CN112771422B

CN112771422B - Film for transferring alignment layer of liquid crystal compound

Info

Publication number: CN112771422B
Application number: CN201980064152.9A
Authority: CN
Inventors: 佐佐木靖; 村田浩一
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2018-10-26
Filing date: 2019-10-21
Publication date: 2023-10-24
Anticipated expiration: 2039-10-21
Also published as: WO2020085309A1; TW202033632A; KR20210082163A; JPWO2020085310A1; CN112771423B; KR20210082159A; WO2020085307A1; JPWO2020085308A1; TWI824046B; KR20210079272A; WO2020085310A1; TW202033339A; CN112805136B; CN112771423A; JPWO2020085309A1; CN112805136A; CN112789531B; WO2020085308A1; JPWO2020085307A1; CN112789531A

Abstract

Providing: the cellulose transfer film is used for transferring a liquid crystal compound alignment layer, and can form a retardation layer and a polarizing layer (liquid crystal compound alignment layer) which reduce the occurrence of dead spots such as pinholes. A film for transferring a liquid crystal compound alignment layer, characterized in that it is a cellulose-based film for transferring a liquid crystal compound alignment layer to an object, and the surface roughness (SRa) of the release surface of the film is 1nm to 30 nm.

Description

Film for transferring alignment layer of liquid crystal compound

Technical Field

The present invention relates to a transfer film for transferring an alignment layer of a liquid crystal compound. More specifically, it relates to: a transfer film for transferring a liquid crystal compound alignment layer, which can be used in the production of a polarizing plate such as a circularly polarizing plate having a phase difference layer formed of a liquid crystal compound alignment layer laminated thereon, a phase difference plate, a polarizing plate having a polarizing layer formed of a liquid crystal compound alignment layer, and the like.

Background

Conventionally, in an image display device, a circularly polarizing plate is disposed on a panel surface on a viewer side of an image display panel in order to reduce reflection of external light. The circularly polarizing plate is composed of a laminate of a linearly polarizing plate and a lambda/4 equal phase difference film, and external light facing the panel surface of the image display panel is converted into linearly polarized light by the linearly polarizing plate, and then into circularly polarized light by the lambda/4 equal phase difference film. When external light based on circularly polarized light is reflected on the surface of the image display panel, the rotation direction of the polarization plane is reversed, and the reflected light is reversely converted into linearly polarized light in the direction shielded by the linear polarizing plate by the lambda/4 or other phase difference film, and then shielded by the linear polarizing plate, so that the emission to the outside can be suppressed. In this way, a circularly polarizing plate is used in which a thin film having a phase difference of λ/4 or the like is bonded to a polarizing plate.

As the retardation film, a separate retardation film such as a stretched film of cyclic olefin (see patent document 1), polycarbonate (see patent document 2), or triacetyl cellulose (see patent document 3) is used. As the retardation film, a retardation film having a laminate of a retardation layer formed of a liquid crystal compound on a transparent film is used (see patent documents 4 and 5). In the above description, it is described that the liquid crystal compound can be transferred when a retardation layer (liquid crystal compound alignment layer) formed of the liquid crystal compound is provided.

In addition, patent document 6 and the like discloses a method of forming a retardation film by transferring a retardation layer formed of a liquid crystal compound to a transparent film. A method of forming a λ/4 thin film by providing a phase difference layer formed of a liquid crystal compound such as λ/4 on a transparent thin film by such a transfer method is also known (see patent documents 7 and 8).

In these transfer methods, various substrates are described as the transfer substrate, and a large number of transparent resin films such as polyester, triacetylcellulose, cyclic polyolefin, and the like are exemplified. Among them, since a cellulose-based film such as triacetyl cellulose has no refractive index anisotropy, it is preferable to check (evaluate) the state of the retardation layer in a state where the retardation layer is provided on the film base material.

However, when a retardation layer laminated polarizing plate (circular polarizing plate) produced using a cellulose film such as triacetyl cellulose as a film base material for transfer is used for antireflection of an image display device, pinhole-like or scratch-like light leakage may occur, which is a problem.

In addition, the following methods are also known: a polarizing plate is produced by transferring a polarizing layer (liquid crystal compound alignment layer) containing a liquid crystal compound and a dichroic dye, which is laminated on a transfer film, to a protective film, but in this case, similar to the above, pinhole-like or scratch-like light leakage may occur, which is a problem.

Prior art literature

Patent literature

Patent document 1: japanese patent application laid-open No. 2012-56222

Patent document 2: japanese patent application laid-open No. 2004-144943

Patent document 3: japanese patent laid-open No. 2004-46166

Patent document 4: japanese patent laid-open No. 2006-243653

Patent document 5: japanese patent laid-open No. 2001-4837

Patent document 6: japanese patent laid-open No. 4-57017

Patent document 7: japanese patent laid-open No. 2014-071381

Patent document 8: japanese patent application laid-open No. 2017-146616

Disclosure of Invention

Problems to be solved by the invention

The present invention has been made in view of the above-described problems of the prior art. That is, the present invention is intended to provide: a cellulose transfer film for transferring a liquid crystal compound alignment layer, wherein the transfer film is capable of forming a retardation layer and a polarizing layer (liquid crystal compound alignment layer) which reduce occurrence of dead spots such as pinholes.

Solution for solving the problem

In order to achieve the above object, the present inventors studied the cause of occurrence of defects such as pinholes in a retardation layer laminated polarizing plate (circularly polarizing plate) produced using a cellulose film as a film base material for transfer. The result shows that: the microstructure of the surface of the film base material greatly affects the alignment state and the retardation of the liquid crystal compound in the retardation layer formed of the liquid crystal compound formed on the film base material, and sometimes the alignment state and the retardation according to the design cannot be obtained, and thus, dead spots such as pinholes are generated. The inventors of the present invention have focused on the surface roughness of the film base material shown by specific parameters in these minute structures, and have found that: the present invention has been completed by using a film substrate having a surface roughness controlled to be within a specific range, and thereby forming a retardation layer and a polarizing layer (liquid crystal compound alignment layer) which reduce the occurrence of dead spots such as pinholes without causing the above-described conventional problems.

That is, the present invention has the following configurations (1) to (4).

(1) A transfer film for a liquid crystal compound alignment layer, characterized in that it is a cellulose film for transferring a liquid crystal compound alignment layer to an object, and the surface roughness (SRa) of the release surface of the transfer film is 1nm to 30 nm.

(2) The liquid crystal compound alignment layer transfer film according to (1), wherein the ten-point surface roughness (SRz) of the release surface of the transfer film is 5nm to 200 nm.

(3) A laminate for transferring a liquid crystal compound alignment layer, which is a laminate comprising a liquid crystal compound alignment layer and a transfer film, wherein the transfer film is the transfer film of (1) or (2).

(4) A method for manufacturing a liquid crystal compound alignment layer laminated polarizing plate, comprising the steps of: a step of bonding a polarizing plate to the liquid crystal compound alignment layer of the laminate of (3) to form an intermediate laminate; and a step of peeling the transfer film from the intermediate laminate.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since a cellulose-based film having a surface roughness controlled within a specific range is used as a transfer film for a retardation layer or a polarizing layer, the alignment state and the retardation of a liquid crystal compound in the retardation layer or the polarizing layer can be designed, and therefore, a retardation layer or a polarizing layer (liquid crystal compound alignment layer) having reduced occurrence of dead spots such as pinholes can be formed.

Detailed Description

The transfer film of the present invention is used for transferring a liquid crystal compound alignment layer to an object (other transparent resin film, polarizing plate, etc.), and has a surface roughness (SRa) of a release surface of the transfer film of 1nm to 30 nm. The transfer film may be a single film, or a release layer may be provided on a film serving as a base material by coating or the like. In addition, an antistatic layer, an easy-slip layer, or the like may be provided on the back surface. In the present invention, a transfer film alone without using a layer such as a release coating layer, a transfer film having a release coating layer, a back coating layer, or the like, and a transfer film having a coating layer, a film having a state before the coating layer, or the like, are collectively referred to as a base film.

The resin constituting the film base material used in the transfer film of the present invention is a cellulose-based resin, and among these, triacetyl cellulose is preferable. Triacetylcellulose can be used as a suitable example for use as an optical film.

The transfer film of the present invention may be a single layer or may be a multilayer structure by coextrusion. In the case of the multilayer, examples thereof include a top layer (release surface side layer a)/back surface side layer (B), a/intermediate layer (C)/a (release surface side layer is the same as back surface side layer), a/C/B, and the like. Further, the structure may be a multi-layer structure of 4 or more layers.

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

The lower limit of the roll length is preferably 100m, more preferably 500m, further preferably 1000m. The upper limit of the roll length is preferably 100000m, more preferably 50000m, further preferably 30000m.

(mold release surface roughness)

The release surface (a layer surface) of the transfer film of the present invention is preferably smooth. In the present invention, the "release surface" of the transfer film means a surface on which the alignment layer of the liquid crystal compound transferred by the transfer film is intended to be provided, among the surfaces of the transfer film. In the case of providing a planarizing coating layer, a release layer, or the like described later, if a liquid crystal compound alignment layer is provided thereon, the surface of these planarizing layer, release layer, or the like (the surface in contact with the liquid crystal compound alignment layer) is the "release surface" of the transfer film.

The lower limit of the three-dimensional arithmetic average roughness (SRa) of the release surface of the transfer film of the present invention is preferably 1nm, more preferably 2nm. If below the above, it may be practically difficult to achieve the value. The upper limit of SRa of the release surface of the transfer film of the present invention is preferably 30nm, more preferably 25nm, further preferably 20nm, particularly preferably 15nm, and most preferably 10nm. If the above is exceeded, the alignment of the liquid crystal compound is sometimes disturbed.

The lower limit of the three-dimensional ten-point average roughness (SRz) of the release surface of the transfer film of the present invention is preferably 5nm, more preferably 10nm, and still more preferably 13nm. If below the above, it may be practically difficult to achieve the value. The upper limit of SRz of the release surface of the transfer film of the present invention is preferably 200nm, more preferably 150nm, further preferably 120nm, particularly preferably 100nm, and most preferably 80nm. If the above is exceeded, the alignment of the liquid crystal compound is sometimes disturbed.

The lower limit of the maximum height of the release surface (SRy: maximum peak height SRp of release surface+maximum valley depth SRv of release surface) of the transfer film of the present invention is preferably 10nm, more preferably 15nm, and still more preferably 20nm. If below the above, it may be practically difficult to achieve the value. The upper limit of SRy of the release surface of the transfer film of the present invention is preferably 300nm, more preferably 250nm, still more preferably 150nm, particularly preferably 120nm, and most preferably 100nm. If the above is exceeded, the alignment of the liquid crystal compound is sometimes disturbed.

The upper limit of the number of protrusions having a height difference of 0.5 μm or more at the release surface of the transfer film of the present invention is preferably 5/m ² More preferably 4/m ² More preferably 3/m ² Particularly preferably 2/m ² Most preferably 1/m ² . If the above is exceeded, the alignment of the liquid crystal compound is sometimes disturbed.

If the roughness of the release surface exceeds the above range, minute portions of the alignment layer of the liquid crystal compound formed on the transfer film of the present invention may not be aligned in accordance with the design, and a phase difference may cause pinhole-like or scratch-like dead spots. The reason for this is considered as follows. First, as described later, it is considered that an alignment control layer such as a rubbing treatment alignment control layer or a photo alignment control layer may be provided between the transfer film and the liquid crystal compound alignment layer, but if the alignment control layer is a rubbing treatment alignment control layer, the alignment control layer in the convex portion is peeled off at the time of rubbing, and the rubbing of the mountain corner portion or the concave portion in the convex portion becomes insufficient, which is a cause of occurrence of a defective dot. In addition, when particles are contained in the release surface layer, the particles fall off during brushing, and scratching the surface is considered to be a cause of occurrence of dead spots. Further, in the case of winding the film in a state where the alignment control layer is provided, no matter the alignment control layer is subjected to brushing treatment or the photo-alignment control layer, the film is rubbed against the back surface layer, and therefore, there is a void in the alignment control layer in the convex portion or the alignment disorder due to pressure is considered to be a cause of occurrence of a defective dot. When the alignment layer of the liquid crystal compound is provided on the alignment control layer due to defects of the alignment control layer, the alignment of the liquid crystal compound is not properly caused in a minute portion thereof, and an alignment state and a retardation according to the design are not obtained, and as a result, it is considered that a pinhole-like or scratch-like dead spot is generated.

In addition, in the case where the alignment layer of the liquid crystal compound is directly formed on the transfer film without providing the alignment control layer, when the liquid crystal compound is applied, the thickness of the alignment layer of the liquid crystal compound becomes thin at the convex portion of the release surface of the transfer film, or conversely, the thickness of the alignment layer of the liquid crystal compound becomes thick at the concave portion of the release surface of the transfer film, and for this reason, it is considered that the failure to obtain a retardation according to the design is also the cause of occurrence of the failure.

In order to set the roughness of the release surface (a) to the above range, the following method is exemplified.

The release surface side layer (surface layer) of the base film is made free of particles.

When the release surface side layer (surface layer) of the base film contains particles, the particles are made small in particle diameter.

Smoothing the casting belt.

Reducing the solvent content of the substrate film when the substrate film is peeled from the casting belt.

In the case where the release surface side layer (surface layer) of the base film contains particles, a planarizing coating layer is provided.

In the present invention, the "release surface side layer" of the base film means a layer having a release surface among the layers of the resin constituting the base film. Here, when the base film is a single layer, the base film may be referred to as a release surface side layer. In this case, the back surface side layer and the release surface side layer, which will be described later, are the same layer.

In addition to the above, it is also important to clean the raw materials and the production steps as follows.

The particle dispersion, triacetyl cellulose solution, and cast dope added to the dope are filtered.

Filtering the coating agent to remove the foreign matter.

Film formation, coating and drying are performed in a clean environment.

The surface layer is preferably substantially free of particles for smoothing. Substantially free of particles means that the particle content is less than 50ppm, preferably less than 30ppm.

In order to improve the sliding properties of the surface, the surface layer may contain particles. In the case of containing particles, the lower limit of the surface layer particle content is preferably 0ppm, more preferably 50ppm, further preferably 100ppm. The upper limit of the surface layer particle content is preferably 20000ppm, more preferably 10000ppm, further preferably 8000ppm, particularly preferably 6000ppm. If the roughness exceeds the above range, the roughness of the surface layer may not be in a preferable range.

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

Even when the surface layer contains no particles or particles having a small particle diameter are formed, the roughness of the release surface layer may be increased by the influence of the particles in the lower layer when the particles are contained in the lower layer. In this case, it is preferable to use a method of increasing the thickness of the release surface layer, or providing a lower layer (intermediate layer) containing no particles, or the like.

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

The particle-free intermediate layer is understood to mean a layer which is substantially free of particles, the content of particles being less than 50ppm, preferably less than 30ppm. The lower limit of the thickness of the intermediate layer is preferably 10%, more preferably 20%, and still more preferably 30% relative to the total thickness of the transfer film. The upper limit is preferably 95%, more preferably 90%.

When the roughness of the surface layer of the transfer film (base film) is high, a planarizing coating layer may be provided. Examples of the resin used for the planarizing coating layer include resins commonly used as coating agents, such as polyesters, acrylics, polyurethanes, polystyrenes, and polyamides. Crosslinking agents such as melamine, isocyanate, epoxy resin, oxazoline compounds are also preferably used. They are applied as a coating agent dissolved or dispersed in an organic solvent, water and dried. Or acrylic, can be solvent-free coated and cured under radiation. The planarizing coating may be an oligomeric barrier coating. In the case of providing the release layer by coating, the release layer itself may be thickened.

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

The planarization coating may be applied in-line during film formation, or may be applied off-line.

(demolding surface)

The resulting base film may have either one of the casting belt surface and the opposite surface as a release surface, and since the roughness of the casting belt surface is generally reduced, the casting belt surface is preferably the release surface.

(Release layer)

The obtained base film can be used as a transfer film as it is, as long as it has peelability from a transfer material (liquid crystal compound alignment layer). In order to adjust the releasability, the film may be surface-treated. The surface treatment may be saponification treatment, corona treatment, plasma treatment, or the like.

In addition, a release layer may be provided. As the release layer, a known release agent can be used, and alkyd resins, amino resins, long-chain acrylic acrylates, silicone resins, and fluororesin are preferable. These may be appropriately selected depending on the adhesion to the transfer material. In order to improve the adhesion between the substrate film and the release layer, the substrate film may be subjected to a surface treatment. The surface treatment may be the above-mentioned treatment. In addition, an easy-to-adhere coating may be performed.

(Back side roughness)

In addition, even if the release surface of the transfer film of the present invention is made smooth, there is a case where a defective dot is generated in the liquid crystal compound alignment layer. This is known to be because the transfer film is supplied in a state of being wound in a roll, the front surface is in contact with the back surface, and the roughness of the back surface is transferred to the front surface (the convex portion of the back surface is transferred to the release layer to form the concave portion). In some cases, a masking film is attached to a transfer film provided with a liquid crystal compound alignment layer to protect the liquid crystal compound alignment layer, but the masking film is directly wound to reduce the cost. When the liquid crystal compound alignment layer is wound in this manner, the liquid crystal compound alignment layer is thought to have a phenomenon of sagging due to the convex portion on the back surface, or a phenomenon of cavitation or alignment disorder. In addition, it is considered that, when the liquid crystal compound alignment layer is provided after the liquid crystal compound alignment layer is not wound in a state where the liquid crystal compound alignment layer is provided, a hole is generated in the liquid crystal compound alignment layer due to the convex portion on the back surface, and the alignment is disturbed. Particularly, these phenomena are easily caused by high pressure in the core portion. Based on the above findings, it is possible to prevent the above-described dead spots by setting the roughness of the surface (back surface) opposite to the parting surface to be within a specific range.

The lower limit of the three-dimensional arithmetic average roughness (SRa) of the back surface of the transfer film of the present invention is preferably 3nm, more preferably 4nm, and still more preferably 5nm. If the amount is less than the above, the sliding property is deteriorated, and the sliding property may be impaired during roll transport or winding, and scratches may be easily caused. The upper limit of SRa on the back surface of the transfer film of the present invention is preferably 50nm, more preferably 45nm, and still more preferably 40nm. If the number exceeds the above, the number of dead spots may be increased.

The lower limit of the three-dimensional ten-point average roughness (SRz) of the back surface of the transfer film of the present invention is preferably 15nm, more preferably 20nm, and still more preferably 25nm. The upper limit of the SRz of the back surface of the transfer film of the present invention is preferably 1500nm, more preferably 1200nm, further preferably 1000nm, particularly preferably 700nm, and most preferably 500nm. If the number exceeds the above, the number of dead spots may be increased.

The lower limit of the maximum height of the back surface (SRy: back surface maximum peak height SRp+back surface maximum valley depth SRv) of the transfer film of the present invention is preferably 20nm, more preferably 30nm, still more preferably 40nm, particularly preferably 50nm. The maximum height SRy of the back surface of the transfer film of the present invention is preferably 2000nm, more preferably 1500nm, still more preferably 1200nm, particularly preferably 1000nm, and most preferably 700nm. If the number exceeds the above, the number of dead spots may be increased.

The upper limit of the number of protrusions having a height difference of 2 μm or more on the back surface of the transfer film of the present invention is preferably 5/m ² More preferably 4/m ² More preferably 3/m ² Particularly preferably 2/m ² Most preferably 1/m ² . If the number exceeds the above, the number of dead spots may be increased.

When the roughness of the back surface of the transfer film of the present invention is lower than the above range, the film may have poor slip properties, and may be less likely to slip during roll transport, winding, or the like, and may be likely to cause scratches. In addition, during winding when a film is produced, winding is unstable, wrinkles are generated, defective products are produced, irregularities at the end of the wound roll become large, and meandering of the film is easily caused in the subsequent steps, or breakage is easily caused.

If the roughness of the back surface of the transfer film of the present invention exceeds the above, the above-mentioned dead spots are likely to occur.

In order to make the roughness of the back surface within the above range, the following method is given.

The back side layer (back layer) of the base film is made to contain specific particles.

The intermediate layer of the substrate film is reduced in thickness so as not to contain particles on the back surface layer side (back surface layer) using a layer containing particles.

When the roughness of the back surface side layer (back surface layer) of the base material film is large, a planarizing coating layer is provided.

When the back surface side layer (back surface layer) of the base film contains no particles and has a small roughness, an easy-slip coating layer (particle-containing coating layer) is provided.

The lower limit of the particle diameter of the back surface layer is preferably 0.005 μm, more preferably 0.01 μm, still more preferably 0.05 μm, particularly preferably 0.1 μm. If the amount is less than the above, the slip property may be deteriorated, and winding failure may be caused. The upper limit of the particle diameter of the back surface layer is preferably 5. Mu.m, more preferably 3. Mu.m, and still more preferably 2. Mu.m. If it exceeds the above, the back surface may be excessively roughened.

In the case where the back surface contains particles, the lower limit of the particle content of the back surface layer is preferably 50ppm, more preferably 100ppm. If the amount is less than the above, the effect of slidability by the addition of particles may not be obtained. The upper limit of the particle content of the back surface layer is preferably 10000ppm, more preferably 7000ppm, and still more preferably 5000ppm. If it exceeds the above, the back surface may be excessively roughened.

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

It is also preferred that the intermediate layer contains particles and the back layer is thinned without particles to control the roughness of the back surface. By taking this form, the roughness of the back surface can be ensured while preventing the particles from falling off.

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

In the case where the back surface of the base film is rough, it is preferable to provide a planarizing coating layer. The planarizing coating may be the same as those exemplified in the planarizing coating of the surface.

The lower limit of the thickness of the back surface planarizing coating layer is preferably 0.01 μm, more preferably 0.03 μm, and further preferably 0.05 μm. If it is lower than the above, the effect of planarization may be small. The upper limit of the thickness of the back surface planarizing coating layer is preferably 10 μm, more preferably 5 μm, and still more preferably 3 μm. Even if the above is exceeded, the effect of planarization is saturated.

An easy slip coating containing particles may be provided on the back side. The slip-coat layer is effective when the back surface side of the base film contains no particles and has insufficient roughness.

The lower limit of the particle diameter of the back slip coating layer is preferably 0.01 μm, more preferably 0.05 μm. If the amount is less than the above, the slipperiness may not be obtained. The upper limit of the particle diameter of the back surface slip coat layer is preferably 5 μm, more preferably 3 μm, still more preferably 2 μm, and particularly preferably 1 μm. If the above is exceeded, the roughness of the back surface is sometimes too high.

The lower limit of the particle content of the back-side slip coating layer is preferably 0.1 mass%, more preferably 0.5 mass%, further preferably 1 mass%, particularly preferably 1.5 mass%, and most preferably 2 mass%. If the amount is less than the above, the slipperiness may not be obtained. The upper limit of the particle content of the back surface slip coating layer is preferably 20 mass%, more preferably 15 mass%, and still more preferably 10 mass%. If the above is exceeded, the roughness of the back surface is sometimes too high.

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

In the case of providing these coatings, the substrate film is preferably subjected to the surface treatment and the adhesion-facilitating coating.

The cellulose film can be produced by a general method such as a casting method or a melt extrusion method. Hereinafter, a casting method will be briefly described as an example.

First, a cellulose resin is dissolved in a solvent to prepare a dope in which particles are dispersed, if necessary. In the case of adding the particles, it is also preferable to prepare a dispersion of the particles in advance and add it to a solution of the cellulose resin.

In order to achieve an appropriate surface roughness, the dispersion of particles and the cement are preferably filtered by a filter to remove coarse particles. The lower limit of the filtration accuracy of the filter used is preferably 0.5 μm, more preferably 1 μm. The upper limit of the filtration accuracy of the filter is preferably 100. Mu.m, more preferably 50. Mu.m, still more preferably 25. Mu.m, particularly preferably 20. Mu.m, most preferably 10. Mu.m. The value thereof can be suitably determined depending on the particle diameter of the added particles.

The cement flows out of the die and spreads on a casting belt of metal or the like.

Casting belt roughness (conveyer belt roughness)

The lower limit of the casting belt roughness (SRa) is preferably 1nm, more preferably 2nm. The upper limit of the casting belt roughness (SRa) is preferably 15nm, more preferably 12nm.

The lower limit of the casting belt roughness (SRz) is preferably 1nm, more preferably 2nm. The upper limit of the casting belt roughness (SRz) is preferably 50nm, more preferably 40nm.

The lower limit of the maximum height (SRy) of the roughness of the casting belt is preferably 2nm. The upper limit of the maximum height (SRy) of the roughness of the casting belt is preferably 100nm.

By setting the parameters of the respective roughnesses of the casting belt to the above-described ranges, it becomes easy to control the roughness of the base material film to an appropriate range.

And (3) blowing air to the adhesive cement on the casting belt to remove the solvent. The air supply temperature is preferably 20 to 100 ℃. The upper limit of the blowing temperature is preferably not more than the boiling point of the solvent contained in the cement. In addition, the temperature is also preferably higher for the latter half. The air volume is preferably initially small to prevent the cement surface from waving due to wind or the latter half becoming large. The dope (film) from which the solvent has been removed to some extent is peeled off from the casting belt, and is further led to a drying step.

(solvent content)

The roughness of the casting belt face of the film when the film is peeled from the casting belt substantially reflects the roughness of the casting belt surface. However, a large amount of solvent generally remains in the film at the time of peeling from the casting tape, and the amount of the remaining solvent is removed to 1% or less in the subsequent drying step. At this time, the volume is reduced, and the irregularities generated by the particles gradually float on the surface of the film. Therefore, by reducing the solvent content of the film when the film is peeled from the casting belt, it is possible to reduce the volume shrinkage thereof or to reduce the irregularities of the surface. In contrast, fine adjustment is performed by increasing the amount of residual solvent to increase the irregularities.

The lower limit of the residual solvent at the time of stripping of the casting belt is preferably 10 mass%, more preferably 15 mass%, further preferably 20 mass%, particularly preferably 25 mass%. If it is lower than the above, the drying time becomes long, or the productivity sometimes decreases. The upper limit of the residual solvent at the time of stripping of the casting tape is preferably 250 mass%, more preferably 200 mass%, further preferably 150 mass%, particularly preferably 100 mass%, and most preferably 80 mass%. If the amount exceeds the above, the roughness may be increased or the film forming property may be lowered.

In the drying step, it is possible to use: a flow dryer in which a film is floated by blowing dry air from above and below and fed, a roll dryer in which a plurality of rolls are provided in the dryer, and the film is gradually fed in a W-shape over the rolls, a tenter dryer in which both ends of the film are held by jigs and dried in a tenter, and the like. They may be used in suitable combination. Among these, drying is preferably performed at 50 to 170℃and more preferably at 60 to 160 ℃. In addition, it is also preferable to apply some stretching in the flow direction by using the peripheral speed difference of the rolls, or to expand the clip width in the tenter and apply some stretching in the width direction. Also depending on the purpose, the stretching ratio is preferably 101 to 200%, more preferably 103 to 150%, particularly preferably 105 to 130%. By setting the above range, the retardation of the cellulose film can be maintained low, and the alignment state of the alignment layer of the liquid crystal compound together with the film can be easily and accurately inspected. In addition, the folds of the film are pressed, or the uniformity of the thickness can be improved.

The dried film is wound around a core. When winding, thickness alignment (cutting) can be performed on both ends.

The lower limit of the residual solvent of the final film is preferably 0%, more preferably 0.001%. If below the above, it may be practically difficult to achieve the value. The upper limit of the final residual solvent is preferably 2%, more preferably 1%, and still more preferably 0.5%. When the content is within the above range, the dimensional stability is excellent when the film is used as a release film.

In the case of performing the in-line coating, it is preferable to perform the coating before a tenter dryer and before a flow dryer used for drying the film, and to dry the film in these dryers, but a separate coating-dryer may be provided after drying the film.

The air in these steps is preferably air having a class 10000 or less and a class 1000 or less by a HEPA filter or the like.

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

(in-plane retardation of transfer film)

The in-plane retardation of the transfer film of the present invention is preferably low. Specifically, the in-plane retardation of the transfer film of the present invention is preferably 50nm or less, more preferably 30nm or less, still more preferably 20nm or less, particularly preferably 10nm or less. By setting the in-plane retardation of the transfer film to the above range, the alignment state of the liquid crystal compound alignment layer can be checked by irradiating linearly polarized light in a state in which the liquid crystal compound alignment layer is laminated on the transfer film. For example, when the liquid crystal compound alignment 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 under inspection, the polarized light of elliptical polarized light is returned to linearly polarized light by the retardation layer through the other retardation layer, and light reception is performed through the polarizing plate in which the linearly polarized light is in an extinction state. Thus, when there is a pinhole-like dead spot in the retardation layer, the dead spot can be detected as a bright spot.

The retardation of the transfer film can be obtained by measuring the refractive index and thickness in the 2-axis direction, or by using a commercially available automatic birefringence measuring apparatus such as KOBRA-21ADH (from prince measuring instruments Co., ltd.).

In order to make the in-plane retardation of the transfer film fall within the above range, the following method is exemplified: in the case where stretching is not performed in the film forming step of the base film, or stretching ratio in the flow direction and the width direction is adjusted in the case where stretching is performed, or as triacetyl cellulose used as a raw material, one having low birefringence of an acetyl group or an additive adjusted is used.

The lower limit of the haze of the transfer film of the present invention is preferably 0.01%, more preferably 0.1%. If below the above, it may be practically difficult to achieve the value. The upper limit of the haze of the transfer film of the present invention is preferably 3%, more preferably 2.5%, further preferably 2%, particularly preferably 1.7%. If the amount exceeds the above, polarized light is disturbed when polarized UV is irradiated, and a retardation layer conforming to the design may not be obtained. In addition, light leakage may occur due to diffuse reflection when inspecting the retardation layer, and inspection may become difficult.

The lower limit of the antistatic property (surface resistance) of the transfer film of the present invention is preferably 1X 10 ⁵ Ω/≡, more preferably 1×10 ⁶ Ω/≡. Even if the effect is lower than the above, the effect is saturated and the effect higher than the above may not be obtained. The upper limit of antistatic property (surface resistance) of the transfer film of the present invention is preferably 1×10 ¹³ Ω/≡, more preferably 1×10 ¹² Ω/≡, further preferably 1×10 ¹¹ Ω/≡. If the amount exceeds the above, the repulsion due to static electricity is generated, or the alignment direction of the liquid crystal compound may be disturbed. The antistatic property (surface resistance) can be set within the above range by kneading an antistatic agent into the transfer film, providing an antistatic coating layer on the lower layer or the opposite surface of the release layer, or adding an antistatic agent to the release layer.

Examples of antistatic agents to be added to the antistatic coating layer, the release layer, and the transfer film include conductive polymers such as polyaniline and polythiophene, ionic polymers such as polystyrene sulfonate, and conductive fine particles such as tin-doped indium oxide and antimony-doped tin oxide.

The transfer film may be provided with a release layer. However, the film itself has low adhesion to the transfer material such as the retardation layer and the alignment layer, and when the release layer is not provided, the release layer may not be provided, if sufficient release properties are obtained. In the case where the adhesion is too low, the surface may be subjected to corona treatment or the like to adjust the adhesion. The release layer may be formed using a known release agent, and alkyd resins, amino resins, long-chain acrylic acrylates, silicone resins, and fluororesin may be used as preferable examples. These may be appropriately selected depending on the adhesion to the transfer material.

(laminate for transferring alignment layer of liquid Crystal Compound)

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 the transfer film of the present invention are laminated. The liquid crystal compound alignment layer must be coated on the transfer film and aligned. As a method of orientation, there are the following methods: a method of applying an alignment control function by subjecting a lower layer (release surface) of the alignment layer of the liquid crystal compound to a brushing treatment or the like; a method of directly aligning a liquid crystal compound by applying a liquid crystal compound and then irradiating the liquid crystal compound with polarized ultraviolet rays or the like.

(orientation control layer)

In addition, a method of providing an alignment control layer on the transfer film and providing a liquid crystal compound alignment layer on the alignment control layer is also preferable. In the present invention, the alignment control layer and the liquid crystal compound alignment layer may be collectively referred to as a liquid crystal compound alignment layer, not as a liquid crystal compound alignment layer alone. The alignment control layer may be any alignment control layer as long as it can bring the liquid crystal compound alignment layer into a desired alignment state, and examples of suitable alignment control layers include a brushing treatment alignment control layer obtained by brushing a resin coating film and a photo alignment control layer having an alignment function by aligning molecules by irradiation with polarized light.

(brushing treatment orientation control layer)

As the polymer material used in the alignment control layer formed by the brushing treatment, polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resins, polysiloxane derivatives, and the like are preferably used.

The method of forming the orientation control layer by the brushing treatment will be described below. First, a coating solution for the alignment control layer containing the polymer material is applied to the release surface of the film, and then heated and dried to obtain the alignment control layer before the brushing treatment. The alignment control layer coating liquid may have a crosslinking agent.

The solvent used for the brushing treatment of the alignment control layer coating liquid is not limited as long as the polymer material is dissolved. Specific examples thereof include alcohols such as water, methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, cellosolve, and the like; ester solvents such as ethyl acetate, butyl acetate, and γ -butyrolactone; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene; ether solvents such as tetrahydrofuran and dimethoxyethane. These solvents may be used alone or in combination.

The concentration of the brushing treatment alignment control layer coating liquid may be appropriately adjusted depending on the type of polymer and the thickness of the alignment control layer to be produced, and is preferably in the range of 0.2 to 20 mass%, particularly preferably 0.3 to 10 mass% in terms of the solid content concentration. As a coating method, a known method such as a coating method such as a gravure coating method, a die coating method, a bar coating method, or an applicator method, or a printing method such as a flexography method can be used.

The heating and drying temperature is preferably in the range of 30 to 170 ℃, more preferably 50 to 150 ℃, and even more preferably 70 to 130 ℃. When the drying temperature is low, a longer drying time is necessary, and productivity is poor. If the drying temperature is too high, the transfer film may be elongated by heat, or may be thermally shrunk to have a large thermal shrinkage, thereby failing to achieve the designed optical function, or may be degraded in planarity. The heating and drying time is, for example, 0.5 to 30 minutes, more preferably 1 to 20 minutes, still more preferably 2 to 10 minutes.

The thickness of the orientation control layer in the brushing treatment is preferably 0.01 to 10. Mu.m, more preferably 0.05 to 5. Mu.m, particularly preferably 0.1 to 1. Mu.m.

Then, a brushing treatment is performed. The brushing treatment can be generally performed by rubbing the surface of the polymer layer with paper or cloth in a constant direction. The surface of the alignment control layer is generally brushed with a brush roll of a napped cloth of fibers such as nylon, polyester, and acrylic. In order to provide a liquid crystal compound alignment control layer aligned in a predetermined direction inclined with respect to the longitudinal direction of the long film, the rubbing direction of the alignment control layer needs to be set at an angle corresponding to the predetermined direction. The angle adjustment can be matched with the angle adjustment of the brush roller and the film, and the adjustment of the conveying speed of the film and the rotating speed of the roller.

The surface of the transfer film may be provided with an orientation control function by directly subjecting the release surface of the transfer film to a brushing treatment, and this is also included in the technical scope of the present invention.

(photo-orientation control layer)

The photo-alignment control layer refers to the following alignment film: a coating liquid containing a polymer or monomer having a photoreactive group and a solvent is applied to a film, and polarized light, preferably polarized ultraviolet light, is irradiated to impart an orientation restriction force. The photoreactive group refers to a group that generates liquid crystal aligning ability by light irradiation. Specifically, a photoreaction, which is the origin of the liquid crystal aligning ability, such as an alignment induction or isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction of molecules generated by irradiation with light, is generated. Among the photoreactive groups, those that cause dimerization reaction or photocrosslinking reaction are preferable in terms of excellent alignment properties and maintaining the smectic liquid crystal state of the liquid crystal compound alignment layer. As the photoreactive group capable of generating the above reaction, an unsaturated bond, particularly 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 the photoreactive group having a c=c bond include a vinyl group, a polyalkenyl group, a distyryl group (stilbene), a stilbene group, an azo stilbene onium group, a chalcone group, and a cinnamoyl group. Examples of the photoreactive group having a c=n bond include groups having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an n=n bond include groups having an azobenzene basic structure such as an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a disazo group, and a formazan group. Examples of the photoreactive group having a c=o bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. These groups may have substituents such as alkyl, alkoxy, aryl, allyloxy, cyano, alkoxycarbonyl, hydroxyl, sulfonic acid, and haloalkyl.

Among them, a photoreactive group capable of causing a photodimerization reaction is preferable, and a photo-alignment layer having a small amount of polarized light irradiation required for photo-alignment of cinnamoyl and chalcone groups, excellent thermal stability and temporal stability is easily obtained is preferable. Further, as the polymer having a photoreactive group, a cinnamoyl group having a structure in which a terminal portion of a side chain of the polymer is cinnamic acid is particularly preferable. Examples of the structure of the main chain include polyimide, polyamide, (meth) acrylic, polyester, and the like.

Specific examples of the orientation control layer include an orientation control layer described in Japanese patent application laid-open No. 2006-285197, japanese patent application laid-open No. 2007-76839, japanese patent application laid-open No. 2007-138138, japanese patent application laid-open No. 2007-94071, japanese patent application laid-open No. 2007-121721, japanese patent application laid-open No. 2007-140465, japanese patent application laid-open No. 2007-156439, japanese patent application laid-open No. 2007-133184, japanese patent application laid-open No. 2009-109831, japanese patent application laid-open No. 2002-229039, japanese patent application laid-open No. 2002-265541, japanese patent application laid-open No. 2002-317013, japanese patent application laid-open No. 2003-520878, japanese patent application laid-open No. 2004-529220, japanese patent application laid-open No. 2013-33248, japanese patent application laid-open No. 2015-7702, and Japanese patent application laid-open No. 2015-129210.

The solvent for the coating liquid for forming the photo-alignment control layer is not limited as long as the polymer having a photoreactive group and the monomer are dissolved. Specific examples of the method for forming the orientation control layer include brushing treatment. It is also preferable to add a photopolymerization initiator, a polymerization inhibitor, and various stabilizers to the coating liquid for forming the photoalignment control layer. In addition, a polymer having a photoreactive group, a polymer other than a monomer, and a monomer having no photoreactive group copolymerizable with the monomer having a photoreactive group may be added.

The concentration of the coating liquid for forming the photo-alignment control layer, the coating method, and the drying conditions may be exemplified by the method for forming the alignment control layer by brushing. The thickness is also the same as the preferred thickness of the brushing process orientation control layer.

The polarized light may be irradiated from the direction of the photo-alignment control layer before alignment or irradiated from the direction of the transfer film surface through the transfer film.

The wavelength of polarized light is preferably in a wavelength region where the photoreactive group of the polymer or monomer having the photoreactive group can absorb light energy. Specifically, ultraviolet rays having a wavelength in the range of 250 to 400nm are preferable. Examples of the light source of the polarized light include ultraviolet light laser such as xenon lamp, high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, krF, arF, etc., and high-pressure mercury lamp, ultra-high-pressure mercury lamp, and metal halide lamp are preferable.

Polarized light can be obtained, for example, by passing light from the aforementioned light source through a polarizing plate. By adjusting the polarization angle of the polarizing plate, the direction of polarized light can be adjusted. Examples of the polarizing plate include polarizing filters, polarizing prisms such as gelan-thompson and gelan-taylor, and wire grid type polarizing plates. The polarized light is preferably substantially parallel light.

By adjusting the angle of the irradiated polarized light, the direction of the orientation restricting force of the photo-orientation control layer can be arbitrarily adjusted.

The irradiation intensity varies depending on the kind and amount of the polymerization initiator and the resin (monomer), and is preferably 10 to 10000mJ/cm, for example, on the basis of 365nm ² Further preferably 20 to 5000mJ/cm ² 。

(alignment layer of liquid Crystal Compound)

The liquid crystal compound alignment layer is not particularly limited as long as the liquid crystal compound is aligned. Specific examples thereof include a polarizing film (polarizing plate) containing a liquid crystal compound and a dichroic dye, and a retardation layer containing a rod-like or plate-like liquid crystal compound.

(polarizing film)

The polarizing film has a function of passing polarized light in only one direction, and includes a dichroic dye.

(dichromatic pigment)

The dichroic dye is a dye having different properties between absorbance in the long axis direction and absorbance in the short axis direction of the molecule.

The dichroic dye preferably has an absorption maximum wavelength (λmax) in the range of 300 to 700 nm. Examples of such a dichroic dye include acridine dye, oxazine dye, cyanine dye, naphthalene dye, azo dye, and anthraquinone dye, and among them, azo dye is preferable. The azo pigment may be monoazo pigment, disazo pigment, trisazo pigment, tetrazo pigment, stilbene azo pigment, or the like, and disazo pigment and trisazo pigment are preferable. The dichroic dye may be used alone or in combination, and 2 or more kinds are preferably used in combination for adjusting (achromatic) color tone. Particularly preferably 3 or more kinds are combined. Particularly, it is preferable to combine 3 or more azo compounds.

Preferred azo compounds include pigments described in Japanese patent application laid-open No. 2007-126628, japanese patent application laid-open No. 2010-168870, japanese patent application laid-open No. 2013-101328, and Japanese patent application laid-open No. 2013-210624.

The dichroic dye is also preferably a dichroic dye polymer introduced into a side chain of a polymer such as an acrylic polymer. Examples of the dichroic dye polymers include polymers listed in Japanese patent application laid-open No. 2016-4055 and polymers obtained by polymerizing compounds of [ chemical 6] to [ chemical 12] of Japanese patent application laid-open No. 2014-206682.

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, still more preferably 1.0 to 15% by mass, and particularly preferably 2.0 to 10% by mass, in the polarizing film, from the viewpoint of improving the alignment of the dichroic dye.

The polarizing film preferably further contains a polymerizable liquid crystal compound to improve film strength, polarization degree, and film uniformity. The polymerizable liquid crystal compound herein also includes a substance after polymerization as a film.

(polymerizable liquid Crystal Compound)

The polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity.

The polymerizable group is a group participating in polymerization reaction, and is preferably a photopolymerizable group. The photopolymerizable group is a group that can undergo polymerization reaction by a living radical, an acid, or the like generated by a photopolymerization initiator described later. Examples of the polymerizable group include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, oxiranyl, oxetanyl, and the like. Among them, acryloyloxy, methacryloyloxy, ethyleneoxy, ethyleneoxide, and oxetanyl groups are preferable, and acryloyloxy is more preferable. The compound exhibiting liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal, or may be a nematic liquid crystal or a smectic liquid crystal in the thermotropic liquid crystal.

In order to obtain higher polarization characteristics, the polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a higher order smectic liquid crystal compound. If the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher order smectic phase, a polarizing film having a higher alignment order can be produced.

Specific examples of the preferable polymerizable liquid crystal compound include those described in JP-A2002-308832, JP-A2007-16207, JP-A2015-163596, JP-A2007-510946, JP-A2013-114131, WO2005/045485, lub et al recl. Trav. Chim. Pays-Bas,115, 321-328 (1996), and the like.

The content ratio 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, still more preferably 80 to 97% by mass, and particularly preferably 83 to 95% by mass in the polarizing film from the viewpoint of improving the alignment property of the polymerizable liquid crystal compound.

The polarizing film may be provided by applying a polarizing film composition coating. The polarizing film composition coating may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, and the like.

As the solvent, a solvent exemplified as the alignment layer coating liquid is preferably used.

The polymerization initiator is not limited as long as the polymerizable liquid crystal compound is polymerized, and a photopolymerization initiator that generates a living radical by light is preferable. Examples of the polymerization initiator include benzoin compounds, benzophenone compounds, alkyl phenone compounds, acyl phosphine oxide compounds, triazine compounds, iodonium salts, sulfonium salts, and the like.

The sensitizer is preferably a photosensitizing agent. Examples thereof include xanthone compounds, anthracene compounds, phenothiazine, rubrene, and the like.

Examples of the polymerization inhibitor include hydroquinones, catechols and thiophenols.

The polymerizable non-liquid crystal compound is preferably a copolymer with a polymerizable liquid crystal compound, and for example, when the polymerizable liquid crystal compound has a (meth) acryloyloxy group, there may be mentioned (meth) acrylates. The (meth) acrylic acid esters may be monofunctional or polyfunctional. By using a multifunctional (meth) acrylate, the strength of the polarizing film can be improved. When the polymerizable non-liquid crystal compound is used, the content of the polymerizable non-liquid crystal compound in the polarizing film is preferably 1 to 15% by mass, more preferably 2 to 10% by mass, and particularly preferably 3 to 7% by mass. If it exceeds 15 mass%, the degree of polarization may be lowered.

Examples of the crosslinking agent include compounds capable of reacting with functional groups of the polymerizable liquid crystal compound and the polymerizable non-liquid crystal compound, and examples thereof include isocyanate compounds, melamine, epoxy resins, and oxazoline compounds.

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

As the coating method, known methods such as a coating method such as a gravure coating method, a die coating method, a bar coating method, and an applicator method, and a printing method such as a flexo printing method can be used as the coating method.

The coated transfer film is then introduced into a hot air dryer, an infrared dryer, or the like, and dried at 30 to 170 ℃, more preferably 50 to 150 ℃, still more preferably 70 to 130 ℃. The drying time is preferably 0.5 to 30 minutes, more preferably 1 to 20 minutes, still more preferably 2 to 10 minutes.

Heating may be performed to more firmly orient 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 polymerizable liquid crystal compound is contained in the polarizing film composition coating material, curing is preferably performed. The curing method includes heating and light irradiation, and light irradiation is preferable. The fixing may be performed in a state in which the dichroic dye is aligned by curing. The curing is preferably performed in a state in which a liquid crystal phase is formed in the polymerizable liquid crystal compound, and the curing may be performed by irradiation with light at a temperature at which the liquid crystal phase is exhibited. Examples of the light to be irradiated include visible light, ultraviolet light, and laser light. Ultraviolet light is preferred in terms of ease of handling.

The irradiation intensity varies depending on the kind and amount of the polymerization initiator and the resin (monomer), and is, for example, preferably 100 to 10000mJ/cm on the basis of 365nm ² Further preferably 200 to 5000mJ/cm ² 。

In the case of a polarizing film, a pigment is aligned with the alignment direction of the alignment layer by applying a polarizing film composition coating to the alignment control layer, and as a result, a polarizing light transmission axis having a predetermined direction is obtained. At this time, polarized light (for example, polarized light in an oblique direction) having a desired direction with respect to the long-dimension direction of the transfer film is irradiated. Further preferably, the dichroic dye is then heat treated to firmly orient the dichroic dye in the alignment direction of the polymer liquid crystal.

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

(phase-difference layer)

The retardation layer may be: a layer provided between a polarizing plate and a liquid crystal cell of a liquid crystal display device to optically compensate, a λ/4 layer, a λ/2 layer, and the like of a circularly polarizing plate are typical layers. As the liquid crystal compound, a rod-like liquid crystal compound such as positive and negative a plates, positive and negative C plates, O plates, or the like, a discotic liquid crystal compound, or the like can be used, depending on the purpose.

In the case of being used as optical compensation of a liquid crystal display device, the degree of the phase difference can be appropriately set according to the type of liquid crystal cell and the nature of the liquid crystal compound used in the cell. For example, in the case of the TN mode, an O plate using discotic liquid crystal is preferably used. In the VA mode and IPS mode, C-plates and a-plates using a rod-like liquid crystal compound and a discotic liquid crystal compound are preferably used. In the case of the λ/4 retardation layer and the λ/2 retardation layer of the circularly polarizing plate, the a plate is preferably formed using a rod-shaped compound. These retardation layers may be used not only as a single layer but also as a combination of layers.

As the liquid crystal compound used in these retardation layers, a polymerizable liquid crystal compound having a polymerizable group such as a double bond is preferable in order to fix the alignment state.

Examples of the rod-like liquid crystal compound include a rod-like liquid crystal compound 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 examples of the compound 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

wherein m and n are integers of 2 to 6,

ph1, ph2 is 1, 4-phenyl (the 2-position of Ph2 may be methyl),

NPh is 2, 6-naphthyl.

These rod-like liquid crystal compounds are commercially available from BASF corporation as LC242 or the like, and can be used.

These rod-like liquid crystal compounds may be used in combination of plural kinds in any ratio.

Examples of discotic liquid crystal compounds include benzene derivatives, truxene derivatives, cyclohexane derivatives, aza crown ethers, phenylacetylene macrocycles, and the like, and various compounds described in JP-A2001-155866 are suitable for use.

Among them, as the disk-shaped compound, a compound having a triphenylene ring represented by the following general formula (1) is preferably used.

Wherein R is ₁ ～R ₆ Each independently is hydrogen, halogen, alkyl, or a group represented by-O-X (where X is alkyl, acyl, alkoxybenzyl, epoxy-modified alkoxybenzyl, acryloyloxy-modified alkyl). R is R ₁ ～R ₆ The acryloyloxy-modified alkoxybenzyl group represented by the following general formula (2) is preferable (here, m is 4 to 10).

The retardation layer can be provided by applying a composition coating for the retardation layer. The composition coating for the retardation layer may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a crosslinking agent, and the like. They may use the alignment control layers, the materials described in the section of the liquid crystal polarizer.

The phase difference layer composition coating is applied to the release surface or the orientation control layer of the transfer film, and then dried, heated, and cured to provide a phase difference layer.

These conditions also use the conditions described in the portions of the alignment control layer and the liquid crystal polarizer as preferable conditions.

In this case, a plurality of phase difference layers may be provided on 1 transfer film, and the phase difference layers may be transferred to the object, or a plurality of materials each having a single phase difference layer provided on 1 transfer film may be prepared and sequentially transferred to the object.

Further, a polarizing layer and a retardation layer may be provided on 1 transfer film, and transferred to an object. Further, a protective layer may be provided between the polarizing plate and the retardation layer, or a protective layer may be provided on the retardation layer or between the retardation layers. These protective layers may be provided on the transfer film together with the retardation layer and the polarizing layer, and transferred to the object.

As the protective layer, a coating layer of a transparent resin may be mentioned. The transparent resin is not particularly limited to polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyester, polyurethane, polyamide, polystyrene, acrylic resin, epoxy resin, and the like. Crosslinking agents may be added to these resins to form crosslinked structures. The composition may be obtained by curing a photocurable composition such as an acrylic composition, for example, a hard coat layer. In addition, after the protective layer is provided on the transfer film, the protective layer may be subjected to a brushing treatment, and an alignment layer of a liquid crystal compound may be provided thereon without providing an alignment layer.

(method for producing 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 manufacturing the liquid crystal compound alignment layer laminated polarizing plate comprises the following steps: a step of bonding a polarizing plate to a liquid crystal compound alignment layer surface of the laminate for transferring a liquid crystal compound alignment layer of the present invention to form an intermediate laminate; and a step of peeling the transfer film from the intermediate laminate.

Hereinafter, a case where the liquid crystal compound alignment layer is used for a circularly polarizing plate will be described as an example. In the case of a circularly polarizing plate, a λ/4 layer is used as a retardation layer (referred to as a liquid crystal compound alignment layer in a laminate for transfer). The front retardation of the lambda/4 layer is preferably 100 to 180nm. Further preferably 120 to 150nm. When the lambda/4 layer is used alone as the circularly polarizing plate, the orientation axis (slow axis) of the lambda/4 layer and the light transmission axis of the polarizing plate are preferably 35 to 55 degrees, more preferably 40 to 50 degrees, and still more preferably 42 to 48 degrees. When the polarizing plate is used in combination with a polarizing plate of a stretched film of polyvinyl alcohol, the absorption axis of the polarizing plate is usually the longitudinal direction of the long-sized polarizing plate film, and therefore, when a λ/4 layer is provided on the long-sized transfer film, it is preferable to orient the liquid crystal compound so that the absorption axis becomes the above-mentioned range with respect to the longitudinal direction of the long-sized transfer film. When the angle of the transmission axis of the polarizing plate is different from the above, the liquid crystal compound is aligned in the above relationship in consideration of the angle of the transmission axis of the polarizing plate.

The λ/4 layer in the transfer laminate in which the λ/4 layer and the transfer film are laminated is transferred to a polarizing plate, thereby producing a circularly polarizing plate. Specifically, an intermediate laminate is formed by bonding a polarizing plate to the λ/4 layer of the transfer laminate, and the transfer film is peeled from the intermediate laminate. The polarizing plate may have a protective film on both surfaces of the polarizing plate, and preferably has a protective film on only one surface. In the case of a polarizing plate having a protective film provided only on one surface, it is preferable to bond the opposite surface (polarizing plate surface) of the protective film to the retardation layer. If the protective films are provided on both surfaces, the retardation layer is preferably bonded to the surface on the side of the hypothetical image cell. The surface on the image unit side is assumed to be a surface which is not subjected to surface processing, such as a low reflection layer, an antireflection layer, and an antiglare layer, which are usually provided on the visual side. The protective film on the side to which the retardation layer is attached is preferably a protective film having no retardation such as TAC, acrylic, COP, or the like.

Examples of the polarizing plate include: a polarizing plate obtained by stretching a PVA film alone; coating PVA on an unstretched base material such as polyester or polypropylene, stretching the substrate together with the PVA to form a polarizer, and transferring the polarizer to a polarizer protective film; a polarizer protective film coated or transferred with a polarizer composed of a liquid crystal compound and a dichroic dye; and the like, are preferably used.

As a method of adhesion, conventionally known ones such as an adhesive and a binder can be used. As the adhesive, a polyvinyl alcohol-based adhesive, an ultraviolet-curable adhesive such as an acrylic adhesive and an epoxy adhesive, and a thermosetting adhesive such as an epoxy adhesive and an isocyanate (urethane) adhesive are preferably used. Examples of the binder include acrylic, urethane, and rubber binders. In addition, an optically clear adhesive sheet without an acrylic base material is also preferably used.

When a transfer type polarizing plate is used as the polarizing plate, the polarizing plate may be transferred onto a retardation layer (liquid crystal compound alignment layer) of the transfer laminate, and then the polarizing plate and the retardation layer may be transferred onto an object (polarizing plate protective film).

As the polarizer protective film on the side opposite to the side on which the retardation layer is provided, TAC, acrylic, COP, polycarbonate, polyester, and the like are generally known. Among them, TAC, acrylic, COP, polyester are preferable. The polyester is preferably polyethylene terephthalate. In the case of the polyester, a zero retardation film having an in-plane retardation of 100nm or less, particularly 50nm or less, or a high retardation film having a retardation of 3000nm to 30000nm is preferable.

In the case of using a polyester high retardation film, the angle between the transmission axis of the polarizing plate and the slow axis of the polyester high retardation film is preferably in the range of 30 to 60 degrees, more preferably in the range of 35 to 55 degrees, for the purpose of preventing dizziness and coloration when an image is observed by wearing a polarized sunglass. In order to reduce rainbow unevenness or the like when seen from an oblique direction having a small angle under the naked eye, the angle between the transmission axis of the polarizing plate and the slow axis of the high retardation film of the polyester is set to 10 degrees or less, more preferably 7 degrees or less, or preferably 80 to 100 degrees, still more preferably 83 to 97 degrees.

An antiglare layer, an antireflection layer, a low reflection layer, a hard coat layer, and the like may be provided on the polarizing plate protective film on the opposite side.

(composite phase-difference layer)

In the case of the λ/4 layer alone, coloring may not occur in a wide range of the visible light region, but λ/4 is not generated. Therefore, a λ/4 layer is sometimes used in combination with a λ/2 layer. The front retardation of the lambda/2 layer is preferably 200 to 360nm. Further preferably 240 to 300nm.

In this case, it is preferable to combine the λ/4 layer and the λ/2 layer at an angle of λ/4. Specifically, the angle (θ) between the orientation axis (slow axis) of the λ/2 layer and the transmission axis of the polarizing plate is preferably 5 to 20 degrees, more preferably 7 to 17 degrees. The angle of the orientation axis (slow axis) of the λ/2 layer to 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 still more preferably in the range of 2θ+45 degrees±3 degrees.

In this case, when the film is used in combination with a polarizing plate of a stretched film of polyvinyl alcohol, the absorption axis of the polarizing plate is usually the longitudinal direction of the long-sized polarizing plate film, and therefore, when λ/2 layers and λ/4 layers are provided on the long-sized transfer film, it is preferable to orient the liquid crystal compound so that the absorption axis is in the above range with respect to the longitudinal direction or the perpendicular direction of the long-sized transfer film. When the angle of the transmission axis of the polarizing plate is different from the above, the liquid crystal compound is aligned in the above relationship in consideration of the angle of the transmission axis of the polarizing plate.

Examples of such methods and retardation layers include Japanese patent application laid-open No. 2008-149577, japanese patent application laid-open No. 2002-303722, WO2006/100830, japanese patent application laid-open No. 2015-64418, and the like.

Further, it is also preferable to provide a C plate layer on the λ/4 layer in order to reduce the change in coloring when viewed obliquely, for example. Depending on the characteristics of the lambda/4 layer, lambda/2 layer, a positive or negative C-plate layer is used for the C-plate layer.

As a lamination method thereof, for example, if a combination of a λ/4 layer and a λ/2 layer, it is possible to employ:

the λ/2 layer is provided on the polarizer by transfer printing, and the λ/4 layer is further provided thereon by transfer printing.

A lambda/4 layer and a lambda/2 layer are sequentially provided on the transfer film, and transferred to the polarizing plate.

A lambda/4 layer, a lambda/2 layer and a polarizing layer are sequentially provided on a transfer film, and transferred to an object.

A lambda/2 layer and a polarizing layer are sequentially provided on a transfer film, and the resultant film is transferred to an object, and a lambda/4 layer is further transferred thereon.

And the like.

In addition, when stacking C plates, it is possible to use: a method of transferring a C plate layer on a λ/4 layer provided on a polarizing plate, a method of providing a C plate layer on a film, and a method of further providing a λ/4 layer or a λ/2 layer and a λ/4 layer thereon and transferring them, and the like.

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

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples, and may be implemented with appropriate modifications within the scope of the gist of the present invention, and these are included in the technical scope of the present invention. The method for evaluating physical properties in examples is as follows.

(1) Three-dimensional surface roughness SRa, SRz, SRy

A three-dimensional roughness meter (SE-3 AK, manufactured by Xiaokaka research, inc.) was used, and the height of each point was collected by a three-dimensional roughness analysis device (SPA-11) by dividing the measurement sample into 500 points at a pitch of 2 μm, and measuring the sample length of the sample at a speed of 0.1 mm/sec at a cut-off value of 0.25mm and a measurement length of 1mm along the longitudinal direction of the film under a condition that the radius of the needle was 2 μm and the load was 30 mg. The same operation as that was continuously performed 150 times at 2 μm intervals in the width direction of the film, that is, 0.3mm across the width direction of the film, and data was collected by the analysis device. Then, the center plane average roughness (SRa), ten-point average roughness (SRz), and maximum height (SRy) were obtained by an analyzer.

(2) The height difference of the demolding surface is more than 0.5 μm (demolding surface) and the number of protrusions is more than 2.0 μm (back surface)

Test pieces with a width of 100mm and a length of 100mm are cut along the length direction of the film, and are clamped between 2 polarizing plates,thereby forming a crossed prism state, and is installed in a state where a extinction position is maintained. In this state, the light was transmitted by a Nikon universal projector V-12 (measurement conditions: projection lens 50 times, transmitted illumination beam switching knob 50 times, transmitted light inspection), and the long diameter of the portion (scratch, foreign matter) that appears to be shiny was 50 μm or more. The test piece was cut into an appropriate size, and the thus-detected portion was observed and measured from a direction perpendicular to the film surface using a three-dimensional shape measuring device (Ryoka System co., ltd., micromap TYPE550; measurement conditions: wavelength 550nm, WAVE mode, objective lens 10 times). In this case, the irregularities close to 50 μm or less when viewed from the direction perpendicular to the film surface are rectangular shapes assumed to cover the same scratches and foreign matter, and the length and width of the rectangular shapes are regarded as the lengths and widths of the scratches and foreign matter. The scratch and foreign matter were quantified by using a cross-sectional image (SURFACE PROFILE DISPLAY). The measurement was performed on 20 test pieces, and the measurement was converted to 1m each ² Is a bad point of (c). The number of bad points is counted in the mold release surface, wherein the difference in height (difference between the highest point and the lowest point) is 0.5 μm or more, and the number of bad points is counted in the back surface, wherein the difference in height is 2.0 μm or more.

(3) Film thickness (thickness of each layer)

After embedding the film in an epoxy resin, a cross section was cut out, and the thickness was determined by observation with an optical microscope.

(4) Residual solvent amount

The film was cut into 10cm by 10cm pieces, and the weight (W1) was measured. Thereafter, the film was dried in a circulating dryer at 150℃for 60 minutes and stored in the dryer. The weight (W2) of the film at room temperature was measured. The value (%) of W1/(W1-W2). Times.100 was calculated as the residual solvent amount.

(5) Inspection of dead spots of phase difference layer

A sample in which an alignment control layer or a photo-alignment control layer was disposed between a transfer film and a liquid crystal compound alignment layer was prepared as a sample for inspection. The specific preparation steps are as follows.

(the orientation control layer is a brush polishing treatment)

The transfer film was cut to the size of A4, and a brush-polished alignment control layer coating material having the following composition was applied on the release layer surface by a bar coater, and dried at 80℃for 5 minutes to form a film having a thickness of 100 nm. Then, the surface of the obtained film was treated with a brush roll around which a nylon-made raised cloth was wound, to obtain a transfer film on which a brush-treated orientation control layer was laminated. The brushing was performed so as to be 45 degrees with respect to the longitudinal direction of the transfer film.

Completely saponified polyvinyl alcohol molecular weight 800 mass parts

Ion exchange water 100 parts by mass

0.1 part by mass of a surfactant

Then, a solution for forming a retardation layer having the following composition was applied to the surface subjected to the brushing treatment by a bar coating method. Drying at 110deg.C for 3 min, and irradiating with ultraviolet to solidify, and providing 1/4 wavelength layer to obtain sample for inspection.

(case where the orientation control layer is a photo-orientation control layer)

Based on the descriptions of example 1, example 2, and example 3 of japanese patent application laid-open publication No. 2013-33248, a 5 mass% cyclopentanone solution of a polymer represented by the following formula was produced as a coating material for a photo-alignment control layer.

Subsequently, the transfer film was cut into A4 size, and the coating material for the photo-alignment control layer having the above composition was applied on the release layer surface by a bar coater, and dried at 80℃for 1 minute to form a film having a thickness of 80 nm. Then, polarized UV light was irradiated at 45 degrees to the longitudinal direction of the film, to obtain a transfer film having a photo-alignment control layer laminated thereon. The coating materials were filtered through a membrane filter having a pore size of 0.2 μm, and were coated and dried in a clean room.

Then, a retardation layer forming solution was applied by bar coating to the surface on which the photo-alignment control layer was laminated. Drying at 110deg.C for 3 min, and irradiating with ultraviolet to solidify, and providing 1/4 wavelength layer to obtain sample for inspection.

Next, using these inspection samples, the dead spots of the retardation layer were inspected in accordance with the following procedure.

The inspection sample prepared as described above was placed on a lower polarizing plate placed on a surface light source using a white LED using a yellow phosphor as a light source, so that the extinction axis direction (absorption axis direction) of the polarizing plate was parallel to the longitudinal direction of the inspection sample. The lambda/4 film formed by further placing thereon a stretched film of a cyclic polyolefin such that the orientation principal axis is oriented in a direction of 45 degrees to the extinction axis of the lower polarizing plate, and placing thereon the upper polarizing plate such that the extinction axis of the upper polarizing plate is parallel to the extinction axis of the lower polarizing plate. In this state, the extinction state was observed with naked eyes (15 cm. Times.20 cm in the center) and a 20-fold magnifying glass (5 cm. Times.5 cm), and the evaluation was performed on the following basis.

And (3) the following materials: no bright spots were observed with the naked eye, but even when observed with a magnifying glass, no bright spots were substantially observed (2 or less in 5cm×5 cm).

O: no bright spots were observed with the naked eye, and a small number of bright spots (3 or more and 20 or less in 5cm×5 cm) were observed with a magnifying glass.

Delta: the bright spots were not confirmed by naked eyes, but the bright spots (more than 20 out of 5 cm. Times.5 cm) were confirmed by observation with a magnifying glass.

X: the bright spots could be confirmed with the naked eye, or the bright spots could not be confirmed but there was light leakage thought to originate from the whole of the presence of a large number of bright spots that could be observed with a magnifying glass.

(6) Inspection of superimposed dead pixels 1

Preparing two inspection samples using the above-mentioned brush polishing alignment control layer, overlapping the respective retardation layer-disposed surfaces with the opposite surfaces, and applying 1kg/cm ² Is loaded for 10 minutes. The same as the inspection of the bad point of the phase difference layer (5)The phase difference layer of the sample was inspected for dead spots.

(7) Inspection of superimposed dead pixels 2

In the inspection 1 of the stacked dead spots, in the case where the roughness of the release surface is large, the influence of the roughness of the back surface is not easily known, and therefore, the influence of the roughness of the back surface of the inspection sample using the photo-alignment control layer of example 3 in which the roughness of the release surface is small was examined by using the photo-alignment control layer of other examples and comparative examples.

Specifically, the retardation layer-mounting surface of the test sample having the 1/4 wavelength layer on the photo-alignment control layer of example 3 was overlapped with the opposite surface of the test sample using the photo-alignment control layers of examples and comparative examples, and 1kg/cm was applied ² Is loaded for 10 minutes. The phase difference layer of this sample (sample for inspection of example 3) was inspected for dead spots in the same manner as in the inspection of (5) phase difference layer dead spots.

Example 1

(adjustment of Fine particle Dispersion (P1))

2.00 parts by mass of hydrophobic fumed silica (Aerosil R812 manufactured by Nippon Aerosil co.ltd. Product) 2.00 parts by mass, triacetyl cellulose, 78.00 parts by mass of methylene chloride, 15 parts by mass of methanol, 3.00 parts by mass of 1-butanol were charged into a grinder and dispersed. The resulting dispersion was filtered through a filter having a nominal caliber of 1. Mu.m, to obtain a fine particle dispersion having a volume average particle diameter of 80nm (0.08 μm).

(preparation of triacetylcellulose solution (A1))

A triacetyl cellulose solution (A1) was prepared by dissolving 20.00 parts by mass of triacetyl cellulose, 68 parts by mass of methylene chloride, 9.5 parts by mass of methanol, and 2.5 parts by mass of 1-butanol with stirring.

(preparation of cement (D1))

The fine particle dispersion (P1) was added to the triacetylcellulose solution (A1), and stirred at 50 ℃ to obtain a cement (D1). The resulting cement was filtered through a filter having a nominal pore size of 2. Mu.m, and then defoamed.

(film-making)

The resulting dope (D1) was spread on a chrome-plated stainless steel casting belt, and dried by blowing dry air at 35 ℃. The casting belt used was a casting belt having an arithmetic average roughness (SRa) of 3nm, a ten-point average roughness (SRz) of 15nm, and a maximum height (SRy) of 23 nm.

After that, the film was peeled from the casting belt. The peeled film was further dried by applying it to 6 rolls in a W-shape and then fed into a wind of 50℃and then introduced into a tenter dryer. The amount of residual solvent in the film at the time of peeling from the casting belt was 65% by mass, and the amount of residual solvent in the film at the time of introducing into the tenter was 18% by mass.

The film fed to the tenter was held at both sides by clamps and transported in the drying zone. The drying zone is as follows: the film was expanded by 110% in the width direction by feeding dry air at 120℃in the front half and 130℃in the rear half.

The edges of the film were cut off at the tenter exit. The film was further passed through a roll dryer formed by 8 rolls. In the roller dryer, dry air at 140℃was blown. And cooling the dried film, knurling the end part and coiling. The film had a thickness of 50 μm and a residual solvent content of 0.3 mass%. The casting belt surface of the obtained film was used as a release surface.

Example 2

A fine particle dispersion having an average particle diameter of 270nm (0.27 μm) was obtained in the same manner as in example 1 except that the dispersion conditions of the fine particle dispersion were changed, and a cement (D2) was obtained using the fine particle dispersion. Thereafter, a film was produced in the same manner as in example 1, except that the air supply amount was adjusted so that the amount of the residual solvent at the time of peeling from the casting belt became 100 mass%.

Example 3

A film was produced in the same manner as in example 1, except that 2 kinds of 2-layer dies were used for casting, and the triacetylcellulose solution (A1) was spread on the casting belt surface as the release layer, and the dope (D1) used in example 1 as the upper layer (back layer) was spread. The thickness is as follows: the release layer was 10 μm and the back layer was 40 μm.

Example 4

(preparation of cement (D3))

Spherical silica particles (KE-P50 manufactured by Japanese catalyst) having a particle diameter of 0.5 μm were added to the triacetylcellulose solution (A1) so that the particle content was 3000ppm in terms of solid content, and the slurry (D3) was obtained by stirring at 50 ℃. The resulting cement (D3) was filtered through a filter having a nominal pore size of 5. Mu.m, and then defoamed.

A film was produced in the same manner as in example 3, except that the dope (D3) was used as the upper layer (back layer) instead of the dope (D1).

Example 5

A film was produced in the same manner as in example 1, except that the cement (D3) prepared in example 4 was used instead of the cement (D1). The casting belt side of the obtained film was corona-treated, and a coating agent having the following composition as a release layer (surface-flattening coating) was applied thereon, and dried in a heating oven at 150 ℃ for 3 minutes. The thickness of the coating was 2 μm.

10 parts by mass of a melamine-crosslinked alkyl-modified alkyd resin (Hitachi Kasei Polymer Co., ltd.: tesfine 322: solid content 40%)

P-toluenesulfonic acid (Hitachi Kasei Polymer Co., ltd.: dryer 900) 0.1 part by mass

40 parts by mass of a solvent (toluene/methyl ethyl ketone=1/1 part by mass)

The coating agent was used after filtration through a 2 μm filter.

Example 6

(preparation of cement (D4))

Spherical silica particles (KE-P250 manufactured by Japanese catalyst Co., ltd.) having a particle diameter of 2.5 μm were added to the triacetylcellulose solution (A1) so that the particle content was 1000ppm in terms of solid content, and the resulting slurry (D4) was obtained by stirring at 50 ℃. The resulting cement (D4) was filtered through a filter having a nominal pore size of 10. Mu.m, and then defoamed.

A film was produced in the same manner as in example 3, except that the adhesive (D4) was used as the upper layer (back layer) instead of the adhesive (D1) so that the thickness of the release layer became 25 μm and the thickness of the back layer became 25 μm.

The air used in the drying was filtered through a HEPA filter having a 95% cutoff diameter of 1 μm and then further filtered through a HEPA filter having a 99.9% cutoff diameter of 0.3 μm with high accuracy. Further, the coating of the thin film with the coating liquid was performed in an environment of class 1000. The coating and drying steps are performed in the same environment as described below.

Example 7

The back side of the film of example 4 was coated with a solid content of 5% of Peltron C-4402 (antimony doped tin oxide particles) as an antistatic layer (back surface planarization coating) by MEK, and dried at 80℃for 3 minutes in a heating oven. The thickness of the coating was 200nm. The surface resistance was 7.3X10 ⁷ Ω/□。

Comparative example 1

A film was produced in the same manner as in example 1, except that the cement (D3) prepared in example 4 was used instead of the cement (D1).

Table 1 shows the production conditions, characteristics, and evaluation results of the transfer films of examples 1 to 7 and comparative example 1, respectively.

TABLE 1

As shown in table 1, in examples 1 to 7, in which the surface roughness of the parting surface satisfies the features of the present invention, the number of defective pixels was significantly small in the defective pixel evaluation, and the occurrence of pinhole-like and scratch-like light leakage was sufficiently suppressed. In examples 1 to 5 and 7, since the surface roughness of the back surface was also suppressed to a low level, the occurrence of pinhole-like and scratch-like light leakage was sufficiently suppressed because the number of superimposed dead spots 1 and 2 was significantly small in the dead spot evaluation. In contrast, in comparative example 1 in which the particle size contained in the surface layer was too large and the surface roughness of the parting surface was too large, the number of dead spots was significantly large in the dead spot evaluation, and the occurrence of pinhole-like and scratch-like light leakage could not be suppressed.

In table 1, the in-plane retardation (Re) of the base material films used in examples and comparative examples was not shown, and as a result, the base material films were 10nm or less in any of the base material films, and the level of the alignment state of the liquid crystal compound alignment layer was examined by irradiating the liquid crystal compound alignment layer with linearly polarized light in a state in which the liquid crystal compound alignment layer was laminated on the transfer film.

Specific steps for measuring the in-plane retardation are as follows. That is, a rectangular shape of 4cm×2cm was cut out from the base film used in examples and comparative examples so that the flow direction was long, and the sample was used for measurement. For this sample, refractive index (flow direction nx, width direction ny) was measured by Abbe refractometer (ATAGO CO., LTD. Manufactured by NAR-4T, measurement wavelength 589 nm). The in-plane retardation (Re) was determined from the product ((nx-ny). Times.d) of the film thickness d (nm) at 5 points (center portion, both end portions, intermediate portion between center portion and end portion) measured in the width direction of the film as the average.

Industrial applicability

The film for transferring a liquid crystal compound alignment layer of the present invention uses a film having a surface roughness controlled within a specific range as a film for transferring a retardation layer or a polarizing layer, and therefore, the alignment state and the retardation of a liquid crystal compound in the retardation layer or the polarizing layer can be designed to be compatible with each other, and a retardation layer or a polarizing layer (liquid crystal compound alignment layer) having reduced occurrence of dead spots such as pinholes can be formed. Therefore, according to the present invention, a laminated polarizing plate with a phase difference layer such as a circularly polarizing plate can be stably manufactured with high quality.

Claims

1. A laminate for transferring a liquid crystal compound alignment layer, characterized in that a liquid crystal compound alignment layer and a cellulose film for transferring a liquid crystal compound alignment layer are laminated,

the liquid crystal compound alignment layer includes at least any one of the following: a polarizing film containing a 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, and a retardation layer of an O plate using a discotic liquid crystal compound, and,

the liquid crystal compound alignment layer is provided by aligning by any of the following methods (a), (b) and (c),

the surface roughness (SRa) of the release surface of the cellulose film for transferring the liquid crystal compound alignment layer is 1nm to 5.0nm,

(a) A method of applying an alignment layer of a liquid crystal compound to a transfer film and aligning the alignment layer, wherein the alignment method is a method of applying a brush-polishing treatment to a release surface of the transfer film to impart an alignment control function;

(b) A method of applying a liquid crystal compound alignment layer to a transfer film and aligning the liquid crystal compound alignment layer, wherein the alignment method is a method of directly aligning the liquid crystal compound by irradiating polarized ultraviolet rays after applying the liquid crystal compound;

(c) And a method of providing an alignment control layer on the release surface of the liquid crystal compound alignment layer transfer film, and providing a liquid crystal compound alignment layer by coating on the alignment control layer.

2. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the surface roughness (SRa) of the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 3nm or less.

3. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the ten-point surface roughness (SRz) of the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 5nm to 200 nm.

4. The laminate for transferring a liquid crystal compound alignment layer according to claim 3, wherein the ten-point surface roughness (SRz) of the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 100nm or less.

5. The laminate for transferring a liquid crystal compound alignment layer according to claim 3, wherein the ten-point surface roughness (SRz) of the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 80nm or less.

6. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the surface roughness (SRa) of the surface of the cellulose film for transferring a liquid crystal compound alignment layer on the side opposite to the release surface is 3nm to 40 nm.

7. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the surface roughness (SRa) of the surface of the cellulose film for transferring a liquid crystal compound alignment layer on the side opposite to the release surface is 5nm or more.

8. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the ten-point surface roughness (SRz) of the surface of the cellulose film for transferring a liquid crystal compound alignment layer on the side opposite to the release surface is 15nm to 500 nm.

9. The laminate for transferring a liquid crystal compound alignment layer according to claim 8, wherein the ten-point surface roughness (SRz) of the surface of the cellulose film for transferring a liquid crystal compound alignment layer on the side opposite to the release surface is 25nm or more.

10. The laminate for transferring a liquid crystal compound alignment layer according to claim 8, wherein the ten-point surface roughness (SRz) of the surface of the cellulose film for transferring a liquid crystal compound alignment layer on the side opposite to the release surface is 32nm or more.

11. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the surface roughness (SRa) of the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 5nm or less and the surface roughness (SRa) of the surface opposite to the release surface is 8nm or more.

12. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the maximum height (SRy) of the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 10nm to 120nm, and the maximum height (SRy) of the surface opposite to the release surface is 25nm to 700 nm.

13. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the number of protrusions having a height difference of 0.5 μm or more from the release surface of the cellulose film for transferring a liquid crystal compound alignment layer is 5/m ² Hereinafter, the number of protrusions having a height difference of 2.0 μm or more on the surface opposite to the release surface was 5/m ² The following is given.

14. The laminate for transferring an alignment layer of a liquid crystal compound according to claim 1, wherein the particle content of the release surface side layer of the base film is less than 50ppm.

15. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the release surface side layer of the base film has a particle content of less than 50ppm, and the back surface side layer of the base film contains particles.

16. The laminate for transferring an alignment layer of a liquid crystal compound according to claim 1, wherein the release surface side layer of the base film contains particles, and further comprises a planarizing coating layer provided thereon.

17. The laminate for transferring an alignment layer of a liquid crystal compound according to claim 1, wherein the back surface side layer of the base film contains particles, and further provided with a planarizing coating layer thereon.

18. The laminate for transferring an alignment layer of a liquid crystal compound according to claim 1, wherein the substrate film has a particle-containing coating layer on the back surface side thereof.

19. The laminate for transferring a liquid crystal compound alignment layer according to claim 1, wherein the particles content of the back side layer of the base film is less than 50ppm, and the particles are contained in the intermediate layer of the base film.

20. A method for manufacturing a liquid crystal compound alignment layer laminated polarizing plate, comprising the steps of: a step of bonding a polarizing plate to the liquid crystal compound alignment layer surface of the liquid crystal compound alignment layer transfer laminate according to any one of claims 1 to 19 to form an intermediate laminate; and a step of peeling the cellulose-based film from the intermediate laminate.