct 76.
[0063] A still another preferred gas flow device 90 for drying is
described. Elements similar to those of the above embodiments are
designated with identical reference numerals. In FIGS. 6 and 7, the
gas flow device 90 is disposed under a path of the self-supporting
cast film 25a in the pin tentering machine 13. The gas flow device
90 includes a blower duct 91, a first gas source 92 and a second
gas source 93. The duct 91 is constituted by a first duct section
94 and a second duct section 95.
[0064] The first duct section 94 includes an inlet opening 97 for
inlet fitting, and is provided with nozzles 98 in a nozzle plate.
The inlet opening 97 is supplied with gaseous medium 96 or
evaporative gas by the first gas source 92. The nozzles 98 blow the
gaseous medium 96. The nozzles 98 are disposed regularly and
opposed to the web middle portion of the self-supporting cast film
25a. The second duct section 95 includes an inlet opening 101 for
inlet fitting, and is provided with nozzles 102 in a nozzle plate.
The inlet opening 101 is supplied with gaseous medium 100 or
evaporative gas by the second gas source 93. The nozzles 102 blow
the gaseous medium 100. The nozzles 102 are disposed regularly and
opposed to portions of the self-supporting cast film 25a except for
its web middle portion. A flow rate control unit 92a as static
pressure adjuster is incorporated in the first gas source 92, and
controls the flow in such a manner as to set a flow rate of the
gaseous medium 96 smaller than that of the gaseous medium 100.
[0065] Note that a flow rate adjuster may be associated with the
second gas source 93 for setting a flow rate of the gaseous medium
100 higher than that of the gaseous medium 96. Flow rate adjusters
may be associated with respectively the first and second gas
sources 92 and 93 for setting a flow rate of the gaseous medium 96
lower than that of the gaseous medium 100. Furthermore, a single
gas source may be associated with both of the first and second gas
sources 92 and 93. For this structure, a shape of the nozzles 102
can be determined differently from that of the nozzles 98.
[0066] A flow rate of the gaseous medium 96 toward the web middle
portion of the self-supporting cast film 25a is set smaller than
that of the gaseous medium 100. In relation to the static pressure,
static pressure on the underside of the web middle portion becomes
lower locally. Thus, the static pressure of the web middle portion
becomes approximately equal to the static pressure of the web edge
portions. The static pressure distribution of the atmosphere under
the self-supporting cast film 25a is regulated in a range from
-200% to +200% of the weight per area of the self-supporting cast
film 25a. Therefore, the web middle portion of the self-supporting
cast film 25a in the pin tentering machine 13 is reliably prevented
from protruding convexly upwards in the transport. Note that
indication of reference numerals in FIG. 7 is simplified for
convenience, for example, the gaseous medium 96 and 100, and the
nozzles 98 and 102.
[0067] In FIGS. 8 and 9, one preferred gas flow device 110 for
drying is illustrated. Elements similar to those of the above
embodiment are designated with identical reference numerals. The
gas flow device 110 is disposed under the self-supporting cast film
25a in the pin tentering machine 13. The gas flow device 110
includes a blower duct 111 and gaseous medium 112 or evaporative
gas. A gas source 113 in the gas flow device supplies the duct 111
with the gaseous medium 112. Nozzle plates 115 are arranged in the
direction X at a regular interval, and extend in the web width
direction Y. Movable plate portions 116 as static pressure adjuster
are disposed between the nozzle plates 115 alternatively and are
arranged in the transport direction X regularly. A shifting
mechanism 118 shifts the movable plate portions 116 in the vertical
direction Z. Nozzles 115a are formed in the nozzle plates 115, are
arranged regularly, and blow the gaseous medium 112. Exhaust
channels 116a are formed in the movable plate portions 116 for
exhausting the gaseous medium 112. Note that the exhaust channels
116a may be omitted from the movable plate portions 116 according
to a specific structure of the gas flow device 110.
[0068] The static pressure of flotation of the self-supporting cast
film 25a can be adjusted by suitably keeping the movable plate
portions 116 shifted in the Z direction in combination with the
nozzle plates 115 of a protruding form. Thus, the static pressure
of the web middle portion becomes approximately equal to the static
pressure of the web edge portions. The static pressure distribution
of the atmosphere under the self-supporting cast film 25a is
regulated in a range from -200% to +200% of the weight per area of
the self-supporting cast film 25a. Therefore, the web middle
portion of the self-supporting cast film 25a of in the pin
tentering machine 13 is reliably prevented from protruding convexly
upwards in the transport. Note that indication of reference
numerals in FIG. 8 is simplified for convenience, for example, the
gaseous medium 112, the nozzle plates 115, the movable plate
portions 116, the nozzles 115a and the exhaust channels 116a.
[0069] In the embodiments, the tentering machine for the transport
is the pin tentering machine. However, a tentering machine in
combination with the feature of the invention can be a clip
tentering machine. Also, a web transport apparatus of the invention
may be any suitable apparatus for transporting web of a continuous
shape different from the self-supporting cast film 25a.
[0070] In the above embodiments, nozzles are disposed in the matrix
form in the nozzle plate. However, the gas flow device of the
invention may be shaped in a bar form extending in the web width
direction Y. The nozzles may be arranged in at least one nozzle
array extending in the web width direction Y.
[0071] Further to the above embodiments, two or more gas flow
devices having each nozzle plate can be used and arranged in the
transport direction X. Each of the plural gas flow devices can
include a number of plural gas flow units of a bar type.
[0072] In the above embodiments, a single dope is cast to form a
polymer film of a single layer. In the solution casting of the
invention, the dopes, namely two or more dopes, can be cast
according to simultaneous multi casting or successive multi
casting. Various methods suggested in JP-A 2005-104148 are usable
in combination with the casting of the invention, the methods
including construction of the casting die, decompression chamber,
support and other mechanical elements, multi casting, stripping,
stretching, conditioning for drying in respective steps, polymer
film handling, winding after eliminating a curl for flatness,
solvent collection, and polymer film collection. Those can be used
in the present invention.
[0073] A. Support of Metal for Solution Casting
[0074] Suggested in JP A 2000-84960, U.S. Pat. No. 2,336,310, U.S.
Pat. No. 2,367,503, U.S. Pat. No. 2,492,078, U.S. Pat. No.
2,492,977, U.S. Pat. No. 2,492,978, U.S. Pat. No. 2,607,704, U.S.
Pat. No. 2,739,069, U.S. Pat. No. 2,739,070, GB A 640731
(corresponding to U.S. Pat. No. 2,492,977), GB A 735892, JP B
45-4554, JP B 49-5614, JP A 60-176834, JP A 60-203430, and JP A
62-115035.
[0075] B. Multi Casting
[0076] Suggested in JP B 62-43846; JP A 61-158414, JP A 1-122419,
JP B 60-27562, JP A 61-94724, JP A 61-947245, JP A 61-104813, JP A
61-158413, JP A 6-134933; JP A 56-162617; JP A 61-94724, JP A
61-94725, and JP A 11-198285.
[0077] C. Specific Methods of Casting of Cellulose Esters
[0078] Suggested in JP A 61-94724, JP A 61-148013, JP A 4-85011
(corresponding to U.S. Pat. No. 5,188,788), JP A 4-286611, JP A
5-185443, JP A 5-185445, JP A 6-278149, and JP A 8-207210.
[0079] D. Stretching
[0080] Suggested in JP A 62-115035, JP A 4-152125, JP A 4-284211,
JP A 4-298310, and JP A 11-48271.
[0081] E. Specific Methods of Drying
[0082] Suggested in JP A 8-134336, JP A 8-259706, and JP A
8-325388.
[0083] F. Drying of Specific Controls of Heat
[0084] Suggested in JP A 04-001009 (corresponding to U.S. Pat. No.
5,152,947), JP A 62-046626, JP A 04-286611, and JP A
2000-002809.
[0085] G. Drying in preventing wrinkles Suggested in JP A
11-123732, JP A 11-138568, and JP A 2000-176950.
[0086] Curls, thickness and their measurement of the wound polymer
film are suggested in known documents mentioned in JP-A
2005-104148. These can be used in the present invention.
[0087] No. 1. Curls and Thickness of the Polymer Film
[0088] Suggested in JP-A 2003-011143, JP-A 2002-214432, JP-A
2002-221620, JP-A 2003-055477, and JP-A 2003-014556.
[0089] No. 2. Thickness and its Measurement
[0090] Suggested in JP-A 2003-098345, JP-A 2000-009931, JP-A
2001-343528 (corresponding to U.S.P. 2002/192397), JP-A
2002-122735, and JP-A 2002-194107.
[0091] At least one of the two surfaces of the polymer film is
preferably processed by surface processing, because suitability for
adhesion to optics such as a panel shaped polarizer element can be
higher. Examples of the surface processing include vacuum glow
discharge processing, atmospheric pressure plasma discharge
processing, ultraviolet radiation applying processing, corona
discharge processing, flame processing, acid processing, alkali
processing and the like.
[0092] At least one of the two surfaces of the polymer film can
preferably be coated with a functional material, to form a
functional film including the polymer film as base, and one or two
functional layers overlaid on the base. Examples of functional
layers include an antistatic layer, hard resin layer, anti
reflection layer, attachment facilitating layer, anti-glare layer,
optical compensation layer and the like. For example, forming of
the anti reflection layer can result in obtaining anti reflection
film of which high image quality is available by preventing
reflection of outer light. Methods of adding the surface processed
functional layers to the cellulose ester film, and their various
conditions are according to techniques suggested in JP-A
2005-104148. Those can be used in the present invention.
[0093] I. Plasma Processing in General
[0094] Suggested in JP A 6-123062 (corresponding to EP A 592979),
JP A 11-5857, and JP A 11-293011.
[0095] II. Specific Methods of Plasma Processing
[0096] Suggested in JP A 2003-161807, JP A 2003-166063
(corresponding to U.S. Pat. No. 6,849,306), JP A 2003-171770, JP A
2003-183836, JP A 2003-201568, and JP A 2003-201570.
[0097] III. Glow Discharge Processing
[0098] Suggested in U.S. Pat. No. 3,462,335, U.S. Pat. No.
3,761,299, U.S. Pat. No. 4,072,769, GB A 891469; JP A 59-056430,
and JP B 60-16614 (corresponding to GB A 1579002).
[0099] IV. Ultraviolet Processing
[0100] Suggested in JP B 43-2603, JP B 43-2604, and JP B 45-3828
(corresponding to GB A 1149812).
[0101] V. Corona Discharge Processing
[0102] Suggested in JP B 39-12838, JP A 47-19824 (corresponding to
U.S. Pat. No. 3,849,166), JP A 48-28067 (corresponding to U.S. Pat.
No. 3755683), and JP A 52-42114 (corresponding to U.S. Pat. No.
4,135,932).
VI. Matte Agents for Undercoats
[0103] Suggested in U.S. Pat. No. 4,142,894, and U.S. Pat. No.
4,396,706.
[0104] VII. Lubricants
[0105] Suggested in JP B 53-292, U.S. Pat. No. 3,933,516, U.S. Pat.
No. 4,275,146; JP B 58-33541, GB A 927446 (corresponding to U.S.
Pat. No. 3,121,060); JP A 55-126238, JP A 58-90633; JP A 58-50534;
and European Patent Application 90108115 (corresponding to U.S.
Pat. No. 5,063,147).
[0106] VIII. Polyorganosiloxanes as Lubricants
[0107] Suggested in JP B 53-292, JP B 55-49294, and JP A
60-140341.
[0108] IX. Antistatic Agents of Ionic Macromolecular Types
[0109] Suggested in JP B 49-23827, JP B 49-23828, JP B 47-28937; JP
B 55-734, JP A 50-54672, JP B 59-14735, JP B 57-18175, JP B
57-18176, JP B 57-56059; JP B 53-13223, JP B 57-15376, JP B
53-45231, JP B 55-145783, JP B 55-65950, JP B 55-67746, JP B
57-11342, JP B 57-19735, JP B 58-56858, JP A 61-27853, and JP B
62-9346.
[0110] X. Polymer Films Coatable with Hard Coat Layers
[0111] Suggested in JP A 6-123806, JP A 9-113728, and JP A
9-203810.
[0112] XI. Photo Polymerizable Compounds
[0113] Suggested in JP A 50-151996, JP A 50-158680; JP A 50-151997
(corresponding to U.S. Pat. No. 4,058,401), JP A 52-30899
(corresponding to U.S. Pat. No. 4,256,828), JP A 55-125105; JP A
56-8428 (corresponding to U.S. Pat. No. 4,299,938), JP A 56-55420
(corresponding to U.S. Pat. No. 4,374,066), JP A 56-149402
(corresponding to U.S. Pat. No. 4,339,567), JP A 57-192429
(corresponding to U.S. Pat. No. 4,387,216); JP B 49-17040; and U.S.
Pat. No. 4,139,655.
[0114] XII. Coatings for Preventing Reflection
[0115] Suggested in JP A 7-126552, JP A 7-188582, JP A 8-48935, JP
A 8-100136, JP A 9-220791, and JP A 9-272169.
[0116] Various examples of liquid crystal display panels are known
and suggested in JP-A 2005-104148, including TN type, STN type, VA
type, OCH type, reflection type and the like. Any of those can be
used in the present invention.
[0117] No. 1. Cellulose Ester Protective Films for Polarizers
[0118] Suggested in JP A 10-095861, JP A 10-095862, and JP A
09-113727.
[0119] No. 2. Uses of Cellulose Ester Films as High Performance
Optical Elements
[0120] Suggested in JP A 2000-284124, JP A 2000-284123, and JP A
11-254466.
[0121] No. 3. Production of Cellulose Ester Films as High
Performance Optical Elements
[0122] Suggested in JP A 2000-131523, JP A 06-130226, JP A
06-235819, JP A 2000-212298 (corresponding to U.S. Pat. No.
6,731,357), and JP A 2000-204173.
[0123] No. 4. Optical Compensation Sheets
[0124] Suggested in JP A 3-9325 (corresponding to U.S. Pat. No.
5,132,147), JP A 6-148429, JP A 8-50206 (corresponding to U.S. Pat.
No. 5,583,679), and JP A 9-26572 (corresponding to U.S. Pat. No.
5,855,971).
[0125] No. 5. TN Type of LCD Panels
[0126] Suggested in JP A 3-9325 (corresponding to U.S. Pat. No.
5,132,147), JP A 6-148429, JP A 8-50206 (corresponding to U.S. Pat.
No. 5,583,679), and JP A 9-26572 (corresponding to U.S. Pat. No.
5,855,971).
[0127] No. 6. Reflection Type of LCD Panels
[0128] Suggested in JP A 10-123478, WO 9848320 (corresponding to
U.S. Pat. No. 6,791,640), JP B 3022477 (corresponding to U.S. Pat.
No. 6,433,845); and WO 00-65384 (corresponding to EP A
1182470).
[0129] No. 7. Discotic Compounds as Coating Cellulose Ester
Films
[0130] Suggested in JP A 7-267902, JP A 7-281028 (corresponding to
U.S. Pat. No. 5,518,783), and JP A 7-306317.
[0131] No. 8. Characteristics of Optical Compensation Sheets
[0132] Suggested in JP A 8-5837, JP A 7-191217, JP A 8-50206, and
JP A 7-281028.
[0133] No. 9. Production of Optical Compensation Sheets
[0134] Suggested in JP A 9-73081, JP A 8-160431, and JP A
9-73016.
[0135] No. 10. Use of Cellulose Ester Films in LCD Panels
[0136] Suggested in JP A 8-95034, JP A 9-197397, and JP A
11-316378. No. 11. LCD elements of guest-host reflection types
Suggested in JP A 6-222350, JP A 8-36174, JP A 10-268300, JP A
10-292175, JP A 10-293301, JP A 10-311976, JP A 10-319442, JP A
10-325953, JP A 10-333138, and JP A 11-38410.
[0137] No. 12. Coating Methods
[0138] Suggested in U.S. Pat. No. 2,681,294; U.S. Pat. No.
2,761,791, U.S. Pat. No. 2,941,898, U.S. Pat. No. 3,508,947, and
U.S. Pat. No. 3,526,528.
[0139] No. 13. Constructions of Overlaying Coatings
[0140] Suggested in JP A 8-122504, JP A 8-110401, JP A 10-300902
(corresponding to U.S. Pat. No. 6,207,263), JP A 2000-111706; JP A
10-206603 (corresponding to U.S. Pat. No. 6,207,263), and JP A
2002-243906.
[0141] No. 14. High refractive index layer and middle refractive
index layer Suggested in JP A 11-295503, JP A 11-153703
(corresponding to U.S. Pat. No. 6,210,858), JP A 2000-9908, JP A
2001-310432, JP A 2001-166104 (corresponding to U.S. Pat. No.
6,791,649), U.S. Pat. No. 6,210,858, JP A 2002-277609
(corresponding to U.S. Pat. No. 6,949,284), JP A 2000-47004, JP A
2001-315242, JP A 2001-31871, JP A 2001-296401, and JP A
2001-293818.
[0142] No. 15. Low Refractive Index Layer
[0143] Suggested in JP A 9-222503, JP A 11-38202, JP A 2001-40284,
JP A 2000-284102, JP A 11-258403, JP A 58-142958, JP A 58-147483,
JP A 58-147484, JP A 9-157582 (corresponding to U.S. Pat. No.
6,183,872), JP A 11-106704 (corresponding to U.S. Pat. No.
6,129,980), JP A 2000-117902, JP A 2001-48590 (corresponding to
U.S. Pat. No. 6,511,721), and JP A 2002-53804 (corresponding to
U.S. Pat. No. 6,558,804).
[0144] No. 16. Hard Coat Layer
[0145] Suggested in JP A 2002-144913, JP A 2000-9908, and WO
00/46617 (corresponding to U.S. Pat. No. 7,063,872).
[0146] No. 17. Front Scattering Layer
[0147] Suggested in JP A 11-38208, JP A 2000-199809 (corresponding
to U.S. Pat. No. 6,348,960), and JP A 2002-107512.
[0148] No. 18. Antiglare Characteristic
[0149] Suggested in Japanese Patent Application 2000-271878
(corresponding to JP A 2002-082207); JP A 2001-281410, Japanese
Patent Application 2000-95893 (corresponding to U.S. Pat. No.
6,778,240), JP A 2001-100004 (corresponding to U.S. Pat. No.
6,693,746), JP A 2001-281407; JP A 63-278839, JP A 11-183710, and
JP A 2000-275401.
[0150] No. 19. Dichroic Compounds
[0151] Suggested in JP A 1-161202, JP A 1-172906, JP A 1-172907, JP
A 1-183602, JP A 1-248105, JP A 1-265205, and JP A 7-261024
(corresponding to U.S. Pat. No. 5,706,131).
[0152] No. 20. Various Devices and Films for Optics
[0153] Suggested in JP A 5-19115, JP A 5-119216, JP A 5-162261, JP
A 5-182518, JP A 5-196819, JP A 5-264811, JP A 5-281411, JP A
5-281417, JP A 5-281537, JP A 5-288921, JP A 5-288923, JP A
5-311119, JP A 5-339395, JP A 5-40204, JP A 5-45512, JP A 6-109922,
JP A 6-123805, JP A 6-160626, JP A 6-214107, JP A 6-214108, JP A
6-214109, JP A 6-222209, JP A 6-222353, JP A 6-234175, JP A
6-235810, JP A 6-241397, JP A 6-258520, JP A 6-264030, JP A
6-305270, JP A 6-331826, JP A 6-347641, JP A 6-75110, JP A 6-75111,
JP A 6-82779, JP A 6-93133, JP A 7-104126, JP A 7-134212, JP A
7-181322, JP A 7-188383, JP A 7-230086, JP A 7-290652, JP A
7-294903, JP A 7-294904, JP A 7-294905, JP A 7-325219, JP A
7-56014, JP A 7-56017, JP A 7-92321, JP A 8-122525, JP A 8-146220,
JP A 8-171016, JP A 8-188661, JP A 8-21999, JP A 8-240712, JP A
8-25575, JP A 8-286179, JP A 8-292322, JP A 8-297211, JP A
8-304624, JP A 8-313881, JP A 8-43812, JP A 8-62419, JP A 8-62422,
JP A 8-76112, JP A 8-94834, JP A 9-137143, JP A 9-197127, JP A
9-251110, JP A 9-258023, JP A 9-269413, JP A 9-269414, JP A
9-281483, JP A 9-288212, JP A 9-288213, JP A 9-292525, JP A
9-292526, JP A 9-294959, JP A 9-318817, JP A 9-80233, JP A 9-99515,
JP A 10-10320, JP A 10-104428, JP A 10-111403, JP A 10-111507, JP A
10-123302, JP A 10-123322, JP A 10-123323, JP A 10-176118, JP A
10-186133, JP A 10-264322, JP A 10-268133, JP A 10-268134, JP A
10-319408, JP A 10-332933, JP A 10-39137, JP A 10-39140, JP A
10-68821, JP A 10-68824, JP A 10-90517, JP A 11-116903, JP A
11-181131, JP A 11-211901, JP A 11-211914, JP A 11-242119, JP A
11-246693, JP A 11-246694, JP A 11-256117, JP A 11-258425, JP A
11-263861, JP A 11-287902, JP A 11-295525, JP A 11-295527, JP A
11-302423, JP A 11-309830, JP A 11-323552, JP A 11-335641, JP A
11-344700, JP A 11-349947, JP A 11-95011, JP A11-95030, JP A
11-95208, JP A 2000-109780, JP A 2000-110070, JP A 2000-119657, JP
A 2000-141556, JP A 2000-147208, JP A 2000-17099, JP A 2000-171603,
JP A 2000-171618, JP A 2000-180615, JP A 2000-187102, JP A
2000-187106, JP A 2000-191819, JP A 2000-191821, JP A 2000-193804,
JP A 2000-204189, JP A 2000-206306, JP A 2000-214323, JP A
2000-214329, JP A 2000-230159, JP A 2000-235107, JP A 2000-241626,
JP A 2000-250038, JP A 2000-267095, JP A 2000-284122, JP A
2000-292780, JP A 2000-292781, JP A 2000-304927, JP A 2000-304928,
JP A 2000-304929, JP A 2000-309195, JP A 2000-309196, JP A
2000-309198, JP A 2000-309642, JP A 2000-310704, JP A 2000-310708,
JP A 2000-310709, JP A 2000-310710, JP A 2000-310711, JP A
2000-310712, JP A 2000-310713, JP A 2000-310714, JP A 2000-310715,
JP A 2000-310716, JP A 2000-310717, JP A 2000-321560, JP A
2000-321567, JP A 2000-329936, JP A 2000-329941, JP A 2000-338309,
JP A 2000-338329, JP A 2000-344905, JP A 2000-347016, JP A
2000-347017, JP A 2000-347026, JP A 2000-347027, JP A 2000-347029,
JP A 2000-347030, JP A 2000-347031, JP A 2000-347032, JP A
2000-347033, JP A 2000-347034, JP A 2000-347035, JP A 2000-347037,
JP A 2000-347038, JP A 2000-86989, and JP A 2000-98392; and
[0154] JP A 2001-4819, JP A 2001-4829, JP A 2001-4830, JP A
2001-4831, JP A 2001-4832, JP A 2001-4834, JP A 2001-4835, JP A
2001-4836, JP A 2001-4838, JP A 2001-4839, JP A 2001-100012, JP A
2001-108805, JP A 2001-108806, JP A 2001-133627, JP A 2001-133628,
JP A 2001-142062, JP A 2001-142072, JP A 2001-174630, JP A
2001-174634, JP A 2001-174637, JP A 2001-179902, JP A 2001-183526,
JP A 2001-183653, JP A 2001-188103, JP A 2001-188124, JP A
2001-188125, JP A 2001-188225, JP A 2001-188231, JP A 2001-194505,
JP A 2001-228311, JP A 2001-228333, JP A 2001-242461, JP A
2001-242546, JP A 2001-247834, JP A 2001-26061, JP A 2001-264517,
JP A 2001-272535, JP A 2001-278924, JP A 2001-2797, JP A
2001-287308, JP A 2001-305345, JP A 2001-311823, JP A 2001-311827,
JP A 2001-350005, JP A 2001-356207, JP A 2001-356213, JP A
2001-42122, JP A 2001-42323, JP A 2001-42325, JP A 2001-51118, JP A
2001-51119, JP A 2001-51120, JP A 2001-51273, JP A 2001-51274, JP A
2001-55573, JP A 2001-66431, JP A 2001-66597, JP A 2001-74920, JP A
2001-81469, JP A 2001-83329, JP A 2001-83515, JP A 2001-91719, JP A
2002-162628, JP A 2002-169024 (corresponding to U.S. Pat. No.
6,606,136), JP A 2002-189421, JP A 2002-201367 (corresponding to
U.S. Pat. No. 6,093,133), JP A 2002-20410 (corresponding to U.S.
Pat. No. 6,974,608), JP A 2002-258046, JP A 2002-275391, JP A
2002-294174, JP A 2002-311214 (corresponding to U.S. Pat. No.
6,841,237), JP A 2002-311246 (corresponding to U.S. Pat. No.
6,965,473), JP A 2002-328233, JP A 2002-338703, JP A 2002-363266
(corresponding to U.S. Pat. No. 6,894,141), JP A 2002-365164, JP A
2002-370303, JP A 2002-40209 (corresponding to U.S. Pat. No.
6,649,271), JP A 2002-48917 (corresponding to U.S. Pat. No.
6,628,369), JP A 2002-6109 (corresponding to U.S. Pat. No.
6,505,942), JP A 2002-71950, JR A 2002-82222, JP A 2002-90528, JP A
2003-105540 (corresponding to U.S. Pat. No. 6,689,479), JP A
2003-114331, JP A 2003-131036 (corresponding to U.S.P.
2003/031848), JP A 2003-139952, JP A 2003-153353, JP A 2003-172819,
JP A 2003-35819, JP A 2003-43252 (corresponding to U.S. Pat. No.
6,552,145), JP A 2003-50318 (corresponding to U.S. Pat. No.
7,136,225), and JP A 2003-96066 (corresponding to U.S. Pat. No.
7,087,273).
[0155] Raw materials for producing the dope in the dope producing
apparatus 20 are hereinafter described.
[0156] For a raw material of the dope, cellulose ester can be
preferably used for obtaining high transparency. Examples of
cellulose esters are cellulose triacetate, cellulose acetate
propionate, cellulose acetate butylate and other cellulose esters
of lower fatty acid. In particular, cellulose acetate is
preferable. Specifically, cellulose triacetate (TAC) is desirable.
Note that the dope in the present embodiment contains cellulose
triacetate (TAC) as polymer. Preferably, 90 wt. % or more of the
entirety of TAC should be particles of 0.1-4 mm.
[0157] Preferable examples of cellulose acylates satisfy all of the
conditions I-III as follows for the purpose of high
transparency:
2.5.ltoreq.A/B.ltoreq.3.0 I
0.ltoreq.A.ltoreq.3.0 II
0.ltoreq.B.ltoreq.2.9 III
[0158] where A and B represent a degree of substitution of an acyl
group formed by substituting hydroxy groups in cellulose. A
represents a degree of substitution of an acetyl group formed by
substituting hydroxy groups in cellulose. B represents a total
degree of substitution of acyl groups having 3-22 carbon atoms.
[0159] The cellulose is constructed by glucose units making a
beta-1, 4 bond, and each glucose unit has a liberated hydroxy group
at 2, 3 and 6-positions. Cellulose acylate is a polymer in which
part or whole of the hydroxy groups are esterified so that the
hydrogen is substituted by acyl groups having two or more carbon
atoms. The degree of substitution for the acyl groups in cellulose
acylate is a degree of esterification at 2, 3 or 6-position in
cellulose. Accordingly, when 100% of the hydroxy group at the same
position is substituted, the degree of substitution at this
position is 1.
[0160] The total degree of substitution DS2+DS3+DS6 for the acyl
groups at 2, 3 or 6-positions is in the range of 2.00-3.00,
preferably 2.22-2.90, and in particular preferably 2.40-2.88. The
sign DS2 is a degree of substitution for the acyl groups at
2-position in hydroxy groups in the glucose unit. The signs DS3 and
DS6 are degrees of substitution for the acyl groups at respectively
3 and 6-positions in hydroxy groups in the glucose unit. Further, a
ratio DS6/(DS2+DS3+DS6) is preferably 0.28 or more, and
particularly 0.30 or more, and especially in the range of
0.31-0.34.
[0161] An acyl group of only one example may be contained in the
cellulose acylate of the invention. However, cellulose acylate may
contain acyl groups of two or more examples. If two or more acyl
groups are contained, one of the plural acyl groups should be
preferably an acetyl group. Let DSA be a total degree of
substitution for the acetyl groups. Let DSB be a total degree of
substitution for other acyl groups at 2, 3 and 6-positions than the
acetyl groups. The value DSA+DSB is preferably in the range of
2.22-2.90, and particularly in the range of 2.40-2.88.
[0162] Further, the DSB is preferably at least 0.30, and especially
at least 0.70. Furthermore, the percentage of a substituent at
6-position in the DSB is preferably at least 20%, preferably at
least 25%, especially at least 30% and most especially at least
33%. Further, the value DSA+DSB at 6-position is at least 0.75,
preferably at least 0.80, and especially at least 0.85. Cellulose
acylate satisfying the above conditions can be used to prepare a
solution or dope having a preferable solubility. Especially,
chlorine-free type organic solvent can be preferably used to
prepare adequate dope. Also, the dope can be prepared to have a low
viscosity, high solubility, and the suitability for filtration
becomes higher.
[0163] Cellulose to produce cellulose acylates can be obtained any
one of linter cotton and pulp cotton, but preferably can be
obtained from linter cotton.
[0164] Examples of acyl groups in cellulose acylates having two or
more carbon atoms can be aliphatic groups, aryl groups, and the
like. For example, cellulose acylates may be alkyl carbonyl esters,
alkenyl carbonyl esters, aromatic carbonyl esters, aromatic alkyl
carbonyl esters, and the like of cellulose, and can further contain
a substitution group. Preferable examples of groups include:
propionyl, butanoyl, pentanoyl, hexanoyl, octanoyl, decanoyl,
dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl,
iso-butanoyl, tert-butanoyl, cyclohexane carbonyl, oleoyl, benzoyl,
naphthyl carbonyl, and cinnamoyl. Among those, particularly
preferable groups are propionyl, butanoyl, dodecanoyl,
octadecanoyl, tert-butanoyl, oleoyl, benzoyl, naphthyl carbonyl,
and cinnamoyl. Further, specifically preferable groups are
propionyl and butanoyl.
[0165] Details of cellulose acylates are according to various
relevant techniques suggested in JP-A 2005-104148. Those examples
and their various features can be used in the present
invention.
[0166] I. Specific Examples of Cellulose Acylates
[0167] Suggested in JP A 57-182737 (corresponding to U.S. Pat. No.
4,499,043), JP A 10-45803 (corresponding to U.S. Pat. No.
5,856,468), JP A 11-269304 (corresponding to U.S. Pat. No.
6,139,785), JP A 8-231761, JP A 10-60170, JP A 9-40792, JP A
11-5851, JP A 9-90101, JP A 4-277530, JP A 11-292989, JP A
2000-131524, and JP A 2000-137115.
[0168] II. Specific Examples of Solvents for Esters and Their
Dissolution
[0169] Suggested in JP A 10-324774, JP A 8-152514, JP A 10-330538,
JP A 9-95538 (corresponding to U.S. Pat. No. 5,663,310), JP A
9-95557 (corresponding to U.S. Pat. No. 5,705,632), JP A 10-235664
(corresponding to U.S. Pat. No. 6,036,913), JP A 2000-63534, JP A
11-21379, JP A 10-182853, JP A 10-278056, JP A 10-279702, JP A
10-323853 (corresponding to U.S. Pat. No. 6,036,913), JP A
10-237186, JP A 11-60807, JP A 11-152342, JP A 11-292988, JP A
11-60752, JP A 2000-95876, and JP A 2000-95877.
[0170] Solvent as raw material of dope is preferably an organic
compound in which polymer is soluble. The term of dope in the
invention is used as mixture obtained by dissolution or dispersion
of polymer in a solvent. It is possible to use a solvent with low
solubility for polymer. Examples of solvents for preparing the dope
include:
[0171] aromatic hydrocarbons, such as benzene and toluene;
[0172] halogenated hydrocarbons, such as dichloromethane,
chloroform and chlorobenzene;
[0173] alcohols, such as methanol, ethanol, n-propanol, n-butanol,
and diethylene glycol;
[0174] ketones, such as acetone and methyl ethyl ketone;
[0175] esters, such as methyl acetate, ethyl acetate, and propyl
acetate;
[0176] ethers, such as tetrahydrofuran and methyl cellosolve.
[0177] It is possible selectively to use two or more of those by
mixture. In particular, dichloromethane can be used to obtain dope
with high solubility. The solvent in the cast film can evaporate to
form the polymer film.
[0178] Halogenated hydrocarbons containing 1-7 carbon atoms are
preferably used, for example, dichloromethane. Specifically, it is
preferable in a mixed solvent to mix one or more alcohols
containing 1-5 carbon atoms with the dichloromethane, for the
purpose of high solubility, easy separability from a support for
casting, mechanical strength of film material, and various optical
characteristics of cellulose triacetate (TAC). Such alcohols are
contained in the mixed solvent preferably in a range of 2-25 wt. %,
and desirably in a range of 5-20 wt. %. Preferable examples of
alcohols are methanol, ethanol, n-propanol, isopropanol, n-butanol
and the like. Among those, specifically preferable alcohols are
methanol, ethanol, n-butanol, and mixture of two or more of
them.
[0179] For the purpose of minimizing influence to environment,
solvents not containing dichloromethane are effectively used in the
publicly suggested manner. Examples of compounds useful to this end
are ethers having 4-12 carbon atoms, ketones having 3-12 carbon
atoms, esters having 3-12 carbon atoms, and alcohols having 1-12
carbon atoms. Ethers, ketones, esters and alcohols of the examples
may have a cyclic structure. Compounds having two or more
functional groups of --O--, --CO--, --COO-- and --OH, namely groups
of ethers, ketones, esters and alcohols, can be used as a solvent.
Furthermore, a solvent for use may contain other functional groups,
such as alcoholic hydroxy groups. If a compound for a solvent
contains two or more functional groups, a number of carbon atoms of
the compound should satisfy a condition of a compound which
contains a selected one of the two or more functional groups.
[0180] Various additives may be mixed in the dope for purposes,
such as plasticizers, ultraviolet (UV) absorbers, deterioration
inhibitors, lubricants, stripping accelerators, and other
additives. Preferable examples of plasticizers are triphenyl
phosphate, biphenyl diphenyl phosphate, and other phosphate esters,
and diethyl phthalate and other phthalate esters, and polyester
polyurethane elastomer.
[0181] Fine particles can be preferably added to dope for the
purpose of preventing adhesion between polymer films, and adjusting
a refractive index. Examples of materials of the fine particles are
silicon dioxide derivatives. Examples of silicon dioxide
derivatives include silicon dioxide, silicone resin in a honeycomb
structure of three dimensions, and the like. Preferably, the
surface of the silicon dioxide derivative is an alkylated surface.
Fine particles processed by alkylation or hydrophobic modification
have high dispersibility in solvent. Dope can be prepared without
agglomeration of fine particles, to produce polymer film reliably.
The polymer film can have high transparency with a reduced amount
of surface defects.
[0182] An example of fine particles with an alkylated surface is
Aerosil R805 (trade name) manufactured by Nippon Aerosil Co., Ltd.,
as a derivative of silicon dioxide with an octyl group on the
surface. The ratio of the content of the fine particles relative to
the solid content of the dope is preferably 0.2% or less for the
purpose of obtaining polymer film with high transparency and with
effects of adding the fine particles. An average particle diameter
of the fine particles, in view of allowing passage of light without
blocking, is equal to or less than 1.0 micron, preferably 0.3-1.0
micron, and desirably 0.4-0.8 micron.
[0183] It is preferable to use the TAC to prepare dope for the
purpose of obtaining highly transparent polymer film. According to
the embodiment, the dope containing TAC at a density equal to or
more than 5 wt. % and equal to or less than 40 wt. % is obtained. A
density of the TAC in the dope is preferably equal to or more than
15 wt. % and equal to or less than 30 wt. %, and desirably equal to
or more than 17 wt. % and equal to or less than 25 wt. %. A density
of the additive, especially a plasticizer, in the dope is
preferably equal to or more than 1 wt. % and equal to or less than
20 wt. % in 100 wt. % of the solid content in the dope.
[0184] Uses of various materials in relation to the polymer have
been suggested in JP-A 2005-104148, including solvents,
plasticizers, deterioration inhibitors, ultraviolet (UV) absorbers,
lubricants, stripping accelerators, optical anisotropy control
agents, retardation control agents, dyes, release agents, and other
additives.
[0185] I. Plasticizers
[0186] Suggested in JP A 4-227941, JP A 5-194788, JP A 60-250053,
JP A 6-16869, JP A 5-271471, JP A 7-286068, JP A 5-5047
(corresponding to U.S. Pat. No. 5,279,659), JP A 11-80381, JP A
7-20317, JP A 8-57879, JP A 10-152568, and JP A 10-120824.
[0187] II. Deterioration Inhibitors and UV Absorbers
[0188] Suggested in JP A 60-235852, JP A 3-199201, JP A 5-190707,
JP A 5-194789, JP A 5-197073, JP A 5-271471, JP A 6-107854, JP A
6-118233, JP A 6-148430, JP A 7-11055, JP A 7-11056, JP A 8-29619,
JP A 8-239509 (corresponding to U.S. Pat. No. 5,806,834), JP A
2000-204173, and JP A 2000-193821.
[0189] In the dope production from cellulose triacetate, various
techniques suggested in JP-A 2005-104148 for dissolution of
materials and additives, filtration, elimination of bubbles, mixing
of additives can be used.
[0190] No. 1. Dissolution Related to Casting
[0191] Suggested in JP A 9-95544 (corresponding to U.S. Pat. No.
5,663,310), JP A 10-45950, JP A 10-95854 (corresponding to U.S.
Pat. No. 5,783,121), and JP A 2000-53784.
[0192] No. 2. Specific Preparing Methods of Solutions
[0193] Suggested in JP A 11-310640 (corresponding to U.S. Pat. No.
6,211,358), JP A 11-323017, JP A 11-302388, and JP A
2000-273184.
[0194] No. 3. Condensation of Solutions
[0195] Suggested in JP A 4-259511; U.S. Pat. No. 2,541,012, U.S.
Pat. No. 2,858,229, U.S. Pat. No. 4,414,341, and U.S. Pat. No.
4,504,355.
Example 1
[0196] In FIG. 1, the cellulose ester film 37 was produced by the
solution casting system 10. At first, the dope producing apparatus
20 supplied the casting die 24 with dope of a suitable amount
through the feed block 22. The die slot of the casting die 24
ejected the dope on to the casting support drum 23 rotating
continuously. A flow rate of the dope was so conditioned as to form
the cellulose ester film 37 being 80 microns thick after drying.
The die slot of the casting die 24 was 1.8 meters wide. The
temperature of the dope being cast was conditioned at 36 deg. C.
The inner temperature of the feed block 22 was conditioned at 36
deg. C. Also, the rear side of the bead was decompressed by
conditioning the pressure of the decompressor 32 at 600 Pa.
[0197] The casting support drum 23 was a drum of stainless steel,
and controllable by a driving device for rotational speed. Heat
exchange medium or coolant was supplied by a heat exchange medium
circulator (not shown) to the casting support drum 23, which was
conditioned at the surface temperature of -10 deg. C. The casting
chamber 11 was conditioned by the temperature adjuster 30 with the
inner temperature of 35 deg. C.
[0198] The cast film 25 was cooled and gelled to have a
self-supporting property. Then the stripping roller 26 stripped the
cast film 25 to deliver the self-supporting cast film 25a. The
self-supporting cast film 25a is moved to the transition region 12
where the fan or blower 36 blew evaporative gas at 40 deg. C. to
the self-supporting cast film 25a transported by the transport
rollers 35, to dry the same.
[0199] The tenter pins 43 in FIG. 2 were pierced into the web edge
portions 45 of the self-supporting cast film 25a in the pin
tentering machine 13, to transport the self-supporting cast film
25a in the direction X. During the transport, the shifting
mechanism 44 operated to stretch the self-supporting cast film 25a
in the direction X. The gas flow device 48 in FIGS. 2 and 3 was
installed under the path for the self-supporting cast film 25a. The
aperture of the exhaust conduits 53a was quadrilateral.
[0200] In FIG. 1, the self-supporting cast film 25a exiting from
the pin tentering machine 13 was sent to the clip tentering machine
14. Evaporative gas was blown to the self-supporting cast film 25a
while the web edge portions 45 of the self-supporting cast film 25a
were clamped and transported with stretch. The self-supporting cast
film 25a was dried to obtain the cellulose ester film 37. The web
edge portions 45 of the self-supporting cast film 25a or the
cellulose ester film 37 were slitted by the web edge slitters 15a
and 15b. A cutter blower (not shown) moved the web edge portions 45
by blowing into the film crusher 65, which ground the web edge
portions 45 into chips or particles with an average area of 80 sq.
mm.
[0201] Between the web edge slitter 15b and the dryer 16, there was
a pre-drying chamber (not shown), which heated the cellulose ester
film 37 with evaporative gas of 100 deg. C. before drying in the
dryer 16. The cellulose ester film 37 was transported through the
dryer 16 by the rollers 67, and dried by the dryer 16. A
temperature adjuster (not shown) conditioned the inner temperature
of the dryer 16 to keep the surface temperature of the cellulose
ester film 37 at 140 deg. C. Time of drying the cellulose ester
film 37 with the dryer 16 was 10 minutes. The surface temperature
of the cellulose ester film 37 was measured by a thermometer (not
shown) disposed close to the surface of the cellulose ester film 37
and directly higher than the path of the cellulose ester film 37.
The solvent gas created from the transition region 12, the pin
tentering machine 13, the clip tentering machine 14 and the dryer
16 was collectively removed by adsorption and desorption of the
adsorption solvent recovery device 69. An agent for adsorption was
activated carbon. Desorption after the absorption was made by use
of dry nitrogen. Then the collected solvent was dehydrated until
the water content of water in the collected solvent became equal to
or less than 0.3 wt. %.
[0202] The cellulose ester film 37 being dried was transported into
a fluidity adjusting chamber (not shown) which was between the
dryer 16 and the cooler 17. Air was supplied in the fluidity
adjusting chamber with temperature of 50 deg. C. and a condensation
point of 20 deg. C. Then air for fluidity adjustment was supplied
directly to the cellulose ester film 37 with temperature of 90 deg.
C. and humidity of 70% RH, to remove curls from the cellulose ester
film 37. Then the cellulose ester film 37 was transported into the
cooler 17, and was gradually cooled to a level equal to or lower
than 30 deg. C.
[0203] Then the cellulose ester film 37 was transported into the
winder 18. A pressure applied by the press roller 71 to the
cellulose ester film 37 on the winding roller 70 was determined 50
N per meter. The winding roller 70 having a diameter of 169 mm
wound the cellulose ester film 37. Tension was sequentially
controlled, and set at 300 N per meter at the initial step of the
winding, and set at 200 N per meter at the end of the winding.
Thus, a roll of the cellulose ester film 37 was obtained.
[0204] The cellulose ester film 37 obtained finally was 80 microns
thick. In the entirety of the solution casting process, an average
drying rate of the self-supporting cast film 25a or the cellulose
ester film 37 was 20 wt. % per minute.
[0205] The following is components for preparing the polymer
solution or dope.
TABLE-US-00001 Cellulose triacetate 100 parts by weight
Dichloromethane 320 parts by weight Methanol 83 parts by weight
1-butanol 3 parts by weight Plasticizer A 7.6 parts by weight
Plasticizer B 3.8 parts by weight UV absorber a 0.7 part by weight
UV absorber b 0.3 part by weight Mixture of citrate esters 0.006
part by weight Fine particles 0.05 part by weight
[0206] In the list, the cellulose triacetate was powder particles
having the following specifics--substitution degree: 2.84,
viscosity average degree of polymerization (DP): 306, water
content: 0.2 wt. %, viscosity of 6 wt. % dichloromethane solution:
315 mPas, average particle diameter of powder particles: 1.5 mm,
standard deviation of the particle diameter of powder particles:
0.5 mm. The plasticizer A was triphenylphosphate. The plasticizer B
was diphenylphosphate. The UV absorber a was
2(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazol. The UV
absorber b was 2(2'-hydroxy-3',5'-di-tert-amylphenyl)
5-chlorobenzotriazol. The citrate ester compound was mixture of
citrate esters (mixture of citric acid, citrate monoethyl ester,
citrate diethyl ester, and citrate triethyl ester). The fine
particles were particles of silicon dioxide with a particle
diameter of 15 nm, and Mohs hardness number of approx. 7. In the
preparation of the dope, 4.0 wt. % of retardation control agent
N-N-di-m-toluoyl-N-P-methoxy phenyl-1,3,5-triazine-2,4,6-triamine
was added at the amount relative to the total weight of the polymer
film.
Example 2
[0207] Example 1 was repeated with a difference in the gas flow in
the pin tentering machine 13. In FIGS. 4 and 5, the gas flow device
75 was disposed under a path for the self-supporting cast film 25a.
The gaseous medium 77 was blown to the self-supporting cast film
25a from the nozzles 82a of the static pressure adjusting recess 82
and the nozzles 80a of portions other than the static pressure
adjusting recess 82.
Example 3
[0208] Example 1 was repeated with a difference in the gas flow in
the pin tentering machine 13. In FIGS. 6 and 7, the gas flow device
90 was disposed under a path for the self-supporting cast film 25a.
The flow rate control unit 92a in the first gas source 92
controlled so as to set a flow rate of the gaseous medium 96
smaller than that of the gaseous medium 100.
Example 4
[0209] Example 1 was repeated with a difference in the gas flow in
the pin tentering machine 13. In FIGS. 8 and 9, the gas flow device
110 was disposed under a path for the self-supporting cast film
25a. The shifting mechanism 118 kept the movable plate portions 116
shifted in the direction Z to lower the static pressure at the web
middle portion.
[0210] In any of Examples 1-4, the static pressure distribution of
the atmosphere under the self-supporting cast film 25a was
regulated in a range from -200% to +200% of the weight per area of
the self-supporting cast film 25a. The static pressure distribution
was regularized, so that the web middle portion of the
self-supporting cast film 25a of in the pin tentering machine 13
was reliably prevented from protruding convexly upwards in the
transport. The polymer film as a product was obtained with stably
high quality.
[0211] Although the present invention has been fully described by
way of the preferred embodiments thereof with reference to the
accompanying drawings, various changes and modifications will be
apparent to those having skill in this field. Therefore, unless
otherwise these changes and modifications depart from the scope of
the present invention, they should be construed as included
therein.
* * * * *