WO2011013292A1

WO2011013292A1 - Web stretching method and method for producing retardation film

Info

Publication number: WO2011013292A1
Application number: PCT/JP2010/004022
Authority: WO
Inventors: 福井剛; 稲澤弘志; 大田一英; 久保賢司; 中村琢司; 藤井正
Original assignee: 東洋鋼鈑株式会社
Priority date: 2009-07-30
Filing date: 2010-06-17
Publication date: 2011-02-03
Also published as: CN102625746A; KR101765138B1; KR20120038924A; CN102625746B; JPWO2011013292A1; JP5530443B2

Abstract

Provided are a web stretching method and a method for producing a retardation film, by which a length in the film moving direction can be shortened in a heating chamber, and variability of the film tension in the width direction as well as scratches, etc., can be prevented. When a web (8) is transferred into a heating chamber (2) and is stretched, by pinch rolls arranged at an entrance side and an exit side of a heating chamber (2), at least one transfer guide (1) is arranged in a heating space (21). Further, heated fluid is discharged from a plurality of fluid discharge holes (9) formed on a surface of the transfer guide (1) to form a fluid layer (11), and the web (8) can be moved without being in contact with the transfer guide (1) using the fluid layer (11) as a transfer surface. Thereby, a film can be uniformly stretched while suppressing the production cost.

Description

Web stretching method and retardation film manufacturing method

The present invention relates to a method for stretching a web film-like object (hereinafter referred to as a web) such as a thermoplastic resin film, and relates to a method for producing a retardation film suitable for a liquid crystal display device based on the web stretching method.

In an optical apparatus such as a liquid crystal display device, a retardation film made of a thermoplastic resin film is used. This retardation film usually develops in-plane retardation (Re) and thickness direction retardation (Rth) by stretching in the longitudinal (longitudinal) direction and transverse (width) direction. Thus, the viewing angle of the liquid crystal display device is increased.
Longitudinal stretching method in which a heating chamber is installed between conveyance guides (nip rolls) having different peripheral speeds as described in Patent Document 1, as stretching in the longitudinal direction when stretching a retardation film Is widely known.

On the other hand, regarding the method of transporting the retardation film, it is usually transported into a heating chamber through a transport guide, and is transported through a transport guide that is also installed in this heating chamber as appropriate. At this time, it is necessary to adjust the film width at the time of stretching the film, and to prevent variation in the peeling point due to the adhesion of the film to the conveyance guide (pass roll) provided in the heating chamber between the conveyance guides. As described above, a method is also known in which air is ejected from a conveyance guide to facilitate separation from the conveyance guide.

JP 2008-221722 A JP-A-9-76343

However, the above conventional techniques have the following problems.
That is, the technique described in Patent Document 1 requires a long heating chamber in the moving direction of the film, and it may be difficult to provide equipment. Also, in actual production, the resin becomes longer in the moving direction of the film, so that the resin is bent due to its own weight, and it is difficult to stretch with high accuracy.

For such a problem, for example, by changing the direction of the film by the conveyance guide in the heating chamber using the technique described in Patent Document 2, the length with respect to the moving direction of the film in the heating chamber is shortened, It is also conceivable to prevent the resin from bending.

However, in the technique described in Patent Document 2, since the resin is transported in contact with a transport guide or the like, wrinkles or scuffs are generated on the surface of the resin even if the film is easily peeled off by air discharge. There is a case. For this reason, various problems such as variations in film tension in the width direction, generation of wrinkles and scuffs, and the like occur.
The present invention solves such problems, and reduces the length in the moving direction of the film in the heating chamber, and does not cause variations in the film tension or scratches in the width direction. It aims at providing the manufacturing method of a phase difference film.

(1) In order to solve the above-described problem, the web stretching method of the present invention moves the web through the transport guide while heating the web at a temperature capable of stretching in a heating chamber having at least one transport guide. A web stretching method in which the fluid is ejected from a fluid ejection hole formed on a surface of the transport guide to form a fluid layer on the surface of the transport guide, and the web is heated in the heating chamber. By moving on the fluid layer, the moving direction of the web is changed without the web coming into contact with the conveyance guide.

(2) In the web stretching method of the present invention, in the above (1), a plurality of fluid discharge holes are formed on the surface of the transport guide, and an introduction flow path leading to the fluid discharge hole is formed inside the transport guide. The fluid layer is formed by the fluid discharged from the plurality of fluid discharge holes.

(3) In the web stretching method of the present invention, in the above (1) or (2), a plurality of the fluid discharge holes are provided in a direction perpendicular to the moving direction of the web and the moving direction. The two fluid ejection holes are arranged so that a virtual line connecting two fluid ejection holes adjacent in a direction intersects the moving direction.

(4) In the web stretching method of the present invention, in any one of the above (1) to (3), a plurality of the conveyance guides are arranged in a heating chamber, and the web is located on a vertical upper side of the plurality of conveyance guides. The discharge amount of the fluid discharged from the transport guide passing therethrough is larger than the discharge amount of the fluid discharged from the transport guide passing through the vertical lower side of the web.

(5) The web stretching method of the present invention is characterized in that, in any one of the above (1) to (4), the stretchable temperature is a temperature equal to or higher than the glass transition point of the web.

(6) In the web stretching method of the present invention, in any one of the above (1) to (5), the temperature of the fluid discharged from the fluid discharge hole is the same as that in the heating chamber. .

(7) The method for producing a retardation film of the present invention is characterized in that the retardation film is stretched using the web stretching method described in any of (1) to (6) above.

According to the present invention, it is possible to shorten the length of the moving direction of the web in the heating chamber as compared with the case where the web is not changed in direction in the heating chamber, and the web to be stretched is not separated from the conveyance guide in the heating chamber. It can be conveyed in contact. Thereby, it is possible to realize uniform stretching of the web without causing problems such as variations in the film tension in the width direction of the web, generation of wrinkles and rubbing.

It is explanatory drawing which shows the structure of the heating chamber regarding Example 1, and a web conveyance mechanism. 3 is a perspective view of a conveyance guide according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a cross section of a conveyance guide according to Embodiment 1. FIG. It is an expanded view which shows arrangement | positioning of the fluid discharge hole formed in the surface of a conveyance guide. It is explanatory drawing which shows the structure of the heating chamber regarding Example 2, and a web conveyance mechanism. It is explanatory drawing which shows the structure of the heating chamber regarding Example 3, and a web conveyance mechanism.

In a preferred embodiment of the present invention, when the web is stretched, at least one conveyance guide is disposed in the heating chamber, and the inlet side roll and the outlet side roll provided at each of the inlet and outlet of the heating chamber are driven. The web is conveyed to the heating chamber. In the heating chamber, the web moves through the conveyance guide while being heated at a temperature equal to or higher than the glass transition point of the web. At this time, fluid is discharged from the fluid discharge holes formed on the surface of the transport guide to form a fluid layer on the surface of the transport guide. At least in the heating chamber, the web moves on the fluid layer to change the moving direction of the web without contacting the web with the conveyance guide.

The web is preferably a thermoplastic resin film that exhibits birefringence when stretched. For example, a cellulose resin, a vinyl chloride resin, a polycarbonate resin, an acrylonitrile resin, an olefin resin, or a polymethyl methacrylate resin. And polysulfone resins, polyarylate resins, polyether sulfone resins, polynorbornene resins, and the like.

The heating chamber is provided with a heating space, which includes a heating furnace in which a gas whose temperature is adjusted is circulated, and a heating tank in which a liquid is circulated. An inlet and an outlet are formed in the heating chamber, and the web is conveyed from the inlet to the heating chamber, heated at a predetermined temperature, and then discharged from the outlet. The size of the heating chamber is not particularly limited because it is appropriately set depending on the shape and size of the web being conveyed.

When the web is transported, the web is transported and stretched by the difference in peripheral speed between the inlet side roll and the outlet side roll. That is, by increasing the peripheral speed of the outlet side roll rather than the inlet side roll, the web is pulled in the moving direction toward the outlet side roll, and the web can be stretched.
The entrance side roll and the exit side roll are preferably made of metal, but not limited to metal, if the roll has heat resistance to the temperature of the heating chamber, other known members such as reinforced plastic can be used. Also good. The shape and diameter of the roll are not limited to the cylindrical shape but may be other shapes such as an elliptical shape as long as the web conveyance is not hindered, and the diameter can be set as appropriate.

The conveyance guide has a long columnar shape, and the upper surface thereof is provided with a so-called bowl-shaped cylindrical curved surface web floating surface, and a plurality of fluid discharge holes provided in a predetermined arrangement on the web floating surface. The web can be lifted and conveyed by discharging a fluid such as a compressed air or a processing gas or a liquid such as an aqueous solution, a processing liquid, or water.
In addition, the shape of the web floating surface of the conveyance guide is a drum shape (convex shape) with a raised central portion, in addition to a straight cylindrical shape, depending on the shape of the end face when the plate-like members are combined radially. In this case, conversely, various shapes such as a drum shape (concave shape) in which the central portion is dented and both ends are raised are conceivable. If the drum type or the drum type is used, a web scooping effect during conveyance can be expected.
A plurality of conveyance guides may be arranged according to the conveyance distance of the web.

In the present invention, a plurality of fluid ejection holes are formed on the surface of the transport guide, and an introduction flow path for fluid ejected from the fluid ejection holes is provided therein. Since fluid is discharged from the fluid discharge hole and a fluid layer is formed on the surface of the conveyance guide, the web does not directly contact the conveyance guide, suppressing variations in tension, generation of wrinkles and scuffs, The web can be stretched uniformly.
A plurality of fluid discharge holes formed on the surface of the conveyance guide are provided in the direction of movement of the web and the direction orthogonal to the direction. The shape of the fluid discharge hole is a quadrangle, but may be other polygons or circles.

The arrangement of the plurality of fluid ejection holes formed on the surface of the transport guide is not particularly limited.
For example, it is also possible to arrange the webs in a moving direction and / or along an orthogonal direction orthogonal to the moving direction, or to deviate from the orthogonal direction.
For example, an imaginary line connecting two adjacent fluid discharge holes in the moving direction of the web is arranged at a position shifted so as to intersect the moving direction at an angle of, for example, 5 to 30 degrees. Also good.
In other words, the positional relationship between the holes adjacent to the moving direction of the web may be shifted by a predetermined interval with respect to the orthogonal direction.

From a fluid discharge hole formed on the surface of the conveyance guide, fluid is discharged at a predetermined pressure to form a fluid layer. In this case, the discharged fluid is preferably discharged after being heated to a temperature equal to or higher than the glass transition point of the web. That is, in order to stretch the web, it is necessary to heat the fluid layer to a temperature equal to or higher than the glass transition point.
Although the kind of fluid discharged from the fluid discharge hole is not limited, fluids such as gas such as compressed air and processing gas, and liquid such as aqueous solution, processing liquid, and water are exemplified.
The thickness of the fluid layer formed on the conveyance guide (approximately equal to the flying height of the web) can be set as appropriate as long as the web does not contact the conveyance guide. For example, the thickness is set within 2 mm as a guide. .

When a plurality of conveyance guides are arranged in the heating chamber, the amount of fluid discharged from the conveyance guide in which the web passes vertically above among the plurality of conveyance guides is such that the web passes vertically below. It is desirable that the discharge amount of the fluid discharged from the transport guide is larger. When the web passes through the vertical upper side, it is more likely to come into contact with the conveyance guide as compared with passing through the vertical lower side due to the influence of gravity. Therefore, by making the fluid layer of the conveyance guide through which the web passes at least vertically above relatively thick, the web can be prevented from coming into contact with the conveyance guide.

In the present embodiment, the web stretching method described above is particularly suitable for the production of a retardation film. That is, a uniform retardation film free from variations in film tension and wrinkles can be produced by applying the web stretching method described above to stretch the retardation film.

Hereinafter, examples relating to a web stretching method and a retardation film manufacturing method to which the present invention is applied will be described with reference to the drawings. In this example, when a retardation film is produced, an embodiment in which the web stretching method of the present invention is used for a web as a material thereof will be described.

FIG. 1 is an explanatory view showing a structure of a heating chamber and a web levitation conveyance device related to Example 1, FIG. 2A is a perspective view of a conveyance guide according to Example 1, and FIG. FIG. 3 is a developed view showing the arrangement of fluid discharge holes formed on the surface of the conveyance guide, and FIG. 4 is a structure of a heating chamber and web floating conveyance relating to Example 2; FIG. 5 is an explanatory view showing a structure of a heating chamber and a web levitation conveyance apparatus according to the third embodiment.

<Example 1>
The apparatus shown in FIG. 1 is a so-called longitudinal uniaxial stretching apparatus, and performs a stretching process along the moving direction of the web (lateral direction in FIG. 1).
As shown in FIG. 1, an inlet side roll 4 and an outlet side roll 5 are arranged on the inlet 22 and outlet 23 sides of the heating chamber 2, respectively. The temperature in the heating chamber 2 is set to be not lower than the glass transition temperature of the web 8 and not higher than the melting temperature.
The web 8 unwound from the unwinding roll P is introduced into the heating chamber 2 from the inlet 22 through the inlet-side roll 4, and three conveyance guides 1 a arranged on a straight line connecting the inlet 22 and the outlet 23. It moves between 1 b and 1 c and is discharged out of the heating chamber 2 through the outlet 23. After that, it passes through the outlet side roll 5 and is taken up by the take-up roll Q.
The inlet side roll 4 and the outlet side roll 5 rotate in the moving direction of the web 8. Since the rotational speed of the exit side roll 5 is faster than the rotational speed of the entrance side roll 4, the web 8 moving between the entrance side roll 4 and the exit side roll 5 is moved in the moving direction in a state of being heated to the glass transition temperature or higher. Is pulled and stretched.
A blower 3 is disposed outside the heating chamber 2, and heated air sent from the blower 3 moves through the moving pipe 31 and is discharged from the fluid discharge hole 9 on the surface of the transport guide 1.

Next, the conveyance guide will be described. As shown in FIGS. 2A and 2B, a plurality of fluid discharge holes 9 are formed in at least a part of the surface of the conveyance guide 1 having the roll diameter 6 and the roll width 7 that faces the web 8. .
The inside of the conveyance guide 1 has a hollow shape 101, and the heated air sent from the blower 3 passes through the hollow shape 101 and is discharged from the fluid discharge hole 9.
As shown in FIG. 2 (b), a fluid layer 11 is formed near the surface of the transport guide 1 by the pressurized heated air discharged from the plurality of fluid discharge holes 9. Then, the web 8 is levitated and conveyed through the fluid layer 11.
In addition, the conveyance guide 1 is not what rotates itself, but is arrange | positioned and fixed in the heating space 21 by the fixing member 12 formed in a part of conveyance guide.

In addition, when the some conveyance guide 1 is arrange | positioned in the heating chamber 2, it is also possible to change the quantity of the fluid discharged from each conveyance guide.
That is, in the case of the embodiment shown in FIG. 1, the web 8 moves below the conveyance guides 1a and 1c and above the conveyance guide 1b. In this case, the fluid discharged from the fluid discharge holes 9 on the surfaces of the transport guides 1a and 1c may have a higher discharge pressure than the fluid discharged to the upper side of the transport guide 1b due to gravity.
Accordingly, the discharge pressure of the fluid discharged to the upper side of the transfer guide 1b is set higher than the discharge pressure of the fluid discharged from the fluid discharge hole 9 on the surfaces of the transfer guides 1a and 1c, thereby the transfer guides 1a and 1b. It is possible to form the fluid layer 11 having the same thickness and the same amount of fluid on 1c.

For the same reason, it is possible to change not only the fluid discharge pressure but also the fluid amount. That is, by increasing the amount of fluid discharged to the upper side of the conveyance guide 1b more than the amount of fluid discharged from the fluid discharge holes 9 on the surfaces of the conveyance guides 1a and 1c, the thickness of the fluid layer 11 and the like It is also possible to adjust.

Next, the fluid discharge holes 9 formed on the surface of the conveyance guide 1 will be described with reference to FIG.
As shown in FIG. 3, a plurality of fluid discharge holes 9 formed in the axial direction of the conveyance guide 1 (orthogonal direction 13 orthogonal to the moving direction 10 of the web) form a fluid discharge hole array 19a, and adjacent fluids The arrangement of the fluid ejection holes in the ejection hole array is not arranged on the same straight line in the circumferential direction (movement direction 10) of the transport guide 1.
That is, the fluid discharge holes 9 are arranged in the orthogonal direction 13 at intervals of a fluid discharge hole distance 9a, and the fluid discharge hole rows are arranged at intervals of a fluid discharge hole distance 9b.

Further, the imaginary line 14 connecting two adjacent fluid ejection holes in the movement direction 10 has the fluid ejection holes 9 arranged in an oblique direction so as to intersect the movement direction 10.
More specifically, as shown in FIG. 3, the fluid discharge holes 9 d and 9 e adjacent to each other with respect to the moving direction 10 are arranged so as to be shifted from each other with respect to the orthogonal direction 13 by a shift width 9 c.
By arranging in this way, the fluid discharged from the fluid discharge holes 9 is uniform with respect to the web 8, and the thickness and the amount of fluid of the formed fluid layer 11 are adjusted to be uniform. Then, it is conveyed along the moving direction 10.

Below, the various conditions regarding Example 1 are shown below.
≪Web stretch conditions≫
Web material: Polynorbornene resin film (glass transition temperature Tg: 120 ° C.)
Web size (size): thickness 150 μm, width 250 mm
Stretch ratio: 2.0 times << Structure and conditions in heating chamber >>
Heating space temperature: 140 ° C. (web temperature during stretching is 140 ° C.)
Number of transport guides: 3
Temperature of fluid discharged from fluid discharge hole: 140 ° C
<< Construction of transport guide >>
Fluid discharge hole shape:
-Size: 0.5 mm width x 0.15 mm height x 20 mm depth-Distance 9a between adjacent fluid discharge holes in the orthogonal direction 13: 1.0 mm
-Distance 9b between adjacent fluid discharge holes in the moving direction 10: 2.0 mm
-Deviation width 9c between fluid ejection holes in the orthogonal direction 13 between adjacent fluid ejection holes in the moving direction 10: 0.2 mm
Total number of fluid discharge holes 9: 22,000 / (conveying guide arcuate surface 180 °) Shape of conveying surface:
・ Roll diameter 6: 95mmφ
・ Roll width 7: 300mm
・ Web wrap angle θ: 180 ° or less ≪Blower 3≫ However, three blower guides are controlled by one blower. Motor output: 1.5 kW
Maximum static pressure: 12kPa
Maximum air volume: 5m ³ / min
≪Measurement data at the time of test≫
Floating pressure on the web: 4-6 kPa (Measures the pressure in the hollow shape 101 inside the conveyance guide)
Tension on the web during stretching (measured between rolls 4-5): 10-30 N at web temperature 140 ° C
Web flying height (substantially synonymous with the thickness of the fluid layer 11): within 2 mm (measurement)

The stretching section (length in the moving direction of the web) between the inlet side roll 4 and the outlet side roll 5 is 800 mm, the peripheral speed of the inlet side roll 4 is 1.0 m / min, and the peripheral speed of the outlet side roll 5 is 2 0.0 m / min.

Under the above conditions, the fluid layer 11 is formed by a substantially static pressure air layer by heated air in the heating chamber set at 140 ° C. by the three conveyance guides 1a, 1b, 1c, and the surface of the fluid layer 11 is the web 8 Functioned as a transfer surface. Note that heated air set at 140 ° C. was discharged as the fluid.

When the retardation value and the orientation angle at a wavelength of 590 nm were measured at intervals of 10 mm in the width direction for the entire width of the obtained stretched web, the average value of the retardation was 140 nm and the retardation value between two points 10 mm apart. It was found that the variation was 10% at the maximum and the difference between the maximum value and the minimum value for the orientation angle was 1.0 °, and the web was uniformly stretched throughout. Also, no wrinkles or scuffs on the web surface were observed.

<Example 2>
FIG. 4 shows a longitudinal uniaxial stretching apparatus according to Example 2 to which the present invention is applied. In Example 2, the three conveyance guides 1 arranged in the heating chamber are arranged in the heating chamber 2 with a difference in height, and the stretching section (the length in the moving direction of the web) is set to 1200 mm. There is a difference from the first embodiment.

Thus, if a plurality of conveyance guides 1 are arranged in the heating chamber 2 with a difference in height, the space of the heating space 21 can be used effectively, and the stretching section can be made long while suppressing the enlargement of the apparatus. It becomes possible. A retardation film was produced in the same manner as in Example 1 except for the points described above.

Also in this example, when the in-plane retardation value and orientation angle at a wavelength of 590 nm were measured at intervals of 10 mm in the width direction for the entire width of the obtained stretched web, the average value of in-plane retardation was 180 nm and 10 mm apart. Further, it was found that the fluctuation of the retardation value between the two points was 10% at the maximum and the difference between the maximum value and the minimum value was 1.0 ° for the orientation angle, so that the web was uniformly stretched throughout. In addition, as in Example 1, wrinkles and scuffs on the web surface were not observed.

<Example 3>
FIG. 5 shows a longitudinal uniaxial stretching apparatus according to Example 3 to which the present invention is applied. The third embodiment is different from the first and second embodiments in that the number of conveyance guides 1 arranged in the heating chamber is one.

As shown in FIG. 5, the conveyance guide 1 is positioned above the heating space 21 of the heating chamber 2, and the web 8 passes through the conveyance guide 1. The blower 3 controls heated air discharged from the fluid discharge holes 9 formed on the surface of the single conveyance guide 1. In addition, it carried out similarly to Example 1 or Example 2 except the above-mentioned point, and manufactured the phase difference film.

As described above, according to the web stretching method and the retardation film manufacturing method to which the present invention is applied, the heating chamber can be reduced in size and the cost can be reduced as compared with the case where the web is not turned in the heating chamber. In addition, since the web to be stretched is conveyed in a non-contact state with the conveyance guide in the heating chamber, problems such as variations in film tension in the width direction, generation of wrinkles and rubbing are not caused. This makes it possible to uniformly stretch the web while suppressing the manufacturing cost, and has an extremely advantageous effect when manufacturing the retardation film.

<Other variations>
In addition, a present Example is not limited to what was mentioned above, Unless it deviates from the meaning of this invention, it can change suitably in view of technical common sense.
For example, when the three conveyance guides 1 are arranged in the heating chamber 2, the fluid discharge hole 9 is formed on the upper surface side of the conveyance guide 1 arranged in the center. The transport guide 1 may have a fluid discharge hole 9 on the upper surface side.

In FIG. 1, the fluid discharge holes 9 formed on the surface of the transport guide 1 are alternately formed on the upper surface side and the lower surface side, but the fluid discharge holes 9 are formed on the same side for the three transport guides 1. It may be. When the fluid discharge holes 9 are formed on the lower side of the three conveyance guides 1, the web is conveyed on the lower side of the conveyance guide 1b in FIG. That is, the web passes under the conveyance guides 1a, 1b, and 1c. Furthermore, the peripheral speed of the inlet-side roll 4 and the peripheral speed of the outlet-side roll 5 can be appropriately set according to the draw ratio, the material of the web, and the like.

The number of the conveyance guides 1 arranged in the heating space 21 is not limited to one or three, and the arrangement position and the number can be appropriately set as long as the space of the heating space 21 is effectively used.

In addition, it is also possible to convey the web while rotating the conveyance guide 1 by providing the fluid discharge holes 9 in the entire circumference direction of the conveyance guide 1 and attaching the conveyance guide 1 to be rotatable.

The present invention is suitable for a stretching method and a stretching apparatus for stretching a web, and can also be applied to a manufacturing method and a manufacturing apparatus for manufacturing a retardation film using the web. Extremely high.

1, 1a, 1b, 1c Conveying guide 2 Heating chamber 21 Heating space 22 Inlet 23 Outlet 3 Blower 31 Moving pipe 4 Inlet side roll 5 Outlet side roll 6 Roll diameter 7 Roll width 8 Web 9

Fluid ejection holes

9a, 9b Fluid ejection holes Distance 9c

Deviation width

9d, 9e Fluid discharge hole 10 Movement direction 11 Fluid layer 12 Fixing member 13 Orthogonal direction 14 Virtual line 19a Fluid discharge hole array 101 Hollow shape P inside the conveyance guide Rewinding roll Q Winding roll

Claims

In a heating chamber having at least one conveyance guide, the web is stretched in the moving direction of the web by moving the web through the conveyance guide while being heated at a temperature at which the web can be stretched,
Fluid is discharged from a fluid discharge hole formed on the surface of the transport guide to form a fluid layer on the surface of the transport guide;
A web stretching method, wherein the web moves in the heating chamber to change the moving direction of the web without contacting the web with the transport guide.
A plurality of fluid discharge holes are formed on the surface of the transport guide,
An introduction flow path leading to the fluid discharge hole is formed inside the conveyance guide,
The web stretching method according to claim 1, wherein the fluid layer is formed by the fluid ejected from the plurality of fluid ejection holes.
A plurality of the fluid discharge holes are provided in a direction perpendicular to the moving direction of the web and the direction perpendicular thereto.
3. The web according to claim 1, wherein the two fluid ejection holes are arranged so that a virtual line connecting the two fluid ejection holes adjacent in the movement direction intersects the movement direction. 4. Stretching method.
A plurality of the conveyance guides are arranged in the heating chamber,
Of the plurality of transport guides, the amount of fluid discharged from the transport guide through which the web passes vertically above is the amount of fluid discharged from the transport guide through which the web passes below vertical. The web stretching method according to claim 1, wherein the web stretching method is more than the amount.
The web stretching method according to any one of claims 1 to 4, wherein the stretchable temperature is a temperature equal to or higher than a glass transition point of the web.
The web stretching method according to any one of claims 1 to 5, wherein the temperature of the fluid discharged from the fluid discharge hole is the same as that in the heating chamber.
A method for producing a retardation film, comprising: stretching a retardation film using the web stretching method according to any one of claims 1 to 6.