JP7539036B2 - Alignment film for liquid crystal compound alignment layer transfer - Google Patents

Description

The present invention relates to a transfer film for transferring a liquid crystal compound alignment layer. More specifically, the present invention relates to a transfer film for transferring a liquid crystal compound alignment layer, which is used when manufacturing polarizing plates and retardation plates such as circular polarizing plates on which a retardation layer made of a liquid crystal compound alignment layer is laminated, and when manufacturing polarizing plates having a polarizing layer made of a liquid crystal compound alignment layer.

Conventionally, in image display devices, a circular polarizer is placed on the panel surface of the image display panel facing the viewer to reduce reflection of external light. This circular polarizer is composed of a laminate of a linear polarizer and a retardation film such as λ/4, and external light toward the panel surface of the image display panel is converted into linearly polarized light by the linear polarizer, and then converted into circularly polarized light by a retardation film such as λ/4. When the circularly polarized external light is reflected on the surface of the image display panel, the direction of rotation of the polarization plane is reversed, and this reflected light is conversely converted into linearly polarized light in the direction blocked by the linear polarizer by a retardation film such as λ/4, and then blocked by the linear polarizer, so that emission to the outside is suppressed. In this way, a circular polarizer is used in which a retardation film such as λ/4 is attached to a polarizer.

As the retardation film, a single retardation film such as a cyclic olefin (see Patent Document 1), a polycarbonate (see Patent Document 2), or a stretched film of triacetyl cellulose (see Patent Document 3) is used. In addition, as the retardation film, a laminated retardation film having a retardation layer made of a liquid crystal compound on a transparent film (see Patent Documents 4 and 5) is used. In the above, it is described that when providing a retardation layer made of a liquid crystal compound (liquid crystal compound alignment layer), the liquid crystal compound may be transferred.

In addition, a method for producing a retardation film by transferring a retardation layer made of a liquid crystal compound onto a transparent film is known in Patent Document 6, etc. A method is also known in which a retardation layer made of a liquid crystal compound such as λ/4 is provided on a transparent film by such a transfer method to produce a λ/4 film (see Patent Documents 7 and 8).

A variety of substrates have been introduced for these transfer methods, with transparent resin films such as polyester, triacetyl cellulose, and cyclic polyolefin being cited as examples.

However, when retardation layer laminated polarizing plates (circular polarizing plates) manufactured using these transparent resin films as film substrates for transfer are used for anti-reflection purposes in image display devices, pinhole-like or scratch-like light leakage can occur, causing problems.

There is also a known method of manufacturing a polarizing plate by transferring a polarizing layer (liquid crystal compound alignment layer) containing a liquid crystal compound and a dichroic dye laminated on a transfer film to a protective film. However, this method also poses the same problem as above, in that light leakage in the form of pinholes or scratches can occur.

JP 2012-56322 A JP 2004-144943 A JP 2004-46166 A JP 2006-243653 A JP 2001-4837 A Japanese Patent Application Publication No. 4-57017 JP 2014-071381 A JP 2017-146616 A

The present invention was made against the background of the problems of the conventional technology. That is, the object of the present invention is to provide a transfer film for transferring a liquid crystal compound alignment layer, which is capable of forming a retardation layer or a polarizing layer (liquid crystal compound alignment layer) with reduced occurrence of defects such as pinholes.

In order to achieve this object, the present inventors have investigated the cause of defects such as pinholes in retardation layer laminated polarizing plates (circular polarizing plates) manufactured using transparent resin films such as polyester films as film substrates for transfer. As a result, they have found that the microstructures on the surfaces of these film substrates have a significant effect on the orientation state and phase difference of the liquid crystal compounds in the retardation layer made of liquid crystal compounds formed on these film substrates, and that the orientation state and phase difference as designed may not be obtained, which leads to the occurrence of defects such as pinholes. Then, the present inventors have focused on the surface roughness of the film substrates represented by specific parameters among these microstructures, and have found that by using a film substrate whose surface roughness is controlled within a specific range, it is possible to form a retardation layer or polarizing layer (liquid crystal compound orientation layer) in which the above-mentioned conventional problems do not occur and the occurrence of defects such as pinholes is reduced, thereby completing the first invention.

Furthermore, since the film substrate is usually stored and supplied in a rolled-up state after production, the release surface of the film substrate (the surface of the two surfaces of the film substrate on which the retardation layer and polarizing layer made of liquid crystal compounds are formed) and the opposite surface (back surface) are in contact under pressure, and the microstructure of the back surface may be transferred to the release surface, and therefore the influence of the microstructure of the back surface is also found to be large. The inventor then focused on the surface roughness of the film substrate, which is expressed by a specific parameter, among the microstructures of the back surface, and discovered that by using a film substrate whose surface roughness is controlled within a specific range, it is possible to form a retardation layer or polarizing layer (liquid crystal compound alignment layer) with reduced occurrence of defects such as pinholes without the above-mentioned conventional problems, which led to the completion of the second invention.

That is, the first invention has the following configurations (1) to (9).
(1) An alignment film for transferring a liquid crystal compound alignment layer to an object, characterized in that the surface roughness (SRa) of the release surface of the alignment film is 1 nm or more and 30 nm or less.
(2) The alignment film for transferring an alignment layer for a liquid crystal compound according to (1), characterized in that the release surface of the alignment film has a 10-point surface roughness (SRz) of 5 nm or more and 200 nm or less.
(3) The alignment film for transferring an alignment layer of a liquid crystal compound according to (1) or (2), wherein the alignment film is a polyester film.
(4) A laminate for transferring a liquid crystal compound alignment layer, comprising a liquid crystal compound alignment layer and an alignment film, the alignment film being the alignment film according to any one of (1) to (3).
(5) A method for producing a liquid crystal compound alignment layer laminated polarizing plate, comprising the steps of: bonding a polarizing plate and a liquid crystal compound alignment layer surface of the laminate described in (4) to form an intermediate laminate; and peeling off the alignment film from the intermediate laminate.
(6) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising the steps of irradiating linearly polarized light having an electric field vibration direction parallel to the orientation direction of the orientation film, or a direction perpendicular to the orientation direction, or to the flow direction of the orientation film, or a direction perpendicular to the flow direction, of the laminate from the orientation film surface, and receiving the light on the liquid crystal compound orientation layer surface side.
(7) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising the steps of irradiating elliptically polarized light from the liquid crystal compound orientation layer surface of the laminate and receiving the light on the orientation film surface side.
(8) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising the steps of: irradiating the orientation film surface of the laminate with linearly polarized light having an electric field vibration direction parallel to the orientation direction of the orientation film, or a direction perpendicular to the orientation direction, or to the flow direction of the orientation film, or a direction perpendicular to the flow direction; reflecting the light transmitted through the laminate with a mirror reflector provided on the liquid crystal compound orientation layer side of the laminate; and receiving the reflected light on the orientation film side.
(9) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising at least the steps of irradiating polarized light onto the laminate and passing the polarized light through the laminate, and receiving the polarized light that has passed through the laminate, characterized in that the polarized light passing through the orientation film of the laminate is linearly polarized light having an electric field vibration direction that is parallel to the orientation direction of the orientation film, or a direction perpendicular to the orientation direction, or to the flow direction of the orientation film, or a direction perpendicular to the flow direction, or the polarized light passing through the liquid crystal compound orientation layer surface of the laminate is elliptically polarized light.

The second invention has the following configurations (1) to (9).
(1) An alignment film for transferring a liquid crystal compound alignment layer to an object, characterized in that the surface roughness (SRa) of the surface opposite to the release surface of the alignment film is 1 nm or more and 50 nm or less, and the 10-point surface roughness (SRz) of the surface opposite to the release surface of the alignment film is 10 nm or more and 1,500 nm or less.
(2) The alignment film for transferring an alignment layer for a liquid crystal compound according to (1), characterized in that the maximum height (SRy) of the surface of the alignment film opposite to the release surface is 15 nm or more and 2000 nm or less.
(3) The alignment film for transferring an alignment layer for a liquid crystal compound according to (1) or (2), wherein the alignment film is a polyester film.
(4) A laminate for transferring a liquid crystal compound alignment layer, comprising a liquid crystal compound alignment layer and an alignment film, the alignment film being the alignment film according to any one of (1) to (3).
(5) A method for producing a liquid crystal compound alignment layer laminated polarizing plate, comprising the steps of: bonding a polarizing plate and a liquid crystal compound alignment layer surface of the laminate described in (4) to form an intermediate laminate; and peeling off the alignment film from the intermediate laminate.
(6) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising the steps of irradiating linearly polarized light having an electric field vibration direction parallel to the orientation direction of the orientation film, or a direction perpendicular to the orientation direction, or to the flow direction of the orientation film, or a direction perpendicular to the flow direction, of the laminate from the orientation film surface, and receiving the light on the liquid crystal compound orientation layer surface side.
(7) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising the steps of irradiating elliptically polarized light from the liquid crystal compound orientation layer surface of the laminate and receiving the light on the orientation film surface side.
(8) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising the steps of: irradiating the orientation film surface of the laminate with linearly polarized light having an electric field vibration direction parallel to the orientation direction of the orientation film, or a direction perpendicular to the orientation direction, or to the flow direction of the orientation film, or a direction perpendicular to the flow direction; reflecting the light transmitted through the laminate with a mirror reflector provided on the liquid crystal compound orientation layer side of the laminate; and receiving the reflected light on the orientation film side.
(9) A method for inspecting the orientation state of a liquid crystal compound orientation layer in the laminate described in (4), comprising at least the steps of irradiating polarized light onto the laminate and passing the polarized light through the laminate, and receiving the polarized light that has passed through the laminate, characterized in that the polarized light passing through the orientation film of the laminate is linearly polarized light having an electric field vibration direction that is parallel to the orientation direction of the orientation film, or a direction perpendicular to the orientation direction, or to the flow direction of the orientation film, or a direction perpendicular to the flow direction, or the polarized light passing through the liquid crystal compound orientation layer surface of the laminate is elliptically polarized light.

According to the present invention, by using a film whose surface roughness is controlled within a specific range as an orientation film for transferring a retardation layer or a polarizing layer, and further by using a film whose surface roughness on the surface opposite to the release surface is controlled within a specific range as an orientation film for transferring a retardation layer or a polarizing layer, the orientation state and phase difference of the liquid crystal compound in the retardation layer or polarizing layer can be controlled as designed, so that a retardation layer or polarizing layer (liquid crystal compound orientation layer) can be formed with reduced occurrence of defects such as pinholes.

The oriented polyester film of the present invention is intended for transferring a liquid crystal compound orientation layer to an object (another transparent resin film, a polarizing plate, etc.), and in the first invention, the surface roughness (SRa) of the release surface of the oriented film is 1 nm or more and 30 nm or less, and in the second invention, the surface roughness (SRa) of the surface opposite to the release surface of the oriented film is 1 nm or more and 50 nm or less. Note that when an oligomer block coating layer, a release layer, a flattening coating layer, an easy-slip coating layer, an antistatic coating layer, etc., which will be described later, are provided, these layers may be included in the term "oriented film."

There are no particular limitations on the resin that constitutes the film substrate used in the oriented film, so long as it maintains the strength required for the substrate of the oriented film. Among these, polyester, polycarbonate, polystyrene, polyamide, polypropylene, cyclic polyolefin, and triacetyl cellulose are preferred, with polyethylene terephthalate, cyclic polyolefin, and triacetyl cellulose being particularly preferred.

The oriented film of the present invention may be a single layer or a multi-layer structure formed by coextrusion. In the case of a multi-layer structure, examples of the structure include surface layer (release surface layer A)/back surface layer (B), A/middle layer (C)/A (where the release surface layer and back surface layer are the same), A/C/B, and the like.

When stretching a film, uniaxial stretching, weak biaxial stretching (stretched in two axial directions but weak in one direction), or biaxial stretching may be used, but uniaxial stretching or weak biaxial stretching is preferred because it allows the orientation direction to be constant over a wide range in the width direction. In the case of weak biaxial stretching, it is preferable to set the main orientation direction to the direction of stretching in the latter stage. In the case of uniaxial stretching, the stretching direction may be either the flow direction of the film production (machine direction) or the direction perpendicular to it (transverse direction).
In the case of biaxial stretching, simultaneous biaxial stretching or sequential biaxial stretching may be used. Stretching in the longitudinal direction is preferably performed by a group of rolls having different speed differences, and stretching in the transverse direction is preferably performed by a tenter.

The transfer orientation film is supplied industrially in the form of a wound film roll. The lower limit of the roll width is preferably 30 cm, more preferably 50 cm, even more preferably 70 cm, particularly preferably 90 cm, and most preferably 100 cm. The upper limit of the roll width is preferably 5000 cm, more preferably 4000 cm, and even more preferably 3000 cm.

The lower limit of the roll length is preferably 100 m, more preferably 500 m, and even more preferably 1000 m. The upper limit of the roll length is preferably 100,000 m, more preferably 50,000 m, and even more preferably 30,000 m.

(Roughness of release surface)
The release surface (A layer surface) of the transfer alignment film of the present invention is preferably smooth. In the present invention, the "release surface" of the alignment film means the surface of the alignment film on which the liquid crystal compound alignment layer to be transferred by the alignment film is intended to be provided. When an oligomer block coat layer, a flattening coat layer, a release layer, etc. described later are provided, if a liquid crystal compound alignment layer is provided thereon, the surfaces of these oligomer block coat layer, flattening layer, release layer, etc. (surfaces in contact with the liquid crystal compound alignment layer) are the "release surface" of the alignment film.

The lower limit of the three-dimensional arithmetic mean roughness (SRa) of the release surface of the transfer orientation film of the present invention is preferably 1 nm, more preferably 2 nm. If it is less than the above, it may be difficult to achieve the numerical value in reality. In addition, the upper limit of the SRa of the release surface of the transfer orientation film of the present invention is preferably 30 nm, more preferably 25 nm, even more preferably 20 nm, particularly preferably 15 nm, and most preferably 10 nm.

The lower limit of the three-dimensional ten-point average roughness (SRz) of the release surface of the transfer orientation film of the present invention is preferably 5 nm, more preferably 10 nm, and even more preferably 13 nm. The upper limit of the SRz of the release surface of the transfer orientation film of the present invention is preferably 200 nm, more preferably 150 nm, even more preferably 120 nm, particularly preferably 100 nm, and most preferably 80 nm.

The lower limit of the maximum height (SRy: maximum peak height SRp of the release surface + maximum valley depth SRv of the release surface) of the transfer orientation film of the present invention is preferably 10 nm, more preferably 15 nm, and even more preferably 20 nm. The upper limit of SRy of the release surface of the transfer orientation film of the present invention is preferably 300 nm, more preferably 250 nm, even more preferably 150 nm, particularly preferably 120 nm, and most preferably 100 nm.

The upper limit of the number of protrusions with a height difference of 0.5 μm or more on the release surface of the transfer orientation film of the present invention is preferably 5 protrusions/ ^m2 , more preferably 4 protrusions/ ^m2 , even more preferably 3 protrusions/ ^m2 , particularly preferably 2 protrusions/ ^m2 , and most preferably 1 protrusion/ ^m2 .

If the roughness of the release surface exceeds the above range, the alignment state and phase difference may not be as designed in the minute parts of the liquid crystal compound alignment layer formed on the transfer alignment film of the present invention, and defects such as pinholes and scratches may occur. The reasons for this are considered as follows. First, as described later, an alignment control layer such as a rubbing treatment alignment control layer or a light alignment control layer can be provided between the transfer alignment film and the liquid crystal compound alignment layer. If this alignment control layer is a rubbing treatment alignment control layer, the alignment control layer in the convex parts may peel off during rubbing, or the rubbing of the foot and recessed parts of the convex parts may be insufficient, which is thought to be the cause of the defects. In addition, if the release surface layer contains particles, the particles may fall off during rubbing and damage the surface, which is thought to be the cause of the defects. In addition, whether it is a rubbing treatment alignment control layer or a light alignment control layer, when the film is wound up with the alignment control layer provided, holes may be made in the alignment control layer in the convex parts due to rubbing with the back layer, or the alignment may be disturbed due to pressure, which is thought to be the cause of the defects. Due to these defects in the alignment control layer, when a liquid crystal compound alignment layer is provided on the alignment control layer, the liquid crystal compound does not orient properly in small areas, and the designed alignment state and phase difference cannot be obtained, resulting in pinhole-like and scratch-like defects.

Even when an orientation control layer is not provided and the liquid crystal compound orientation layer is formed directly on the transfer orientation film, defects are also thought to occur because, during application of the liquid crystal compound, the thickness of the liquid crystal compound orientation layer becomes thinner at the convex parts of the release surface of the orientation film, and conversely, the thickness of the liquid crystal compound orientation layer becomes thicker at the concave parts of the release surface of the orientation film, and therefore the designed phase difference cannot be obtained.

In order to set the roughness of the release surface (A) within the above range, when the oriented film for transfer of the present invention is a stretched film, the following method can be mentioned.
The release side layer (surface layer) of the original film does not contain particles.
When the release side layer (surface layer) of the original film contains particles, the particles should be small in size.
If the release side layer (surface layer) of the original film contains particles, a flattening coat is provided.
In the present invention, the "release surface side layer" of the oriented film means a layer having a release surface among the resin layers constituting the oriented film. Here, even when the film is a single layer, it may be called the release surface side layer. In this case, the back surface side layer and the release surface side layer described later are the same layer.

In addition to the above, it is also important to make raw materials and manufacturing processes clean as follows:
- Filter the particle slurry during polymerization. Filter before chipping.
・Make the cooling water for chipping clean. Keep the environment clean from chip transportation to feeding into the film-making machine.
- During film production, the molten resin is filtered to remove agglomerated particles and foreign matter.
・Filter the coating agent to remove foreign matter.
- Film formation, coating and drying are carried out in a clean environment.

For smoothing purposes, the surface layer is preferably substantially free of particles. By substantially free of particles, we mean that the particle content is less than 50 ppm, preferably less than 30 ppm.

To increase the slipperiness of the surface, the surface layer may contain particles. If particles are contained, the lower limit of the surface layer particle content is preferably 50 ppm, and more preferably 100 ppm. The upper limit of the surface layer particle content is preferably 20,000 ppm, more preferably 10,000 ppm, even more preferably 8,000 ppm, and particularly preferably 6,000 ppm. If the above amount is exceeded, the roughness of the surface layer may not be within the preferred range.

The lower limit of the surface layer particle diameter is preferably 0.005 μm, more preferably 0.01 μm, and even more preferably 0.02 μm. The upper limit of the surface layer particle diameter is preferably 3 μm, more preferably 1 μm, even more preferably 0.5 μm, and particularly preferably 0.3 μm. If the upper limit exceeds the above, the roughness of the surface layer may not be within the preferred range.

Even if the surface layer does not contain particles or the particles are small in diameter, if the layer below it contains particles, the roughness of the release surface layer may increase due to the influence of the particles in the lower layer. In such cases, it is preferable to increase the thickness of the release surface layer or provide a lower layer (intermediate layer) that does not contain particles.

The lower limit of the surface layer thickness is preferably 0.1 μm, more preferably 0.5 μm, even more preferably 1 μm, particularly preferably 3 μm, and most preferably 5 μm. The upper limit of the surface layer thickness is preferably 97%, more preferably 95%, and even more preferably 90% of the total thickness of the transfer orientation film.

The particle-free intermediate layer contains substantially no particles, meaning that the particle content is less than 50 ppm, and preferably less than 30 ppm. The lower limit of the thickness of the intermediate layer is preferably 10%, more preferably 20%, and even more preferably 30% of the total thickness of the transfer orientation film. The upper limit is preferably 95%, more preferably 90%.

If the surface roughness of the transfer orientation film is high, a flattening coat may be provided. Resins used in the flattening coat include polyester, acrylic, polyurethane, polystyrene, polyamide, and other resins commonly used in coating agents. It is also preferable to use crosslinking agents such as melamine, isocyanate, epoxy resins, and oxazoline compounds. These are applied as coating agents dissolved or dispersed in an organic solvent or water and then dried. Alternatively, in the case of acrylic, they may be applied without a solvent and cured by radiation. The flattening coat may be an oligomer block coat. When a release layer is provided by coating, the release layer itself may be made thick.

The lower limit of the thickness of the surface flattening coating layer is preferably 0.01 μm, more preferably 0.1 μm, even more preferably 0.2 μm, and particularly preferably 0.3 μm. If it is less than the above, the flattening effect may be insufficient. Furthermore, the upper limit of the thickness of the surface flattening coating layer is preferably 10 μm, more preferably 7 μm, even more preferably 5 μm, and particularly preferably 3 μm. If it exceeds the above, further flattening effect may not be obtained.

The planarizing coat may be applied as an in-line coat during the film production process, or it may be applied separately offline.

(Roughness on the back side)
In addition, even if the release surface of the transfer orientation film of the present invention is smoothed, defects may occur in the liquid crystal compound orientation layer. It was found that this is because the transfer orientation film is supplied in a rolled-up state, and the release surface and the back surface are in contact with each other, and the roughness of the back surface is transferred to the release surface (the convex parts of the back surface are transferred to the release layer to form concave parts). In some cases, a masking film is attached to the transfer orientation film provided with a liquid crystal compound orientation layer to protect the liquid crystal compound orientation layer, but it is often wound up as is to reduce costs. In this way, when the film is wound up with the liquid crystal compound orientation layer provided, it is considered that the liquid crystal compound orientation layer is dented, holes are formed, and the orientation is disturbed due to the convex parts on the back surface. In addition, even if the liquid crystal compound orientation layer is not wound up with the liquid crystal compound orientation layer provided, but is provided later, it is considered that the convex parts on the back surface cause holes in the liquid crystal compound orientation layer and the orientation is disturbed. In particular, the pressure is high at the core, and these phenomena are likely to occur. From the above findings, it has been found that the above-mentioned drawbacks can be effectively prevented by setting the roughness of the surface opposite to the release surface (rear surface) within a specific range.

The lower limit of the three-dimensional arithmetic mean roughness (SRa) of the back surface of the transfer orientation film of the present invention is preferably 1 nm, more preferably 2 nm, even more preferably 3 nm, particularly preferably 4 nm, and most preferably 5 nm. The upper limit of the SRa of the back surface of the transfer orientation film of the present invention is preferably 50 nm, more preferably 45 nm, and even more preferably 40 nm. If the above is exceeded, many defects may occur.

The lower limit of the three-dimensional ten-point average roughness (SRz) of the back surface of the transfer orientation film of the present invention is preferably 10 nm, more preferably 15 nm, particularly preferably 20 nm, and most preferably 25 nm. The upper limit of the SRz of the back surface of the transfer orientation film of the present invention is preferably 1500 nm, more preferably 1200 nm, even more preferably 1000 nm, particularly preferably 700 nm, and most preferably 500 nm. If the above is exceeded, many defects may occur.

The lower limit of the maximum height of the back surface of the transfer orientation film of the present invention (SRy: maximum peak height of the back surface SRp + maximum valley depth of the back surface SRv) is preferably 15 nm, more preferably 20 nm, even more preferably 25 nm, particularly preferably 30 nm, and most preferably 40 nm. The upper limit of the maximum height SRy of the back surface of the transfer orientation film of the present invention is preferably 2000 nm, more preferably 1500 nm, even more preferably 1200 nm, particularly preferably 1000 nm, and most preferably 700 nm. If the above is exceeded, many defects may occur.

The upper limit of the number of protrusions with a height difference of 2 μm or more on the back surface of the transfer orientation film of the present invention is preferably 5 pieces/m ² , more preferably 4 pieces/m ² , even more preferably 3 pieces/m ² , particularly preferably 2 pieces/m ² , and most preferably 1 piece/m ^2. If the number exceeds the above, there may be many defects.

If the roughness of the back surface of the transfer orientation film of the present invention, which is represented by the above parameters, is less than the above range, the slipperiness of the film will be poor, and the film will not slide easily when transported on a roll or when wound up, and may be easily scratched. In addition, when winding up the film during production, the winding will be unstable, causing wrinkles and resulting in defective products, or the unevenness of the end of the wound roll will become large, making the film more likely to meander or break in the next process.
If the roughness of the rear surface of the transfer orientation film of the present invention exceeds the above range, the above-mentioned defects are likely to occur.

In order to set the roughness of the back surface within the above range, when the oriented film for transfer of the present invention is a stretched film, the following method can be mentioned.
The back layer (back layer) of the original film is made to contain specific particles.
The intermediate layer of the film roll contains particles, and the back layer side (back layer) does not contain particles, making the thickness thinner.
If the back layer (back layer) of the original film is very rough, a flattening coat is provided.
If the back side layer (back side layer) of the original film does not contain particles or has low roughness, a slippery coating (particle-containing coating) is applied.

The lower limit of the particle diameter of the back layer is preferably 0.01 μm, more preferably 0.05 μm, and even more preferably 0.1 μm. If it is less than the above, the slipperiness may deteriorate and winding problems may occur. Furthermore, the upper limit of the particle diameter of the back layer is preferably 5 μm, more preferably 3 μm, and even more preferably 2 μm. If it exceeds the above, the back surface may become too rough.

When the back surface contains particles, the lower limit of the particle content of the back surface layer is preferably 50 ppm, more preferably 100 ppm. If it is less than the above, the slipperiness effect of adding particles may not be obtained. Furthermore, the upper limit of the particle content of the back surface layer is preferably 10,000 ppm, more preferably 7,000 ppm, and even more preferably 5,000 ppm. If it exceeds the above, the back surface may become too rough.

The lower limit of the thickness of the back layer is preferably 0.1 μm, more preferably 0.5 μm, even more preferably 1 μm, particularly preferably 3 μm, and most preferably 5 μm. The upper limit of the thickness of the back layer is preferably 95%, more preferably 90%, and even more preferably 85% of the total thickness of the transfer orientation film.

It is also preferable to control the roughness of the back surface by including particles in the intermediate layer and making the back surface layer thin and particle-free. By adopting such a form, it is possible to ensure the roughness of the back surface while preventing the particles from falling off.

The particle size and amount of the particles in the intermediate layer are the same as those in the back layer. In this case, the lower limit of the thickness of the back layer is preferably 0.5 μm, more preferably 1 μm, and even more preferably 2 μm. The upper limit of the thickness is preferably 30 μm, more preferably 25 μm, and even more preferably 20 μm.

If the back surface of the original film is rough, it is also preferable to provide a flattening coat. The flattening coat can be the same as those listed for the front surface flattening coat.

The lower limit of the thickness of the back surface flattening coating layer is preferably 0.01 μm, more preferably 0.03 μm, and even more preferably 0.05 μm. If it is less than the above, the flattening effect may be reduced. Furthermore, the upper limit of the thickness of the back surface flattening coating layer is preferably 10 μm, more preferably 5 μm, and even more preferably 3 μm. If it exceeds the above, the flattening effect becomes saturated.

The back side of the original film may be free of particles, and a particle-containing easy-slip coating may be provided on the back side. Also, if the roughness of the back side of the original film is small, a easy-slip coating may be provided.

The lower limit of the particle size of the back surface easy-slip coating layer is preferably 0.01 μm, more preferably 0.05 μm. If it is less than the above, easy slippage may not be obtained. Furthermore, the upper limit of the particle size of the back surface easy-slip coating layer is preferably 5 μm, more preferably 3 μm, even more preferably 2 μm, and particularly preferably 1 μm. If it exceeds the above, the roughness of the back surface may be too high.

The lower limit of the particle content of the back surface easy-slip coating layer is preferably 0.1% by mass, more preferably 0.5% by mass, even more preferably 1% by mass, particularly preferably 1.5% by mass, and most preferably 2% by mass. If it is less than the above, easy slippage may not be obtained. Furthermore, the upper limit of the particle content of the back surface easy-slip coating layer is preferably 20% by mass, more preferably 15% by mass, and even more preferably 10% by mass. If it exceeds the above, the roughness of the back surface may be too high.

The lower limit of the thickness of the back surface easy-slip coating layer is preferably 0.01 μm, more preferably 0.03 μm, and even more preferably 0.05 μm. The upper limit of the thickness of the back surface easy-slip coating layer is preferably 10 μm, more preferably 5 μm, even more preferably 3 μm, particularly preferably 2 μm, and most preferably 1 μm.

In the above, the case where the transfer orientation film of the present invention is a stretched film has been described, but even in the case of an unstretched film produced by a casting method in which a dope in which triacetyl cellulose or the like is dissolved in a solvent is spread on a metal belt or the like and the solvent is dried, by adding particles, the roughness can be adjusted because unevenness due to the particles occurs on the upper surface (the opposite side of the metal belt) as the solvent is removed. In this case, it is preferable to reduce the surface roughness of the metal belt and use the metal belt surface as the release surface. In addition, when the dope contains particles, if it is peeled off from the metal belt in a state where the solvent content is high, unevenness due to the particles may also appear on the metal belt surface, so it is also preferable to peel it off from the metal belt after drying until the solvent content is low. The roughness can also be adjusted by the timing of these peeling. In addition, when the dope is stretch-dried in a tenter in a state where it contains a small amount of solvent, the roughness can also be adjusted by the stretching ratio, etc. In addition, when it does not contain particles, the roughness of the metal belt can be adjusted to use the metal belt surface as the back surface. In addition, it is also possible to dry the dope while passing it between rolls with different roughness and transfer the roughness to the surface.

Even in the case of unstretched films produced by casting molten resin such as COP, the roughness can be adjusted by adding particles. By using particles such as inorganic particles that have a different thermal expansion coefficient from the film resin, the added particles can form unevenness on the surface due to the thermal contraction that occurs during cooling. In this case, it is preferable to reduce the surface roughness of the cooling roll that extrudes the molten resin into a sheet to form a release surface. Alternatively, the cooling roll may be made rough to transfer the roughness to the back surface. The roughness may be transferred by passing the film resin through rolls with different roughness at a temperature above the Tg of the film resin.

In addition, just like with stretched films, the roughness of these unstretched films can also be adjusted by applying a smooth coating or a slippery coating containing particles.

Next, additional features of the transfer orientation film of the present invention will be described.

(Orientation characteristics and physical properties of the transfer orientation film)
When the transfer orientation film is an unstretched film and has almost zero retardation, the liquid crystal compound orientation layer can be inspected by irradiating it with linearly polarized light in a state where the liquid crystal compound orientation layer is laminated on the transfer orientation film. For example, when the liquid crystal compound orientation layer is a retardation layer, the sample is irradiated with linearly polarized light in an oblique direction (for example, 45 degrees) with respect to the slow axis of the retardation layer to be inspected, and the polarized light that has been elliptically polarized by the retardation layer is passed through another retardation layer to return to linearly polarized light, and this linearly polarized light is received through a polarizing plate that is in an extinct state. As a result, if there is a pinhole-shaped defect in the retardation layer, the defect can be detected as a bright spot.

On the other hand, when a stretched film or the like has retardation, it may be difficult to inspect the alignment state of the liquid crystal compound alignment layer when it is laminated due to the influence of retardation. Conventionally, it was possible to detect defects such as foreign matter in a retardation layer provided on a transfer alignment film having retardation by irradiating it with non-polarized light, but defects in the polarization state required peeling off the retardation layer and inspecting it alone, or transferring it to an object without retardation such as glass and inspecting it.

However, it was found that by using a film with a slow axis within a specific range as a transfer alignment film, it is possible to inspect the alignment state of the liquid crystal compound alignment layer when it is laminated.

Polarizers are generally made by stretching polyvinyl alcohol in the film flow direction and absorbing iodine or an organic dichroic dye, with the extinction axis (absorption axis) of the polarizer being in the film flow direction. In the case of circular polarizing plates, the retardation layer is a λ/4 layer whose slow axis (orientation direction) is laminated at 45 degrees to the extinction axis, or a λ/4 layer and a λ/2 layer are laminated at an oblique angle (10 to 80 degrees). Optical compensation layers used in liquid crystal displays are also laminated at an oblique angle to the extinction axis of the polarizer.

Therefore, the orientation state of the retardation layer can be inspected (evaluated) by, for example, irradiating the retardation layer with linearly polarized light having a vibration direction parallel or perpendicular to the flow direction of the film from the transfer orientation film side, and detecting the light with a light receiving element through a light receiving side retardation plate for returning the light that has become elliptically polarized by the retardation layer to linearly polarized light, and a light receiving side polarizing plate installed in a direction that does not pass the linearly polarized light returned by the retardation plate. Conversely, elliptically polarized light may be irradiated from the retardation layer side, and the light that has become linearly polarized by the retardation layer may be detected in the same way. Specifically, if there is a pinhole-shaped defect in the retardation layer, the defect can be detected as a bright spot.

Therefore, if the transfer orientation film has birefringence, if the orientation direction of the film is shifted from a direction parallel to the film flow direction (MD direction) or perpendicular to the film flow direction (TD direction), the linearly polarized light passing through the film becomes elliptically polarized light, causing light leakage and making it difficult to accurately evaluate the retardation layer.

The lower limit of the angle (maximum point) between the MD or TD of the transfer orientation film of the present invention and the orientation direction is preferably 0 degrees. The upper limit of the angle between the MD or TD of the transfer orientation film of the present invention and the orientation direction is preferably 14 degrees at the maximum, more preferably 7 degrees, even more preferably 5 degrees, particularly preferably 4 degrees, and most preferably 3 degrees. If the above is exceeded, it may become difficult to evaluate the orientation state of the retardation layer (liquid crystal compound orientation layer).

The lower limit of the difference in the orientation angle across the entire width (width direction) of the transfer orientation film of the present invention is preferably 0 degrees. The upper limit of the difference in the orientation angle across the entire width of the transfer orientation film of the present invention is preferably 7 degrees, more preferably 5 degrees, even more preferably 3 degrees, and particularly preferably 2 degrees. If the above is exceeded, it may become difficult to evaluate the orientation state of the retardation layer (liquid crystal compound orientation layer) in the width direction.

When stretching in the TD direction in a tenter, the film is subjected to a force that shrinks it in the MD direction in the stretching zone and heat setting zone. The ends of the film are fixed with clips, but the center is not fixed, so the bowing phenomenon occurs, where the film emerges late in a bow shape at the exit of the tenter. This causes distortion in the orientation direction.

In order to reduce distortion in the orientation direction and achieve the above-mentioned properties, the stretching temperature, stretching ratio, stretching speed, heat setting temperature, temperature in the relaxation process, relaxation process ratio, and width-wise temperature distribution of each temperature may be appropriately adjusted.

In addition, if the orientation direction does not fall within the specified range over the entire width of the produced film, it is preferable to use a portion that falls within the above characteristic range, such as near the center of a stretched wide film. In addition, since the distortion in the orientation direction tends to decrease as the orientation in the uniaxial direction becomes stronger, it is also a preferred method to use a weak biaxial or uniaxially stretched film. In particular, weak biaxial or uniaxially stretched films in which the MD direction is the main orientation direction are preferred.

In the present invention, the angle between the orientation direction of the transfer orientation film and the flow direction of the oriented film or the direction perpendicular to the flow direction, and the angle difference between the orientation angles in the width direction of the film are determined as follows.
First, the film was pulled out from the roll, and the orientation direction was determined at five points: both ends (5 cm inward from each end), the center, and the middle part between the center and both ends. The middle part between the center and both ends is located at a position that divides the distance between the center and both ends in half. The orientation direction was determined as the slow axis direction of the film determined using a molecular orientation meter. Next, it was examined whether the overall orientation direction of the film was close to the flow direction (MD) or the width direction (TD). Then, when the overall orientation direction of the film was close to the flow direction, the angle between the orientation direction and the flow direction of the film was determined at each of the above five points, and the value at the point where the angle was the largest was adopted as the maximum value of "the angle between the orientation direction of the oriented film and the flow direction of the oriented film". On the other hand, when the overall orientation direction of the film was close to the width direction, the angle between the orientation direction and the direction perpendicular to the flow direction of the film was determined at each of the above five points, and the value at the point where the angle was the largest was adopted as the maximum value of "the angle between the orientation direction of the oriented film and the direction perpendicular to the flow direction of the oriented film".
The difference between the maximum and minimum angles among the angles determined at the above five locations was defined as the "angle difference of the orientation angle in the width direction of the film."

The angle is considered to be a positive value if the orientation direction is on the same side as the maximum value in the longitudinal or width direction, and a negative value if the orientation direction is on the opposite side of the longitudinal or width direction, and the minimum value is evaluated while distinguishing between positive and negative.

The lower limit of the difference in heat shrinkage rate at 150°C for 30 minutes in the MD direction and TD direction of the transfer orientation film of the present invention is preferably 0%. In addition, the upper limit of the difference in heat shrinkage rate at 150°C for 30 minutes in the MD direction and TD direction of the transfer orientation film of the present invention is preferably 4%, more preferably 3%, even more preferably 2%, particularly preferably 1.5%, and most preferably 1%. If it exceeds the above, when a high temperature is required for the orientation treatment of the liquid crystal compound or when multiple liquid crystal compounds are stacked and the temperature history is long, the orientation direction of the liquid crystal compound may deviate from the design, and light leakage may occur when the polarizing plate is used in a display.

The lower limit of the heat shrinkage rate in the MD direction of the transfer orientation film of the present invention at 150°C for 30 minutes is preferably -2%, more preferably -0.5%, even more preferably -0.1%, particularly preferably 0%, and most preferably 0.01%. If it is less than the above, it may be difficult to actually achieve the numerical value. Furthermore, the upper limit of the heat shrinkage rate in the MD direction of the transfer orientation film of the present invention at 150°C for 30 minutes is preferably 4%, more preferably 3%, even more preferably 2.5%, particularly preferably 2%, and most preferably 1.5%. If it exceeds the above, it may become difficult to adjust the difference in heat shrinkage rate. Furthermore, the flatness may deteriorate, and workability may deteriorate.

The lower limit of the heat shrinkage rate in the TD direction of the transfer orientation film of the present invention at 150°C for 30 minutes is preferably -2%, more preferably -0.5%, even more preferably -0.1%, particularly preferably 0%, and most preferably 0.01%. If it is less than the above, it may be difficult to achieve the numerical value in reality. Furthermore, the upper limit of the heat shrinkage rate in the TD direction of the transfer orientation film of the present invention at 150°C for 30 minutes is preferably 4%, more preferably 2.5%, even more preferably 2%, particularly preferably 1.5%, and most preferably 1%. If it exceeds the above, it may be difficult to adjust the difference in heat shrinkage rate. Furthermore, the flatness may be deteriorated, and the workability may be deteriorated.

The lower limit of the difference in heat shrinkage rate at 150°C for 30 minutes in the direction of 45 degrees to the MD direction and the direction of 135 degrees to the MD direction of the transfer orientation film of the present invention is preferably 0%. If it is less than the above, it may be difficult to achieve the numerical value in reality. In addition, the upper limit of the difference in heat shrinkage rate at 150°C for 30 minutes in the direction of 45 degrees to the MD direction and the direction of 135 degrees to the MD direction of the transfer orientation film of the present invention is preferably 4%, more preferably 3%, even more preferably 2%, particularly preferably 1.5%, and most preferably 1%. If it is out of the above range, the orientation direction of the liquid crystal compound deviates from the design, and light leakage may occur when the polarizing plate is used in a display.

The heat shrinkage properties of the film can be adjusted by the stretching temperature, stretching ratio, heat setting temperature, relaxation step ratio, and relaxation step temperature. It is also preferable to release the film from the clips and wind it up when the surface temperature of the film is 100°C or higher during the cooling step. The film can be released from the clips by opening the clips or by cutting off the ends held by the clips with a blade or the like. Offline heat treatment (annealing) is also an effective method.

In order to achieve the above-mentioned heat shrinkage characteristics of the transfer orientation film of the present invention at 150°C for 30 minutes, it is preferable that the material of the transfer orientation film is polyester, particularly polyethylene terephthalate.

The lower limit of the maximum heat shrinkage rate at 95°C of the transfer orientation film of the present invention is preferably 0%, more preferably 0.01%. If it is less than the above, it may be difficult to achieve the numerical value in reality. Furthermore, the upper limit of the maximum heat shrinkage rate at 95°C of the transfer orientation film of the present invention is preferably 2.5%, more preferably 2%, even more preferably 1.2%, particularly preferably 1%, and most preferably 0.8%. If it exceeds the above, light leakage may occur when the polarizing plate is used in a display.

The lower limit of the angle between the maximum heat shrinkage direction of the transfer orientation film of the present invention and the MD or TD direction is preferably 0 degrees. The upper limit of the angle between the maximum heat shrinkage direction of the transfer orientation film of the present invention and the MD or TD direction is preferably 20 degrees, more preferably 15 degrees, even more preferably 10 degrees, particularly preferably 7 degrees, and most preferably 5 degrees. If the above is exceeded, the orientation direction of the liquid crystal compound may deviate from the design, and light leakage may occur when the polarizing plate is used in a display.

The lower limit of the elastic modulus in the MD direction and the elastic modulus in the TD direction of the transfer orientation film of the present invention is preferably 1 GPa, more preferably 2 GPa. If it is less than the above, it may stretch during each process and the orientation direction may not be as designed. In addition, the upper limit of the elastic modulus in the MD direction and the elastic modulus in the TD direction of the transfer orientation film of the present invention is preferably 8 GPa, more preferably 7 GPa. If it exceeds the above, it may be difficult to practically achieve the numerical value.

When the transfer orientation film of the present invention is a polyester film, the lower limit of the amount of ester cyclic trimer precipitated on the surface of the release surface of the oriented polyester film after heating at 150 ° C for 90 minutes (hereinafter referred to as the surface oligomer precipitate amount (150 ° C 90 min)) is preferably 0 mg / m ² , more preferably 0.01 mg / m ^2. If it is less than the above, it may be difficult to achieve the numerical value in reality. The upper limit of the surface oligomer precipitate amount (150 ° C 90 min) is preferably 1 mg / m ² , more preferably 0.7 mg / m ² , even more preferably 0.5 mg / m ² , and particularly preferably 0.3 mg / m ^2. If it exceeds the above, when multiple liquid crystal compound alignment layers are laminated or alignment treatment at high temperatures is required, haze increases or foreign matter is generated, and polarization is disturbed during alignment control by ultraviolet irradiation, and the retardation layer or polarizing layer as designed may not be obtained. In the present invention, the "release surface" of the alignment film means the surface of the alignment film on which the liquid crystal compound alignment layer to be transferred from the alignment film is intended to be provided. When an oligomer block coat layer, a flattening coat layer, a release layer, or the like is provided and a liquid crystal compound alignment layer is provided thereon, the surfaces of the oligomer block coat layer, the flattening layer, the release layer, or the like (surfaces in contact with the liquid crystal compound alignment layer) are the "release surface" of the alignment film.

In order to reduce the amount of surface oligomer precipitation, it is preferable to provide a coating layer (hereinafter referred to as an oligomer block coating layer) on the surface of the transfer orientation film to block the precipitation of oligomers (ester cyclic trimers).

The oligomer block coat layer preferably contains 50% by weight or more of a resin with a Tg of 90°C or higher. Such resins are preferably amino resins such as melamine, alkyd resins, polystyrene, acrylic resins, etc. The upper limit of the resin Tg is preferably 200°C.

The lower limit of the thickness of the oligomer block coat layer is preferably 0.01 μm, more preferably 0.03 μm, and even more preferably 0.05 μm. If it is less than the above, a sufficient blocking effect may not be obtained. The upper limit of the thickness of the oligomer block coat layer is preferably 10 μm, more preferably 5 μm, and even more preferably 2 μm. If it exceeds the above, the effect may become saturated.

In addition, in order to reduce the amount of surface oligomer precipitation, it is also preferable to reduce the content of oligomer (ester cyclic trimer) in the polyester resin constituting the release surface side layer of the transfer orientation film (hereinafter referred to as the surface layer oligomer content). The lower limit of the surface layer oligomer content is preferably 0.3 mass%, more preferably 0.33 mass%, and even more preferably 0.35 mass%. If it is less than the above, it may be difficult to achieve the numerical value in reality. The upper limit of the surface layer oligomer content is preferably 0.7 mass%, more preferably 0.6 mass%, and even more preferably 0.5 mass%. In the present invention, the "release surface side layer" of the orientation film means the layer in which the release surface exists among the polyester layers constituting the orientation film. Here, even if the film is a single layer, it may be called the release surface side layer. In this case, the back side layer and the release surface side layer described later are the same layer.

In order to reduce the surface oligomer content, it is preferable to reduce the oligomer content in the raw polyester. The lower limit of the oligomer content in the raw polyester is preferably 0.23% by mass, more preferably 0.25% by mass, and even more preferably 0.27% by mass. The upper limit of the oligomer content in the raw polyester is preferably 0.7% by mass, more preferably 0.6% by mass, and even more preferably 0.5% by mass. The oligomer content in the raw polyester can be reduced by subjecting the solid-state polyester to a heat treatment at a temperature of 180°C or higher and below the melting point, such as solid-phase polymerization. It is also preferable to deactivate the polyester catalyst.

In addition, shortening the melting time during film production is also effective in reducing the amount of surface oligomer precipitation.

The lower limit of the haze of the transfer orientation film of the present invention is preferably 0.01%, more preferably 0.1%. If it is less than the above, it may be difficult to achieve the numerical value in reality. Furthermore, the upper limit of the haze of the transfer orientation film of the present invention is preferably 3%, more preferably 2.5%, even more preferably 2%, and particularly preferably 1.7%. If it exceeds the above, the polarization may be disturbed when irradiated with polarized UV light, and the retardation layer or polarizing layer may not be obtained as designed. Furthermore, when inspecting the retardation layer or polarizing layer, light leakage may occur due to diffuse reflection, making the inspection difficult.

The lower and upper limits of haze of the transfer orientation film of the present invention after heating at 150°C for 90 minutes are the same as above.

The lower limit of the haze change of the transfer orientation film of the present invention before and after heating at 150°C for 90 minutes is preferably 0%. The upper limit is preferably 0.5%, more preferably 0.4%, and even more preferably 0.3%.

The lower limit of the antistatic property (surface resistance) of the transfer orientation film of the present invention is preferably 1×10 ⁵ Ω/□, more preferably 1×10 ⁶ Ω/□. If it is less than the above, the effect may be saturated and no further effect may be obtained. The upper limit of the antistatic property (surface resistance) of the transfer orientation film of the present invention is preferably 1×10 ¹³ Ω/□, more preferably 1×10 ¹² Ω/□, and even more preferably 1×10 ¹¹ Ω/□. If it exceeds the above, repelling due to static electricity may occur, or the alignment direction of the liquid crystal compound may be disturbed. The antistatic property (surface resistance) can be made within the above range by kneading an antistatic agent into the transfer orientation film, providing an antistatic coating layer on the lower layer or the opposite side of the release layer, or adding an antistatic agent to the release layer.

Antistatic agents that can be added to antistatic coating layers, release layers, and transfer orientation films include conductive polymers such as polyaniline and polythiophene, ionic polymers such as polystyrene sulfonate, and conductive microparticles such as tin-doped indium oxide and antimony-doped tin oxide.

A release layer may be provided on the transfer orientation film. However, if the film itself has low adhesion to the transferred material such as the retardation layer or the orientation layer, and has sufficient releasability without providing a release layer, a release layer may not be provided. If the adhesion is too low, the adhesion may be adjusted by performing a corona treatment on the surface. The release layer can be formed using a known release agent, and preferred examples include alkyd resins, amino resins, long-chain acrylic acrylates, silicone resins, and fluororesins. These can be selected appropriately according to the adhesion to the transferred material.

Furthermore, in the transfer orientation film of the present invention, an easy-adhesion layer may be provided as an underlayer of the oligomer block coat layer, the antistatic layer, and the release layer.

The lower limit of the intrinsic viscosity (IVf) of the polyester constituting the transfer oriented polyester film of the present invention is preferably 0.45 dl/g, more preferably 0.5 dl/g, and even more preferably 0.53 dl/g. If it is less than the above, the impact resistance of the film may be poor. Also, film formation may be difficult or the thickness uniformity may be poor. The upper limit of IVf is preferably 0.9 dl/g, more preferably 0.8 dl/g, and even more preferably 0.7 dl/g. If it exceeds the above, the heat shrinkage rate may be high. Also, film formation may be difficult.

The lower limit of the light transmittance of the transfer alignment film of the present invention at a wavelength of 380 nm is preferably 0%. The upper limit of the light transmittance of the transfer alignment film of the present invention at a wavelength of 380 nm is preferably 20%, more preferably 15%, even more preferably 10%, and particularly preferably 5%. If it exceeds the above, when a specific alignment direction is achieved by irradiating polarized ultraviolet light, the directional uniformity of the alignment layer or liquid crystal compound alignment layer may deteriorate due to reflection from the back surface. The light transmittance at a wavelength of 380 nm can be kept within the range by adding a UV absorber.

When the transfer orientation film of the present invention is a polyethylene terephthalate film, the lower limit of the refractive index nx in the slow axis direction minus the refractive index ny in the fast axis direction is preferably 0.005, more preferably 0.01, even more preferably 0.02, particularly preferably 0.03, and most preferably 0.04. If it is less than the above, it may be difficult to achieve the numerical value in reality. Furthermore, the upper limit of nx-ny is preferably 0.15, more preferably 0.13, and even more preferably 0.12. If it exceeds the above, it may be difficult to achieve the numerical value in reality.

In the case of biaxial stretching, the lower limit of nx-ny is preferably 0.005, more preferably 0.01. If it is less than the above, it may be difficult to practically achieve the numerical value. In addition, in the case of biaxial stretching, the upper limit of nx-ny is preferably 0.05, more preferably 0.04, and even more preferably 0.03. If it exceeds the above, it may be difficult to practically achieve the numerical value.

In the case of uniaxial stretching, the lower limit of nx-ny is preferably 0.05, more preferably 0.06. If it is less than the above, the benefits of uniaxial stretching may be diminished. In addition, in the case of uniaxial stretching, the upper limit of nx-ny is preferably 0.15, more preferably 0.13. If it exceeds the above, it may be difficult to achieve the numerical value in reality.

The lower limit of the refractive index (ny) in the fast axis direction of the transfer orientation film of the present invention is preferably 1.55, more preferably 1.58, and even more preferably 1.57. The upper limit of the refractive index (ny) in the fast axis direction of the transfer orientation film of the present invention is preferably 1.64, more preferably 1.63, and even more preferably 1.62.

The lower limit of the refractive index (nx) in the slow axis direction of the transfer orientation film of the present invention is preferably 1.66, more preferably 1.67, and even more preferably 1.68. The upper limit of the refractive index (nx) in the slow axis direction of the transfer orientation film of the present invention is preferably 1.75, more preferably 1.73, even more preferably 1.72, and particularly preferably 1.71.

(Method for producing an orientation film for transfer)
Hereinafter, a method for producing an orientation film for transfer of the present invention in the case where the orientation film for transfer is a stretched film will be described.
When MD stretching is performed, the lower limit of the MD magnification is preferably 1.5 times. The upper limit is preferably 6 times, more preferably 5.5 times, and even more preferably 5 times. When TD stretching is performed, the lower limit of the TD magnification is preferably 1.5 times. The upper limit of the TD magnification is preferably 6 times, more preferably 5.5 times, and even more preferably 5 times.

The lower limit of the HS temperature is preferably 150°C, more preferably 170°C. If it is less than the above, the thermal shrinkage rate may not decrease. The upper limit of the HS temperature is preferably 240°C, more preferably 230°C. If it exceeds the above, the resin may deteriorate.

The lower limit of the TD relaxation rate is preferably 0.1%, and more preferably 0.5%. If it is less than the above, the thermal shrinkage rate may not decrease. Furthermore, the upper limit of the TD relaxation rate is preferably 8%, more preferably 6%, and even more preferably 5%. If it exceeds the above, sagging may cause poor flatness or uneven thickness.

The preferred annealing method is to unroll the film, pass it through an oven and then rewind it.

The lower limit of the annealing temperature is preferably 80°C, more preferably 90°C, and even more preferably 100°C. If the temperature is lower than the above, the annealing effect may not be obtained. Furthermore, the upper limit of the annealing temperature is preferably 200°C, more preferably 180°C, and even more preferably 160°C. If the temperature exceeds the above, the flatness may decrease and the thermal shrinkage may increase.

The lower limit of the annealing time is preferably 5 seconds, more preferably 10 seconds, and even more preferably 15 seconds. If it is less than the above, the annealing effect may not be obtained. Furthermore, the upper limit of the annealing time is preferably 10 minutes, more preferably 5 minutes, even more preferably 3 minutes, and especially preferably 1 minute. If it exceeds the above, not only will the effect saturate, but a larger oven may be required and productivity may be poor.

In the annealing process, the relaxation rate can be adjusted by adjusting the difference in peripheral speed between the unwinding speed and the winding speed, or by adjusting the winding tension. The lower limit of the relaxation rate is preferably 0.5%. If it is less than this, the annealing effect may not be obtained. The upper limit of the relaxation rate is preferably 8%, more preferably 6%, and even more preferably 5%. If it exceeds this, the flatness may decrease or poor winding may occur.

(Laminate for transferring liquid crystal compound alignment layer)
Next, the laminate for transferring a liquid crystal compound alignment layer of the present invention will be described.
The laminate for transferring a liquid crystal compound alignment layer of the present invention has a structure in which a liquid crystal compound alignment layer and an alignment film for transfer of the present invention are laminated. The liquid crystal compound alignment layer needs to be coated on the alignment film for transfer and aligned. As an alignment method, there is a method of providing an alignment control function by subjecting the lower layer (release surface) of the liquid crystal compound alignment layer to a rubbing treatment or the like, and a method of directly aligning the liquid crystal compound by irradiating it with polarized ultraviolet light or the like after coating the liquid crystal compound.

(Orientation Control Layer)
Also, a method of providing an orientation control layer on the transfer orientation film and providing a liquid crystal compound orientation layer on the orientation control layer is preferred. In the present invention, the liquid crystal compound orientation layer may be a collective term for the orientation control layer and the liquid crystal compound orientation layer, rather than the liquid crystal compound orientation layer alone. As the orientation control layer, any orientation control layer may be used as long as it can bring the liquid crystal compound orientation layer into a desired orientation state. Suitable examples of the orientation control layer include a rubbing treatment orientation control layer obtained by rubbing a resin coating film, and a photo-orientation control layer that aligns molecules by irradiating polarized light to generate an orientation function.

(Rubbing Treatment Alignment Control Layer)
As the polymer material used for the alignment control layer formed by rubbing treatment, polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resin, polysiloxane derivatives, etc. are preferably used.

The method for forming the rubbing treatment alignment control layer is described below. First, the rubbing treatment alignment control layer coating liquid containing the above-mentioned polymer material is applied onto the release surface of the alignment film, and then heated and dried to obtain the alignment control layer before rubbing treatment. The alignment control layer coating liquid may contain a crosslinking agent.

As the solvent for the rubbing treatment alignment control layer coating solution, any solvent that dissolves the polymer material can be used without limitation. Specific examples include alcohols such as water, methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, and cellosolve; ester-based solvents such as ethyl acetate, butyl acetate, and gamma-butyrolactone; ketone-based solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene or xylene; and ether-based solvents such as tetrahydrofuran or dimethoxyethane. These solvents may be used alone or in combination.

The concentration of the rubbing treatment alignment control layer coating solution can be adjusted as appropriate depending on the type of polymer and the thickness of the alignment control layer to be produced, but it is preferable to set it to 0.2 to 20 mass % in terms of solids concentration, and a range of 0.3 to 10 mass % is particularly preferable. As the coating method, known methods such as gravure coating, die coating, bar coating, applicator method, and printing methods such as flexography can be used.

The heating and drying temperature depends on the transfer orientation film, but for PET it is preferably in the range of 30°C to 170°C, more preferably 50 to 150°C, and even more preferably 70 to 130°C. If the drying temperature is low, a long drying time will be required, which may result in poor productivity. If the drying temperature is too high, the transfer orientation film may stretch due to heat or experience significant thermal shrinkage, making it impossible to achieve the designed optical function or resulting in poor flatness. The heating and drying time may be, for example, 0.5 to 30 minutes, more preferably 1 to 20 minutes, and even more preferably 2 to 10 minutes.

The thickness of the rubbing treatment orientation control layer is preferably 0.01 to 10 μm, more preferably 0.05 to 5 μm, and particularly preferably 0.1 μm to 1 μm.

Next, a rubbing treatment is performed. Rubbing treatment can generally be performed by rubbing the surface of the polymer layer in a certain direction with paper or cloth. Generally, a rubbing roller made of raised cloth made of fibers such as nylon, polyester, or acrylic is used to rub the surface of the alignment control layer. In order to provide a liquid crystal compound alignment control layer that is oriented in a specific direction oblique to the longitudinal direction of a long film, the rubbing direction of the alignment control layer must also be set at a corresponding angle. The angle can be adjusted by adjusting the angle between the rubbing roller and the alignment film, and by adjusting the conveying speed of the alignment film and the rotation speed of the roller.

It is also possible to directly perform a rubbing treatment on the release surface of the transfer orientation film to impart an orientation control function to the surface of the transfer orientation film, and this case also falls within the technical scope of the present invention.

(Photo-Alignment Control Layer)
The photo-alignment control layer refers to an alignment film in which a coating liquid containing a polymer or monomer having a photoreactive group and a solvent is applied to an alignment film, and the alignment film is irradiated with polarized light, preferably polarized ultraviolet light, to impart an alignment control force. The photoreactive group refers to a group that generates a liquid crystal alignment ability by light irradiation. Specifically, it is a group that generates a photoreaction that is the origin of the liquid crystal alignment ability, such as molecular orientation induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction, which occurs by light irradiation. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferred in terms of excellent alignment and maintaining the smectic liquid crystal state of the liquid crystal compound alignment layer. As the photoreactive group that can cause the above-mentioned reaction, an unsaturated bond, especially a double bond, is preferable, and a group having at least one selected from the group consisting of a C=C bond, a C=N bond, an N=N bond, and a C=O bond is particularly preferable.

Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazolyl groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, and formazan groups, as well as groups having an azoxybenzene basic structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

Among these, photoreactive groups capable of causing a photodimerization reaction are preferred, and cinnamoyl and chalcone groups are preferred because the amount of polarized light irradiation required for photoalignment is relatively small, and a photoalignment layer having excellent thermal stability and stability over time is easily obtained. Furthermore, as a polymer having a photoreactive group, one having a cinnamoyl group such that the terminal of the polymer side chain has a cinnamic acid structure is particularly preferred. Examples of the main chain structure include polyimide, polyamide, (meth)acrylic, and polyester.

Specific examples of the orientation control layer include those described in JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, JP-A-2007-121721, JP-A-2007-140465, JP-A-2007-156439, JP-A-2007-133184, and JP-A-2009 Examples of the alignment control layers include those described in JP-A-109831, JP-A-2002-229039, JP-A-2002-265541, JP-A-2002-317013, JP-T-2003-520878, JP-T-2004-529220, JP-A-2013-33248, JP-A-2015-7702, and JP-A-2015-129210.

As the solvent for the coating liquid for forming the photo-alignment control layer, any solvent that dissolves the polymer and monomer having a photoreactive group can be used without limitation. Specific examples include those mentioned in the method for forming the alignment control layer by rubbing treatment. It is also preferable to add a photopolymerization initiator, a polymerization inhibitor, and various stabilizers to the coating liquid for forming the photo-alignment control layer. In addition, polymers other than the polymer and monomer having a photoreactive group, and monomers that do not have a photoreactive group and are copolymerizable with the monomer having a photoreactive group may be added.

The concentration, coating method, and drying conditions of the coating liquid for forming the photoalignment control layer can be exemplified by those mentioned in the method for forming the rubbing treatment alignment control layer. The thickness is also the same as the preferred thickness of the rubbing treatment alignment control layer.

It is preferable to irradiate the polarized light from the direction of the surface of the photo-alignment control layer before orientation. If the orientation direction of the photo-alignment control layer is parallel or perpendicular to the orientation direction of the transfer orientation film, the polarized light may be irradiated through the transfer orientation film.

The wavelength of the polarized light is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy. Specifically, ultraviolet light with a wavelength in the range of 250 to 400 nm is preferred. Light sources for polarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being preferred.

Polarized light can be obtained, for example, by passing the light from the light source through a polarizer. The direction of polarization can be adjusted by adjusting the polarization angle of the polarizer. Examples of the polarizer include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire grid type polarizers. It is preferable that the polarized light is substantially parallel light.

By adjusting the angle of the irradiated polarized light, the direction of the alignment control force of the optical alignment control layer can be adjusted as desired.

The irradiation intensity differs depending on the type and amount of the polymerization initiator and resin (monomer), but is preferably 10 to 10,000 mJ/cm ² , more preferably 20 to 5,000 mJ/cm ² , based on 365 nm.

(Liquid Crystal Compound Alignment Layer)
The liquid crystal compound alignment layer is not particularly limited as long as the liquid crystal compound is aligned. Specific examples include a polarizing film (polarizer) containing a liquid crystal compound and a dichroic dye, and a retardation layer containing a rod-shaped or discotic liquid crystal compound.

(Polarizing film)
The polarizing film has a function of transmitting polarized light in only one direction, and contains a dichroic dye.

(Dichroic dye)
A dichroic dye is a dye that has different absorbance in the long axis direction of the molecule and absorbance in the short axis direction.

The dichroic dye preferably has a maximum absorption wavelength (λMAX) in the range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, with azo dyes being preferred. Azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, with bisazo dyes and trisazo dyes being preferred. The dichroic dyes may be used alone or in combination, but it is preferred to combine two or more types in order to adjust the color tone (achromatic color). It is particularly preferred to combine three or more types. It is particularly preferred to combine three or more types of azo compounds.

Preferred azo compounds include the dyes described in JP-A-2007-126628, JP-A-2010-168570, JP-A-2013-101328, and JP-A-2013-210624.

It is also preferred that the dichroic dye is a dichroic dye polymer introduced into the side chain of a polymer such as acrylic. Examples of such dichroic dye polymers include the polymers listed in JP-A-2016-4055 and polymers obtained by polymerizing the compounds of [Chemical formula 6] to [Chemical formula 12] in JP-A-2014-206682.

From the viewpoint of achieving good orientation of the dichroic dye, the content of the dichroic dye in the polarizing film is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, even more preferably 1.0 to 15% by mass, and particularly preferably 2.0 to 10% by mass.

It is preferable that the polarizing film further contains a polymerizable liquid crystal compound to improve the film strength, degree of polarization, and film uniformity. Note that the polymerizable liquid crystal compound here also includes the polymerized film.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound is a compound that has a polymerizable group and exhibits liquid crystallinity.
The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group is an active radical or acid generated from a photopolymerization initiator, which will be described later. The polymerizable group is a group that can undergo a polymerization reaction by the above reaction. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, Among them, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group are preferred, and acryloyloxy group is more preferred. The compound exhibiting liquid crystallinity is either a thermotropic liquid crystal or a lyotropic liquid crystal. Also, in the thermotropic liquid crystal, either nematic liquid crystal or smectic liquid crystal may be used.

As the polymerizable liquid crystal compound, a smectic liquid crystal compound is preferred because it provides higher polarization characteristics, and a higher-order smectic liquid crystal compound is more preferred. If the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher-order smectic phase, a polarizing film with a higher degree of orientation order can be produced.

Specific preferred polymerizable liquid crystal compounds include those described in, for example, JP 2002-308832 A, JP 2007-16207 A, JP 2015-163596 A, JP 2007-510946 A, JP 2013-114131 A, WO 2005/045485 A, Lub et al. Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), etc.

From the viewpoint of increasing the orientation of the polymerizable liquid crystal compound, the content of the polymerizable liquid crystal compound in the polarizing film is preferably 70 to 99.5% by mass, more preferably 75 to 99% by mass, even more preferably 80 to 97% by mass, and particularly preferably 83 to 95% by mass.

The polarizing film can be provided by applying a polarizing film composition paint. The polarizing film composition paint may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, etc.

As the solvent, those listed as the solvents for the alignment layer coating liquid are preferably used.

The polymerization initiator is not limited as long as it polymerizes the polymerizable liquid crystal compound, but a photopolymerization initiator that generates active radicals by light is preferred. Examples of polymerization initiators include benzoin compounds, benzophenone compounds, alkylphenone compounds, acylphosphine oxide compounds, triazine compounds, iodonium salts, and sulfonium salts.

The sensitizer is preferably a photosensitizer. Examples include xanthone compounds, anthracene compounds, phenothiazine, rubrene, etc.

Polymerization inhibitors include hydroquinones, catechols, and thiophenols.

As the polymerizable non-liquid crystal compound, one that copolymerizes with the polymerizable liquid crystal compound is preferred. For example, when the polymerizable liquid crystal compound has a (meth)acryloyloxy group, (meth)acrylates can be used. The (meth)acrylates may be monofunctional or polyfunctional. By using polyfunctional (meth)acrylates, the strength of the polarizing film can be improved. When a polymerizable non-liquid crystal compound is used, it is preferable that the amount of the polymerizable non-liquid crystal compound in the polarizing film is 1 to 15% by mass, more preferably 2 to 10% by mass, and particularly preferably 3 to 7% by mass. If the amount exceeds 15% by mass, the degree of polarization may decrease.

Examples of cross-linking agents include compounds that can react with the functional groups of polymerizable liquid crystal compounds and polymerizable non-liquid crystal compounds, such as isocyanate compounds, melamine, epoxy resins, and oxazoline compounds.

The polarizing film composition paint is applied directly onto the transfer alignment film or onto the alignment control layer, and then dried, heated, and cured as necessary to form a polarizing film.

As a coating method, known methods such as gravure coating, die coating, bar coating, and applicator coating, and printing methods such as flexography are used.

After coating, the transfer orientation film is introduced into a hot air dryer, infrared dryer, or the like and dried at 30 to 170°C, more preferably 50 to 150°C, and even more preferably 70 to 130°C. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, and even more preferably 2 to 10 minutes.

Heating can be performed to more firmly align the dichroic dye and the polymerizable liquid crystal compound in the polarizing film. The heating temperature is preferably set to a temperature range in which the polymerizable liquid crystal compound forms a liquid crystal phase.

When the polarizing film composition coating contains a polymerizable liquid crystal compound, it is preferable to cure it. Examples of curing methods include heating and light irradiation, with light irradiation being preferred. The dichroic dye can be fixed in an oriented state by curing. Curing is preferably carried out in a state in which a liquid crystal phase has been formed in the polymerizable liquid crystal compound, and curing may be carried out by irradiating light at a temperature at which the compound exhibits a liquid crystal phase. Examples of light used in light irradiation include visible light, ultraviolet light, and laser light. Ultraviolet light is preferred in terms of ease of handling.

The irradiation intensity differs depending on the type and amount of the polymerization initiator and resin (monomer), but is preferably 100 to 10,000 mJ/cm ² , more preferably 200 to 5,000 mJ/cm ² , based on 365 nm.

A polarizing film is formed by applying a polarizing film composition paint onto an orientation control layer, so that the dye is oriented along the orientation direction of the orientation layer, resulting in a polarized transmission axis in a specified direction. However, if the composition is directly applied to a transfer orientation film without providing an orientation control layer, the polarizing film can also be oriented by irradiating it with polarized light to harden the composition for forming the polarizing film. In this case, polarized light in the desired direction (for example, polarized light in an oblique direction) is irradiated to the longitudinal direction of the transfer orientation film. It is preferable to then further heat the film to firmly align the dichroic dye along the orientation direction of the polymer liquid crystal.

The thickness of the polarizing film is 0.1 to 5 μm, preferably 0.3 to 3 μm, and more preferably 0.5 to 2 μm.

(Retardation Layer)
Representative examples of the retardation layer include a layer provided between a polarizer and a liquid crystal cell of a liquid crystal display device for optical compensation, a λ/4 layer, a λ/2 layer of a circular polarizer, etc. As the liquid crystal compound, a rod-shaped liquid crystal compound, a discotic liquid crystal compound, etc., such as a positive or negative A plate, a positive or negative C plate, an O plate, etc., can be used according to the purpose.

When used as optical compensation for a liquid crystal display device, the degree of retardation is appropriately set depending on the type of liquid crystal cell and the properties of the liquid crystal compound used in the cell. For example, in the case of the TN mode, an O plate using a discotic liquid crystal is preferably used. In the case of the VA mode or IPS mode, a C plate or A plate using a rod-shaped liquid crystal compound or a discotic liquid crystal compound is preferably used. In addition, in the case of the λ/4 retardation layer and λ/2 retardation layer of a circular polarizer, it is preferable to use an A plate using a rod-shaped compound. These retardation layers may be used not only as a single layer, but also in combination as multiple layers.

The liquid crystal compounds used in these retardation layers are preferably polymerizable liquid crystal compounds having a polymerizable group such as a double bond, in order to fix the alignment state.

Examples of the rod-shaped liquid crystal compound include rod-shaped liquid crystal compounds having a polymerizable group described in JP-A-2002-030042, JP-A-2004-204190, JP-A-2005-263789, JP-A-2007-119415, JP-A-2007-186430, and JP-A-11-513360.
Specific compounds include:
CH ₂ =CHCOO-(CH ₂ )m-O-Ph1-COO-Ph2-OCO-Ph1-O-(CH ₂ )n-OCO-CH=CH ₂
CH ₂ =CHCOO-(CH ₂ )m-O-Ph1-COO-NPh-OCO-Ph1-O-(CH ₂ )n-OCO-CH=CH ₂
CH ₂ =CHCOO-(CH ₂ )m-O-Ph1-COO-Ph2-OCH ₃
CH ₂ =CHCOO-(CH ₂ )m-O-Ph1-COO-Ph1-Ph1-CH ₂ CH(CH ₃ )C ₂ H ₅
In the formula, m and n are integers from 2 to 6,
Ph1 and Ph2 are 1,4-phenyl groups (Ph2 may have a methyl group at the 2-position),
NPh is a 2,6-naphthyl group.
These rod-shaped liquid crystal compounds are commercially available as LC242 manufactured by BASF, and these compounds can be used.

Multiple types of these rod-shaped liquid crystal compounds may be used in any combination in any ratio.

Examples of discotic liquid crystal compounds include benzene derivatives, truxene derivatives, cyclohexane derivatives, azacrowns, and phenylacetylene macrocycles. Various compounds are described in JP-A-2001-155866, and these compounds are preferably used.
Among them, as the discotic compound, a compound having a triphenylene ring represented by the following general formula (1) is preferably used.
In the formula, R ₁ to R ₆ are each independently hydrogen, halogen, an alkyl group, or a group represented by -O-X (wherein X is an alkyl group, an acyl group, an alkoxybenzyl group, an epoxy-modified alkoxybenzyl group, an acryloyloxy-modified alkoxybenzyl group, or an acryloyloxy-modified alkyl group). R ₁ to R ₆ are preferably an acryloyloxy-modified alkoxybenzyl group represented by the following general formula (2) (wherein m is 4 to 10):

The retardation layer can be provided by applying a retardation layer composition paint. The retardation layer composition paint may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, etc. These can be the same as those described in the alignment control layer and liquid crystal polarizer sections.

The retardation layer composition paint is applied onto the release surface or orientation control layer of the alignment film, and then dried, heated, and cured to form the retardation layer.

These conditions are also preferably used in addition to the conditions described in the sections on the alignment control layer and liquid crystal polarizer.

Multiple retardation layers may be provided. In this case, multiple retardation layers may be provided on a single transfer orientation film and then transferred to the target object, or multiple types of films each having a single retardation layer on a single transfer orientation film may be prepared and then transferred to the target object in sequence.

The polarizing layer and the retardation layer may also be provided on a single transfer orientation film, which is then transferred to the object. Furthermore, a protective layer may be provided between the polarizer and the retardation layer, or on or between the retardation layers. These protective layers may also be provided on the transfer orientation film together with the retardation layer and the polarizing layer, and then transferred to the object.

The protective layer may be a coating layer of a transparent resin. Examples of the transparent resin include, but are not limited to, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyester, polyurethane, polyamide, polystyrene, acrylic resin, and epoxy resin. A crosslinking agent may be added to these resins to form a crosslinked structure. A hard coat may also be formed by curing a photocurable composition such as acrylic. In addition, after providing a protective layer on an alignment film, the protective layer may be subjected to a rubbing treatment, and a liquid crystal compound alignment layer may be provided on the protective layer without providing an alignment layer.

(Method of manufacturing a liquid crystal compound alignment layer laminated polarizing plate)
Next, a method for producing the liquid crystal compound alignment layer laminated polarizing plate of the present invention will be described.
The method for producing a liquid crystal compound alignment layer laminated polarizing plate of the present invention includes a step of bonding a polarizing plate and a liquid crystal compound alignment layer surface of the liquid crystal compound alignment layer transfer laminate of the present invention to form an intermediate laminate, and a step of peeling off the alignment film from the intermediate laminate.
Hereinafter, the liquid crystal compound alignment layer will be described as an example when it is used in a circular polarizing plate. In the case of a circular polarizing plate, a λ/4 layer is used as the retardation layer (referred to as a liquid crystal compound alignment layer in the transfer laminate). The front retardation of the λ/4 layer is preferably 100 to 180 nm. More preferably, it is 120 to 150 nm. When only a λ/4 layer is used as a circular polarizing plate, the alignment axis (slow axis) of the λ/4 layer and the transmission axis of the polarizer are preferably 35 to 55 degrees, more preferably 40 to 50 degrees, and even more preferably 42 to 48 degrees. When used in combination with a polarizer of a stretched film of polyvinyl alcohol, the absorption axis of the polarizer is generally in the length direction of the long polarizer film, so when a λ/4 layer is provided on a long transfer orientation film, it is preferable to align the liquid crystal compound so that it is in the above range with respect to the length direction of the long transfer orientation film. Note that, when the angle of the transmission axis of the polarizer is different from the above, the liquid crystal compound is oriented so that the above relationship is satisfied by taking into account the angle of the transmission axis of the polarizer.

A circular polarizing plate is produced by transferring the λ/4 layer in the transfer laminate in which the λ/4 layer and the alignment film are laminated to a polarizing plate. Specifically, the polarizing plate and the λ/4 layer surface of the transfer laminate are bonded to form an intermediate laminate, and the alignment film is peeled off from this intermediate laminate. The polarizing plate may have a protective film on both sides of the polarizer, but it is preferable that the protective film is provided only on one side. If the polarizing plate has a protective film provided only on one side, it is preferable to bond the retardation layer to the opposite side (polarizer surface) of the protective film. If protective films are provided on both sides, it is preferable to bond the retardation layer to the surface intended for the image cell side. The surface intended for the image cell side is a surface that is not surface-treated, such as a low-reflection layer, an anti-reflection layer, or an anti-glare layer, which is generally provided on the viewing side. The protective film on the side to which the retardation layer is bonded is preferably a protective film with no retardation, such as TAC, acrylic, or COP.

Examples of polarizers include polarizers made by stretching a PVA-based film alone, polarizers made by coating an unstretched substrate such as polyester or polypropylene with PVA and stretching the substrate together to create a polarizer that is then transferred to a polarizer protective film, and polarizers made of a liquid crystal compound and a dichroic dye that are coated or transferred to a polarizer protective film. All of these are preferably used.

As a method of attachment, conventional adhesives, pressure sensitive adhesives, etc. can be used. Preferred adhesives include polyvinyl alcohol adhesives, UV-curable adhesives such as acrylic or epoxy, and heat-curable adhesives such as epoxy or isocyanate (urethane). Examples of pressure sensitive adhesives include acrylic, urethane, and rubber-based adhesives. It is also preferred to use an optically transparent pressure sensitive adhesive sheet without an acrylic substrate.

When using a transfer type polarizer, the polarizer can be transferred onto the retardation layer (liquid crystal compound orientation layer) of the transfer laminate, and then the polarizer and retardation layer can be transferred to the target object (polarizer protective film).

As the polarizer protective film on the side opposite to the side where the retardation layer is provided, commonly known films such as TAC, acrylic, COP, polycarbonate, and polyester can be used. Among these, TAC, acrylic, COP, and polyester are preferred. Polyester is preferably polyethylene terephthalate. In the case of polyester, it is preferred that the film is a zero retardation film with an in-plane retardation of 100 nm or less, particularly 50 nm or less, or a high retardation film of 3000 nm to 30,000 nm.

When a high retardation film is used, in order to prevent blackout or coloration when viewing an image through polarized sunglasses, the angle between the transmission axis of the polarizer and the slow axis of the high retardation film is preferably in the range of 30 to 60 degrees, more preferably in the range of 35 to 55 degrees. In order to reduce rainbow spots and the like that may appear when observing with the naked eye from a shallow oblique angle, it is preferable that the angle between the transmission axis of the polarizer and the slow axis of the high retardation film is 10 degrees or less, more preferably 7 degrees or less, or 80 to 100 degrees, more preferably 83 to 97 degrees.

The polarizer protective film on the opposite side may be provided with an anti-glare layer, an anti-reflection layer, a low-reflection layer, a hard coat layer, etc.

(Composite Retardation Layer)
A λ/4 layer alone may not be λ/4 over a wide range of the visible light region, and coloring may occur. Therefore, a λ/4 layer may be used in combination with a λ/2 layer. The front retardation of the λ/2 layer is preferably 200 to 360 nm, and more preferably 240 to 300 nm.

In this case, it is preferable that the λ/4 layer and the λ/2 layer are arranged at an angle such that the combined angle is λ/4. Specifically, the angle (θ) between the orientation axis (slow axis) of the λ/2 layer and the transmission axis of the polarizer is preferably 5 to 20 degrees, and more preferably 7 to 17 degrees. The angle between the orientation axis (slow axis) of the λ/2 layer and the orientation axis (slow axis) of the λ/4 layer is preferably in the range of 2θ+45 degrees±10 degrees, more preferably in the range of 2θ+45 degrees±5 degrees, and even more preferably in the range of 2θ+45 degrees±3 degrees.

In this case, too, when used in combination with a polarizer made of a stretched polyvinyl alcohol film, the absorption axis of the polarizer generally runs in the length direction of the long polarizer film, so when a λ/2 layer or λ/4 layer is provided on a long transfer orientation film, it is preferable to orient the liquid crystal compound so that it falls within the above range with respect to the length direction or perpendicular to the length of the long transfer orientation film. If the angle of the transmission axis of the polarizer is different from the above, the liquid crystal compound is oriented to satisfy the above relationship, taking into account the angle of the transmission axis of the polarizer.

Examples of these methods and retardation layers can be found in JP 2008-149577 A, JP 2002-303722 A, WO 2006/100830 A, JP 2015-64418 A, etc.

In addition, it is also a preferred embodiment to provide a C-plate layer on the λ/4 layer to reduce changes in color when viewed from an oblique angle. A positive or negative C-plate layer is used depending on the characteristics of the λ/4 or λ/2 layer.

As a lamination method for these, for example, in the case of a combination of a λ/4 layer and a λ/2 layer,
A λ/2 layer is provided on a polarizer by transfer, and a λ/4 layer is further provided thereon by transfer.
A λ/4 layer and a λ/2 layer are provided in this order on an orientation film for transfer, and this is then transferred onto a polarizer.
A λ/4 layer, a λ/2 layer and a polarizing layer are provided in this order on an orientation film for transfer, and this is then transferred onto an object.
A λ/2 layer and a polarizing layer are provided in this order on an orientation film for transfer, which is then transferred to an object, and a λ/4 layer is then transferred onto this.
Various methods can be adopted.

When laminating a C plate, various methods can be used, such as transferring a C plate layer onto a λ/4 layer provided on a polarizer, or providing a C plate layer on an oriented film, and then providing a λ/4 layer or a λ/2 layer and a λ/4 layer on top of this, and then transferring this.

The thickness of the circularly polarizing plate thus obtained is preferably 120 μm or less, more preferably 100 μm or less, even more preferably 90 μm or less, particularly preferably 80 μm or less, and most preferably 70 μm or less.

(Method 1 for inspecting laminate for transferring liquid crystal compound alignment layer)
Next, a method for inspecting the laminate for transferring a liquid crystal compound alignment layer of the present invention will be described.
The method for inspecting the laminate for transferring the alignment layer of a liquid crystal compound of the present invention includes the steps of irradiating the alignment film surface of the laminate with linearly polarized light having an electric field oscillation direction parallel to the alignment direction of the alignment film, or a direction perpendicular to the alignment direction, or a flow direction of the alignment film, or a direction perpendicular to the flow direction, receiving the light on the liquid crystal compound alignment layer surface side, and inspecting whether or not the received light is in an extinction state. Thus, in the present invention, the laminate for transferring the alignment layer of a liquid crystal compound can be inspected for its optical properties in a state where it is laminated on the alignment film for transfer, even if the alignment film for transfer has birefringence and the alignment layer of a liquid crystal compound is a retardation layer.

To inspect the optical state of the retardation layer, linearly polarized light parallel or perpendicular to the orientation direction of the transfer orientation film is irradiated, and the change in the polarization state is detected by a receiver installed on the opposite side of the laminate. Parallel to the orientation direction of the transfer orientation film is preferably -10 to +10 degrees, more preferably -7 to 7 degrees, even more preferably -5 to 5 degrees, particularly preferably -3 to 3 degrees, and most preferably -2 to 2 degrees. Perpendicular to the orientation direction of the transfer orientation film is preferably 80 to 100 degrees, more preferably 83 to 97 degrees, even more preferably 85 to 95 degrees, particularly preferably 87 to 93 degrees, and most preferably 88 to 92 degrees. If the above range is exceeded, the polarized light that hits the retardation layer or that has passed through it may be disturbed by the phase difference of the substrate, making it impossible to perform an accurate evaluation.

It is possible to adjust the angle of the linearly polarized light each time according to the orientation direction of the transfer orientation film, but this makes the inspection cumbersome. Therefore, it is also preferable to fix the linearly polarized light to be irradiated as parallel or perpendicular to the flow direction of the transfer orientation film and perform the inspection. The range of parallel or perpendicular here is the same as above.

In addition, if the transfer orientation film does not have birefringence, it is preferable to inspect it by irradiating it with linearly polarized light parallel or perpendicular to the flow direction (MD direction) of the transfer orientation film. Here, the range of parallel or perpendicular is the same as above.

It is preferable to provide a polarizing filter between the light receiver and the laminate for transferring the liquid crystal compound alignment layer (retardation layer) (film to be inspected). It is also preferable to provide a retardation plate between the laminate for transferring the liquid crystal compound alignment layer (retardation layer) and the polarizing filter to convert the light that has become elliptically polarized by the retardation layer of the laminate for transferring the liquid crystal compound alignment layer (retardation layer) into linearly polarized light if the light is elliptically polarized as designed. For example, by configuring in this way, if the retardation layer is as designed, the light detected by the light receiver is in an extinction state, but if there is light leakage, it is found that the retardation layer is deviated from the design. It is also possible to install multiple types of light receivers with slightly different angles of the polarizing filter and angles and retardation of the retardation plate to detect in which direction and how much the retardation and orientation direction of the retardation layer are deviated. Also, if there are defects in the retardation layer in a small area due to pinholes or scratches, they can be detected as bright spots.

(Method 2 for inspecting laminate for transferring liquid crystal compound alignment layer)
There is another method for inspecting the laminate for transferring a liquid crystal compound alignment layer of the present invention, and this inspection method will be described below.
In another method, elliptically polarized light is irradiated from the retardation layer surface of the laminate for transferring the liquid crystal compound alignment layer (retardation layer) and received on the alignment film surface side. The elliptically polarized light to be irradiated is elliptically polarized light that is converted into linearly polarized light when the retardation layer of the laminate is as designed. It is preferable that such elliptically polarized light is emitted as linearly polarized light and converted by a retardation plate.
The direction of the outgoing linearly polarized light is the same as that described in the inspection method 1.

The linearly polarized light converted by the retardation layer of the laminate passes through the alignment film as linearly polarized light without being disturbed by the retardation of the alignment film. It is preferable to place a polarizing filter between the photodetector and the laminate (film to be inspected) for transferring the liquid crystal compound alignment layer (retardation layer). It is preferable to orient the polarizing filter in a direction that does not allow the linearly polarized light that has passed through it to pass through.

For example, by using the above configuration, defects and misalignments in the retardation layer can be detected in the same way as inspection method 1.

(Method 3 for inspecting laminate for transferring liquid crystal compound alignment layer)
In the above two inspection methods, a light source and a light receiver are provided on either side of the laminate for transferring the liquid crystal compound alignment layer, but inspection can also be performed using a method in which the light source and the light receiver are provided on the same side and a mirror reflector is provided on the opposite side, so this method will be explained below.
In this method, linearly polarized light is irradiated from the alignment film surface of the laminate for transferring a liquid crystal compound alignment layer. The direction of the irradiated linearly polarized light is the same as that explained in the inspection method 1.

For example, the light converted into circularly polarized light by the liquid crystal compound alignment layer is reflected by a mirror reflector provided on the opposite side to the light source, and returns to the laminate in a circularly polarized state. It is then converted back into linearly polarized light by the liquid crystal compound alignment layer of the laminate, and is received through the alignment film. All the light passing through the alignment film is linearly polarized, and by setting the above angle, it passes through the alignment film as linearly polarized light without being disturbed by the phase difference of the alignment film.
It is preferable to provide a polarizing filter between the light receiver and the film to be inspected, and the polarizing filter is preferably oriented in such a way that it cannot transmit the reflected linearly polarized light.

As a specular reflector, metal plates, metal-vapor-deposited glass, metal-vapor-deposited resin plates and other optical surface mirrors can be used.

A retardation plate may be provided between the film to be inspected and the mirror reflector. When the liquid crystal compound alignment layer is a λ/4 retardation layer or a λ/2 retardation layer, the retardation plate is not necessarily required, but as in method 1, a retardation plate having a slight retardation may be provided so that it is possible to know how the retardation of the liquid crystal compound alignment layer deviates from the design.
When the liquid crystal compound alignment layer is not a λ/4 retardation layer or a λ/2 retardation layer, it is preferable to provide a retardation plate that returns linearly polarized light when the linearly polarized light passes through the liquid crystal compound alignment layer--retardation plate--mirror reflector--retardation plate--liquid crystal compound alignment layer.

(Inspection of the polarizing layer)
When the liquid crystal compound alignment layer is a polarizing layer, the polarizing layer can be inspected by irradiating it with natural light (non-polarized light) and receiving the transmitted light through a polarizing filter. Alternatively, the transfer laminate can be inspected by irradiating it with linearly polarized light through a polarizing filter and receiving the transmitted light. In these cases, the polarizing filter is set to an angle at which the polarizing layer provided on the transfer alignment film is extinguished when it is as designed.

In addition, by installing multiple types of receivers with slightly different polarizing filter angles, it is possible to detect in which direction and by how much the orientation direction has shifted.

In these cases, it is preferable to irradiate the film from the transfer orientation film side when using natural light, and from the polarizing layer side when using linearly polarized light.

The above-mentioned polarizing layer is inspected by transmitting light through the laminate for transfer, but as an alternative method, a specular reflector may be provided on the opposite side of the light source and light may be received on the same side as the light source, as in inspection method 3 for the laminate for transfer of a liquid crystal compound alignment layer. As described above, the light to be irradiated may be natural light or linearly polarized light. When natural light is irradiated and received through a polarizing filter, the polarizing filter may be placed either between the laminate and the specular reflector, or between the laminate and the receiver.

The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples, and can be modified as appropriate within the scope of the invention, and all of these are included in the technical scope of the present invention. The methods for evaluating physical properties in the examples are as follows.

(1) Three-dimensional surface roughness SRa, SRz, SRy
Using a stylus-type three-dimensional roughness meter (SE-3AK, manufactured by Kosaka Laboratory Co., Ltd.), measurements were taken over a measurement length of 1 mm in the longitudinal direction of the film with a cutoff value of 0.25 mm and a needle feed rate of 0.1 mm/sec under conditions of a needle radius of 2 μm and a load of 30 mg, and the film was divided into 500 points at a pitch of 2 μm, and the height of each point was captured in a three-dimensional roughness analyzer (SPA-11). The same operation was performed continuously 150 times at intervals of 2 μm in the width direction of the film, that is, over a width of 0.3 mm in the width direction of the film, and the data was captured in the analyzer. Next, the center surface average roughness (SRa), ten-point average roughness (SRz), and maximum height (SRy) were determined using the analyzer.

(2) Number of protrusions with a release surface height difference of 0.5 μm or more (release surface) and 2.0 μm or more (reverse surface) A test piece with a width of 100 mm and a length of 100 mm was cut out in the longitudinal direction of the film, and this was sandwiched between two polarizing plates to be in a cross-Nicol state, and set in a state in which the extinction position was maintained. In this state, a Nikon universal projector V-12 (measurement conditions: projection lens 50 times, transmitted illumination light beam switching knob 50 times, transmitted light inspection) was used to detect parts (scratches, foreign matter) that transmit light and appear to be shiny with a major axis of 50 μm or more. The parts detected in this way were cut out to an appropriate size from the test piece, and observed and measured from a direction perpendicular to the film surface using a three-dimensional shape measuring device (manufactured by Ryoka Systems, Micromap TYPE 550; measurement conditions: wavelength 550 nm, WAVE mode, objective lens 10 times). At this time, when observed from a direction perpendicular to the film surface, the irregularities that are close to each other within 50 μm are assumed to be the same scratches or foreign matter, and a rectangle covering them is assumed to be the length and width of the scratches or foreign matter. The number of defects for these scratches and foreign matters was quantified using a cross-sectional image (SURFACE PROFILE DISPLAY). The measurement was performed on 20 test pieces and converted into the number of defects per ^m2 . The number of defects with a height difference (difference between the highest point and the lowest point) of 0.5 μm or more was counted on the release surface, and the number of defects with a height difference of 2.0 μm or more was counted on the back surface.

(3) Inspection of defects in the retardation layer A sample for inspection was prepared by disposing a rubbing treatment alignment control layer or a photoalignment control layer between the alignment film for transfer and the liquid crystal compound alignment layer. The specific preparation procedure is as follows.

(When the alignment control layer is a rubbed alignment control layer)
The transfer orientation film was cut into A4 size, and the release layer surface was coated with the following composition for the rubbing treatment orientation control layer paint using a bar coater, and dried at 80°C for 5 minutes to form a film with a thickness of 100 nm. The cut-out was made so that the orientation axis of the transfer orientation film was parallel to the long side of the A4. Subsequently, the surface of the obtained film was treated with a rubbing roll wrapped with a nylon nap cloth to obtain a transfer orientation film laminated with a rubbing treatment orientation control layer. The rubbing was performed at an angle of 45 degrees to the longitudinal direction of the transfer orientation film.

Completely saponified polyvinyl alcohol, molecular weight 800, 2 parts by weight Ion-exchanged water, 100 parts by weight Surfactant, 0.1 parts by weight

Subsequently, a retardation layer forming solution having the following composition was applied to the rubbed surface by a bar coating method, dried at 110° C. for 3 minutes, and cured by irradiation with ultraviolet light to provide a quarter-wave layer, thereby obtaining a test sample.
LC242 (manufactured by BASF) 95 parts by weight Trimethylolpropane triacrylate 5 parts by weight Irgacure 379 3 parts by weight Surfactant 0.1 parts by weight Methyl ethyl ketone 250 parts by weight

(When the alignment control layer is a photoalignment control layer)
Based on the descriptions in Examples 1, 2, and 3 of JP 2013-33248 A, a 5% by mass solution of a polymer represented by the following formula in cyclopentanone was prepared and used as a coating material for a photoalignment layer.

Next, the transfer orientation film was cut into A4 size pieces, and the release layer surface was coated with the above-mentioned composition of the photo-alignment control layer paint using a bar coater, and dried at 80°C for 1 minute to form a film with a thickness of 80 nm. The film was then irradiated with polarized UV light at 45 degrees to the longitudinal direction to obtain a transfer orientation film with a photo-alignment control layer laminated thereon. These paints were filtered through a membrane filter with a pore size of 0.2 μm, and coating and drying were carried out in a clean room.

Next, a solution for forming a retardation layer was applied by bar coating to the surface on which the optical alignment control layer was laminated. The solution was dried at 110°C for 3 minutes and then cured by irradiating with ultraviolet light to form a quarter-wave layer, and a test sample was obtained.

Next, using these test samples, defects in the retardation layer were inspected in the following procedure.
A lower polarizing plate was placed on a surface-emitting light source using a white LED with a yellow phosphor as a light source, and the test sample prepared as described above was placed on the lower polarizing plate so that the extinction axis direction (absorption axis direction) of the polarizing plate was parallel to the long side direction of the test sample. A λ/4 film made of a stretched film of a cyclic polyolefin was placed on the lower polarizing plate so that the orientation main axis was in a direction of 45 degrees to the extinction axis of the lower polarizing plate, and an upper polarizing plate was placed on the upper polarizing plate so that the extinction axis of the upper polarizing plate was parallel to the extinction axis of the lower polarizing plate. In this state, the extinction state was observed with the naked eye (center 15 cm x 20 cm) and with a 20x magnifying glass (5 cm x 5 cm), and evaluated according to the following criteria.
⊚: No bright spots were observed with the naked eye, and almost no bright spots were observed even with magnifying glass observation (2 or less in an area of 5 cm x 5 cm).
◯: No bright spots were observed with the naked eye, but a small number of bright spots were observed with a magnifying glass (3 to 20 in an area of 5 cm×5 cm).
Δ: No bright spots were observed with the naked eye, but bright spots were observed with a magnifying glass (more than 20 spots in an area of 5 cm×5 cm).
×: Bright spots were observed with the naked eye, or no bright spots were observed but there was overall light leakage which was likely due to the presence of many bright spots observed with a magnifying glass.

(4) Inspection of defects after overlay 1
Two samples for inspection using the above-mentioned rubbing treatment alignment control layer were prepared, and the retardation layer-mounted surface and the opposite surface of each sample were stacked together, and a load of 1 kg/ ^cm2 was applied for 10 minutes. The retardation layer of this sample was inspected for defects in the same manner as in (3) Inspection of retardation layer defects.

(5) Inspection of defects after overlay 2
In inspection 1 for defects after overlay, since it is difficult to determine the effect of the roughness of the back surface when the roughness of the release surface is large, an inspection sample using the optical alignment control layer of experimental example 2A, which has a small release surface roughness, was used to investigate the effect of the roughness of the back surface of inspection samples using optical alignment control layers of other experimental examples.
Specifically, the retardation layer installation surface of the test sample in which a quarter-wavelength layer was provided on the optical alignment control layer of Experimental Example 2A was overlapped with the opposite surface of the test sample using the optical alignment control layer of each experimental example, and a load of 1 kg/cm ² was applied for 10 minutes. The retardation layer defects of this sample (test sample of Experimental Example 2A) were inspected in the same manner as in (3) Inspection of retardation layer defects.

(6) Intrinsic Viscosity 0.2 g of a resin sample was dissolved in 50 ml of a mixed solvent of phenol/1,1,2,2-tetrachloroethane (60/40 (weight ratio)), and the intrinsic viscosity was measured using an Ostwald viscometer at 30° C. For the sample of surface layer A, layer A alone was extruded to prepare a film sample, which was used as the sample.

(7) Content of ester cyclic trimer The polyester resin constituting the release surface side layer of the polyester film was scraped off with a cutter knife and finely frozen and crushed. 0.1 g of this crushed resin was dissolved in 3 ml of a mixed solvent of hexafluoroisopropanol (HFIP)/chloroform (2/3 (volume ratio)). 20 ml of chloroform was added to the obtained solution and mixed uniformly. 10 ml of methanol was added to the obtained mixed liquid to reprecipitate the linear polyester. Next, this mixed liquid was filtered, and the precipitate was washed with 30 ml of a mixed solvent of chloroform/methanol (2/1 (volume ratio)), and further filtered. The obtained filtrate was concentrated to dryness using a rotary evaporator. 10 ml of dimethylformamide was added to the concentrated and dried product to prepare an ester cyclic trimer measurement solution, and the content of the ester cyclic trimer was determined by liquid chromatography.
(Measurement conditions)
Equipment: L-7000 (Hitachi)
Column: μ-Bondasphere C18 5μ 100 angstroms 3.9 mm×15 cm (Waters)
Solvents: Eluent A: 2% acetic acid/water (v/v)
Eluent B: Acetonitrile Gradient B%: 10→100% (0→55 min)
Flow rate: 0.8ml/min Temperature: 30℃
Detector: UV-258 nm

(8) Amount of ester cyclic trimer precipitated on the surface of the release side of the film The polyester film was cut to 15 cm x 15 cm and heated in an oven at 150 ° C for 90 minutes. The heat-treated film was then placed on a 15 cm x 15 cm stainless steel plate with the release side facing up, and a 15 cm x 15 cm silicone sheet (thickness 5 mm) with a 10 cm x 10 cm hole in the center was placed on top of it, and a stainless steel plate of the same shape (thickness 2 mm) as the silicone sheet was placed on top of it, and the periphery was fastened with clips. Next, 4 ml of DMF (dimethylsulfamide) was placed in the central hole and left for 3 minutes, and then the DMF was collected. The amount of ester cyclic trimer in the collected DMF was determined by liquid chromatography. This value was divided by the area of the film contacted with DMF to obtain the amount of ester cyclic trimer precipitated (mg / m ² ) on the surface of the release side of the film.
(Measurement conditions)
Equipment: ACQUITY UPLC (manufactured by Waters)
Column: BEH-C18 2.1 x 150 mm (Waters)
Mobile phase: Eluent A: 0.1% formic acid (v/v)
Eluent B: Acetonitrile Gradient B%: 10 → 98 → 98% (0 → 25 → 30 min)
Flow rate: 0.2 ml/min Column temperature: 40° C.
Detector: UV-258 nm

(9) Winding Stability The winding state of the film having a width of 1800 cm produced in the experimental example was visually evaluated.
◯: No wrinkles were formed, the roll ends were uniform, and stable winding was possible.
Δ: Some wrinkles were observed, but the ends of the roll were generally uniform, allowing stable winding.
×: Wrinkles were generated irregularly, and the roll ends were significantly uneven, making stable winding impossible.

<Production of polyester resin for transfer orientation film>
(Production of particle-free polyester resin (PET(X-m)))
When the temperature of the esterification reactor reached 200°C, 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged, and 0.017 parts by mass of antimony trioxide, 0.064 parts by mass of magnesium acetate tetrahydrate, and 0.16 parts by mass of triethylamine were charged as catalysts while stirring. Next, the temperature was increased under pressure, and a pressurized esterification reaction was carried out under conditions of a gauge pressure of 0.34 MPa and 240°C, after which the esterification reactor was returned to normal pressure and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was increased to 260°C over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Next, after 15 minutes, a dispersion treatment was carried out using a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reactor and a polycondensation reaction was carried out under reduced pressure at 280°C.

After the polycondensation reaction was completed, the mixture was filtered using a Naslon filter with a 95% cutoff diameter of 5 μm, extruded from a nozzle in the form of strands, cooled and solidified using cooling water that had been previously filtered (pore diameter: 1 μm or less), and cut into pellets to obtain polyethylene terephthalate resin (PET (X-m)). PET (X-m) had an intrinsic viscosity of 0.62 dl/g, an ester cyclic trimer content of 1.05% by mass, and was substantially free of inactive particles and internally precipitated particles.

(Production of Silica Particle-Containing Polyester Resin (PET (Z-Si1))
In the production of PET (X-m),
The temperature was raised to 260° C., and 15 minutes after the addition of trimethyl phosphate, the ethylene glycol slurry of the silica particles was added to the resulting polyester in an amount of 10,000 ppm.
A silica particle-containing polyethylene terephthalate resin having an intrinsic viscosity of 0.63 dl/g was obtained in the same manner, except that the filtration was carried out using a Naslon filter (manufactured by Nippon Seisen Co., Ltd.) having a 95% cutoff diameter of 20 μm.
The ethylene glycol slurry of silica particles was prepared by adding silica particles (manufactured by Fuji Silysia Chemical Ltd.) having an average particle size of 2.5 μm to ethylene glycol, and then filtering the mixture through a viscose rayon filter having a 95% cutoff diameter of 30 μm.

(Production of Silica Particle-Containing Polyester Resin (PET (Z-Si2))
The same procedure was carried out in the production of PET (Z-Si1), except that porous colloidal silica having an average particle size of 0.9 μm was used as the silica particles, to obtain a polyethylene terephthalate resin containing silica particles and having an intrinsic viscosity of 0.63 dl/g.

(Production of Silica Particle-Containing Polyester Resin (PET (Z-Si3))
The same procedure was carried out in the production of PET (Z-Si1), except that porous colloidal silica having an average particle size of 0.2 μm was used as the silica particles, to obtain a polyethylene terephthalate resin containing silica particles and having an intrinsic viscosity of 0.63 dl/g.

(Production of Silica Particle-Containing Polyester Resin (PET (Z-Si4))
The same procedure was carried out in the production of PET (Z-Si1), except that porous colloidal silica having an average particle size of 0.06 μm was used as the silica particles, to obtain a polyethylene terephthalate resin containing silica particles and having an intrinsic viscosity of 0.63 dl/g.

(Production of Polyester Resin Containing Calcium Carbonate Particles (PET(Z-Ca)))
The same procedure was carried out for the production of PET (Z-Si1), except that an ethylene glycol slurry of calcium carbonate particles was used instead of the ethylene glycol slurry of silica particles, to obtain a polyethylene terephthalate resin containing calcium carbonate particles and having an intrinsic viscosity of 0.63 dl/g.
The ethylene glycol slurry of calcium carbonate particles was prepared by using calcium carbonate particles having an average particle size of 0.6 μm (manufactured by Maruo Calcium Co., Ltd.) instead of silica particles.

(Production of Crosslinked Polystyrene Particle-Containing Polyester Resin (PET(Z-St))) PET(X-m) and a 10% by mass aqueous dispersion of crosslinked polystyrene particles having an average particle size of 0.30 μm were fed into a vented twin-screw extruder and heated and melted at 280° C. The vent hole was reduced in pressure to 1 kPa or less to remove moisture. The molten polyester was filtered through a Naslon filter having a 95% cutoff diameter of 20 μm, extruded from a nozzle in the form of a strand, cooled and solidified using cooling water that had been previously filtered (pore diameter: 1 μm or less), and cut into pellets. The obtained crosslinked polystyrene particle-containing polyester resin (PET(Z-St)) had an intrinsic viscosity of 0.62 dl/g and a crosslinked polystyrene particle content of 10,000 ppm.

Experimental Examples 1A to 4A
As a raw material for the release layer side of the transfer orientation film, PET (X-m) resin pellets containing no particles were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours and then fed to extruder 1, and as a raw material for the opposite surface layer (back surface layer), PET (X-m) resin pellets and polyester (PET (Z-Si1)) resin pellets containing particles were blended in such a ratio that the particle content of the opposite surface layer (back surface layer) was the specified value shown in Table 1, dried, fed to extruder 2, and melted at 285 ° C. These two types of molten polymers were each filtered with a stainless steel sintered filter material (nominal filtration accuracy 10 μm particle 95% cut) in a two-type two-layer confluence block, laminated, extruded in a sheet shape from a die, and then wrapped around a casting drum with a surface temperature of 30 ° C. using an electrostatic application casting method and cooled and solidified to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the thickness of the release layer and the back surface layer were the specified values shown in Table 1.

The unstretched film was introduced into a tenter stretching machine, and while holding the ends of the film with clips, it was introduced into a hot air zone at a temperature of 125 ° C., and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, it was heat-set at a temperature of 210 ° C. for 10 seconds, and further subjected to a 3.0% relaxation treatment. Then, both ends of the film cooled to 130 ° C. were cut with a shear blade, and the ears were cut off with a tension of 0.5 kg / mm ² and then wound up to obtain a uniaxially oriented PET film (width 1800 cm) with a film thickness of 50 μm. The center of the obtained film was slit into a width of 50 cm to obtain a film roll (transfer orientation film) with a length of about 500 m.

Experimental Examples 5A and 6A
A film roll (transfer orientation film) was obtained in the same manner as in Experimental Examples 1A to 4A, except that the PET (Z-Si1) resin pellets were changed to PET (Z-Ca) among the raw materials for the opposite surface layer (reverse surface layer).

Experimental Example 7A
The unstretched film produced in the same manner as in Experimental Example 1A was heated to 105°C using a heated roll group and an infrared heater, then stretched 3.3 times in the running direction by a roll group with a difference in peripheral speed, then introduced into a hot air zone at a temperature of 135°C and stretched 3.5 times in the width direction, and the heat setting temperature was set to 225°C, and the other steps were the same as those for the transfer orientation film in Experimental Example 1A to obtain a biaxially oriented PET film in Experimental Example 7A. The central part of the obtained film was slit to a width of 50 cm to obtain a film roll with a length of about 500 m. The film thickness was adjusted by changing the extrusion amount to increase the thickness of the unstretched film.

Experimental Example 8A
A film roll (oriented film for transfer) was obtained in the same manner as in Experimental Example 7A, except that an unstretched film produced in the same manner as in Experimental Example 5A was used.

Experimental Example 9A
Among the raw materials for the opposite surface layer (reverse surface layer), the PET (Z-Si1) resin pellets were changed to a combination of PET (Z-Si2) and PET (Z-Ca), and the same procedure was followed as in Experimental Examples 1A to 4A to obtain a film roll (transfer orientation film).

Experimental Example 10A
As a raw material for the release layer side of the transfer orientation film, PET (X-m) resin pellets and PET (Z-Si4) resin pellets were blended in such a ratio that the particle content of the release layer was the specified value shown in Table 1, and the blend was dried under reduced pressure (1 Torr) at 135 ° C for 6 hours and then supplied to extruder 1. As a raw material for the opposite surface layer (back surface layer), PET (X-m) resin pellets and particle-containing polyester (PET (Z-Si3) and PET (Z-St)) resin pellets were blended in such a ratio that the particle content of the opposite surface layer (back surface layer) was the specified value shown in Table 1, and then dried and supplied to extruder 2. As a raw material for the intermediate layer, PET (X-m) resin pellets were dried and supplied to extruder 3 and melted at 285 ° C. These three kinds of molten polymers were filtered with a stainless steel sintered filter material (nominal filtering accuracy 10 μm particles 95% cut), laminated in a three-kind three-layer merging block, extruded from a die into a sheet, and then wrapped around a casting drum with a surface temperature of 30° C. using an electrostatic casting method to cool and solidify, producing an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the thickness of the release layer and back layer were the specified values shown in Table 1. Thereafter, uniaxial stretching was performed in the same manner as in Experimental Examples 1A to 4A, and a film roll (transfer oriented film) was obtained.

Experimental Example 11A
A film roll (oriented film for transfer) was obtained in the same manner as in Experimental Example 10A, except that biaxial stretching was carried out as in Experimental Example 7A, instead of uniaxial stretching.

Experimental Example 12A
A coating agent having the following composition was applied to the release layer surface of the film of Experimental Example 1A, and dried in a heating oven at 150° C. for 3 minutes to form a flattening and oligomer block coating layer. The coating layer had a thickness of 2 μm.
Melamine crosslinked alkyl modified alkyd resin (Hitachi Chemical Polymer Co., Ltd.: Tesfine 322: solid content 40%) 10 parts by mass p-toluenesulfonic acid (Hitachi Chemical Polymer Co., Ltd.: Dryer 900)
0.1 parts by weight, solvent (toluene/methyl ethyl ketone = 1/1 parts by weight) 40 parts by weight. The coating agent was filtered through a 2 μm filter, and the air used for drying was filtered through a HEPA filter with a 95% cut diameter of 1 μm, and then further filtered with a HEPA filter with a 99.9% cut diameter of 0.3 μm. Furthermore, the coating agent was applied to the film in a class 1,000 environment. The following coating and drying processes were carried out in the same environment.

Experimental Example 13A
A film roll (transfer orientation film) was obtained in the same manner as in Experimental Example 12A, except that the thickness of the front layer was changed from 10 μm to 25 μm and the thickness of the back layer was changed from 40 μm to 25 μm.

Experimental Example 14A
A coating liquid prepared by diluting Vylon RV220 (manufactured by Toyobo) with a toluene/methyl ethyl ketone (=1:1) solution to a solids content of 7% by mass was applied to the surface opposite the release surface of Experimental Example 9A using a gravure coater, and dried at 120°C for 30 seconds to form a flattening coating layer on the back surface.

Experimental Example 15A
Particle-free PET (X-m) resin pellets were supplied to both extruders 1 and 2 to produce an unstretched film. Next, a coating solution having the following composition was applied to one side of this unstretched film so that the coating amount after drying was 0.1 g/ ^m2 , and then the film was introduced into a dryer and dried at 80°C for 20 seconds to form a lubricating coating layer on the back side. The lubricating coating layer was provided on the surface that came into contact with the casting drum as the back side.

(Coating Solution 1)
Water 50.00 parts by weight Isopropyl alcohol 36.10 parts by weight Polyester water dispersion 13.00 parts by weight (MD-1200, manufactured by Toyobo Co., Ltd., solid content concentration 34% by weight)
Colloidal silica 0.60 parts by mass (Nissan Chemical, MP2040, average particle size 200 nm, solid content concentration 40% by mass)
Surfactant (fluorine-based, solid content concentration 10% by mass) 0.30 parts by mass

The unstretched film was then introduced into a tenter stretching machine, and while holding the ends of the film with clips, it was introduced into a hot air zone at a temperature of 125 ° C., and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, it was heat-set at a temperature of 210 ° C. for 10 seconds, and further relaxed by 3.0%. Thereafter, both ends of the film cooled to 130 ° C. were cut with a shear blade, and the ears were cut off with a tension of 0.5 kg / mm ² , and then wound up to obtain a uniaxially oriented PET film (width 1800 cm) with a film thickness of 50 μm. The center of the obtained film was slit to a width of 50 cm to obtain a film roll (transfer oriented film) with a length of about 500 m.

Experimental Example 16A
A film roll (orientation film for transfer) having a lubricating coating layer formed on the back surface was obtained in the same manner as in Experimental Example 15A, except that the coating liquid was changed to a coating liquid having the following composition.

Water 55.62% by weight
Isopropanol 30.00% by mass
Polyurethane resin (D-1) 11.29% by mass
Oxazoline-based crosslinking agent (E-1) 2.26% by mass
Particles 0.71% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
Particles 0.07% by mass
(Silica sol with an average particle size of 450 nm, solid content concentration of 40% by mass)
Surfactant: 0.05% by mass
(Silicone-based, solid content 100% by weight)
(Solid content concentration 10% by mass)

The polyurethane resin (D-1) and the oxazoline-based crosslinking agent (E-1) in the above composition were produced by the following procedure.
(Production of Polyurethane Resin (D-1))
A polyurethane resin D-1 containing an aliphatic polycarbonate polyol as a constituent component was produced by the following procedure. 43.75 parts by mass of 4,4-diphenylmethane diisocyanate, 12.85 parts by mass of dimethylolbutanoic acid, 153.41 parts by mass of polyhexamethylene carbonate diol having a number average molecular weight of 2000, 0.03 parts by mass of dibutyltin dilaurate, and 84.00 parts by mass of acetone as a solvent were added to a four-neck flask equipped with a stirrer, a Dimroth condenser, a nitrogen inlet tube, a silica gel drying tube, and a thermometer, and the mixture was stirred at 75°C for 3 hours under a nitrogen atmosphere, and it was confirmed that the reaction solution reached a predetermined amine equivalent. Next, the reaction solution was cooled to 40°C, and then 8.77 parts by mass of triethylamine was added to obtain a polyurethane prepolymer solution. Next, 450 g of water was added to a reaction vessel equipped with a homodisper capable of high speed stirring, and the temperature was adjusted to 25°C. The polyurethane prepolymer solution was added and dispersed in water while stirring and mixing at 2000 min-1. Then, acetone and a part of the water were removed under reduced pressure to prepare a water-soluble polyurethane resin (D-1) having a solid content concentration of 35 mass%. The glass transition temperature of the obtained polyurethane resin (D-1) was -30°C.

(Production of Oxazoline-Based Crosslinking Agent (E-1))
A mixture of 58 parts by mass of ion-exchanged water and 58 parts by mass of isopropanol as an aqueous medium, and 4 parts by mass of a polymerization initiator (2,2'-azobis(2-amidinopropane) dihydrochloride) were charged into a flask equipped with a thermometer, a nitrogen gas inlet tube, a reflux condenser, a dropping funnel, and a stirrer. Meanwhile, a mixture of 16 parts by mass of 2-isopropenyl-2-oxazoline as a polymerizable unsaturated monomer having an oxazoline group, 32 parts by mass of methoxypolyethylene glycol acrylate (average number of moles of ethylene glycol added: 9 moles, manufactured by Shin-Nakamura Chemical Co., Ltd.), and 32 parts by mass of methyl methacrylate was charged into the dropping funnel, and the mixture was dropped at 70°C for 1 hour under a nitrogen atmosphere. After the dropping was completed, the reaction solution was stirred for 9 hours and cooled to obtain a water-soluble resin (E-1) having an oxazoline group with a solid content concentration of 40% by mass.

Experimental Example 17A
In Experimental Example 1A, the particle content in the back layer was changed from 300 ppm to 2000 ppm, the thickness ratio of the release layer to the back layer was changed from 10/40 to 25/25, and a flattening and oligomer block coating layer was applied to the release layer surface as in Experimental Example 12A. A film roll (transfer orientation film) was obtained in the same manner as in Experimental Example 1A.

Experimental Example 18A
As a raw material for the release layer side of the transfer orientation film, PET (X-m) resin pellets were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours and then fed to extruder 1, as a raw material for the opposite surface layer (back surface layer), PET (X-m) resin pellets were dried and fed to extruder 2, as a raw material for the intermediate layer, PET (X-m) resin pellets and PET (Z-Si1) resin pellets were blended in a ratio such that the particle content of the intermediate layer was a predetermined value shown in Table 1, dried and fed to extruder 3 and melted at 285 ° C. These three types of molten polymers were each filtered with a stainless steel sintered filter medium (nominal filtration accuracy 10 μm particles 95% cut) and laminated in a three-type three-layer junction block, extruded from a die in the form of a sheet, and then wound around a casting drum with a surface temperature of 30 ° C. using an electrostatic application casting method, cooled and solidified, and an unstretched film was produced. At this time, the discharge amount of each extruder was adjusted so that the thicknesses of the release layer, intermediate layer, and back layer were the predetermined values shown in Table 1. Thereafter, uniaxial stretching was performed in the same manner as in Experimental Examples 1A to 4A to obtain a film roll (oriented film for transfer).

Experimental Example 1B
As a raw material for the release layer side of the transfer orientation film, PET (X-m) resin pellets containing no particles were dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours and then fed to extruder 1, and as a raw material for the opposite surface layer (back surface layer), PET (X-m) resin pellets and polyester (PET (Z-Si1)) resin pellets containing particles were blended in such a ratio that the particle content of the opposite surface layer (back surface layer) was the specified value shown in Table 1, dried, fed to extruder 2, and melted at 285 ° C. These two types of molten polymers were each filtered with a stainless steel sintered filter material (nominal filtration accuracy 10 μm particle 95% cut) in a two-type two-layer confluence block, laminated, extruded in a sheet shape from a die, and then wrapped around a casting drum with a surface temperature of 30 ° C. using an electrostatic application casting method and cooled and solidified to produce an unstretched film. At this time, the discharge amount of each extruder was adjusted so that the thickness of the release layer and the back surface layer were the specified values shown in Table 1.

The unstretched film was introduced into a tenter stretching machine, and while holding the ends of the film with clips, it was introduced into a hot air zone at a temperature of 125 ° C., and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, it was heat-set at a temperature of 210 ° C. for 10 seconds, and further subjected to a 3.0% relaxation treatment. Then, both ends of the film cooled to 130 ° C. were cut with a shear blade, and the ears were cut off with a tension of 0.5 kg / mm ² and then wound up to obtain a uniaxially oriented PET film (width 1800 cm) with a film thickness of 50 μm. The center of the obtained film was slit into a width of 50 cm to obtain a film roll (transfer orientation film) with a length of about 500 m.

Experimental Example 2B
A commercially available biaxially oriented polyester film (Toyobo Ester® Film, E5100, manufactured by Toyobo Co., Ltd.) was used as the orientation film for transfer. The non-corona side was used as the release surface.

Experimental Example 3B
Except for not providing the easy-slip coating layer, the film roll (transfer orientation film) was obtained in the same manner as in Experimental Example 16A. Since wrinkles were generated during winding and stable winding could not be performed, the transfer orientation film was not evaluated. In addition, in the measurement of roughness, the surface that does not contact the casting drum is evaluated as the release surface, and the surface that contacts the casting drum is evaluated as the back surface.

Table 1 shows the production conditions, characteristics, and evaluation results of the transfer alignment films of Experimental Examples 1A to 18A and Experimental Examples 1B to 3B.

As is clear from Table 1, in all of Experimental Examples 1A to 18A, in which the surface roughness of the release surface meets the requirements of the first invention, the number of defects in the case of having a rubbing treatment alignment control layer and the number of defects in the case of having a light alignment control layer were significantly small, and the occurrence of pinhole-shaped and scratch-shaped light leakage was sufficiently suppressed. In contrast, Experimental Example 1B, in which the particle content of the back surface layer is too high and the surface roughness of the release surface is too large, had significantly more defects in the case of having a rubbing treatment alignment control layer and the number of defects in the case of having a light alignment control layer, and was unable to suppress the occurrence of pinhole-shaped and scratch-shaped light leakage. Similarly, Experimental Example 2B, which does not have a lubrication coating layer on the back surface and has a surface roughness of the release surface that is too large compared to Experimental Examples 15A and 16A, had significantly more defects in the case of having a rubbing treatment alignment control layer and the number of defects in the case of having a light alignment control layer, and was unable to suppress the occurrence of pinhole-shaped and scratch-shaped light leakage.

As is clear from Table 1, all of Experimental Examples 1A to 3A, 5A to 16A, and 18A, in which the surface roughness of the surface opposite to the release surface (back surface) satisfies the requirements of the second invention, had significantly fewer defects in the defect evaluation, and the occurrence of light leakage in the form of pinholes or scratches was sufficiently suppressed. In contrast, Experimental Example 3B, in which the surface roughness of the back surface is too small because it does not contain particles and does not have an easy-slip coating layer applied to the back surface, had poor winding stability and could not be wound stably. Moreover, Experimental Examples 4A and 1B, in which the particle content of the back surface layer was too high and the surface roughness of the back surface was too large, had significantly more defects 1 and 2, especially after lamination, and the occurrence of light leakage in the form of pinholes or scratches could not be suppressed.

The alignment film for transferring an alignment layer of a liquid crystal compound of the present invention uses a film whose surface roughness is controlled within a specific range as an alignment film for transferring a retardation layer or a polarizing layer, and further uses a film whose surface roughness on the surface opposite to the release surface is controlled within a specific range as an alignment film for transferring a retardation layer or a polarizing layer, so that the alignment state and phase difference of the liquid crystal compound in the retardation layer or polarizing layer can be as designed, and a retardation layer or polarizing layer (liquid crystal compound alignment layer) with reduced occurrence of defects such as pinholes can be formed. Therefore, according to the present invention, a retardation layer-laminated polarizing plate such as a circular polarizing plate can be stably manufactured with high quality.

Claims (15)

A laminate for transferring a liquid crystal compound alignment layer, comprising a liquid crystal compound alignment layer and a stretched alignment film as a transfer film,
The liquid crystal compound alignment layer is a layer in which a composition containing a polymerizable liquid crystal compound is fixed in an aligned state,
The liquid crystal compound alignment layer comprises at least
A polarizing film containing a polymerizable liquid crystal compound and a dichroic dye;
A retardation layer of an A plate using a rod-like liquid crystal compound or a discotic liquid crystal compound;
a retardation layer of an O-plate using a discotic liquid crystal compound;
The stretched and oriented film has a release surface having a surface roughness (SRa) of 1 nm or more and 11 nm or less, and a back surface having a surface roughness (SRa) of 1 nm or more and 45 nm or less. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, characterized in that the 10-point surface roughness (SRz) of the release surface of the stretched alignment film is 5 nm or more and 200 nm or less. The laminate for transferring a liquid crystal compound alignment layer according to claim 1 or 2, characterized in that the 10-point surface roughness (SRz) of the back surface of the stretched alignment film is 10 nm or more and 1500 nm or less. The laminate for transferring a liquid crystal compound alignment layer according to any one of claims 1 to 3, characterized in that the stretched alignment film is a polyester film. A method for producing a laminate for transferring a liquid crystal compound alignment layer, comprising laminating a liquid crystal compound alignment layer and a stretched alignment film as a transfer film, the method comprising the steps of:
The liquid crystal compound alignment layer is a layer in which a composition containing a polymerizable liquid crystal compound is fixed in an aligned state,
The liquid crystal compound alignment layer comprises at least
A polarizing film containing a polymerizable liquid crystal compound and a dichroic dye;
A retardation layer of an A plate using a rod-like liquid crystal compound or a discotic liquid crystal compound;
a retardation layer of an O-plate using a discotic liquid crystal compound,
A method for producing a laminate for transferring a liquid crystal compound alignment layer, comprising the following steps (A) and (B):
(A) preparing a stretch-oriented film having a surface roughness (SRa) of a release surface of 1 nm or more and 11 nm or less and a surface roughness (SRa) of a back surface of 1 nm or more and 45 nm or less;
(B) A step of fixing the polymerizable liquid crystal compound in an oriented state on the release surface side of the stretched and oriented film. The method for producing a laminate for transferring a liquid crystal compound alignment layer according to claim 5, wherein the step of fixing the polymerizable liquid crystal compound in an aligned state includes any one of the following methods (a), (b), and (c):
(a) A method of coating a liquid crystal compound alignment layer on a release surface of a stretched alignment film to effect alignment, in which the release surface of the stretched alignment film is subjected to a rubbing treatment to impart an alignment control function;
(b) A method in which a liquid crystal compound alignment layer is applied to the release surface of a stretched alignment film to align the liquid crystal compound, and the liquid crystal compound is directly oriented by irradiating the liquid crystal compound with polarized light after coating;
(c) A method in which an orientation control layer is provided on the release surface of a stretched orientation film, and a liquid crystal compound orientation layer is provided on the orientation control layer by coating. The method for producing a laminate for transferring a liquid crystal compound alignment layer according to claim 5 or 6, characterized in that the 10-point surface roughness (SRz) of the release surface of the stretched alignment film is 5 nm or more and 200 nm or less. The method for producing a laminate for transferring a liquid crystal compound alignment layer according to any one of claims 5 to 7, characterized in that the surface roughness (SRa) of the surface of the stretched alignment film opposite to the liquid crystal compound alignment layer is 10 nm or more and 1500 nm or less. The method for producing a laminate for transferring a liquid crystal compound alignment layer according to any one of claims 5 to 8, characterized in that the stretched orientation film is a polyester film. A method for producing a liquid crystal compound alignment layer laminated polarizing plate, comprising a step of laminating a liquid crystal compound alignment layer surface of a laminate for transferring a liquid crystal compound alignment layer, the liquid crystal compound alignment layer being a retardation layer of an A plate using a rod-shaped liquid crystal compound or a discotic liquid crystal compound, or a retardation layer of an O plate using a discotic liquid crystal compound, to a polarizing plate to form an intermediate laminate, and a step of peeling off a stretched alignment film from the intermediate laminate. A method for producing a liquid crystal compound alignment layer laminated polarizing plate, comprising the steps of: obtaining a laminate for transferring a liquid crystal compound alignment layer, in which the liquid crystal compound alignment layer is a retardation layer of an A plate using a rod-shaped liquid crystal compound or a discotic liquid crystal compound, or a retardation layer of an O plate using a discotic liquid crystal compound, by the method according to any one of claims 5 to 9; bonding the liquid crystal compound alignment layer surface of the obtained laminate for transferring a liquid crystal compound alignment layer to a polarizing plate to form an intermediate laminate; and peeling off the stretched alignment film from the intermediate laminate. A method for inspecting the orientation state of a liquid crystal compound orientation layer in a laminate according to any one of claims 1 to 4, comprising the steps of irradiating the laminate from the stretched orientation film surface with linearly polarized light having an electric field oscillation direction parallel to the orientation direction of the stretched orientation film, or a direction perpendicular to the orientation direction, or a flow direction of the stretched orientation film, or a direction perpendicular to the flow direction, and receiving the light on the liquid crystal compound orientation layer surface side. A method for inspecting the alignment state of the liquid crystal compound alignment layer in the laminate according to any one of claims 1 to 4, comprising the steps of irradiating the liquid crystal compound alignment layer surface of the laminate with elliptically polarized light and receiving the light on the stretched alignment film surface side. A method for inspecting the orientation state of the liquid crystal compound orientation layer in the laminate according to any one of claims 1 to 4, comprising the steps of irradiating the stretched orientation film surface of the laminate with linearly polarized light having an electric field oscillation direction parallel to the orientation direction of the stretched orientation film, or a direction perpendicular to the orientation direction, or a flow direction of the stretched orientation film, or a direction perpendicular to the flow direction, reflecting the light transmitted through the laminate with a mirror reflector provided on the liquid crystal compound orientation layer side of the laminate, and receiving the reflected light on the stretched orientation film side. A method for inspecting the alignment state of the liquid crystal compound alignment layer in the laminate according to any one of claims 1 to 4, comprising at least the steps of irradiating the laminate with polarized light to pass the polarized light through the laminate and receiving the polarized light that has passed through the laminate, characterized in that the polarized light passing through the stretched alignment film of the laminate is linearly polarized light having an electric field oscillation direction parallel to the alignment direction of the stretched alignment film, or a direction perpendicular to the alignment direction, or to the flow direction of the stretched alignment film, or a direction perpendicular to the flow direction, or the polarized light passing through the liquid crystal compound alignment layer surface of the laminate is elliptically polarized light.