TWI902874B - Manufacturing method of optical film - Google Patents

Abstract

The method for manufacturing the optical film of this invention involves conveying a laminate (8) with a protective film (2) detachably bonded to the first main surface of a long strip film substrate (1) along its length to a peeling section (10) using rollers. At the peeling section, the protective film is peeled off from the first main surface of the film substrate. During the conveying of the film substrate after the protective film has been peeled off from the peeling section to the coating section (30), the rollers do not contact the center portion of the first main surface of the film substrate in the width direction, and the membrane pressing mechanism (15) contacts both ends of the first main surface of the film substrate in the width direction at least once. The membrane pressing mechanism does not contact the center portion of the first main surface of the film substrate in the width direction.

Description

Manufacturing method of optical film

This invention relates to a method for manufacturing an optical film having a liquid crystal layer.

Optical films, used for optical compensation in liquid crystal displays and anti-reflection of organic EL elements, employ liquid crystal layers (aligned liquid crystal layers) with liquid crystal compounds aligned in a specific direction. Liquid crystal compounds can be aligned in a specific direction by shear forces when applied to a substrate or by alignment-regulating forces of the substrate, resulting in various aligned liquid crystal layers with optical anisotropy. For example, a parallel-aligned liquid crystal film, in which nematic liquid crystal molecules with positive refractive index anisotropy are aligned parallel to the substrate surface, can be used as a positive A-plate with refractive index anisotropy of nx > ny = nz.

In Patent 1, a liquid crystal compound is coated onto an inclined, extended film substrate, with the liquid crystal compound aligned parallel to the extension direction (alignment direction) of the film substrate, thus creating an alignment layer. By coating the liquid crystal compound onto the film substrate while simultaneously transporting the film substrate, a long strip of liquid crystal film can be formed. As described in Patent 1, if an inclined, extended film substrate is used, the liquid crystal molecules are aligned parallel to the alignment direction of the film substrate, thus enabling the fabrication of long strip liquid crystal films where the liquid crystal molecules are not aligned parallel to the transport direction of the film substrate.

Furthermore, Patent 1 discloses a circular polarizer used as an anti-reflective film in an organic EL display device, fabricated by laminating liquid crystal films with a 45° angle between the late-phase axis of the liquid crystal film and the absorption axis of the linear polarizing element. By laminating a strip of liquid crystal film with non-parallel transport directions of the liquid crystal molecules and a polarizing element having an absorption axis parallel to the transport direction in a roll-to-roll manner, a strip of circular polarizer can be fabricated.

[Previous Technical Documents] [Patent Documents]

[Patent Document 1] WO2016/121856

Sometimes, liquid crystal layers formed by coating liquid crystal compositions while simultaneously transporting the film substrate exhibit defects due to misalignment of the liquid crystal molecules. This is particularly true in liquid crystal layers where the liquid crystal molecules are aligned non-parallel to the transport direction of the film substrate, where the number of defects caused by misalignment tends to increase. The purpose of this invention is to provide an optical film containing a liquid crystal layer with fewer misalignment defects.

One embodiment of the present invention is a method for manufacturing a strip optical film including a liquid crystal layer, wherein a liquid crystal layer is formed on the first main surface of a strip film substrate having a first main surface and a second main surface. First, a laminate with a protective film removably bonded to the first main surface of the strip film substrate is prepared. The laminate is then conveyed along the length of the film substrate to a peeling section (first conveying step), where the protective film is peeled off from the first main surface of the film substrate (protective film peeling step).

The film substrate after the protective film has been peeled off is transferred along its length from the peeling section to the coating section (second transfer step). In the coating section, a liquid crystal assembly is coated on the first main surface of the film substrate (coating step).

During the transport of the membrane substrate after the protective film has been removed to the coating section, the roller does not contact the center portion of the first main surface of the membrane substrate in the width direction, while the membrane pressing mechanism contacts both ends of the first main surface of the membrane substrate in the width direction at least once. The membrane pressing mechanism does not contact the center portion of the first main surface of the membrane substrate in the width direction. The membrane pressing mechanism may be a pressing roller that only contacts both ends of the first main surface of the membrane substrate in the width direction.

During the transfer of the membrane substrate after the protective film has been removed to the coating section, the conveyor roller can contact the second main surface of the membrane substrate. The conveyor roller can make full contact with the second main surface of the membrane substrate in the width direction.

When applying the liquid crystal composition to the film substrate, the liquid crystal composition can be applied to the inner side of the first main surface of the film substrate in the width direction, further inward than the contact portion with the film pressing mechanism. At an appropriate time after applying the liquid crystal composition, the areas at both ends of the film substrate in the width direction that contact the film pressing mechanism can be cut off and removed by means of incisions or the like.

The film substrate for coating liquid crystal compositions can be an alignment-regulating force that aligns liquid crystal molecules in a specific direction. For example, the film substrate can be an extended film in which molecules are aligned non-parallel to their length direction, or it can be a tilted extended film. The film substrate can also be one where an alignment film is not disposed on the first main surface.

Optical films can be formed by laminating other optical layers onto a liquid crystal layer in a roll-to-roll manner. The optical layers laminated on the liquid crystal layer may include polarizing elements. An optical film can be a circular polarizing plate formed by laminating a liquid crystal layer and polarizing elements.

1: Membrane substrate

1A: First Main Page

1B: Second Main Page

2: Protective film

3: Liquid crystal layer

4: Optical Layer (Polarizing Plate)

5: Next, the coating layer

6: Adhesive layer

7: Isolation Components

8: Laminated Body

9: Laminated sheets (optical films)

10: Peeling Section

11: Peeling the chariot

13: Transport Roller

15: Pressing the roller

15A: Pressing Roller

15B: Pressing Roller

15C: Connecting Shaft

15L: Roller

15R: Roll

16: 輥

20: Wrapped Body

21: Roller

23: Transporting Rollers

25: Transporting Rollers

30: Painting Section

31: Support roller

33: Mold tip

37: The central area in the width direction of the membrane substrate

38: Regions at both ends of the membrane substrate in the width direction

39: Regions at both ends of the membrane substrate in the width direction

50: Heating section

55: Heating furnace

60: Hardened section

61: Light Source

71: Transporting Rollers

73: Transporting Rollers

75: Transporting Rollers

77: Transporting Rollers

79: Transporting Rollers

80: Curled Body

81: Roll out

83: Transporting Rollers

85: Transporting Rollers

87: Transporting Rollers

90: Curled Body

91: Roller

96: Laminated Structures (Optical Films)

97: Laminated Structures (Optical Films)

98: Laminated Structures (Optical Films)

151: Pressing Roller

201: Membrane Substrate

202: Protective Film

211: Peeling the chariot

213: 輥

231:Backup roller

233: Mold tip

Figure 1 is a cross-sectional view of an optical film having a liquid crystal layer on a film substrate.

Figure 2 is a cross-sectional view of a laminate with a protective film temporarily bonded to a membrane substrate.

Figure 3 is a schematic diagram illustrating the film-forming apparatus and steps for forming a liquid crystal layer on a film substrate.

Figure 4 is a schematic diagram of the conveying path of the membrane substrate from the peeling roller to the support roller.

Figure 5 is a schematic diagram of the transport path of the membrane substrate in the comparative example.

Figure 6 is a schematic diagram of the transport path of the membrane substrate in the comparative example.

Figure 7 is a schematic diagram of the transport path of the membrane substrate in one embodiment.

Figure 8 is a three-dimensional view showing one example of the shape of a pressing roller.

Figure 9 is a cross-sectional view of an optical film in one embodiment.

Figure 10 is a cross-sectional view of an optical film in one embodiment.

Figure 11 is a cross-sectional view of an optical film in one embodiment.

This invention relates to a method for manufacturing an optical film comprising a liquid crystal layer. In one embodiment of the invention, a liquid crystal layer is formed by coating a liquid crystal assembly onto a main surface of a strip film substrate. Figure 1 is a cross-sectional view of an optical film 9 having a liquid crystal layer 3 disposed on a first main surface 1A of a film substrate 1. Figure 2 is a cross-sectional view of a laminate 8 having a protective film 2 peelably bonded to the first main surface 1A of the film substrate 1.

If scratches exist on one side of the film substrate where the liquid crystal composition is coated (the liquid crystal layer forming surface), the liquid crystal molecules are prone to aligning along the direction of the scratch, resulting in misalignment defects. This is especially true when the film substrate is being transported in a roll-to-roll manner while the liquid crystal composition is being coated; contact and friction with the transport rollers easily cause scratches along the length of the film substrate.

In this embodiment, a protective film 2 is temporarily attached to the film substrate 1 just before the liquid crystal composition is coated on the first main surface 1A of the film substrate 1. By temporarily attaching the protective film 2, the first main surface 1A of the film substrate 1 does not come into contact with the transport rollers, thus preventing damage to the film substrate 1 due to transport and suppressing misalignment of liquid crystal molecules in the liquid crystal layer 3.

Figure 3 is a conceptual diagram showing the general outline of the film-forming apparatus and steps for forming a liquid crystal layer 3 on a film substrate 1. The film-forming apparatus winds the film from a long strip of film wound on a take-up roller 81 and conveys it to the coating section 30. In the coating section 30, a liquid crystal composition is coated on the film to form a liquid crystal layer. The take-up roller 91 then takes the film (optical film 9) with the liquid crystal layer to form a winding 90. Between the coating section 30 and the take-up roller 91, heating can be performed in the heating section 50, and photocuring of the liquid crystal monomers can be performed in the curing section 60.

In Figure 3, a roll 80, obtained by winding a strip of film of the laminate 8 into a cylindrical shape, is wound onto a take-off roll 81. As described above, the laminate 8 has a protective film 2 that is peelably adhered to the first main surface of the film substrate 1.

The laminate 8, wound from the winding body 80, moves continuously to the downstream side of the transport path formed by the transport rollers 83, 85, and 87, and is transported to the peeling section 10 (first transport step). During the period from the unwinding roller 81 to reaching the peeling section 10, a protective film 2 is adhered to the first main surface 1A of the membrane substrate 1, thus preventing direct contact between the first main surface 1A of the membrane substrate 1 and the transport rollers 87. Therefore, damage to the first main surface of the membrane substrate due to contact with the transport rollers 87 can be prevented.

In the peeling section 10, the protective film 2 is peeled off from the first main surface of the membrane substrate 1 (peeling step). There is no particular limitation on the method of peeling the protective film; typically, peeling is performed on the peeling roller 11. As long as the downstream conveying rollers 13 and 23 of the peeling roller 11 are arranged such that the angle of the protective film 2 relative to the peeling roller 11 is larger than the angle of the membrane substrate 1 relative to the peeling roller 11, the protective film 2 can be peeled off from the membrane substrate 1 on the peeling roller 11. The peeling roller can be one of two clamping rollers holding the laminated bodies 8 between the upper and lower laminations.

The protective film 2, peeled from the first main surface of the membrane substrate 1, is conveyed along a conveying path based on conveyor rollers 23 and 25, and wound into a coil 20 by winding roller 21.

By peeling off the protective film 2, the first main surface 1A of the film substrate 1 is exposed. The film substrate 1, after the protective film has been removed, is transferred from the peeling section 10 to the coating section 30 (second transfer step). In the coating section 30, with the second main surface 1B of the film substrate 1 in contact with the support roller 31, the liquid crystal assembly ejected from the nozzle 33 is coated onto the first main surface 1A of the film substrate 1 (coating step).

In the second conveying step, the first main surface 1A of the film substrate 1 is exposed. Therefore, during the conveying of the film substrate 1 from the peeling section 10 (peeling roller 11) to the coating section 30 (support roller 31), if the conveying roller comes into contact with the first main surface 1A of the film substrate 1, scratches will occur at the contact point between the first main surface and the conveying roller, resulting in poor liquid crystal alignment.

Figure 4 is a schematic diagram of the conveying path of the film substrate 1 from the peeling roller 11 to the support roller 31 in the apparatus shown in Figure 3, viewed from the second main surface 1B of the film substrate 1. Regions 38 and 39 at both ends of the film substrate 1 in the width direction are areas outside the product. Region 37 in the center of the film substrate 1 in the width direction is the product area. In the coating section, with the second main surface 1B of the film substrate 1 in contact with the support roller 31, the liquid crystal composition ejected from the nozzle 33 is coated in region 37 of the first main surface 1A of the film substrate 1. The liquid crystal composition is not coated in regions 38 and 39 at the two ends of the film substrate 1.

In the configuration shown in Figures 3 and 4, during the transfer of the membrane substrate 1 from the peeling roller 11 of the peeling section 10 to the support roller 31 of the coating section 30, the pressing rollers 15 (rollers 15A and 15B) of the membrane pressing mechanism contact the regions 38 and 39 at both ends of the first main surface 1A of the membrane substrate 1. During the transfer path from the peeling roller 11 to the support roller 31, the second main surface 1B of the membrane substrate 1 may contact the transfer roller 13.

Figure 5 is a schematic diagram showing the transport path of the film substrate in a comparative example. In this example, no other rollers are arranged between the peeling roller 211 and the support roller 231. Therefore, the film substrate 201, after the protective film 202 is peeled off on the peeling roller 211, is transported to the support roller 231 without contacting other rollers and is coated with the liquid crystal composition ejected from the nozzle 233. After the protective film 202 is peeled off, the first main surface of the film substrate 201 is coated with the liquid crystal composition without contacting the rollers, thus preventing scratches caused by roller transport.

However, in this example, the peeling force applied to the film substrate 201 when the protective film 202 is peeled off causes the film substrate between the peeling roller 11 and the support roller 231 to vibrate up and down, resulting in uneven coating. Specifically, the liquid crystal layer formed on the film substrate develops segmental thickness unevenness extending along the width direction, leading to poor optical properties.

An aerial turning method is known as a non-contact membrane transport method. By employing an aerial turning method in the second transport step, scratches on the first main surface of the membrane substrate can be prevented. However, in the aerial turning method, the membrane substrate also vibrates, thus resulting in uneven coating, similar to the example described above.

As shown in Figure 6, when a roller 213, which contacts the second main surface of the membrane substrate 201, is positioned between the peeling roller 211 and the support roller 231, the second main surface of the membrane substrate 201 (upper side in the figure) is pressed downwards by the roller 213. Therefore, compared to the arrangement shown in Figure 4, there is a tendency to suppress vibration of the membrane substrate 201 (membrane swaying). However, the peeling force of the protective membrane 202 acts in a way that stretches the membrane substrate 201 towards the first main surface side (lower side in the figure). Therefore, even with the roller 213 in contact with the second main surface of the membrane substrate 201, the vibration suppression effect on the membrane substrate 201 is limited.

On the other hand, if a conveyor roller is configured to contact the first main surface of the film substrate 201, although the vibration of the film substrate 201 can be effectively suppressed, the contact between the conveyor roller and the first main surface of the film substrate 201 will cause scratches, resulting in misalignment of the liquid crystal layer.

In this embodiment of the invention, as shown in Figure 4, by bringing the rollers 15A and 15B, which serve as the film pressing mechanism, into contact with regions 38 and 39 at both ends of the first main surface of the film substrate 1 in the width direction, a pressing force from the first main surface side (lower side) to the upper side of the figure is applied to the film substrate 1. Therefore, vibration of the film substrate 1 caused by the peeling force of the protective film 2 can be reduced, thus suppressing uneven coating of the liquid crystal layer.

In the central region 37 of the film substrate 1 along its width, the pressing roller 15 does not contact the first main surface 1A, and the other rollers also do not contact the first main surface 1A of the film substrate 1. Therefore, damage to the film substrate 1 in the product region 37 where the liquid crystal composition is coated can be prevented, thereby reducing alignment defects in the liquid crystal layer 3.

As shown in Figures 3 and 4, if a roller 13, which is in contact with the second main surface 1B of the membrane substrate 1, is arranged between the peeling roller 11 and the pressing roller 15, the membrane substrate 1 is also pressed from the second main surface 1B side. Therefore, the vibration of the membrane substrate 1 caused by the peeling force of the protective film 2 can be more effectively suppressed. A roller in contact with the second main surface of the membrane substrate 1 can be arranged between the pressing roller 15 and the support roller 31. Rollers in contact with the second main surface 1B of the membrane substrate 1 can be arranged between both the peeling roller 11 and the pressing roller 15, and between the pressing roller 15 and the support roller 31.

The roller 15, which contacts the second main surface 1B of the membrane substrate 1, may only contact both ends of the membrane substrate, or it may be contacted along the entire width direction of the membrane substrate as shown in Figure 4. From the viewpoint of membrane substrate transportability, it is preferable that the roller 15 is contacted along the entire width direction of the second main surface of the membrane substrate.

Two or more pressing rollers may be provided between the peeling roller 11 and the supporting roller 31, connecting to regions 38 and 39 at both ends of the first main surface 1A of the membrane substrate 1 in the width direction.

In Figure 4, pressing rollers 15A and 15B are arranged to extend outwards from both ends of the membrane substrate 1. However, the pressing rollers do not necessarily have to extend beyond the membrane substrate 1. For example, the pressing rollers can be positioned within 30 cm, 20 cm, 15 cm, 10 cm, 5 cm, 3 cm, or 1 cm of the end of the membrane substrate in the width direction.

In regions 38 and 39 at both ends of the membrane substrate, the width of the portion of the membrane substrate in contact with the pressing roller is, for example, 1 to 50 cm. If the width of the portion in contact with the pressing roller is too small, the vibration suppression effect of the membrane substrate becomes insufficient, or the mobility of the membrane substrate decreases. If the width of the portion in contact with the pressing roller is too large, the large width of the non-product area of the optical film becomes a cause of reduced production efficiency or yield. The width of the portion in contact with the pressing roller can be 2 cm or more, 3 cm or more, or 5 cm or more, or it can be less than 30 cm, less than 25 cm, less than 20 cm, less than 15 cm, or less than 10 cm.

As shown in Figure 7, the pressing roller 15 can be paired with roller 16 to clamp the membrane substrate. Roller 16 is in contact with the second main surface 1B of the membrane substrate 1. In the configuration shown in Figure 6, the roller 16 in contact with the second main surface of the membrane substrate 1 can be in contact with the central portion of the membrane substrate 1 in the width direction.

The shape of the pressing roller 15 is not limited to two rollers 15A and 15B separately arranged at both ends in the width direction as shown in Figure 4. For example, a lever-shaped roller 151 as shown in Figure 8 may also be used, with cylindrical rollers 15R and 15L at both ends, connected by a connecting shaft 15C with a diameter smaller than that of the rollers.

The membrane pressing mechanism disposed between the peeling section 10 and the coating section 30 does not necessarily need to be a rotating body; it only needs to be able to press both ends of the membrane substrate 1 from the first main surface side to suppress vibration of the membrane substrate 1 caused by the peeling of the protective film 2. For example, the membrane pressing mechanism can also be a pin or the like that pressing the membrane substrate from the first main surface side (bottom of the figure) to the second main surface side.

After the protective film 2 is peeled off from the first main surface 1A of the membrane substrate 1, the two ends of the membrane substrate can be held in place by a tenter frame clamp. In this case, the rollers can be pressed against the two ends of the membrane substrate in the width direction from both sides of the first and second main surfaces, preventing the rollers from contacting the center of the membrane substrate in the width direction, thereby suppressing the vibration of the membrane substrate 201 caused by the peeling off of the protective film 2. In this case, the clamp that is in contact with the first main surface of the membrane substrate functions as a membrane pressing mechanism.

As described above, in this embodiment of the invention, by temporarily attaching a protective film to the first main surface of the film substrate beforehand, scratches on the first main surface of the film substrate during the transport path can be prevented before the protective film is peeled off. During the transport path of the film substrate after the protective film is peeled off at the peeling section and before the liquid crystal composition is applied at the coating section, the rollers do not contact the center portion of the first main surface of the film substrate in the width direction, thus preventing scratches from occurring in the area of the film substrate where the liquid crystal composition is applied (the product area). Therefore, it is possible to suppress the formation of misalignment defects in the liquid crystal layer caused by scratches on the film substrate, resulting in an optical film with fewer optical defects.

Furthermore, during the transport path of the film substrate after the protective film is peeled off in the peeling section and before the liquid crystal composition is applied in the coating section, by contacting the two ends of the film pressing mechanism, such as the pressing roller, with the two ends of the first main surface of the film substrate in the width direction, vibration of the film substrate caused by the peeling of the protective film can be suppressed, thus reducing uneven coating of the liquid crystal composition. In the area contacted by the film pressing mechanism, scratches may occur on the first main surface of the film substrate; however, these areas are non-manufacturing areas where the liquid crystal composition has not been applied or are excluded during product manufacturing, and therefore do not affect the quality of the optical film.

The following provides specific examples illustrating the materials used to form optical films and the manufacturing methods of optical films.

<Membrane Substrate>

By using a long strip film substrate 1 as the substrate for coating liquid crystal compositions, a series of steps, including coating, alignment, and photocuring of the liquid crystal compositions, can be performed in a roll-to-roll manner. Furthermore, the step of bonding the liquid crystal layer 3 formed on the film substrate 1 to other substrates can also be performed in a roll-to-roll manner, thus improving the manufacturability of the optical film.

The width of the membrane substrate 1 is preferably 30 cm or more, but can also be 50 cm or more, 80 cm or more, 100 cm or more, or 120 cm or more. From the perspective of optical film production, the larger the width of the membrane substrate 1, the better; it is usually less than 500 cm, but can also be less than 400 cm or less, or less than 300 cm. The length of the membrane substrate is preferably 100 m or more, but can also be more than 300 m, 500 m or more, 800 m or more, 1000 m or more, or more than 1200 m. There is no particular upper limit to the length of the membrane substrate 1; it is usually less than 10000 m, but can also be less than 7000 m or less, or less than 5000 m. The thickness of the membrane substrate 1 is preferably around 10~200 μm.

The resin material constituting the film substrate 1 is not particularly limited as long as it is insoluble in the solvent of the liquid crystal assembly and has heat resistance for heating to orient the liquid crystal assembly. Examples include: polyesters such as polyethylene terephthalate and polyethylene naphthalate; polyolefins such as polyethylene and polypropylene; and other polyolefins. Cyclic polyolefins such as olefin polymers; cellulose polymers such as diacetate cellulose and triacetate cellulose; acrylic polymers; styrene polymers; polycarbonate, polyamide, polyimide, etc.

The film substrate 1 may have alignment regulating forces for aligning liquid crystal molecules along a specific direction. For example, an alignment film may be provided on the first main surface of the film substrate 1. The alignment film may be appropriately selected depending on the type of liquid crystal compound or the material of the substrate. For example, an alignment film obtained by rubbing a polyimide-based or polyvinyl alcohol-based alignment film can be used to align liquid crystal molecules in a parallel direction. Alternatively, a photoalignment film may be used. A resin film may also be rubbed without providing an alignment film.

The film substrate 1 may also be an alignment film for vertically aligning liquid crystal molecules. Examples of alignment agents used to form the vertically aligned alignment film (vertical alignment film) include: lecithin, stearic acid, hexadecyltrimethylammonium bromide, octadecylamine hydrochloride, monocarboxylic acid chromium complexes, silane coupling agents, or organosilanes such as siloxanes, perfluorodimethylcyclohexane, tetrafluoroethylene, and polytetrafluoroethylene.

As the film substrate 1, an extended film can be used. In the extended film, the resin material (polymer) constituting the film is aligned along the extension direction, which has the function of aligning the liquid crystal molecules along the extension direction. By using an extended film, even when an alignment film is not formed on the film substrate, an alignment regulating force for aligning liquid crystal molecules in a specific direction can be achieved. Since it is not necessary to form an alignment film, the manufacturing cost of the optical film can be reduced. Furthermore, by not providing an alignment film, contamination caused by friction residue or misalignment can be prevented.

The extension direction (polymer alignment direction) of the stretched film is not particularly limited; it can be parallel to or non-parallel to the length direction of the film substrate. By using a stretched film in which the molecules are aligned non-parallel to the length direction, a liquid crystal layer in which the liquid crystal molecules are aligned non-parallel to the length direction can be formed.

The elongation ratio of the stretched film only needs to be sufficient to exert the alignment control force, for example, approximately 1.1 to 5 times. The stretched film can be a biaxial stretched film. Even with a biaxial stretched film, if the elongation ratios in the longitudinal and transverse directions are different, the liquid crystal molecules can still be aligned along the direction with the greater elongation ratio.

The stretched film can also be a tilted stretched film. A tilted stretched film has an alignment axis along a direction that is neither parallel nor orthogonal to the length direction (e.g., a direction at 10-80° relative to the length direction). Therefore, by using a tilted stretched film as the film substrate 1, a liquid crystal layer in which liquid crystal molecules are aligned along a direction neither parallel nor orthogonal to the length direction can be formed.

Protective Film

The protective film 2, temporarily adhered to the first main surface 1A of the membrane substrate 1, is flexible, and its material is not particularly limited; metal foil or resin film can be used. The protective film 2 can be transparent or opaque. Resin film is preferred due to its low cost and excellent processability. Specific examples of resin materials for the protective film 2 include those described above as the resin material for the membrane substrate 1. The protective film 2 can also be an extended film. The thickness of the protective film 2 is not particularly limited. Considering both self-support and flexibility, the thickness of the protective film 2 is preferably around 10~100μm.

The protective film 2 preferably has an adhesive layer on the surface in contact with the membrane substrate 1. The adhesive layer can adhere to the membrane substrate 1 and is only required to be peelable from it; it can be composed of an adhesive used in general adhesive tapes, etc. As a protective film, a self-adhesive film obtained by integrally molding the resin material constituting the film and the resin material of the adhesive layer through multi-layer extrusion can be used.

The method for laminating the protective film 2 onto the membrane substrate 1 is not particularly limited. For example, during the manufacturing process of the membrane substrate 1, the protective film 2 can be applied to the membrane substrate 1 in a roll-to-roll manner before the membrane substrate 1 is rolled into a cylindrical shape. By continuously applying the protective film 2 in conjunction with the manufacturing process of the membrane substrate 1, the number of contacts between the roller and the first main surface 1A of the membrane substrate 1 can be reduced, thus suppressing the formation of scratches.

When the membrane substrate 1 is an extended membrane, it is preferable to apply the protective film 2 immediately after the extension is performed. For example, by applying the protective film 2 after the extension is performed by stretching the two ends of the holding film and before the first main surface 1A of the membrane substrate 1 comes into contact with the conveyor roller, scratches on the first main surface 1A of the membrane substrate 1 can be prevented.

The laminate 8, on which the protective film 2 is bonded, can be temporarily wound into a cylindrical shape 80. Alternatively, the laminate 8 can be directly transferred to the peeling section 10 without being wound, and the protective film 2 can be peeled off from the membrane substrate 1.

<Liquid crystal material>

The liquid crystal layer 3 formed on the film substrate 1 contains liquid crystal molecules. Preferably, the liquid crystal molecules in the liquid crystal layer 3 are aligned along a specific direction. For example, a liquid crystal layer 3 with liquid crystal molecules aligned along a specific direction is formed by coating a liquid crystal compound containing a liquid crystal compound onto the film substrate 1, aligning the liquid crystal compound along a specific direction, and then fixing the alignment state.

Examples of liquid crystal compounds include rod-shaped and disc-shaped liquid crystal compounds. Rod-shaped liquid crystal compounds are preferred because they are easily aligned parallel to each other using the alignment control forces of the film substrate. Rod-shaped liquid crystal compounds can be either main-chain or side-chain liquid crystals. They can be liquid crystal polymers or polymers of polymerizable liquid crystal compounds. As long as the liquid crystal compound (monomer) exhibits liquid crystal properties before polymerization, it is acceptable; it is not necessary for it to exhibit liquid crystal properties after polymerization.

The liquid crystal compound is preferably a thermotropic liquid crystal, which exhibits liquid crystal properties upon heating. Thermotropic liquid crystals undergo phase transitions with temperature changes, changing between a crystalline phase, a liquid crystal phase, and an isotropic phase. The liquid crystal compound contained in the liquid crystal assembly can be any of nematic liquid crystals, stratified liquid crystals, or cholesterol liquid crystals. Chiral agents can also be added to nematic liquid crystals to impart cholesterol-like orientation.

Examples of rod-shaped liquid crystal compounds exhibiting thermotropic properties include: methylene azo compounds, oxo azo compounds, cyanobiphenyl compounds, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane compounds, cyano-substituted phenylpyrimidine compounds, alkoxy-substituted phenylpyrimidine compounds, and phenyl diphenyl... Alkanes, diphenylacetylenes, alkenylcyclohexylbenzonitriles, etc.

Examples of polymerizable liquid crystal compounds include those whose alignment can be fixed using polymeric adhesives, and those possessing polymeric functional groups that can fix the alignment of liquid crystal compounds through polymerization. Among these, photocurable liquid crystal compounds possessing photocurable functional groups are preferred.

A photocurable liquid crystal compound (liquid crystal monomer) has a liquid crystal primitive and at least one photocurable functional group in one molecule. The temperature at which the liquid crystal monomer exhibits liquid crystal properties (liquid crystal phase transition temperature) is preferably 40~200℃, more preferably 50~150℃, and even more preferably 55~100℃.

Examples of liquid crystal monomers that form cyclic structures include: biphenyl, phenylbenzoate, phenylcyclohexyl, oxoazophenyl, methyleneazo, azophenyl, phenylpyrimidinyl, diphenylethynyl, diphenylbenzoate, dicyclohexyl, cyclohexylphenyl, and triphenyl. These cyclic units may have cyano, alkyl, alkoxy, or halogen substituents at their ends.

Examples of photocurable functional groups include (meth)acrylic, epoxy, and vinyl ether groups. Among these, (meth)acrylic is preferred. The photocurable liquid crystal monomer preferably has two or more photocurable functional groups in one molecule. By using a liquid crystal monomer containing two or more photocurable functional groups, a cross-linking structure is introduced into the photocured liquid crystal layer, thus tending to improve the durability of the optical film.

As a photocurable liquid crystal monomer, any suitable liquid crystal monomer can be used. Examples include: International Patent No. 00/37585, US Patent No. 5211877, US Patent No. 4388453, International Patent No. 93/22397, European Patent No. 0261712, German Patent No. 19504224, German Patent No. 4408171, British Patent No. 2280445, Japanese Patent Application Publication No. 2017-206460, International Patent No. 2014/126113, International Patent No. 2016/114348, International Patent No. 2014/010325, and Japanese Patent Application Publication No. 2015-20087. Compounds described in Japanese Patent Publication No. 7, Japanese Patent Publication No. 2010-31223, International Patent Publication No. 2011/050896, Japanese Patent Publication No. 2011-207765, Japanese Patent Publication No. 2010-31223, Japanese Patent Publication No. 2010-270108, International Patent Publication No. 2008/119427, Japanese Patent Publication No. 2008-107767, Japanese Patent Publication No. 2008-273925, International Patent Publication No. 2016/125839, and Japanese Patent Publication No. 2008-273925. By selecting the liquid crystal monomer, the performance of birefringence or the wavelength dispersion of delay can also be adjusted.

In addition to liquid crystal monomers, liquid crystal compositions may also contain compounds that control the alignment of the liquid crystal monomers in a specific direction. For example, by including a side-chain liquid crystal polymer in the liquid crystal composition, the liquid crystal compound (monomer) can be vertically aligned. Furthermore, by adding a chiral agent to the liquid crystal composition, cholesterol alignment of the liquid crystal compound can be achieved.

Liquid crystal compositions may contain photopolymerization initiators. When curing liquid crystal monomers by ultraviolet irradiation, the liquid crystal composition preferably contains a photopolymerization initiator (photoradical generator) that generates free radicals upon light irradiation to promote photocuring. Depending on the type of liquid crystal monomer (the type of photocurable functional group), a photocation generator or a photoanion generator can be used. The amount of photopolymerization initiator used is approximately 0.01 to 10 parts by weight relative to 100 parts by weight of the liquid crystal monomer. In addition to photopolymerization initiators, sensitizers, etc., may also be used.

Liquid crystal compositions can be prepared by mixing liquid crystal monomers with various alignment control agents, polymerization initiators, etc., and solvents as needed. There are no particular limitations on the solvent, as long as it can dissolve the liquid crystal monomers and does not corrode the substrate (or has low corrosivity). Examples include: halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, and ortho-dichlorobenzene; phenols such as phenol and p-chlorophenol; aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, and 1,2-dimethoxybenzene; and acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, and 2-pyrrolidine. Ketone solvents such as ketones and N-methyl-2-pyrrolidone; ester solvents such as ethyl acetate and butyl acetate; alcohol solvents such as butanol, glycerol, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, and 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; nitrile solvents such as acetonitrile and butyronitrile; ether solvents such as diethyl ether, dibutyl ether, and tetrahydrofuran; ethyl solvents and butyl solvents, etc. Mixed solvents of two or more solvents may also be used.

The solid content of liquid crystal compositions is typically around 5-60% by weight. Liquid crystal compositions may also contain additives such as surfactants or leveling agents.

Formation of liquid crystal layer on substrate

A laminate 8, to which a protective film 2 is peelably bonded, is conveyed to the peeling section 10, where the protective film 2 is peeled off. The film substrate 1, after the protective film 2 has been removed, is then conveyed to the coating section 30, where a liquid crystal assembly is coated on the first main surface 1A of the film substrate 1. As described above, during the conveying path from the peeling section 10 to the coating section 30, the roller does not contact the central area 37 of the first main surface 1A of the film substrate 1 in the width direction. Therefore, the area 37 of the first main surface 1A has fewer scratches due to contact with the roller, thus reducing liquid crystal alignment defects.

Figure 3 illustrates the method of coating the liquid crystal composition from the nozzle 33, which is positioned opposite the support roller 31. However, the method of coating the liquid crystal composition on the film substrate 1 is not particularly limited. Examples of coating methods, besides molding, include: contact roller coating, gravure coating, reverse coating, spraying, Mayer rod coating, doctor blade roller coating, and air knife coating.

As described above, the central region 37 of the first main surface 1A of the film substrate 1 in the width direction does not contact the rollers after the protective film 2 is peeled off. Therefore, by coating the liquid crystal composition in this region, misalignment caused by scratches on the film substrate can be reduced. Furthermore, the liquid crystal composition can also be coated in the contact regions 38 and 39 with the film pressing mechanism at both ends of the film substrate 1 in the width direction. In this case, the contact regions with the film pressing mechanism can be cut off from the product at an appropriate stage after coating the liquid crystal composition by methods such as cutting the optical film or making end cuts.

The coating thickness of the liquid crystal assembly is preferably adjusted so that the thickness of the liquid crystal assembly layer (the thickness of liquid crystal layer 3) after solvent drying is approximately 0.1 to 20 μm. The film substrate 1 after coating with the liquid crystal assembly can be heated in the heating unit 50. The heating unit 50, for example, includes a heating furnace 55, and the film substrate 1 and the liquid crystal assembly coated thereon are heated during the transfer of the film substrate 1 into the heating furnace 55. For example, heating can remove the solvent contained in the liquid crystal assembly.

When the liquid crystal compound contained in the liquid crystal assembly is a thermotropic liquid crystal, a liquid crystal phase is formed by heating the liquid crystal assembly layer, and the liquid crystal compound aligns along a specific direction. Specifically, the liquid crystal assembly coated on a film substrate is heated to above the N (nematic phase) - I (isotropic liquid phase) transition temperature to create an isotropic liquid state. Subsequently, it is slowly cooled as needed to exhibit a nematic phase. Ideally, the temperature for exhibiting the liquid crystal phase is temporarily maintained to allow liquid crystal phase domains to grow and form monodomains. Alternatively, after coating the liquid crystal assembly, the temperature can be maintained for a certain period within the temperature range for exhibiting the nematic phase, thereby causing the liquid crystal molecules to align along a specific direction.

The heating temperature for aligning the liquid crystal compound along a specific direction can be appropriately selected according to the type of liquid crystal compound, typically around 40~200℃. If the heating temperature is too low, the transfer to the liquid crystal phase tends to be insufficient; if the heating temperature is too high, alignment defects may increase. The heating time can be adjusted to ensure sufficient growth of the liquid crystal phase domain, typically around 30 seconds to 30 minutes.

Preferably, the liquid crystal compound is aligned by heating, followed by cooling to a temperature below the glass transition temperature. The cooling method is not particularly limited; for example, removing it from the heated atmosphere to room temperature is sufficient. Strong cooling methods such as air cooling or water cooling can also be used.

When the liquid crystal compound exhibits curing properties, curing is preferably performed in the curing section 60. For example, when the liquid crystal compound exhibits photocuring properties, photocuring is performed when the photocurable liquid crystal compound (liquid crystal monomer) exhibits liquid crystal regularity. The irradiation light from the light source 61 is sufficient to polymerize the photocurable liquid crystal compound; ultraviolet light or visible light with a wavelength of 250-450 nm is typically used. When the liquid crystal compound contains a photopolymerization initiator, light with a wavelength to which the photopolymerization initiator is sensitive can be selected. As the irradiation light source, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, LEDs, black lights, chemical lamps, etc., can be used. To promote the photocuring reaction, light irradiation is preferably performed in an inert gas atmosphere such as nitrogen.

During photocuring, the liquid crystal compound can be aligned in a specific direction by using polarized light in a specific orientation. As described above, when the liquid crystal compound is aligned by the alignment regulating force of the film substrate 1, the irradiated light can also be unpolarized light (natural light).

The irradiation intensity can be adjusted appropriately according to the composition of the liquid crystal assembly or the amount of photopolymerization initiator added. The irradiation energy (cumulative irradiation light intensity) is usually around 20~10000 mJ/ ^cm² , preferably 50~5000 mJ/ ^cm² , and even more preferably 100~800 mJ/ ^cm² . To promote the photocuring reaction, light irradiation can be performed under heating conditions.

The polymer resulting from photocuring liquid crystal monomers is non-liquid crystal, and does not undergo temperature-dependent phase transitions between liquid crystal, glassy, and crystalline phases. Therefore, photocured liquid crystal layers, where liquid crystal monomers are aligned in a specific direction, are less prone to temperature-dependent molecular alignment changes. Furthermore, liquid crystal layers exhibit significantly higher birefringence compared to films containing non-liquid crystal materials, thus allowing for a substantial reduction in the thickness of optical anisotropic elements with desired latency.

The optical properties of liquid crystal layer 3 are not particularly limited. The frontal delay and thickness direction delay of liquid crystal layer 3 can be appropriately set according to the application. When the liquid crystal molecules are parallel aligned, the frontal delay of liquid crystal layer 3 is, for example, approximately 20~1000nm. When liquid crystal layer 3 is a quarter-wavelength plate, the frontal delay is preferably 100~180nm, more preferably 120~150nm. When liquid crystal layer 3 is a half-wavelength plate, the frontal delay is preferably 200~340nm, more preferably 240~300nm. When the liquid crystals are vertically aligned, the in-plane delay of liquid crystal layer 3 is approximately 0 (e.g., below 5nm, preferably below 3nm), and the absolute value of the thickness direction delay is approximately 30~500nm.

The alignment direction of the liquid crystal molecules in liquid crystal layer 3 can be parallel to or non-parallel to the length direction (roll-to-roll transport direction) of the film substrate 1. As described above, by utilizing the alignment regulating force of an inclined stretching film, a liquid crystal layer in which the liquid crystal molecules are aligned non-parallel to the length direction can be formed. When the liquid crystal molecules are non-parallel to the length direction, if there are scratches along the length direction on the film substrate, the liquid crystal molecules formed on it will align along the scratches in the length direction, thus causing misalignment. By temporarily attaching a protective film to the film substrate 1 as described above and preventing it from contacting the rollers after peeling off the protective film, scratches on the film substrate can be suppressed, reducing misalignment of the liquid crystal layer.

A strip of optical film is obtained by winding a laminate 9 (optical film) on the first main surface 1A of the film substrate 1 with a winding roller 91. This laminate 9 can be used directly as an optical film. The regions 38 and 39 at both ends of the film substrate 1 in the width direction are non-product regions; therefore, they are preferably cut off by a slit at an appropriate stage after the formation of the liquid crystal layer 3 and before winding with the winding roller 91, or after winding with the winding roller 91. Alternatively, the film can be punched to cut out single-piece products without including the regions 38 and 39 at both ends in the width direction.

<Lamination Methods of Optical Films>

A laminate 9 having a liquid crystal layer 3 formed on the first main surface 1A of the film substrate 1 can be directly used as an optical film, or the film substrate 1 can be peeled off, leaving only the liquid crystal layer 3 as an optical film. Furthermore, other layers can also be deposited on the liquid crystal layer 3. For example, by bonding an optical layer 4 to the liquid crystal layer 3 via an adhesive layer 5, the laminate 96 shown in FIG. 9 is obtained.

The optical layer 4 laminated on the liquid crystal layer 3 is not particularly limited, and optically isotropic or optically anisotropic films commonly used as optical films can be used without particular restriction. Specific examples of the optical layer 4 include transparent films such as retardation films or polarizer protective films, polarizers, viewing angle widening films, viewing angle limiting (anti-spying) films, and brightness enhancing films. The optical layer 4 can be a single layer or a laminate. The optical layer 4 can be a liquid crystal layer. For example, the optical layer 4 can be a polarizing plate with a transparent protective film laminated to one or both sides of the polarizing element. When a transparent protective film is provided on one side of the polarizing plate, the polarizing element can be laminated to the liquid crystal layer, or the transparent protective film can be laminated to the liquid crystal layer.

The adhesive constituting adhesive layer 5 is not particularly limited in material as long as it is optically transparent. Examples include epoxy resin, polysiloxane resin, acrylic resin, polyurethane, polyamide, polyether, and polyvinyl alcohol. The thickness of adhesive layer 5 is appropriately set according to the type of substrate being bonded or the material of the adhesive. When using a curing adhesive that exhibits adhesion through a cross-linking reaction after application, the thickness of adhesive layer 5 is preferably 0.01~5μm, more preferably 0.03~3μm.

As an adhesive, various forms can be used, including aqueous adhesives, solvent-based adhesives, hot-melt adhesives, and active energy line curing adhesives. Among these, aqueous adhesives and active energy line curing adhesives are preferred because they can reduce the thickness of the adhesive layer.

The liquid crystal layer 3 and the optical layer 4 are deposited via an adhesive layer 5 by applying and curing an adhesive to either or both of the surfaces of the liquid crystal layer 3 and the optical layer 4. The curing of the adhesive is appropriately selected based on its type. For example, water-based adhesives can be cured by heating. Active energy line curing adhesives can be cured by irradiation with active energy lines such as ultraviolet light.

A laminate 96, in which the liquid crystal layer 3 on the film substrate 1 is bonded with the optical layer 4 via an adhesive layer 5, can also be directly used as an optical film. In this case, the film substrate 1 constitutes part of the optical film. As shown in Figure 10, the film substrate can be peeled off from the liquid crystal layer 3. Alternatively, as shown in Figure 11, a suitable adhesive layer 6 can be deposited on the surface of the liquid crystal layer 3 exposed by peeling off the film substrate.

The adhesive constituting adhesive layer 6 is not particularly limited, and can be appropriately selected from acrylic polymers, polysiloxane polymers, polyesters, polyurethanes, polyamides, polyethers, fluoropolymers, rubber polymers, etc., as the base polymer. Acrylic adhesives or rubber adhesives with excellent transparency, exhibiting suitable wetting, aggregation, and adhesion properties, as well as excellent weather resistance or heat resistance are particularly preferred. The thickness of the adhesive layer can be appropriately set according to the type of substrate being adhered to, typically around 5~500 μm.

The adhesive layer 6 is deposited onto the liquid crystal layer 3, for example, by bonding a pre-formed sheet-like adhesive to the surface of the liquid crystal layer 3. The adhesive layer 6 can be formed by drying, cross-linking, or photocuring the solvent after applying the adhesive composition to the liquid crystal layer 3. To improve the adhesion (anchoring force) between the liquid crystal layer 3 and the adhesive layer 6, surface treatments such as corona treatment or plasma treatment can be applied to the surface of the liquid crystal layer 3, or an easily bondable layer can be formed before depositing the adhesive layer 6.

Preferably, a release element 7 is temporarily adhered to the surface of the adhesive layer 6. The release element 7 protects the surface of the adhesive layer 6 until the optical film is bonded to other components. Suitable materials for the release element include acrylic resins, polyolefins, cyclic polyolefins, and polyester films. The thickness of the release element is typically around 5–200 μm. Preferably, a release treatment is applied to the surface of the release element. Examples of release agents include polysiloxane materials, fluorine-based materials, long-chain alkyl materials, and fatty acid amide materials.

Other optical layers can be deposited on the exposed surface of the liquid crystal layer 3 after the film substrate 1 has been peeled off, using a suitable adhesive layer or binder layer. For example, other optical layers can be deposited on the liquid crystal layer 3 using a suitable adhesive layer, or a binder layer can be further deposited on it.

Optical films containing a liquid crystal layer can be used, for example, as optical films for image display devices. As an example of an optical film in which another optical layer 4 is laminated onto a liquid crystal layer 3, a circular polarizer formed by laminating a liquid crystal layer 3 and a polarizing plate can be cited.

A polarizing plate can be formed from a single polarizing element, or, as described above, a transparent protective film can be laminated to one or both sides of the polarizing element. Examples of polarizing elements include those formed by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films (where iodine or dichroic dyes are adsorbed onto the film), partially formaldehyde-modified polyvinyl alcohol films, or partially saponified ethylene-vinyl acetate copolymer films, as well as polyene-based alignment films such as dehydrated polyvinyl alcohol or dehydrochlorinated polyvinyl chloride.

Among these, polyvinyl alcohol (PVA) polarizing elements, obtained by adsorbing dichroic substances such as iodine or dichroic dyes onto polyvinyl alcohol (PVA) films or partially formaldehyde-modified PVA films and aligning them in a specific direction, are preferred due to their high polarization. For example, PVA polarizing elements can be obtained by iodine staining and stretching a PVA film. Alternatively, a PVA resin layer can be formed on a resin substrate, and iodine staining and stretching can be performed in a laminated state.

In a circular polarizer formed by laminating a polarizing plate and a liquid crystal layer, it is preferable that the liquid crystal molecules in at least one liquid crystal layer are parallelly aligned. In the circular polarizer, the alignment direction of the liquid crystal molecules in the parallel-aligned liquid crystal layer is neither parallel nor orthogonal to the absorption axis of the polarizing element.

For example, when the circular polarizer has only one liquid crystal layer, the liquid crystal layer 3 is a quarter-wavelength plate, and the angle between the absorption axis of the polarizing element and the alignment direction of the liquid crystal molecules (usually the late-phase axis) is set to 45°. The angle between the absorption axis of the polarizing element and the alignment direction of the liquid crystal molecules can be 35~55°, 40~50°, or 43~47°.

In a configuration where the optical axes of the polarizing plate 4 and the liquid crystal layer 3 (serving as a quarter-wavelength plate) form a 45° angle, a liquid crystal layer with liquid crystal molecules perpendicularly aligned to the substrate surface (vertical alignment) can be further achieved. By sequentially depositing the liquid crystal layer 3 (serving as a quarter-wavelength plate) and the vertically aligned liquid crystal layer (serving as a positive C-plate) on the polarizing plate, a circular polarizing plate that can block reflected light from external light coming from an inclined direction can be formed. Alternatively, a vertically aligned liquid crystal layer (positive C-plate) and a parallel-aligned liquid crystal layer (serving as a quarter-wavelength plate, positive A-plate) can be sequentially deposited on the polarizing plate.

In a circular polarizing plate on which a plurality of liquid crystal layers are deposited, all liquid crystal layers may be parallel-aligned liquid crystal layers. In this case, it is preferable that the liquid crystal layer disposed near the polarizing plate 4 is a 1/2 wavelength plate and the liquid crystal layer disposed away from the polarizing plate is a 1/4 wavelength plate. In this deposition configuration, it is preferable that the angle between the late phase axis direction of the 1/2 wavelength plate and the absorption axis direction of the polarizing element is 75°±5°, and the angle between the late phase axis direction of the 1/4 wavelength plate and the absorption axis direction of the polarizing element is 15°±5°. This type of layered circular polarizer functions as a circular polarizer across a wide wavelength range of visible light, thus reducing the chromatic aberration of reflected light.

As described above, the liquid crystal layer manufactured by the embodiment of this invention suppresses scratches on the first main surface (the coating surface of the liquid crystal assembly) of the film substrate. Therefore, even when the liquid crystal molecules are not aligned parallel to the length direction of the film substrate, alignment defects are fewer, resulting in good display characteristics.

1: Membrane substrate

2: Protective film

8: Laminated Body

9: Laminated sheets (optical films)

10: Peeling Section

11: Peeling the chariot

13: Transport Roller

15: Pressing the roller

20: Wrapped Body

21: Roller

23: Transporting Rollers

25: Transporting Rollers

30: Painting Section

31: Support roller

33: Mold tip

50: Heating section

55: Heating furnace

60: Hardened section

61: Light Source

71: Transporting Rollers

73: Transporting Rollers

75: Transporting Rollers

77: Transporting Rollers

79: Transporting Rollers

80: Curled Body

81: Roll out

83: Transport Roller

85: Transport Roller

87: Transporting Rollers

90: Curled Body

91: Roller

Claims (12)

A method for manufacturing an optical film, comprising a strip optical film including a liquid crystal layer, includes the following steps: A step of preparing a laminate formed by peelably bonding a protective film onto the first main surface of a strip film substrate having a first main surface and a second main surface; A first conveying step of conveying the laminate to a peeling section along the length direction of the film substrate using a roller; A protective film peeling step of peeling the protective film from the first main surface of the film substrate at the peeling section; A second conveying step of conveying the film substrate after the protective film has been peeled off from the peeling section to a coating section along the length direction of the film substrate; and The coating step involves applying the liquid crystal composition to the first main surface of the film substrate using the aforementioned coating portion; In the aforementioned second conveying step, the roller does not contact the center portion of the first main surface of the film substrate in the width direction, the film pressing mechanism contacts both ends of the first main surface of the film substrate in the width direction at least once, and the film pressing mechanism does not contact the center portion of the first main surface of the film substrate in the width direction. As in the method for manufacturing the optical film of claim 1, the film pressing mechanism is a pressing roller that only contacts the two ends of the first main surface of the film substrate in the width direction. The method for manufacturing the optical film as claimed in claim 1, wherein in the second conveying step described above, the conveying roller contacts the second main surface of the film substrate at least once. As in the method for manufacturing the optical film of claim 3, the aforementioned conveying roller is integrally connected to the second main surface of the aforementioned film substrate in the width direction. The method for manufacturing an optical film according to any one of claims 1 to 4, wherein in the above coating step, the liquid crystal composition is coated on the inner side of the first main surface of the film substrate, more so than the contact portion of the film pressing mechanism, in the width direction. The method for manufacturing an optical film according to any one of claims 1 to 4 includes, after the above coating step, a step of cutting off and removing the areas at both ends of the film substrate in the width direction that are in contact with the film pressing mechanism. The method for manufacturing an optical film according to any one of claims 1 to 4, wherein the film substrate is an extended film in which the molecules are aligned non-parallel to the length direction. For example, the method for manufacturing an optical film as described in claim 7, wherein the film substrate is an inclined stretching film. The method of manufacturing an optical film according to any one of claims 1 to 4, wherein an alignment film is not provided on the first main surface of the aforementioned film substrate. A method for manufacturing an optical film according to any one of claims 1 to 4, wherein the liquid crystal composition comprises a photocurable liquid crystal compound, following the above coating step, further comprising a step of photocuring the liquid crystal compound. The method for manufacturing an optical film according to any one of claims 1 to 4 includes the step of depositing other optical layers on the liquid crystal layer in a roll-to-roll manner. The method for manufacturing an optical film, as described in claim 11, wherein the optical layer includes a polarizing element.