JP6954502B1 - Laminate for thin film layer transfer - Google Patents

Abstract

Provided is a thin film layer transfer laminate capable of forming a transferred product in which defects such as pinholes and transfer defects are suppressed. The releasable base film, the thin film layer, and the masking film are laminated in this order, and satisfy the following formulas (1), (2), and (3). 0.01 ≤ Y / X ≤ 0.7 (1) (X: release strength between the releasable base film and the thin film layer, Y: release strength between the thin film layer and the masking film) Sku ≤ 40 (2) ( Sku: Kurtosis of the release surface of the release base film) Sq ≤ 20 nm (3) (Sq: Squared average square root roughness of the release surface of the release base film)

Description

The present invention relates to a laminate for transferring a thin film layer. More specifically, when transferring a thin film layer including a layer in which a liquid crystal compound is oriented, which is used in the production of a polarizing plate such as a circular polarizing plate or a retardation plate or a polarizing plate having a polarizing layer made of a liquid crystal compound. The present invention relates to a laminate preferably used in the above.

A technique of providing a thin film layer on a releasable substrate and transferring the thin film layer to an object has been known for a long time. This transfer method is not limited to the conventional transfer of patterns, but in recent years, in the fields of optics, electrical and electronic fields, etc., a retardation layer, a polarizing layer, an absorption layer such as ultraviolet rays and infrared rays, a reflection layer, an electromagnetic wave shield layer, and an electrode A method has been adopted in which a thin film layer having various functions such as a layer, an antireflection layer, and a refractive index adjusting layer is provided on an object by transfer.

For example, in an image display device, conventionally, a circularly polarizing plate is arranged on the panel surface of the image display panel on the viewer side in order to reduce the reflection of external light. This circular polarizing plate is composed of a laminate of a linear polarizing plate and a retardation film such as λ / 4, and converts external light toward the panel surface of the image display panel into linearly polarized light by the linear polarizing plate, followed by λ /. It is converted to circularly polarized light by a retardation film of 4 mag. When the external light due to circularly polarized light is reflected on the surface of the image display panel, the rotation direction of the polarizing surface is reversed, and on the contrary, this reflected light is shielded by a linear polarizing plate by a retardation film such as λ / 4. Since it is converted to linearly polarized light in the direction of light and then shielded by a linear polarizing plate, emission to the outside is suppressed. As described above, as the circularly polarizing plate, one in which a retardation film such as λ / 4 is bonded to the polarizing plate is used.

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

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

In these transfer methods, a transfer laminate in which a retardation layer in which a liquid crystal compound is oriented is provided on a releasable base film for transfer (hereinafter, may be simply referred to as a base film) is prepared, and this transfer is performed. The retardation layer of the laminate is bonded to a target film or the like and transferred.

Normally, the transfer laminate is produced as a long roll, but when it is wound as a roll, a masking film may be attached to a phase difference layer and wound up in order to protect the phase layer (patented). Document 9). When the retardation layer is transferred to the object using the roll of the transfer laminate, the masking film is peeled off and the object and the retardation layer are bonded to each other with an adhesive or the like. The base film of the transfer laminate may be wound up as a roll while being laminated without being peeled off, but it is peeled off before it becomes the final product, such as when it is attached to an image display cell. NS.

However, when the retardation layer is provided on the base film by these steps, there has been a problem of drawbacks such as pinholes. In particular, even if there are no defects immediately after the retardation layer is provided on the base film, defects may occur in the final product, and improvement has been sought.

Japanese Unexamined Patent Publication No. 2012-56222 Japanese Unexamined Patent Publication No. 2004-144943 Japanese Unexamined Patent Publication No. 2004-46166 Japanese Unexamined Patent Publication No. 2006-243653 Japanese Unexamined Patent Publication No. 2001-4837 Japanese Unexamined Patent Publication No. 4-57017 Japanese Unexamined Patent Publication No. 2014-071381 Japanese Unexamined Patent Publication No. 2017-146616 Japanese Unexamined Patent Publication No. 2016-224128

The present invention has been made against the background of the problems of the prior art. That is, an object of the present invention is a transfer laminate for transferring a thin film layer, which can form a transfer product in which defects such as pinholes and transfer defects are suppressed. It is what we are trying to provide.

In order to achieve such an object, the present inventors have defects such as pinholes in a retardation layer laminated polarizing plate (circular polarizing plate) manufactured by using a transparent resin film as a base film for transfer. We examined the cause of the problem. As a result, even if there are no defects such as pinholes when the liquid crystal compound layer is provided on the base film, the transfer laminate to which the masking film is attached is stored in a roll state, and the transfer laminate is obtained from this roll. It has been found that pinholes occur when the masking film is peeled off in the process of unwinding and transferring to the object, or when the base film is peeled off. Further, this pinhole maintains an appropriate relationship between the peeling force between the base film and the liquid crystal compound layer and the peeling force between the liquid crystal compound layer and the masking film, and further, the roughness of the release surface of the base film. We have found that it can be suppressed by setting it within a specific range, and have completed the present invention. The laminate for thin film layer transfer of the present invention has the following points.

The releasable base film, the thin film layer, and the masking film are laminated in this order, and are characterized by satisfying the following formulas (1), (2), and (3).
0.01 ≤ Y / X ≤ 0.7 (1)
X: Peeling strength between the releasable base film and the thin film layer Y: Peeling strength between the thin film layer and the masking film Sku ≦ 40 (2)
Sku: Kurtosis of the release surface of the release base film Sq ≤ 20 nm (3)
Sq: Root mean square roughness of the release surface of the release base film

The thin film layer transfer laminate of the present invention preferably further satisfies the following formula (4).
-1.0 ≤ Sk ≤ 2.0 (4)
Sk: Releasability The skewness of the release surface of the base film

The thin film layer transfer laminate of the present invention preferably further satisfies the following formula (5).
0.005N / 25mm ≤ Y ≤ 2.0N / 25mm (5)

The thin film layer preferably contains a layer in which the liquid crystal compound is oriented.

The thin film layer transfer laminate for transferring the thin film layer of the present invention is excellent in handleability, and in particular, the thin film layer can be easily transferred to an object by roll-to-roll. Furthermore, by using the thin film layer transfer laminate of the present invention, it is possible to obtain a transferred product in which the occurrence of defects such as pinholes and transfer defects is suppressed.

(Releasable base film)
The resin constituting the base film raw material of the releasable base film is not particularly limited as long as it can maintain the strength as a transfer base material, but among them, polyester, polycarbonate, polystyrene, polyamide, polypropylene, and cyclic polyolefin. , Triacetyl cellulose is preferable, and polyethylene terephthalate, cyclic polyolefin, and triacetyl cellulose are particularly preferable. In the description of the present invention, the releasable base film includes a layer to be post-processed, such as a coat layer to be added as needed, to the base film raw fabric obtained in the film forming process. The base film raw fabric refers to a film obtained in a film forming process, and refers to a form used for producing a laminate for transferring a liquid crystal compound.

The base film raw fabric may be composed of a single layer or a plurality of layers by coextrusion. In the case of a plurality of layers, only one surface is a release surface [release surface side layer (A)] / [back surface side layer (B)], and both sides are release surfaces and another intermediate is in between. The configuration of the [release surface side layer (A)] / [intermediate layer (C)] / [release surface side layer (A)] having the layer (C), and only one surface is the release surface and the mold is released. Examples thereof include a configuration of a [release surface side layer (A)] / [intermediate layer (C)] / [back surface side layer (B)] having an intermediate layer (C) between the front surface and the back surface side layer.

In the present invention, the "release surface side layer" of the base film raw fabric means the layer on the side where the release surface exists among the layers of the resin constituting the base film raw fabric. Here, even when the film is a single layer, it 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. Further, the release surface side layer may be simply referred to as a surface layer.

The base film raw fabric may be a stretched film or an unstretched film. When stretching, either uniaxial stretching, weak biaxial stretching (stretching in the biaxial direction but weak in one direction), or biaxial stretching may be used, but the orientation direction is constant over a wide range in the width direction. Uniaxial stretching or weak biaxial stretching is preferable in terms of being able to do so. In the case of weak biaxial stretching, it is preferable that the main orientation direction is the stretching direction of the subsequent stage. In the case of uniaxial stretching, the stretching direction may be the flow direction (longitudinal direction) of film production or the direction orthogonal to the flow direction (lateral direction).

In the case of biaxial stretching, simultaneous biaxial stretching or sequential biaxial stretching may be used. Stretching in the longitudinal direction is preferably stretched by roll groups having different speed differences, and stretching in the lateral direction is preferably tenter stretching. In particular, when the base film raw material is polyethylene terephthalate, it is preferably a stretched film.

The base film raw fabric may be an easy-adhesion coating, a release coating, an antistatic coating, or the like at the time of film formation.

The releasable base film is industrially supplied in rolls around which the film is wound. The lower limit of the roll width is preferably 30 cm, more preferably 50 cm, still more preferably 70 cm, particularly preferably 90 cm, and most preferably 100 cm. The upper limit of the roll width is preferably 5000 cm, more preferably 4000 cm, further preferably 3000 cm, even more preferably 500 cm, particularly preferably 400 cm, and most preferably 300 cm.

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

The lower limit of the thickness of the releasable base film is preferably 3 μm, more preferably 5 μm, further preferably 8 μm, particularly preferably 10 μm, and most preferably 12 μm. The upper limit of the thickness is preferably 150 μm, more preferably 100 μm, further preferably 80 μm, particularly preferably 70 μm, and most preferably 60 μm. Within the above range, it is easy to handle and economically advantageous in terms of cost.

(Roughness of mold release surface)
The release surface of the releasable base film is preferably smooth. In the present invention, the "release surface" of the releasable base film is intended to provide a thin film layer (for example, a liquid crystal compound layer) to be transferred on the surface of the releasable base film. Means the surface. When an oligomer block coat layer, a flattening coat layer, a release layer, etc., which will be described later, are provided, if a thin film layer is provided on this, the surface of these oligomer block coat layers, the flattening layer, the release layer, etc. That is, the surface in contact with the thin film layer is the "release surface" of the releasable base film.

As described in the examples, the parameters of each roughness of the present invention are in accordance with ISO 25178, using a non-contact surface shape measurement system (VertScan R550H-M100 manufactured by Ryoka System Co., Ltd.) under the following conditions. It was measured.
(Measurement condition)
Measurement mode: WAVE mode Objective lens: 50x 0.5 x Tube lens Measurement area: 187 μm x 139 μm
(Analysis conditions)
Surface correction: 4th correction
Interpolation processing: Complete interpolation ISO parameter processing: S-Filter 1 μm designation

The thin film layer transfer laminate of the present invention satisfies the following formula (2).
Sk ≤ 40 (2)
Here, Sk is a Kurtosis of the release surface of the release base film. Kurtosis, which is one of the roughness parameters, is an index showing the sharpness of the height distribution, and the larger the value, the sharper it is, and the larger the value is when there are sharp peaks or valleys. When the height distribution is a normal distribution, the value of Kurtosis is 3. The upper limit of the Kurtosis (Sku) of the release surface of the releasable base film of the present invention is 40. The upper limit of the Sku is more preferably 30, still more preferably 20, particularly preferably 15, and most preferably 12. The lower limit of Sku is not particularly defined, but 1.0 is preferable, more preferably 2.0, still more preferably 3.0, and Sku is particularly preferably more than 3.0. It is also acceptable to be 0 or more, 4.5 or more, or 5.0 or more.

When transferring the thin film layer to the target film using the thin film layer transfer laminate, the masking film is peeled off, and the releasable base film is peeled off before the final product is produced. By setting the Sk on the release surface of the releasable base film to the above range, smooth peeling becomes possible, and a liquid crystal compound layer remains on the convex portion of the masking film or the base film, or this portion is a trigger. It is possible to effectively suppress transfer defects such as a region where the streaky liquid crystal compound layer is not transferred. Further, if the Sku is more than 3.0, 4.0 or more, 4.5 or more, or 5.0 or more, the unevenness of the release surface of the release base film has a certain degree of sharpness. , It is possible to prevent the release base film from sticking to the thin film layer and perform smooth peeling.

The thin film layer transfer laminate of the present invention satisfies the following formula (3).
Sq ≤ 20 nm (3)
Here, Sq is the root mean square roughness of the release surface of the release base film. The upper limit of the root mean square roughness (Sq) of the release surface of the releasable base film is 20 nm, preferably 15 nm, more preferably 10 nm, still more preferably 7 nm, and most preferably 5 nm. The lower limit of Sq is not particularly defined, but is preferably 0.5 nm or more, more preferably 0.8 nm or more, and particularly preferably 1.0 nm or more. By setting Sq in the above range, it is possible to suppress problems such as defects in the thin film layer itself when the thin film layer is provided on the releasable base film, and transfer defects during transfer.

The thin film layer transfer laminate of the present invention preferably satisfies the following formula (4).
-1.0 ≤ Sk ≤ 2.0 (4)
Here, Sk is the skewness of the release surface of the release base film. Skewness, which is one of the roughness parameters, is an index showing the symmetry of the height distribution. When the value is 0, it indicates that the height distribution is vertically symmetrical, and when the value is positive, the surface has many peaks. , When the value is negative, it indicates that the surface has many valleys. The lower limit of the skewness (Ssk) of the release surface of the releasable base film is preferably -1.0, more preferably -0.7, and even more preferably -0.5, particularly. It is preferably −0.3. By doing the above, the releasable base film can be stably wound. The upper limit of Ssk on the release surface of the releasable base film is preferably 2.0, more preferably 1.7, still more preferably 1.5, and particularly preferably 1.3. Most preferably, it is 0.6. By setting the above range, transfer defects can be further suppressed. Further, since the surface of the release base film can be a surface having a certain number of peaks rather than valleys, it is possible to suppress the release base film from sticking to the thin film layer and perform smooth peeling.

The upper limit of the arithmetic mean roughness (Sa) of the release surface of the releasable base film is preferably 15 nm, more preferably 10 nm, still more preferably 5 nm, particularly preferably 4 nm, and most preferably. Is 3 nm. The lower limit of Sa on the release surface of the releasable base film is preferably 0.2 nm, more preferably 0.4 nm, and even more preferably 0.5 nm. By setting the Sa of the release surface of the releasable base film within the above range, defects occur in the thin film layer itself when the thin film layer is provided on the releasable base film, and transfer defects occur during transfer. The problem can be suppressed.

The upper limit of the developed area (Sdr) of the interface of the release surface of the releasable base film is preferably 0.0015%, more preferably 0.001%, and further preferably 0.0007%. By setting the above or less, it is possible to suppress problems such as defects in the thin film layer itself when the thin film layer is provided on the releasable base film, and transfer defects during transfer. The lower limit of the developed area (Sdr) of the interface is preferably 0.0001%. Sdr is an index showing how large the area of the actual interface is with respect to the area seen from the upper part, and tends to be large when there are many small irregularities and when the inclination of the irregularities is steep. It is considered that the smaller the Sdr, the less the catch during transfer, and the more the transfer defect can be suppressed.

The lower limit of the average (Spc) of the principal curvatures of the peaks of the release surface of the releasable base film is preferably 1 (1 / mm), more preferably 3 (1 / mm), and even more preferably. It is 5 (1 / mm), particularly preferably 7 (1 / mm), and most preferably 8 (1 / mm). It can be done by making it more than the above. The upper limit of the average (Spc) of the principal curvatures of the peaks of the release surface of the releasable base film is preferably 100 (1 / mm), more preferably 80 (1 / mm), and even more preferably. It is 70 (1 / mm), particularly preferably 60 (1 / mm), and most preferably 50 (1 / mm). Spc is an index showing the curvature of the apex of the protrusion, and the larger the value, the sharper the apex, and the smaller the value, the smoother the apex. It is considered that if the apex of the roughness of the release surface of the releasable base film is smooth, the catching at the time of transfer can be reduced and the transfer failure can be suppressed. When calculating Spc, it may be a negative value depending on the software used, but the above range may be applied as an absolute value.

In order to make the roughness of the release surface of the releasable base film within the above range, the following methods can be mentioned.
(A) It is assumed that the release surface side layer of the base film raw material does not contain particles or foreign substances.
(B) When the release surface side layer of the base film original fabric contains particles, the particles have a small particle size.
(C) If the release surface side layer of the base film original fabric contains particles or foreign substances, a flattening coat is provided.

In addition to the above, it is also important to clean the raw materials and manufacturing process as follows.
(D) Select conditions that make it difficult for foreign matter, especially catalyst-derived foreign matter, to be generated during polymerization.
(E) Filter the particle slurry during polymerization. Filter before chipping.
(F) Make the chipped cooling water clean. Clean the environment from chip transfer to introduction of the film-forming machine.
(G) At the time of film formation, the molten resin is filtered to remove agglomerated particles and foreign substances.
(H) Filter the coating agent to remove foreign matter.
(I) Perform in a clean environment during film formation, coating, and drying.

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

The surface layer may contain particles in order to increase the slipperiness of the surface. When particles are included, the lower limit of the surface particle content is preferably 10 ppm, more preferably 50 ppm, and even more preferably 100 ppm. The upper limit of the surface particle content is preferably 20000 ppm, more preferably 10000 ppm, still more preferably 8000 ppm, and particularly preferably 6000 ppm. If it exceeds the above, the roughness of the surface layer may not be within a preferable range.

The lower limit of the surface particle size is preferably 0.005 μm, more preferably 0.01 μm, and even more preferably 0.02 μm. The upper limit of the surface particle size is preferably 1 μm, more preferably 0.5 μm, still more preferably 0.3 μm, and particularly preferably 0.1 μm. If it exceeds the above, the roughness of the surface layer may not be within the preferable range, and even if the smoothing coating is applied, the roughness of the release surface may not be within the preferable range.

Even when the surface layer does not contain particles or has particles having a small particle size, if the lower layer contains particles, the roughness of the release surface layer may increase due to the influence of the particles in the lower layer. In such a case, it is preferable to take a method such as increasing the thickness of the surface layer or providing a lower layer (intermediate layer) containing no particles.

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

The particle-free intermediate layer is substantially particle-free, and the particle content is less than 50 ppm, preferably less than 30 ppm. The lower limit of the thickness of the intermediate layer is preferably 10%, more preferably 20%, still more preferably 30% with respect to the total thickness of the releasable base film. The upper limit is preferably 95%, more preferably 90%.

If the surface layer of the base film raw material has a high roughness, a flattening coat may be provided. Examples of the resin used for the flattening coat include those generally used as a resin for a coating agent such as polyester, acrylic, polyurethane, polystyrene, and polyamide. It is also preferable to use a cross-linking agent such as melamine, isocyanate, epoxy resin, or oxazoline compound. These are applied and dried as a coating agent dissolved or dispersed in an organic solvent or water. Alternatively, in the case of acrylic, it may be coated without a solvent and cured by radiation. The flattening coat may be an oligomer block coat. When the release layer is provided with a coat, the release layer itself may be thickened.

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

The flattening coat may be provided as an in-line coat during the film forming process, or may be separately provided offline.

When the surface layer of the base film raw material or the coat layer above it contains relatively large particles or foreign substances, even if Sa, Sq and the like are small, Sk and Sk may not satisfy the above-mentioned preferable range. In that case, it can be within the range by referring to the above guideline.

In the above, the case where the base film raw material is mainly a stretched film has been described, but the film is not formed by a casting method in which a dope prepared by dissolving triacetyl cellulose or the like in a solvent is developed on a metal belt or the like and the solvent is dried. Even in the case of a stretched film, by adding the particles, unevenness due to the particles is generated on the upper surface (opposite surface of the metal belt) as the solvent is removed, so that the roughness can be adjusted. In this case, it is preferable to reduce the surface roughness of the metal belt and use the metal belt surface as the release surface. Even in the case of the casting method, the above (a) to (i) are preferable methods. In this case, in the methods (e) and (g), a filter is applied during the production of the raw material resin, and the dope is filtered to remove agglomerated particles and foreign substances.

In addition, when the dope contains particles, if it is peeled off from the metal belt in a state where the solvent content is high, unevenness due to the particles may appear on the metal belt surface. It is also preferable to peel off. Roughness can also be adjusted at the timing of these peelings. Further, when stretching and drying in a tenter with a small amount of solvent contained, the roughness can be adjusted by a stretching ratio or the like. When particles are not contained, the roughness of the metal belt may be adjusted so that the metal belt surface is the back surface. Further, the roughness may be transferred to the surface while being dried while being passed between rolls having different roughness.

Even in the case of an unstretched film formed by casting a molten resin such as COP, the roughness can be adjusted by adding particles. By using particles having a coefficient of thermal expansion different from that of the film resin, such as inorganic particles, it is possible to form irregularities on the surface due to the added particles due to heat shrinkage that occurs during cooling. In this case, it is preferable to reduce the surface roughness of the cooling roll that extrudes the molten resin into a sheet to form a release surface. Alternatively, the cooling roll may be roughened to transfer the roughness and used as the back surface. Roughness may be transferred between rolls having different roughness at a temperature of Tg or more of the film resin. Further, even in the case of an unstretched film, the above (a) to (i) are preferable methods.

(Roughness on the back side)
The lower limit of the arithmetic mean roughness (Sa) of the surface (back surface) opposite to the release surface of the releasable base film is preferably 1.0 nm, more preferably 1.3 nm, and even more preferably. It is 1.5 nm. The upper limit of Sa on the back surface is preferably 50 nm, more preferably 40 nm, and even more preferably 30 nm.

The lower limit of the root mean square roughness (Sq) of the back surface of the releasable base film is preferably 1.3 nm, more preferably 1.5 nm, still more preferably 1.8 nm, and particularly preferably. It is 2.0 nm. The upper limit of Sq on the back surface is preferably 70 nm, more preferably 60 nm, still more preferably 50 nm, and particularly preferably 45 nm.

By setting Sa and Sq on the back surface of the releasable base film within the above ranges, the releasable base film can be easily wound, and even when the releasable base film is stored in the wound state, unwinding and blocking occur. Furthermore, it is difficult, and even when the unevenness of the back surface is transferred to the front surface, the state of surface roughness can be maintained within an appropriate range.

The Sku on the back surface of the releasable base film is preferably larger than the Sku on the releasable surface. Specifically, the lower limit of (Sku on the back surface) / (Sku on the release surface) is preferably 1.2, more preferably 1.4, and even more preferably 1.5. The upper limit of (Sku on the back surface) / (Sku on the release surface) is preferably 40, more preferably 30, still more preferably 25, and particularly preferably 20.

The upper limit of the Sku on the back surface of the releasable base film is preferably 200, more preferably 170. The lower limit of the Sku on the back surface is preferably 3, more preferably 5, and even more preferably 7.

The Ssk on the back surface of the releasable base film is preferably larger than the Ssk on the releasable surface. Specifically, the lower limit of the absolute value of (Ssk on the back surface) / (Ssk on the release surface) is preferably 1.2, more preferably 1.5, still more preferably 1.8, and particularly preferably 2. .. The upper limit of (Ssk on the back surface) / (Ssk on the release surface) is preferably 20, more preferably 17, and even more preferably 15.

The lower limit of Ssk on the back surface of the releasable base film is preferably -3, more preferably -1, but more than 0 is preferable for stable winding, and further 1 or more. Is preferable. The upper limit of Ssk on the back surface of the releasable base film is preferably 20, more preferably 15, still more preferably 12, and particularly preferably 10.

Releasability Even when the roughness parameters of the release surface of the base film are within the above-mentioned preferable ranges and the back surface Sa and Sq are within the above-mentioned preferable ranges, the release surface and the back surface Sa and Sq If is close to the lower limit, the rewindability and storage stability may deteriorate. By setting either or preferably both Sk and Sk on the back surface and the release surface as described above, it is possible to prevent pinholes in the thin film layer and suppress excessive air entrainment during winding, resulting in good winding. It is possible to secure the releasability and storage stability.

In order to make the roughness of the back surface within the above range, for example, the following method can be mentioned.
-The back surface side layer (back surface layer) of the base film raw fabric contains specific particles.
-Use a base film that contains particles in the intermediate layer of the original fabric, and reduce the thickness by assuming that the back surface layer side (back surface layer) does not contain particles.
-If the back surface side layer (back surface layer) of the base film raw fabric has a large roughness, a flattening coat is provided.
-If the back surface side layer (back surface layer) of the base film raw fabric does not contain particles or the roughness is small, an easy-to-slip coat (particle-containing coat) is provided.

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

When the back surface layer contains particles, the lower limit of the back surface layer particle content is preferably 50 ppm, more preferably 100 ppm. If it is less than the above, the slippery effect due to the addition of particles may not be obtained. The upper limit of the back layer particle content is preferably 10000 ppm, more preferably 7000 ppm, and even more preferably 5000 ppm. If it exceeds the above, the back surface may become too rough.

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

It is also preferable to control the roughness of the back surface by including particles in the intermediate layer and thinning the back surface layer without containing particles. By taking such a form, it is possible to secure the roughness of the back surface while preventing the particles from falling off.

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

When the back surface of the base film raw fabric is rough, it is also preferable to provide a flattening coat. As the flattening coat, those listed in the surface flattening coat can be used in the same manner.

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

The back surface side of the base film raw fabric may not contain particles, and an easy-slip coat layer containing particles may be provided on the back surface side. Further, when the roughness of the back surface of the base film raw fabric is small, an easy-to-slip coat layer may be provided.

The lower limit of the particle size of the back surface slippery coat layer is preferably 0.01 μm, more preferably 0.05 μm. If it is less than the above, slipperiness may not be obtained. The upper limit of the particle size of the back surface slippery coat layer is preferably 5 μm, more preferably 3 μm, still more preferably 2 μm, and particularly preferably 1 μm. If it exceeds the above, the roughness of the back surface may be too high.

The lower limit of the particle content of the back surface slippery coat layer is preferably 0.1% by mass, more preferably 0.5% by mass, still more preferably 1% by mass, and particularly preferably 1.5% by mass. Most preferably, it is 2% by mass. If it is less than the above, slipperiness may not be obtained. The upper limit of the particle content of the back surface slippery coat layer is preferably 20% by mass, more preferably 15% by mass, and further preferably 10% by mass. If it exceeds the above, the roughness of the back surface may be too high.

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

In the above, the case where the releasable base film of the present invention is a stretched film has been described, but the film is formed by a casting method in which a dope obtained by dissolving triacetyl cellulose or the like in a solvent is developed on a metal belt or the like and the solvent is dried. Even in the case of the unstretched film, by adding the particles, unevenness due to the particles is generated on the upper surface (opposite surface of the metal belt) as the solvent is removed, so that the roughness can be adjusted. In this case, it is preferable to reduce the surface roughness of the metal belt and use the metal belt surface as the release surface. In addition, when the dope contains particles, if it is peeled off from the metal belt in a state where the solvent content is high, unevenness due to the particles may appear on the metal belt surface. It is also preferable to peel off. Roughness can also be adjusted at the timing of these peelings. Further, when stretching and drying in a tenter with a small amount of solvent contained, the roughness can be adjusted by a stretching ratio or the like. When particles are not contained, the roughness of the metal belt may be adjusted so that the metal belt surface is the back surface. Further, the roughness may be transferred to the surface while being dried while being passed between rolls having different roughness.

Further, even in the case of an unstretched film formed by casting a molten resin such as COP, the roughness can be adjusted by adding particles. By using particles having a coefficient of thermal expansion different from that of the film resin, such as inorganic particles, it is possible to form irregularities on the surface due to the added particles due to heat shrinkage that occurs during cooling. In this case, it is preferable to reduce the surface roughness of the cooling roll that extrudes the molten resin into a sheet to form a release surface. Alternatively, the cooling roll may be roughened to transfer the roughness and used as the back surface. Roughness may be transferred between rolls having different roughness at a temperature of Tg or more of the film resin. As with the stretched film, the roughness of these unstretched films can be adjusted by a smooth coating or an easy-slip coating containing particles.

(Thin film layer)
Next, the thin film layer will be described. The thin film layer preferably contains a layer in which the liquid crystal compound is oriented. Further, the thin film layer may be a retardation layer, a polarizing layer, an absorption layer such as ultraviolet rays or infrared rays, a reflection layer, an electromagnetic wave shield layer, an electrode layer, an antireflection layer, a refractive index adjusting layer, or the like. These thin film layers may be a single layer or a plurality of layers.

The lower limit of the thickness of the thin film layer is preferably 0.001 μm, more preferably 0.005 μm, and even more preferably 0.01 μm. The upper limit of the thickness is preferably 20 μm, more preferably 10 μm, still more preferably 7 μm, particularly preferably 5 μm, and most preferably 4.5 μm. When there are a plurality of thin film layers, the total thickness is preferably in the above range.

(Liquid crystal compound layer)
Next, a liquid crystal compound layer, which is a thin film layer suitable for the present invention, will be described. The liquid crystal compound layer is used as a retardation layer or a polarizing layer, and in this case, the liquid crystal compound layer needs to be coated and oriented on the releasable base film. As a method of orienting, a method of rubbing the lower layer (separation surface) of the liquid crystal compound layer to give an orientation control function, or a method of directly orienting the liquid crystal compound by irradiating it with polarized ultraviolet rays or the like after applying the liquid crystal compound. There is.

(Orientation control layer)
Further, a method in which an orientation control layer is provided on the releasable base film and a liquid crystal compound layer is provided on the orientation control layer is also preferable. The orientation control layer may be any orientation control layer as long as the liquid crystal compound layer can be brought into a desired orientation state. A preferred example is a photo-orientation control layer that orients molecules by irradiation with polarized light to generate an orientation function.

(Rubbing treatment orientation control layer)
As the polymer material used for the orientation control layer formed by the rubbing treatment, polyvinyl alcohol and its derivatives, polyimide and its derivatives, acrylic resins, polysiloxane derivatives and the like are preferably used.

Hereinafter, a method for forming the rubbing treatment orientation control layer will be described. First, a coating material for forming a rubbing treatment orientation control layer containing the above polymer material is applied onto the release surface of a releasable base film, and then heat-dried to obtain an orientation control layer before the rubbing treatment. The coating material for forming a rubbing orientation control layer may have a cross-linking agent.

As the solvent for the coating material for forming the rubbing treatment orientation control layer, any solvent can be used as long as it dissolves the polymer material. Specific examples include water, alcohol solvents, ester solvents, ketone solvents, aromatic hydrocarbon solvents, ether solvents and the like. These solvents may be used alone or in combination.

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

The rubbing treatment can generally be carried out by rubbing the surface of the polymer layer with paper or cloth in a certain direction. Generally, a rubbing roller of a brushed cloth made of fibers such as nylon, polyester, and acrylic is used to rub the surface of the orientation control layer. In order to provide the orientation control layer that is oriented diagonally with respect to the traveling direction of the releasable base film, it is necessary to set the rubbing direction of the orientation control layer at an angle corresponding to the rubbing direction. The angle can be adjusted by adjusting the angle between the rubbing roller and the releasable base film, and adjusting the transport speed of the releasable base film and the rotation speed of the roller.

(Photo-orientation control layer)
The photo-orientation control layer is a coating containing a polymer or monomer having a photoreactive group and a solvent (paint for forming a photo-orientation control layer) applied to the release surface of a releasable base film, and is polarized, preferably. It refers to an alignment film that is given an orientation-regulating force by irradiating it with polarized ultraviolet light. The photoreactive group refers to a group that produces a liquid crystal alignment ability by irradiation with light. Specifically, it produces a photoreaction that is the origin of the liquid crystal orientation ability, such as a molecule orientation-inducing or isomerization reaction, a dimerization reaction, a photocrosslinking reaction, or a photodecomposition reaction that occurs when light is irradiated. be. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferable in that they have excellent orientation and maintain the smectic liquid crystal state of the polarizing film. The photoreactive group capable of causing the above reaction is preferably an unsaturated bond, particularly a double bond, and is a group consisting of a C = C bond, a C = N bond, an N = N bond, and a C = O bond. A group having at least one selected from the above is particularly preferable.

Examples of the photoreactive group having a C = C bond include a vinyl group, a polyene group, a stilbene group, a stillbazol group, a stillvazolium group, a chalcone group and a cinnamoyl group. Examples of the photoreactive group having a C = N bond include a group having a structure such as an aromatic Schiff base and an aromatic hydrazone. Examples of the photoreactive group having an N = N bond include an azobenzene group, an azonaphthalene group, an aromatic heterocyclic azo group, a bisazo group and a formazan group, and those having an azoxylene basic structure. Examples of the photoreactive group having a C = O bond include a benzophenone group, a coumarin group, an anthraquinone group, a maleimide group and the like. These groups may have substituents such as an alkyl group, an alkoxy group, an allyl group, an allyloxy group, a cyano group, an alkoxycarbonyl group, a hydroxyl group, a sulfonic acid group and an alkyl halide group.

Among them, a photoreactive group capable of causing a photodimerization reaction is preferable, and a photo-alignment layer in which a cinnamoyl group and a chalcone group require a relatively small amount of polarization for photo-orientation and is excellent in thermal stability and temporal stability is obtained. It is preferable because it is easy to obtain. Furthermore, as the polymer having a photoreactive group, a polymer having a cinnamoyl group such that the terminal portion of the side chain of the polymer has a cinnamic acid structure is particularly preferable. Examples of the structure of the main chain include polyimide, polyamide, (meth) acrylic, polyester, and the like.

By adjusting the angle of the polarized light to be irradiated, the direction of the orientation regulating force of the optical orientation control layer can be arbitrarily adjusted.

At the time of transfer, it is preferable that the orientation control layer is peeled off together with the liquid crystal compound layer and transferred. Further, the alignment control layer and the liquid crystal compound layer may be collectively referred to as a liquid crystal compound layer.

(Liquid crystal compound layer)
The liquid crystal compound layer is not particularly limited as long as the liquid crystal compound is oriented. Specific examples include a polarizing film (polarizer) containing a liquid crystal compound and a dichroic dye, a retardation layer containing a rod-shaped or discotic liquid crystal compound, and a circularly polarized light reflecting layer having a cholesteric liquid crystal structure containing a rod-shaped liquid crystal compound. Can be mentioned.

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

(Dichroic pigment)
The dichroic dye refers to a dye having a property in which the absorbance in the major axis direction and the absorbance in the minor axis direction of the molecule are different.

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 an acridine dye, an oxazine dye, a cyanine dye, a naphthalene dye, an azo dye and an anthraquinone dye, and among them, the azo dye is preferable. Examples of the azo dye include a monoazo dye, a bisazo dye, a trisazo dye, a tetrakisazo dye and a stilbene azo dye, and preferably a bisazo dye and a trisazo dye. The dichroic dyes may be used alone or in combination, but in order to adjust the color tone (achromatic color), it is preferable to combine two or more kinds, and it is more preferable to combine three or more kinds. In particular, it is preferable to combine three or more kinds of azo compounds.

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

The dichroic dye is also preferably a dichroic dye polymer introduced into the side chain of a polymer such as acrylic. Examples of these dichroic dye polymers include polymers listed in JP-A-2016-4055 and polymers obtained by polymerizing compounds [Chemical formula 6] to [Chemical formula 12] in JP-A-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 in the polarizing film from the viewpoint of improving the orientation of the dichroic dye. , 1.0 to 15% by mass is more preferable, and 2.0 to 10% by mass is particularly preferable.

The polarizing film preferably further contains a polymerizable liquid crystal compound in order to improve the film strength, the degree of polarization, and the film homogeneity. Here, the polymerizable liquid crystal compound also includes a film after polymerization.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity. The polymerizable group means a group involved in the polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group refers to a group that can undergo a polymerization reaction with an active radical, an acid, or the like generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxylanyl group, an oxetanyl group and the like. Of these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxylanyl group and an oxetanyl group are preferable, and an acryloyloxy group is more preferable. The liquid crystal compound may be a thermotropic liquid crystal or a riotropic liquid crystal, and may be a nematic liquid crystal or a smectic liquid crystal in the thermotropic liquid crystal.

The polymerizable liquid crystal compound is preferably a smectic liquid crystal compound, and more preferably a higher-order smectic liquid crystal compound, in that higher polarization characteristics can be obtained. When the liquid crystal phase formed by the polymerizable liquid crystal compound is a higher-order smectic phase, a polarizing film having a higher degree of orientation order can be produced.

Specific preferred polymerizable liquid crystal compounds include, for example, JP-A-2002-308832, JP-A-2007-16207, JP-A-2015-163596, JP-A-2007-510946, JP-A-2013-114131. No., WO2005 / 045485, Lub et al. Recl. Trav. Chim. Examples thereof include those described in 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, and further preferably 75 to 99% by mass in the polarizing film from the viewpoint of increasing the orientation of the polymerizable liquid crystal compound. It is preferably 80 to 97% by mass, and particularly preferably 83 to 95% by mass.

The polarizing film can be provided by applying a coating film for forming a polarizing film. The coating material for forming a polarizing film may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a cross-linking agent and the like.

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

Examples of the cross-linking agent include a polymerizable liquid crystal compound and a compound capable of reacting with a functional group of a polymerizable non-liquid crystal compound, and examples thereof include an isocyanate compound, a melamine, an epoxy resin, and an oxazoline compound.

The polarizing film is provided by applying the polarizing film forming paint directly on the releasable base film or the orientation control layer, and then drying, heating, and curing as necessary.

Heat treatment can be performed to more strongly orient the dichroic dye and the polymerizable liquid crystal compound in the polarizing film. The heating temperature is preferably in the temperature range in which the polymerizable liquid crystal compound forms a liquid crystal phase.

When the coating film for forming a polarizing film contains a polymerizable liquid crystal compound, it is preferably cured. Examples of the curing method include heating and light irradiation, and light irradiation is preferable. By curing, the dichroic dye can be fixed in an oriented state. The curing is preferably carried out in a state where the polymerizable liquid crystal compound has a liquid crystal phase formed therein, and may be cured by irradiating light at a temperature indicating the liquid crystal phase. Examples of the light in the light irradiation include visible light, ultraviolet light and laser light. Ultraviolet light is preferable because it is easy to handle.

By applying the polarizing film forming paint on the alignment control layer, the polarizing film is oriented along the orientation direction of the alignment layer, and as a result, the polarizing film has a polarization transmission axis in a predetermined direction. However, when the film is directly applied to the releasable base film without providing the orientation control layer, the polarizing film can be oriented by irradiating polarized light to cure the liquid crystal compound and the dye. At this time, polarized light in an oblique direction with respect to the longitudinal direction of the releasable base film is irradiated. Further, it is preferable that the dichroic dye is firmly oriented along the orientation direction of the polymer liquid crystal by heat treatment at that time.

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

(Phase difference layer)
Typical examples of the retardation layer are those provided for optical compensation between the polarizer of the liquid crystal display device and the liquid crystal cell, and λ / 4 layer and λ / 2 layer of a circular polarizing plate. As the liquid crystal compound, a rod-shaped liquid crystal compound, a discotic liquid crystal compound, or the like can be used depending on the purpose, such as a positive or negative A plate, a positive or negative C plate, or an O plate.

The liquid crystal compound used for these retardation layers is preferably a polymerizable liquid crystal compound having a polymerizable group such as a double bond in terms of being able to fix the orientation state.

Examples of the rod-shaped liquid crystal compound include JP-A-2002-030042, JP-A-2004-204190, JP-A-2005-263789, JP-A-2007-119415, JP-A-2007-186430, and special publications. Examples thereof include rod-shaped liquid crystal compounds having a polymerizable group described in Kaihei 11-513360.

Specific compounds include
CH ₂ = CHCOO- (CH ₂ ) _m- O-Ph1-COO-Ph2-OCO-Ph1-O- (CH ₂ ) _n -OCO-CH = CH ₂
CH ₂ = CHCOO- (CH ₂ ) _m- O-Ph1-COO-NPh-OCO-Ph1-O- (CH ₂ ) _n -OCO-CH = CH ₂
CH ₂ = CHCOO- (CH ₂ ) _m- O-Ph1-COO-Ph2-OCH ₃
CH ₂ = CHCOO- (CH ₂ ) _m- O-Ph1-COO-Ph1-Ph1-CH ₂ CH (CH ₃ ) C ₂ H ₅
In the formula, m and n are integers of 2 to 6 and
Ph1 and Ph2 are 1,4-phenyl groups (Ph2 may have a methyl group at the 2-position).
NPh is a 2,6-naphthyl group.
These rod-shaped liquid crystal compounds are commercially available from BASF as LC242 and the like, and they can be used. A plurality of these rod-shaped liquid crystal compounds may be used in combination at any ratio.

式中、Ｒ₁〜Ｒ₆はそれぞれ独立して水素、ハロゲン、アルキル基、又は−Ｏ−Ｘで示される基（ここで、Ｘは、Ｘはアルキル基、アシル基、アルコキシベンジル基、エポキシ変性アルコキシベンジル基、アクリロイルオキシ変性アルコキシベンジル基、アクリロイルオキシ変性アルキル基である）である。Ｒ₁〜Ｒ₆は、下記一般式（２）で表されるアクリロイルオキシ変性アルコキシベンジル基（ここで、ｍは４〜１０）であることが好ましい。

Examples of the discotic liquid crystal compound include a benzene derivative, a tolucene derivative, a cyclohexane derivative, an azacrown-based compound, a phenylacetylene-based macrocycle, and the like, and various ones are described in JP-A-2001-155866. Is preferably used. Among them, as the discotic compound, a compound having a triphenylene ring represented by the following general formula (1) is preferably used.

In the formula, R _{1 to} R ₆ are independently represented by hydrogen, halogen, alkyl group, or -OX (where X is X is an alkyl group, an acyl group, an alkoxybenzyl group, or an epoxy-modified group. It is an alkoxybenzyl group, an acryloyloxy-modified alkoxybenzyl group, and an acryloyloxy-modified alkyl group). R _{1 to} R ₆ are preferably acryloyloxy-modified alkoxybenzyl groups represented by the following general formula (2) (where m is 4 to 10).

The retardation layer can be provided by applying a paint for forming a retardation layer. The retardation layer forming coating material may contain a solvent, a polymerization initiator, a sensitizer, a polymerization inhibitor, a leveling agent, a polymerizable non-liquid crystal compound, a cross-linking agent and the like. As these, those described in the orientation control layer and the liquid crystal polarizer can be used.

A retardation layer is provided by applying a paint for forming a retardation layer on a release surface or an orientation control layer of a releasable base film, and then drying, heating, and curing. As for these conditions, the conditions described in the orientation control layer and the liquid crystal polarizer are used as preferable conditions.

(Circularly polarized light reflective layer)
The circularly polarized light reflecting layer is preferably a cholesteric liquid crystal oriented liquid crystal compound. As the liquid crystal compound, the rod-shaped liquid crystal compound mentioned in the above retardation layer can be mentioned as a preferable example.

In order to orient the liquid crystal compound of the circularly polarized light reflecting layer in a cholesteric liquid crystal, it is preferable to add a chiral agent to the liquid crystal compound. The chiral agent has the function of inducing the helical structure of the cholesteric liquid crystal phase.

Examples of chiral agents include Liquid Crystal Device Handbook (Chapter 3, 4-3, TN, Chiral Auxiliary for STN, 199 pages, edited by Japan Society for the Promotion of Science 142, 1989), JP-A-2003-287623, JP. Examples thereof include the compounds described in JP-A-2002-302487, JP-A-2002-80478, JP-A-2002-80851, JP-A-2010-181852, and JP-A-2014-034581. The chiral agent generally contains an asymmetric carbon atom, but an axial asymmetric compound or a surface asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent. Examples of axial or asymmetric compounds include binaphthyl, helicene, paracyclophane and derivatives thereof. Moreover, the chiral agent may be a liquid crystal compound.

The chiral agent preferably has a polymerizable group. By having the same polymerizable group as the liquid crystal compound, the cholesteric liquid crystal structure can be immobilized together with the liquid crystal compound. As the chiral agent, an isosorbide derivative, an isomannide derivative, or a binaphthyl derivative can be preferably used. As the isosorbide derivative, a commercially available product such as LC-756 manufactured by BASF may be used. The chiral agent is preferably 0.01 mol% to 200 mol%, more preferably 1 mol% to 30 mol%, based on the total molar amount of the polymerizable liquid crystal compound.

The circularly polarized light reflecting layer can be provided on the releasable base film in the same manner as the above retardation layer.

A plurality of liquid crystal compound layers may be provided on the releasable base film. A plurality of retardation layers, a plurality of circularly polarized light reflecting layers, a polarizing layer and a retarding layer, a polarizing layer and a circularly polarized light reflecting layer, and a circularly polarized light reflecting layer and a retardation layer may be provided. Further, when an interlayer protective coating layer is provided between the polarizer and the retardation layer, between the retardation layer and the circularly polarized light reflecting layer, above the retardation layer, between the retardation layers, etc. to prevent the transfer of components of each layer. There is. These interlayer protection coating layers may also be provided on the releasable base film together with the retardation layer, the polarizing layer, and the circularly polarized light reflecting layer and transferred to the object.

Examples of the interlayer protection coating layer include a transparent resin coating layer. 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. A cross-linking agent may be added to these resins to form a cross-linked structure. Further, a photocurable composition such as a hard coat may be cured. Further, after the interlayer protection coat layer is provided on the releasable base film, the interlayer protection coat layer may be subjected to a rubbing treatment, and a liquid crystal compound layer may be provided on the interlayer protection coat layer without providing an orientation control layer.

(Masking film)
In the present invention, a masking film is bonded on the thin film layer (the surface of the thin film layer opposite to the surface facing the releasable base film). The masking film is composed of at least a base material layer and an adhesive layer, and the adhesive layer surface of the masking film is directly bonded onto the thin film layer or the interlayer protective coating layer.

The base material of the masking film is preferably a resin film, and examples of the film material include polypropylene, polyethylene, polyester, polyamide, and polyurethane. Of these, polypropylene, polyethylene and polyethylene terephthalate are preferable. These may be copolymerized in order to adjust various physical properties such as the flexibility of the film. The resin film may be an unstretched film or a stretched film. In the case of a stretched film, it may be uniaxially stretched or biaxially stretched.

As the adhesive layer of the masking film, a conventional adhesive such as a rubber-based adhesive, an acrylic-based adhesive, or a polyolefin-based adhesive can be used. Examples of the rubber type include rubbers such as natural rubber, butadiene rubber and isoprene rubber, and styrene block copolymer elastomers such as SBS, SIS, SEBS and SEPS. In the acrylic system, the copolymer weight of methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. Examples include cross-linked coalescing. Examples of the cross-linking agent include isocyanate compounds, epoxy compounds, metal chelating agents, and compounds containing a plurality of double bonds.

Examples of the polyolefin-based material include ethylene-propylene rubber such as EPM and EPDM, those in which these are soft segments and polyethylene or polypropylene is used as a hard segment, and blends of ethylene-propylene rubber and polyethylene or polypropylene.

Various adhesive strength modifiers and stabilizers such as tack fire, fatty acid esters, fatty acid bisamides, polyglycerin, silicone oil, and silicone resin may be added to these pressure-sensitive adhesives.

Examples of the pressure-sensitive adhesive include a method of coating the resin film as the base material and providing the pressure-sensitive adhesive, and a method of co-extruding the resin of the base material and the resin serving as the pressure-sensitive adhesive layer at the time of forming the resin film.

It is preferable that the masking film has a thin film layer provided on the releasable base film, is bonded before being wound up, and then wound up in a roll shape.

The present invention is a laminate in which a releasable base film, a thin film layer, and a masking film are laminated in this order, and the peel strength between the releasable base film and the thin film layer is X (N / 25 mm). When the peel strength between the thin film layer and the masking film is Y (N / 25 mm), the following formula (1) is satisfied.
0.01 ≤ Y / X ≤ 0.7 (1)

The lower limit of Y / X is more preferably 0.02, further preferably 0.03, particularly preferably 0.04, and most preferably 0.05.

The upper limit of Y / X is more preferably 0.6, still more preferably 0.5, particularly preferably 0.4, and most preferably 0.35.

By setting Y / X to the above value or more, stable handling is possible without the masking film being unnecessarily peeled off when handling the thin film layer transfer laminate, such as winding, unwinding, and slitting. Further, when the thin film layer is transferred to the object using the thin film layer transfer laminate, the releasable base film is easily peeled off, and pinholes and transfer defects are less likely to occur in the thin film layer at the time of peeling.

Further, by setting Y / X to the above value or less, the masking film can be easily peeled off when the masking film is peeled off from the thin film layer transfer laminate, and pinholes or the thin film layer can be peeled off in the liquid crystal compound layer at the time of peeling. It becomes difficult to get up.

The peel strength Y between the thin film layer and the masking film preferably satisfies the following formula (5).
0.005N / 25mm ≤ Y ≤ 2.0N / 25mm (5)
The lower limit of the peel strength Y between the thin film layer and the masking film is preferably 0.005 N / 25 mm, more preferably 0.01 N / 25 mm, further preferably 0.03 N / 25 mm, and particularly preferably 0. It is .05N / 25mm. The upper limit of the peel strength Y is preferably 2.0 N / 25 mm, more preferably 1.5 N / 25 mm, still more preferably 1.2 N / 25 mm, and even more preferably 1.0 N / 25 mm. Yes, particularly preferably 0.7 N / 25 mm, most preferably 0.5 N / 25 mm.

By setting the peel strength Y between the thin film layer and the masking film to the above or higher, stable handling is possible without the masking film being unnecessarily peeled when handling the thin film layer transfer laminate, such as winding, unwinding, and slitting. It will be possible. Further, by setting the peeling strength Y between the thin film layer and the masking film to the above or less, the releasable base film can be easily peeled off when the thin film layer is transferred to the object using the thin film layer transfer laminate. , Pinholes and transfer defects are less likely to occur in the thin film layer during peeling.

The peel strength Y between the thin film layer and the masking film can be adjusted according to the composition of the thin film layer and the like, the composition of the pressure-sensitive adhesive of the masking film, the coating conditions, and the like.

The lower limit of the peel strength X between the thin film layer and the releasable base film is preferably 0.01 N / 25 mm, more preferably 0.03 N / 25 mm, and further preferably 0.05 N / 25 mm. Particularly preferably, it is 0.07 N / 25 mm. The upper limit of the peel strength X between the thin film layer and the releasable base film is preferably 2.0 N / 25 mm, more preferably 1.5 N / 25 mm, and further preferably 1.2 N / 25 mm. It is particularly preferably 1.0 N / 25 mm, and most preferably 0.8 N / 25 mm.

The peel strength X between the thin film layer and the releasable base film is determined by surface treatment such as corona treatment of the releasable base film and release layer according to the composition of the thin film layer and the conditions at the time of coating. It can be adjusted by changing the composition, etc.

(Transfer target of thin film layer)
The transfer target of the thin film layer is not particularly limited, but is preferably a film or a sheet, and examples thereof include a resin film, a glass film, a resin sheet, a glass plate, and a metal plate. Of these, a resin film is preferable.

In one embodiment of the present invention when the thin film layer is a liquid crystal compound layer, when a transparent resin film is used as a transfer target, a polarizing film is transferred to produce a polarizing plate, and a retardation layer is transferred. The retardation layer and the polarizer, which are used as a retardation film, are transferred to form a polarizing plate for circularly polarized light or an optical compensation layer, and the circularly polarized light reflecting layer and the retardation layer (λ / 4 retardation layer) are transferred to improve brightness. Examples include the use of a film.

In one embodiment of the present invention, a circularly polarized light reflecting layer and a retardation layer (λ / 4 retardation layer) in which a retardation layer is transferred to a polarizing plate of circularly polarized light or an optical compensation layer laminate for a polarizing plate. Is transferred to obtain a brightness-improving layer laminated polarizing plate.

In one embodiment of the present invention, a liquid crystal display cell is targeted, and an organic EL display cell or the like in which a polarizing layer or a retardation layer and a polarizing layer are transferred and a polarizing layer is directly laminated on the liquid crystal display cell is targeted. A mode such as transferring a layer and a polarizing layer, a circularly polarized light reflecting layer, a retardation layer, and a polarizing layer to laminate an antireflection circularly polarized light layer or a circularly polarized light layer with a brightness improving layer to form an image display panel. Can be mentioned.

In one embodiment of the present invention, the retardation layer and the polarizing layer, the circularly polarized light reflecting layer and the retarding layer and the polarizing layer are transferred to the surface cover sheet of the image display device to transfer the antireflection circularly polarized light layer and the brightness improvement. Examples thereof include laminating circularly polarized light layers with layers to obtain a surface cover sheet with an antireflection function for an organic EL display device and the like.

The transfer is preferably performed by roll-to-roll, but if the transfer target is a non-long object such as an image display cell, a panel, or a surface cover sheet for reasons such as aligning the optic axis, perform the transfer with a single sheet. May be good.

(Manufacturing method of circularly polarizing plate)
As an example, a method for producing a circularly polarizing plate in which the thin film layer transfer laminate of the present invention is preferably used will be described.

First, a λ / 4 retardation layer made of a liquid crystal compound is provided on the release surface of the releasable base film, and a masking film is bonded to obtain a roll-like laminate for thin film layer transfer. After that, the thin film layer transfer laminate is unwound from the roll, the masking film is peeled off, the λ / 4 retardation layer and the linear polarizing plate are bonded together with an adhesive or the like, the releasable base film is peeled off, and circularly polarized light is formed. Get the board.

The front retardation of the λ / 4 retardation layer is preferably 100 to 180 nm. More preferably, it is 120 to 150 nm. The angle between the orientation axis (slow phase axis) of the λ / 4 retardation layer and the width direction of the releasable base film (direction orthogonal to the film forming running direction of the film) is preferably 45 degrees, and an error is also present. It is preferably in the range of 43 to 47 degrees including.

Further, the λ / 4 retardation layer may be a composite λ / 4 retardation layer in which the λ / 4 retardation layer and the λ / 2 retardation layer are combined. The front retardation of the λ / 2 retardation layer is preferably 200 to 360 nm. More preferably, it is 240 to 300 nm.

In this case, it is preferable that the λ / 4 retardation layer and the λ / 2 retardation layer are arranged at an angle such that the retardation is λ / 4 in total by using a circularly polarizing plate. Specifically, the angle (θ) between the orientation axis (slow phase axis) of the λ / 2 retardation layer and the transmission axis of the polarizer is preferably 5 to 20 degrees, more preferably 7 to 17 degrees, and λ. The angle between the orientation axis (slow phase axis) of the / 2 retardation layer and the orientation axis (slow phase axis) of the λ / 4 retardation layer is preferably in the range of 2θ + 45 degrees ± 10 degrees, more preferably 2θ + 45 degrees ± 5. It is in the range of degrees, more preferably in the range of 2θ + 45 degrees ± 3 degrees. In the case of a polarizer obtained by stretching a polyvinyl alcohol film adsorbing iodine, which is widely used, the width direction is the transmission axis, so the width direction of the releasable base film (direction orthogonal to the film forming running direction of the film). ) Is also preferably in the above range.

In the production of a circularly polarizing plate having a composite λ / 4 retardation layer, a λ / 4 retardation layer and a λ / 2 retardation layer may be provided on a releasable base film and transferred thereof, or they may be transferred separately. A λ / 4 retardation layer and a λ / 2 retardation layer may be provided on the releasable base film and these may be transferred. Further, in the circularly polarizing plate, a retardation layer such as a C plate layer may be provided. Also in this case, the entire retardation layer may be provided on the releasable base film and transferred, or may be transferred separately.

The linear polarizing plate to be transferred is not particularly limited, but a linear polarizing plate in which a polarizing element protective film is provided on both sides or one side of the polarizer is preferable.

The polarizer protects the polarizer produced by stretching a PVA-based film alone or by applying PVA to an unstretched base material such as polyester or polypropylene and stretching the entire base material. Examples thereof include those transferred to a film and those in which a polarizer composed of a liquid crystal compound and a dichroic dye is coated or transferred to a polarizer protective film, and all of them are preferably used.

As the polarizer protective film, generally known ones such as TAC, acrylic, COP, polycarbonate, and polyester can be used. Of these, TAC, acrylic, COP, and polyester are preferable. Polyethylene terephthalate is preferable as the polyester. In the case of polyester, an in-plane retardation of 100 nm or less, particularly a zero retardation film of 50 nm or less, or a high retardation polyester film of 3000 nm to 30,000 nm is preferable.

As a method of sticking, conventionally known ones such as an adhesive and an adhesive can be used. As the adhesive, a polyvinyl alcohol-based adhesive, an ultraviolet curable adhesive such as acrylic or epoxy, and a heat-curable adhesive such as epoxy or isocyanate (urethane) are preferably used. Examples of the adhesive include acrylic, urethane, and rubber adhesives. It is also preferable to use an optical transparent adhesive sheet without an acrylic base material.

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

This application claims the benefit of priority under Japanese Patent Application No. 2020-56823 filed on March 26, 2020. The entire contents of the specification of Japanese Patent Application No. 2020-56823 filed on March 26, 2020 are incorporated herein by reference.

(1) Surface Roughness The parameters of each roughness were measured according to ISO 25178 using a non-contact surface shape measurement system (VertScan R550H-M100 manufactured by Ryoka System Co., Ltd.) under the following conditions.
(Measurement condition)
Measurement mode: WAVE mode Objective lens: 50x 0.5 x Tube lens Measurement area: 187 μm x 139 μm
(Analysis conditions)
Surface correction: Fourth-order correction Interpolation processing: Complete interpolation ISO parameter processing: S-Filter 1 μm designation The measurement was performed at 5 points, and the average value was calculated.

(2) Peeling strength (2-1) Preparation of sample A sample obtained by cutting a laminate of the releasable base film / retardation layer / masking film obtained in Examples and Comparative Examples into a width of 25 mm and a length of 160 mm. Was produced. The length direction of the sample was the width direction of the releasable base film. Further, the sample was prepared by unwinding from a roll of laminated film left in a room at 24 ° C. and 50% relative humidity for 1 week after the masking film was attached, and cutting out from a position 100 m from the core of the roll.

(2-2) Peeling strength between the retardation layer and the masking film The releasable base film surface of the sample is laminated on an acrylic plate having the same width and length as the 1 mm thick sample using double-sided tape. rice field. Peel off the masking film at one end of the sample in the length direction of about 20 mm, and use double-sided tape to apply a biaxially stretched polyester film with a width of 25 mm, a length of 160 mm, and a thickness of 50 μm to the peeled part of the surface masking film. I pasted it. The retardation layer / releasable film laminate at the part where the surface masking film was peeled off was grasped together with the acrylic plate with the lower chuck of the tensile tester, and the opposite end to which the surface masking film of the biaxially stretched polyester film was bonded. The part was grasped by the upper chuck, and the peel strength when peeled by 180 degrees at a speed of 300 mm / min was measured. An autograph (registered trademark) (AG-X) manufactured by Shimadzu Corporation was used as a testing machine, and the average value from 2 seconds to 25 seconds after the start of peeling was determined by measurement. It was carried out at 5 points of the sample, and the average value was taken as the peel strength. The temperature in the measurement room was 24 ° C.

(2-3) Release strength between releasable base film and retardation layer Adhesive tape of polypropylene base material with a width of 25 mm on the retardation layer of the sample from which the masking film after the above measurement was peeled off (Damplon manufactured by Nitto Denko KK) Ace No. 3200 (registered trademark) cut to a length of 160 mm was accurately bonded. At this time, the end portion of the biaxially stretched polyester film having a width of 25 mm, a length of 160 mm, and a thickness of 50 μm was attached to a portion of the adhesive tape corresponding to the chucked portion in the above measurement. In the bonding, a hand roller was used to prevent air bubbles from entering. The same points as the above measurement of the sample are held by the lower chuck of the tensile tester, and the upper chuck holds the end on the opposite side of the biaxially stretched polyester film bonded to the adhesive tape. It was measured under the same conditions as above.

(3) Transfer workability The transfer workability was evaluated from the viewpoints of peeling of the masking film during cutting and handling, ease of peeling of the masking film, and ease of peeling of the base film.
◯: There was no problem in either case.
Δ: There was some problem in one of them, and attention was required for the transfer work.
X: There was a problem in one of them, and the transfer work was difficult.

(4) Transferability Place the obtained circularly polarizing plate on an aluminum plate whose surface is mirror-polished so that the λ / 4 layer is on the bottom, and irradiate light from above to change the transfer state of the λ / 4 layer. Observed. Observations were made with the naked eye and loupe.
⊚: Almost no pinholes were seen with the naked eye or loupe observation.
◯: Some pinholes were observed in the loupe observation, but not with the naked eye.
Δ: A relatively large number of pinholes were observed by loupe observation, but not by the naked eye.
X: A pinhole that was clearly visible to the naked eye was observed, or a portion where the λ / 4 layer could not be transferred was observed.

(5) Rewindability The winding state of the releasable base film during film formation and the releasable base film during slitting was observed. Further, the releasable base film after slitting was stored in a warehouse for one month, and then the state of the roll was observed.
◯: It was possible to wind up without problems such as wrinkles, meandering and air entrainment, and there was no abnormality even after storage.
Δ: It was possible to wind up without problems such as wrinkles, meandering, and air entrainment, but some abnormalities (end face deviation, partial loosening, surface slack, etc.) were observed in the roll after storage.
X: Problems such as wrinkles, meandering, and air entrainment were observed during winding.

(Manufacturing of raw material polyester resin)
(Manufacture of particle-free polyester resin (PET (X1)))
When the temperature of the esterification reaction can was raised to 200 ° C., 86.4 parts by mass of terephthalic acid and 64.6 parts by mass of ethylene glycol were charged, and 0.011 parts by mass of antimony trioxide was used as a catalyst while stirring. 0.16 parts by mass of triethylamine was charged. Then, the pressure was raised, the pressure esterification reaction was carried out under the conditions of a gauge pressure of 0.34 MPa and 240 ° C., and 0.064 parts by mass of magnesium acetate tetrahydrate was added in the subsequent stage of the reaction, and the addition was continued. A pressure esterification reaction was carried out. Then, the esterification reaction can was returned to normal pressure, and 0.014 parts by mass of phosphoric acid was added. Further, the temperature was raised to 260 ° C. over 15 minutes, and 0.012 parts by mass of trimethyl phosphate was added. Then, after 15 minutes, dispersion treatment was carried out with a high-pressure disperser, and after 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction can, and a polycondensation reaction was carried out under reduced pressure at 280 ° C.

After completion of the polycondensation reaction, filtration is performed with a Naslon filter having a 95% cut diameter of 5 μm, extruded into strands from a nozzle, and cooled and solidified using cooling water that has been previously filtered (pore diameter: 1 μm or less). , It was cut into pellets to obtain a polyethylene terephthalate resin (PET (X1)). The intrinsic viscosity of PET (X1) was 0.62 dl / g, the content of the ester cyclic trimer was 1.05% by mass, and the inert particles and internally precipitated particles were substantially not contained.

(Manufacture of particle-free polyester resin (PET (X2)))
The amount of antimony trioxide added was 0.017 parts by mass, magnesium acetate tetrahydrate was added at the same time as the addition of antimony trioxide, and the Naslon filter was changed to one with a 95% cut diameter of 20 μm. A polyethylene terephthalate resin (PET (X2)) was obtained in the same manner as in PET (X1) except for the above.

(Silica particle-containing polyester resin (manufacturing of PET (XSi)))
In the production of PET (X1), the temperature was raised to 260 ° C., and 15 minutes after the addition of trimethyl phosphate, the ethylene glycol slurry of the following silica particles was added to the produced polyester so as to be 10000 ppm, and 95. Similar to the production of PET (X1), it contains silica particles with an intrinsic viscosity of 0.63 dl / g, except that it was filtered with a Naslon filter (manufactured by Nippon Seisen Co., Ltd.) having a% cut diameter of 20 μm. A polyethylene terephthalate resin (PET (XSi)) was obtained. For the ethylene glycol slurry of silica particles, silica particles (manufactured by Fuji Silysia Chemical Ltd.) having an average particle diameter of 2.5 μm are charged in ethylene glycol, and further filtered with a viscose rayon filter having a 95% cut diameter of 30 μm. Manufactured by doing.

(Polyester resin containing calcium carbonate particles (manufacturing of PET (XCa)))
In the production of PET (XSi), the same procedure was carried out except that the ethylene glycol slurry of calcium carbonate particles was used instead of the ethylene glycol slurry of silica particles, and the polyethylene terephthalate resin containing calcium carbonate particles having an intrinsic viscosity of 0.63 dl / g ( PET (XCa)) was obtained. The ethylene glycol slurry of calcium carbonate particles was produced by using calcium carbonate particles (manufactured by Maruo Calcium Co., Ltd.) having an average particle diameter of 0.6 μm instead of silica particles.

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

(Manufacturing of oxazoline-based cross-linking agent)
A flask equipped with a thermometer, a nitrogen gas introduction tube, a reflux condenser, a dropping funnel, and a stirrer, a mixture of 58 parts by mass of ion-exchanged water as an aqueous medium and 58 parts by mass of isopropanol, and a polymerization initiator (2,2). '-Azobis (2-amidinopropane), dihydrochloride) 4 parts by mass was added. On the other hand, in the dropping funnel, 16 parts by mass of 2-isopropenyl-2-oxazoline as a polymerizable unsaturated monomer having an oxazoline group, methoxypolyethylene glycol acrylate (average number of moles of ethylene glycol added: 9 mol, Shin-Nakamura Chemical Co., Ltd.) A mixture of 32 parts by mass and 32 parts by mass of methyl methacrylate was added and added dropwise at 70 ° C. for 1 hour under a nitrogen atmosphere. After completion of the dropping, the reaction solution was stirred for 9 hours and cooled to obtain a water-soluble resin having an oxazoline group having a solid content concentration of 40% by mass.

(Preparation of coating liquid 1 for easy adhesive layer)
The following coating agents were mixed to prepare a coating liquid for an easy-adhesion layer.
Water 55.62% by mass
Isopropanol 30.00% by mass
Polyurethane resin 11.29% by mass
Oxazoline-based cross-linking agent 2.26% by mass
Particle A 0.70% by mass
(Silica sol with an average particle size of 40 nm, solid content concentration of 40% by mass)
Particle B 0.07% by mass
(Silica sol with an average particle size of 500 nm, solid content concentration of 40% by mass)
Surfactant 0.05% by mass
(Silicone type, solid content concentration 100% by mass)

(Preparation of coating liquid 2 for easy adhesive layer)
The following coating agents were mixed to prepare a coating liquid for an easy-adhesion layer.
Water 55.62% by mass
Isopropanol 30.00% by mass
Polyurethane resin 11.29% by mass
Oxazoline-based cross-linking agent 2.26% by mass
Surfactant 0.05% by mass
(Silicone type, solid content concentration 100% by mass)

(Manufacturing of film A)
As a raw material for the release layer side of the alignment film for transfer, PET (X1) resin pellets containing no particles are dried under reduced pressure (1 Torr) at 135 ° C. for 6 hours and then supplied to the extruder 1 to supply the opposite surface layer (back surface). As a raw material for the layer), a PET (X1) resin pellet and a polyester (PET (XSi)) resin pellet containing particles are used, and the particle content of the opposite surface layer (back surface layer) becomes a predetermined value shown in Table 1. The blended product in such a ratio was dried and supplied to the extruder 2 and melted at 285 ° C. These two types of molten polymers are each filtered through a filter medium of a stainless sintered body (nominal filtration accuracy of 10 μm particles 95% cut), laminated with a two-type two-layer confluence block, extruded into a sheet from a mouthpiece, and then extruded. An unstretched film was produced by winding it around a casting drum having a surface temperature of 30 ° C. and cooling and solidifying it using an electrostatic application casting method. At this time, the discharge amount of each extruder was adjusted so that the thickness of the release layer and the back surface layer became the predetermined values shown in Table 1.

This unstretched film was guided to a tenter stretching machine, and while gripping the end of the film with a clip, it was guided to a hot air zone having a temperature of 125 ° C. and stretched 4.0 times in the width direction. Next, while maintaining the width stretched in the width direction, heat fixing treatment was performed at a temperature of 210 ° C. for 10 seconds, and further relaxation treatment of 3.0% was performed. Then, after cutting both ends of the film cooled to 130 ° C. with a shear blade, the PET (X1) surface is subjected to corona treatment ^{, wound around the core with a tension of 0.5 kg / mm 2} , and uniaxially oriented PET with a film thickness of 50 μm. A film (width 1800 cm, length 5000 m) was obtained. The central portion of the obtained film was slit to a width of 50 cm to obtain a film roll (film A) having a length of about 500 m. The PET (X1) surface was used as the release surface.

(Manufacturing of film B)
A film roll (film B1) was obtained in the same manner except that the PET (XSi) resin pellet was changed to PET (XCa) among the raw materials for the opposite surface layer (back surface layer). Further, the film in which the strength of the corona treatment was increased was designated as the film B2, and the film in which the corona treatment was not performed was designated as B3.

(Manufacturing of film C)
A film roll (film C) was obtained in the same manner as in Example 2 except that the thickness ratio was changed.

(Manufacturing of film D)
PET (X1) pellets are supplied to an extruder as a raw material for a film, extruded into a sheet from a mouthpiece, and then wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method to be cooled and solidified. A stretched film was produced. Next, the coating liquid 1 for the easy-adhesion layer was applied to one side of this unstretched PET film ^{so that the coating amount after drying was 0.12 g / m 2} , and then guided to a dryer and dried at 80 ° C. for 20 seconds.

The unstretched film on which this coating layer was formed was guided to a tenter stretching machine, and while gripping the end of the film with a clip, it was guided to a hot air zone having a temperature of 135 ° C. and stretched four times in the width direction. Next, the film was treated at a temperature of 225 ° C. for 30 seconds while maintaining the width stretched in the width direction, and then both ends of the cooled film were cut with a shear blade to form a film A on the opposite surface of the coating layer. Similarly, corona treatment and slitting were performed to obtain a film roll (film D) having a width of 50 cm and a length of about 500 m. The corona-treated surface was used as the release surface.

(Manufacturing of film E)
A film roll (film E) was obtained in the same manner as in film D except that PET (X2) was used as a raw material for film.

(Manufacturing of film F)
A film F having a coating layer on both sides was obtained in the same manner as the film D except that the coating liquid 1 for an easy-adhesion layer was applied to both sides. No corona treatment was performed.

(Manufacturing of film G)
A film G having easy-adhesive layers on both sides was obtained in the same manner as the film D except that the easy-adhesive layer coating liquid 1 was applied to one side and the easy-adhesive layer coating liquid 2 was applied to the other side. The coating liquid 2 coating surface for the easy-adhesion layer of this film was used as the release surface. No corona treatment was performed.

(Manufacturing of film H)
As a raw material for a film, a PET (X1) resin pellet and a polyester (PET (XSi)) resin pellet containing particles are blended at a ratio such that the particle content becomes a predetermined value shown in Table 1 and dried. The film was supplied to the extruder 2 and extruded into a sheet from a mouthpiece, and then wound around a casting drum having a surface temperature of 30 ° C. using an electrostatic application casting method to be cooled and solidified to produce an unstretched film. Next, the unstretched film was guided to a tenter stretching machine, and while gripping the end portion of the film with a clip, the unstretched film was guided to a hot air zone having a temperature of 135 ° C. and stretched 3.5 times in the width direction. Next, while maintaining the width stretched in the width direction, the film was treated at a temperature of 225 ° C. for 30 seconds, and then both ends of the cooled film were cut with a shear blade and subjected to corona treatment to uniaxially orient the film with a thickness of 50 μm. A PET film (width 1800 cm, length 5000 m) was obtained. Further, corona treatment and slitting were performed in the same manner as in film A to obtain a film roll (film H) having a width of 50 cm and a length of about 500 m. The corona treatment was performed on the surface that was in contact with the casting drum when the resin was extruded, and the corona treatment surface was used as the release surface.

(Manufacturing of Film I)
A film having an easy-adhesion layer on one side was obtained by using the coating liquid 2 for an easy-adhesion layer on one side of the film H in the same manner as in the method of film D. A coating agent having the following composition was applied to the easy-adhesion layer surface of the obtained film and dried in a heating oven at 150 ° C. for 3 minutes to obtain Film I having a flattening coating layer. The flattening layer surface was used as the release surface.

(Preparation of flattening coating agent)
The following coating agents were mixed to prepare a flattening coating agent.
Melamine cross-linked alkyl-modified alkyd resin (Hitachi Kasei Polymer Co., Ltd .: Tessfine 322: Solid content 40%) 10 parts by mass P-toluenesulfonic acid (Hitachi Kasei Polymer Co., Ltd .: Dryer 900)
0.1 parts by mass Solvent (toluene / methyl ethyl ketone = 1/1 parts by mass)
20 parts by mass

The coating agent was filtered through a 2 μm filter, and the air during drying was filtered through a HEPA filter having a 95% cut diameter of 1 μm and then further filtered through a HEPA filter having a 99.9% cut diameter of 0.3 μm with high precision. I used the one. Further, the coating agent was applied to the film in a class 1,000 environment.

In the examples, the coating / drying steps were performed in the same environment.

(Preparation of masking film)
Five types of masking films p, q, r, s, and t using commercially available polypropylene as a base material and provided with an adhesive layer were prepared.

Examples 1-12, Comparative Examples 1-4
A λ / 4 retardation layer was provided on the films A to I by the method of Preparation 1 of Preparation of the λ / 4 retardation layer described below, and the masking films were laminated and wound. Table 1 shows the details of Examples and Comparative Examples and the evaluation results.

(Preparation of λ / 4 retardation layer 1)
(Formation of rubbing treatment orientation control layer)
After unwinding the above film as a base film and performing corona treatment on the release surface, a coating for a rubbing treatment orientation control layer having the following composition is applied using a bar coater, dried at 80 ° C. for 5 minutes, and has a thickness of 200 nm. Formed a film. Subsequently, the surface of the obtained film was treated with a rubbing roll wrapped with a brushed nylon cloth to obtain a transfer orientation film in which a rubbing treatment orientation control layer was laminated. For rubbing, the base film is hung diagonally with respect to the rubbing roll, and the transport speed of the base film and the number of rotations of the rubbing roll are adjusted so that the rubbing direction is 45 degrees with respect to the width direction of the base film. went.
Fully saponified polyvinyl alcohol (weight average molecular weight 800) 2 parts by mass Ion-exchanged water 100 parts by mass Surfactant 0.5 parts by mass

トリメチロールプロパントリアクリレート ５質量部
イルガキュア３７９ ３質量部
界面活性剤 ０．１質量部
メチルエチルケトン ２５０質量部(Formation of oriented liquid crystal compound oriented layer)
Subsequently, a solution for forming an oriented liquid crystal compound layer having the following composition was applied to the surface subjected to the rubbing treatment by a bar coating method. The film was dried at 110 ° C. for 3 minutes and cured by irradiating with ultraviolet rays to form an oriented liquid crystal compound layer (λ / 4 layer) on the film. The film on which the oriented liquid crystal compound layer was laminated was wound by laminating a masking film on the surface of the liquid crystal compound layer.
Rod-shaped liquid crystal compound (LC242 manufactured by BASF) 75 parts by mass 20 parts by mass of the compound represented by the following formula (3)

Trimethylolpropane Triacrylate 5 parts by mass Irgacure 379 3 parts by mass Surfactant 0.1 parts by mass Methyl ethyl ketone 250 parts by mass

Example 13, Comparative Example 5
A λ / 4 retardation layer was provided on the films B2 and B3 by the method of Preparation 2 of the following λ / 4 retardation layer, and the masking films were laminated and wound. Table 1 shows the details of Examples and Comparative Examples and the evaluation results.

(Preparation of λ / 4 retardation layer 2)
(Formation of light treatment orientation control layer)
A coating material for a photoalignment layer having the following composition was applied to one side of a base film using a bar coater and dried at 80 ° C. for 1 minute to form a film having a thickness of 150 nm. Subsequently, it was irradiated with polarized UV light to obtain a base film on which a photoalignment layer was laminated. The polarization direction of the UV light was 45 degrees with respect to the longitudinal direction of the film.

界面活性剤 ０．１質量部
シクロペンタノン ９５質量部(Paint for photo-alignment layer)
Based on the description of Example 1, Example 2, and Example 3 of JP2013-33248A, a 5% by mass solution of the polymer represented by the following formula (4) to cyclopentanone was produced.
5 parts by mass of the compound represented by the following formula (4)

Surfactant 0.1 parts by mass Cyclopentanone 95 parts by mass

The above-mentioned solution for forming an oriented liquid crystal compound layer was applied onto the photoaligned layer to produce a laminate in the same manner as in Preparation 1 of the λ / 4 retardation layer.

(Preparation of circularly polarizing plate)
The oriented liquid crystal compound layer laminated film on which the masking films of Examples and Comparative Examples were laminated was unwound, and the laminated body in the vicinity of 90 to 100 m from the winding core was cut into a length of 60 cm together with the masking film. Further, both ends in the width direction were cut at a position 2 cm from the end to remove the portion to which the oriented liquid crystal compound layer was not applied, and then the masking film was peeled off.

On the other hand, a polarizing plate having a length of 46 cm and a width of 60 cm (a polarizing element in which iodine is adsorbed on a stretched film of polyvinyl alcohol is protected by a 60 μm thick polarizer film made of triacetyl cellulose and an 80 μm thick polarizer made of polyethylene terephthalate. After applying an ultraviolet curable adhesive to the triacetyl cellulose surface (sandwiched between films), the adhesive surface of the adhesive surface and the oriented liquid crystal compound layer surface of the oriented liquid crystal compound layer laminated film were laminated and irradiated with ultraviolet rays to bond them together. .. Then, the base film was peeled off to obtain a circularly polarizing plate. Transfer workability and transferability were evaluated. The results are shown in Table 1.

Comparative Example 6
A film roll (film J) without a coating layer was obtained in the same manner as the film E except that the coating liquid 1 for the easy-adhesion layer was not applied. Table 1 shows the film thickness and the roughness parameters of the release surface. The obtained film roll had air bubbles and wrinkles, and was not suitable for use as a releasable base film.

Claims (19)

A laminate in which a releasable base film, a thin film layer, and a masking film are laminated in this order, and is used for thin film layer transfer, which satisfies the following formulas (1), (2), and (3). Laminated body.

0.01 ≤ Y / X ≤ 0.7 (1)
X: Peeling strength between the releasable base film and the thin film layer Y: Peeling strength between the thin film layer and the masking film

1.0 ≤ Sku ≤ 40 (2)
Sku: Kurtosis of the release surface of the release base film

0.5 nm ≤ Sq ≤ 20 nm (3)
Sq: Root mean square roughness of the release surface of the release base film The laminate for thin film layer transfer according to claim 1, which satisfies the following formula (4).

-1.0 ≤ Sk ≤ 2.0 (4)
Sk: Releasability The skewness of the release surface of the base film The laminate for thin film layer transfer according to claim 1 or 2, wherein the Sk on the release surface of the releasable base film is more than 3.0 and 20 or less. The laminate for thin film layer transfer according to claim 1 or 2, wherein the Sq of the release surface of the releasable base film is 1.0 nm or more and 7 nm or less. The laminate for thin film layer transfer according to claim 1 or 2, wherein the arithmetic mean roughness (Sa) of the release surface of the releasable base film is 0.5 nm or more and 5 nm or less. The laminate for thin film layer transfer according to claim 1 or 2, wherein the developed area (Sdr) of the interface of the release surface of the releasable base film is 0.0001% or more and 0.0007% or less. The thin film layer transfer according to claim 1 or 2, wherein the average (Spc) of the principal curvatures of the peaks of the release surface of the releasable base film is 7 (1 / mm) or more and 70 (1 / mm) or less. Laminated body for. The laminate for thin film layer transfer according to claim 1 or 2, wherein the arithmetic average roughness (Sa) of the back surface of the releasable base film is 1.5 nm or more and 30 nm or less. The laminate for thin film layer transfer according to claim 1 or 2, wherein the root mean square roughness (Sq) of the back surface of the releasable base film is 2.0 nm or more and 45 nm or less. The first or second claim, wherein the Sku on the back surface of the releasable base film is 7 or more and 170 or less, and the (Sku on the back surface) / (Sku on the releasable surface) is 1.5 or more and 20 or less. Thin film layer transfer laminate. The first or second claim, wherein the Ssk on the back surface of the releasable base film is 1 or more and 10 or less, and the absolute value of (Ssk on the back surface) / (Ssk on the releasable surface) is 2 or more and 15 or less. Thin film layer transfer laminate. The laminate for thin film layer transfer according to claim 1 or 2, wherein Y / X is 0.05 or more and 0.35 or less. The laminate for thin film layer transfer according to claim 1 or 2, which satisfies the following formula (5).

0.005N / 25mm ≤ Y ≤ 2.0N / 25mm (5) The laminate for thin film layer transfer according to claim 13, wherein the peel strength Y is 0.03 N / 25 mm or more and 0.5 N / 25 mm or less. The laminate for thin film layer transfer according to claim 13, wherein the peel strength X is 0.05 N / 25 mm or more and 0.8 N / 25 mm or less. The laminate for transferring a thin film layer according to claim 1 or 2, wherein the thickness of the thin film layer is 0.01 μm or more and 4.5 μm or less. The thin film layer transfer laminate according to claim 1 or 2 , wherein the thin film layer includes a layer in which a liquid crystal compound is oriented. The laminate for thin film layer transfer according to claim 1 or 2, wherein the resin constituting the base film raw material of the releasable base film is any one of polyethylene terephthalate, cyclic polyolefin, and triacetyl cellulose. The laminate for thin film layer transfer according to claim 18, wherein the base film raw fabric of the releasable base film has a retardation of 3000 nm to 30,000 nm, and the resin constituting the base film raw fabric is polyethylene terephthalate. ..