JP6879883B2 - Optical film manufacturing method, polarizing plate, and image display device - Google Patents

Description

The present invention relates to a method for producing an optical film, an optical film, a polarizing plate, and an image display device.

Conventionally, a film having a retardation layer in which a liquid crystal compound is oriented and fixed has been widely studied. Such a retardation layer is usually formed by forming an alignment layer on a transparent substrate (support) and applying a liquid crystal compound to the surface of the alignment layer.

For example, Patent Document 1 contains a transparent substrate made of a cycloolefin resin and a polymer of a polymerizable monomer formed in contact with the transparent substrate and having a predetermined polymerizable group, and further comprises a liquid crystal material. A cohesive alignment layer having an orientation regulating force for homeotropic orientation, a liquid crystal material formed on the cohesive alignment layer, and a refractive index nx in any x-direction and y-direction that are orthogonal to each other in the in-plane direction. A retardation film having a retardation layer in which the relationship of nx = ny <nz is established between ny and the refractive index nz in the thickness direction is disclosed.

Japanese Unexamined Patent Publication No. 2008-09328 Japanese Unexamined Patent Publication No. 2010-064013

On the other hand, due to the recent demand for thinner display devices, further thinning of optical films is required. The most effective is the thinning of the polymer film that constitutes the transparent substrate. Conventionally, the polymer film has been mainly 100 μm to 40 μm, but there has been a strong demand in the industry for the polymer film to be 30 μm or less in order to reduce the thickness of display devices in recent years. For this polymer film, in addition to the conventionally used cellulosic polymer, it is conceivable to use a cycloolefin polymer having higher optical anisotropy. However, if the polymer film constituting the transparent substrate is 30 μm or less, it will be extended by heat when the liquid crystal having a crosslinkable group and the coating liquid containing the crosslinkable monomer are applied and then irradiated with ultraviolet rays to solidify the liquid crystal. When the polymer film of the substrate is broken into a chevron shape without moving due to friction with the guide roller, creases occur and a serious quality failure occurs. This broken wrinkle may be referred to as UV wrinkle from the cause of occurrence.

As a method of preventing breakage wrinkles (UV wrinkles), a method of laminating a protective film on a polymer film constituting a transparent substrate in advance via an adhesive or an adhesive is effective. However, when the thickness of the polymer film constituting the transparent substrate is 30 μm or less, the protective film must be thicker than that, preferably 60 μm or more, to prevent breakage wrinkles. However, if the laminated protective film is thickened, curling occurs in the drying zone, resulting in a serious quality failure.

Furthermore, there has been a method for producing an optical film for optical compensation of a liquid crystal display device using a polymer film constituting a transparent substrate having a slow axis parallel to the transport direction. It originally has corrugated plate-like (totan-like) wrinkles parallel to the direction, and when it is irradiated with ultraviolet rays after applying a coating liquid containing a liquid crystal having a crosslinkable group and a crosslinkable monomer, the wrinkles are formed. Due to the unevenness caused by the unevenness, the method of applying heat to the coating liquid becomes non-uniform, and the phase difference value of the solidified liquid crystal layer becomes phase difference unevenness along the wrinkles, resulting in a serious quality failure. In order to prevent this, it is common sense in the industry to increase the tension applied to the film so that the base is evenly adhered to the backup roller during UV curing. However, this increases the frictional force between the polymer film of the substrate and the roller that supports the polymer film on the opposite surface to the coating layer, and the creases (UV wrinkles) generated in the polymer film of 30 μm or less are further exacerbated. ..

Therefore, in the present invention, a polymer film having a slow phase axis parallel to the transport direction and having a thickness of 30 μm or less is used, and a liquid crystal layer containing a liquid crystal compound having a crosslinkable functional group is provided adjacent to the polymer film. Even in this case, an optical film having no curl and uneven phase difference (UV wrinkles), a polarizing plate using the optical film, an image display device, and a method for manufacturing the optical film. The challenge is to provide.

As a result of diligent studies to achieve the above problems, the present inventors precisely control the temperature of the backup roller that supports the film during ultraviolet irradiation, and determine the distance between the guide roller that supports the film immediately before ultraviolet irradiation and the backup roller. We have found a method for producing an optical compensation film having a thickness of 30 μm or less, in which liquid crystal compounds are oriented and fixed without causing breakage wrinkles (UV wrinkles) and exacerbating retardation unevenness by appropriately bringing them closer to each other. The improvement mechanism is not completely understood. For example, in Patent Document 2, a cured resin layer is applied to a base film to control a holding angle when the surface opposite to the film coating film surface when irradiated with ionizing radiation is supported by a temperature control roll. By doing so, it claims to improve curls and wrinkles. However, in the present invention, this method was completely ineffective, and it was concluded that the film hugging angle was not a factor in the presence or absence of wrinkles. The difference is presumed to be due to the fact that the present invention is a polymer film having a slow phase axis parallel to the transport direction and having a retardation axis of 30 μm or less and that the liquid crystal compound is cured.

The thickness of the web is very small with respect to the width, and when tension is applied in the longitudinal direction, the polymer film constituting the transparent substrate having a slow axis parallel to the transport direction is easily deformed in the width direction due to the contraction force in the width direction. However, it becomes a corrugated plate-like (galvanized iron-like) deformation. At this point, it has not yet become a permanent deformation wrinkle. It is presumed that the critical buckling stress should be small because wrinkles will not occur if this galvanized iron-like deformation is restored when riding on a backup roller that is irradiated with ultraviolet rays. It has been found that the critical buckling stress of this deformation is dramatically reduced by reducing the distance between the backup roller supporting the polymer film during ultraviolet irradiation and the guide roller immediately before the backup roller to a value below the specific value of the present invention. .. Further, in the present invention, by combining precise control of the manufacturing method, a desired polymer film having a thickness of 30 μm or less is desired without causing all failures such as phase difference unevenness, creases (UV wrinkles), curls, and galvanized iron. We have found a manufacturing method for obtaining an optical film.
That is, it was found that the above-mentioned problems can be achieved by the following configuration.

[1] A coating liquid containing a liquid crystal compound having a crosslinkable functional group is applied onto a transparent polymer film having a slow axis parallel to the transport direction and having a thickness of 30 μm or less, and dried to form a coating layer, and then a coating layer is formed. There is a backup roller that supports a surface of the film having the coating layer opposite to the side of the coating layer when the coating layer is irradiated with ultraviolet rays to cure the liquid crystal compound, and the temperature of the backup roller is set to 30. At ° C to 80 ° C., immediately before the backup roller, there is a guide roller that supports the surface of the film having the coating layer on the side opposite to the side of the coating layer, and the film having the coating layer is placed on the guide roller. A method for producing an optical film, wherein the distance from the separation point to the landing point of the film having the coating layer on the backup roller is 0.5 m or less.

[2] A plurality of units in which the backup roller and the ultraviolet irradiation light source are paired are provided in series on the film transport line, and the temperature of the backup roller on the side far from the coating is higher than that on the side closer to the coating. The optical film manufacturing method according to [1], wherein the temperature is the same or higher.

[3] The temperature measured by a radiation thermometer of the film having the coating layer between the landing point on the backup roller and the detachment point on the guide roller is −15 with respect to the temperature of the backup roller. The optical film manufacturing method according to [1] or [2], wherein the temperature of the film having the coating layer is adjusted so as to be in the range of ° C. to + 15 ° C.

[4] Any of [1] to [3], wherein the guide roller is a concave roller or a roller in which tape is wound on a side closer to both ends than the center of the straight roller so that the diameters of both sides are larger than the center portion. The optical film manufacturing method described in Crab.

[5] The transparent polymer film is attached to any of [1] to [4] in which a protective film is previously attached via an adhesive on the side opposite to the surface on which the coating layer is applied. The optical film manufacturing method described.

[6] The method for producing an optical film according to any one of [1] to [5], wherein the liquid crystal compound is a rod-shaped liquid crystal compound.

[7] Any of [1] to [6], wherein the coating liquid contains 0.5 to 7.0% by mass of the compound represented by the following (I) with respect to the mass of the liquid crystal compound. The optical film manufacturing method according to.
Equations (I) (Z) _n − L ¹⁰⁰ − (Q) _m
In the formula (I),
Z represents a substituent having a polymerizable group, n represents an integer of 0 to 4, and when n is an integer of 2 to 4, two or more Zs are different even if they are the same. May be good.
Q represents a substituent containing at least one boron atom, m represents 1 or 2, and when m is 2, the two Qs may be the same or different, respectively.
L ¹⁰⁰ represents a linking group having an n + m valence. However, when n represents 0 and m represents 1, L ¹⁰⁰ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituent. Alternatively, it represents an unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

[8] A polarizing plate having an optical film produced by the production method according to any one of [1] to [7] and a polarizer.

[9] An image display device having an optical film manufactured by the production method according to any one of [1] to [7] or a polarizing plate according to [8].

According to the present invention, even when a liquid crystal layer is provided adjacent to a polymer film having a slow phase axis parallel to the transport direction and having a slow phase axis of 30 μm or less and the coating layer is irradiated with ultraviolet rays to cure the liquid crystal. It is possible to provide a method for producing an optical film without creases (UV wrinkles) without causing curl and phase difference unevenness, and a polarizing plate and an image display device using the same.

FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an optical film produced by the production method of the present invention. FIG. 2 is a schematic view showing an example of the layer structure of the liquid crystal display device in the embodiment. FIG. 3 is a schematic view showing an example of the method for producing an optical film of the present invention.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

Further, in the present specification, the polarizing plate means a polarizing plate in which a protective layer or a functional layer is arranged on at least one surface of the polarizing element, and the polarizing element and the polarizing plate are used separately.

Further, in the present specification, parallel and orthogonal do not mean parallel and orthogonal in a strict sense, but mean a range of ± 8 ° from parallel or orthogonal, respectively.

Further, in the present specification, "(meth) acrylate" is a notation that means either acrylate or methacrylate, and "(meth) acrylic" is a notation that means either acrylic or methacrylic. "(Meta) acryloyl" is a notation that means either acryloyl or methacrylic.

Further, in the present specification, the liquid crystal composition and the liquid crystal compound include those which no longer exhibit liquid crystal property due to curing or the like as a concept.

《Letteration》
In the present invention, Re (λ) and Rth (λ) represent in-plane retardation at wavelength λ and retardation in the thickness direction, respectively. Unless otherwise specified, the wavelength λ is 550 nm.
In the present invention, Re (λ) and Rth (λ) are values measured at a wavelength λ in AxoScan OPMF-1 (manufactured by Optoscience). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d (μm)) in AxoScan,
Slow phase axial direction (°)
Re (λ) = R0 (λ)
Rth (λ) = ((nx + ny) /2-nz) × d is calculated.

《Refractive index》
In the present invention, the refractive indexes nx, ny and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) and a sodium lamp (λ = 589 nm) as a light source. Further, when measuring the wavelength dependence, it can be measured with a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. In addition, the values in the Polymer Handbook (JOHN WILEY & SONS, INC) and the catalogs of various optical films can also be used. The values of the average refractive index of the main optical films are illustrated below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethylmethacrylate (1.49), It is polystyrene (1.59).

<Optical film>
The optical film produced by the production method of the present invention has a polymer film and a liquid crystal layer provided adjacent to the polymer film. The polymer film used is not limited to a specific material, but a cycloolefin polymer or a cellulosic polymer is preferable. The optical film of the present invention may be formed by using a liquid crystal composition in which a liquid crystal layer contains a liquid crystal compound and a compound represented by the formula (I) described later. In that case, the composition contains 0.5 to 7.0% by mass of the compound represented by the formula (I) described later with respect to the mass of the liquid crystal compound.

Generally, at the interface between the polymer film and the coating layer, a soaking layer in which the coating layer and the polymer film are mixed may be formed. Further, it is generally understood that the formation of such a soaking layer is advantageous for adhesion. When it is desired to reduce the adhesion such as when the liquid crystal layer is peeled off in a later process, it is preferable that the dyed layer is small.
When the compound represented by the above formula (I) is used, it is preferable that the soaking layer is small, and the polymer film and the compound represented by the above formula (I) can effectively interact with each other to improve the orientation. Conceivable. Further, even if there is a soaked layer, it is considered that the orientation can be improved by locally unevenly distributing the compound represented by the above formula (I).

Here, in the present invention, the "penetration layer" means a region in which both the material of the polymer film and the material of the liquid crystal layer are detected. The thickness of the soaked layer is preferably in the range of 30 to 300 nm, more preferably in the range of 50 to 250 nm. Within this range, the adhesion between the liquid crystal layer and the polymer film is good, and the orientation of the liquid crystal layer can be improved.

FIG. 1 shows a schematic cross-sectional view of an example of the optical film of the present invention.
The optical film 10 shown in FIG. 1 has a polymer film 1 containing a cycloolefin-based polymer and a liquid crystal layer 2 adjacent to the polymer film 1. A soaking layer may be formed between the 1 and 2. Further, the polymer film is not limited to this.
Next, the polymer film and the liquid crystal layer constituting the optical film of the present invention will be described in detail.

[Polymer film]
The polymer film contained in the optical film of the present invention needs to be transparent. In the present invention, "transparent" means that the transmittance of visible light is 60% or more. In the present invention, the transmittance is preferably 80% or more.

Examples of the material of the polymer film include cellulose-based polymers such as triacetyl cellulose (TAC), diacetyl cellulose, and cellulose acetate propionate; acrylic polymers such as polymethacrylic acid ester and polyacrylic acid ester; polycarbonate-based polymers; polyethylene. Polyester-based polymers such as terephthalate and polyethylene naphthalate; styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin); polyolefin-based polymers such as polyethylene, polypropylene and ethylene-propylene copolymers; norbornene-based polymers, Polymers having an alicyclic structure such as monocyclic cyclic olefin polymers, cyclic conjugated diene polymers, vinyl alicyclic hydrocarbon polymers; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamides; Iimide-based polymer; Sulfon-based polymer; Polyether sulfone-based polymer; Polyether ether ketone-based polymer; Polyphenylene sulfide-based polymer; Vinylidene chloride-based polymer; Vinyl alcohol-based polymer; Vinyl butyral-based polymer; Arilate-based polymer; Polyoxymethylene-based polymer ; Epoxy-based polymer; or a polymer in which these polymers are mixed; and the like.
Of these materials, a cellulosic polymer or a cycloolefin polymer is more preferable.

{Cycloolefin polymer}
It is a polymer film containing a cycloolefin-based polymer. The content of the cycloolefin-based polymer is preferably 60% by mass or more, more preferably 80% by mass or more, based on the total solid content in the polymer film.

Examples of the cycloolefin-based polymer used in the present invention include (1) norbornene-based polymer, (2) monocyclic cycloolefin polymer, (3) cyclic conjugated diene polymer, and (4) vinyl alicyclic. There are formula hydrocarbon polymers, hydrides (1) to (4), and the like. Specific examples of the cycloolefin-based polymer include an addition (co) polymer cyclopolyolefin containing at least one repeating unit represented by the following general formula (III), and the following general formula (III). Preferable examples thereof include an addition (co) polymer cyclopolyolefin containing at least one of the repeating units represented by the following general formula (II) in addition to the repeating unit represented by.
Further, as the cycloolefin-based polymer, a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the following general formula (IV) can also be preferably used.

In the above general formulas (II) to (IV), m represents an integer of 0 to 4. R ¹ to R ⁶ are each a hydrogen atom or a hydrocarbon group having 1 to 10 carbon ^atoms, X 1 to X ³ and ^Y 1 to Y ³ are each a hydrogen atom, a hydrocarbon having 1 to 10 carbon atoms Group, halogen atom, hydrocarbon group with 1 to 10 carbon atoms substituted with halogen atom,-(CH ₂ ) _n COOR ¹¹ ,-(CH ₂ ) _n OCOR ¹² ,-(CH ₂ ) _n NCO,-(CH 2) ₂ ) _n NO ₂ ,-(CH ₂ ) _n CN,-(CH ₂ ) _n CONR ¹³ R ¹⁴ ,-(CH ₂ ) _n NR ¹³ R ¹⁴ ,-(CH ₂ ) _n OZ,-(CH ₂ ) _n W or (-CO) ₂ O or (-CO) ₂ NR ^{15 composed of X 1} and Y ¹ , X ² and Y ² or X ³ and Y ³ is shown. R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ represent a hydrogen atom and a hydrocarbon group having 1 to 20 carbon atoms, respectively, and Z represents a hydrocarbon group or a hydrocarbon group substituted with a halogen. W indicates SiR ¹⁶ _p D _3-p (R ¹⁶ indicates a hydrocarbon group having 1 to 10 carbon atoms, D indicates a halogen atom, -OCOR ¹⁶ or -OR ¹⁶ ; p indicates an integer of 0 to 3). , N represent an integer from 0 to 10.

In the above general formulas (II) to (IV), by introducing a highly polar ^{functional group into the substituents of X 1 to} X ³ and Y ^{1 to Y 3} , the Rth of the optical film is increased and Re is expressed. The sex can be increased. A film having a large Re-expressing property can have a large Re value by stretching in the film-forming process.

As the cycloolefin-based polymer used in the present invention, those disclosed in JP-A-10-7732, JP-A-2002-504184, US20024297157A1 or International Publication No. 2004/070463A1 pamphlet should also be used. Can be done. It is obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. Also, if necessary, norbornene-based polycyclic unsaturated compounds and conjugated diene such as ethylene, propylene, butene, butadiene, isoprene; non-conjugated diene such as etylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, maleic anhydride. It is also possible to carry out addition polymerization with a linear diene compound such as an acid, an acrylic acid ester, a methacrylate ester, a maleimide, vinyl acetate, or vinyl chloride.
As the norbornene-based addition (co) polymer, a commercially available product can also be used. Specifically, it is sold by Mitsui Chemicals, Inc. under the trade name of Apel, and has different grades such as APL8008T (Tg70 ° C), APL6013T (Tg125 ° C) or APL6015T (Tg145 ° C) with different glass transition temperatures (Tg). There is. Polyplastics Co., Ltd. has released pellets such as TOPAS 8007, 6013, and 6015. Furthermore, the Appear 3000 is on sale from Ferrania.

The norbornene-based polymer hydride is described in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19801, JP-A-2003-1159767, or JP-A-2003-1159767. As disclosed in Japanese Patent Application Laid-Open No. 2004-309979, those prepared by addition polymerization or metathesis ring-opening polymerization of a polycyclic unsaturated compound and then hydrogenating can be used.
In the norbornene-based polymer used in the present invention, R ^{5 to} R ⁶ in the general formula (IV) are preferably hydrogen atoms or −CH ₃ ^{, and X 3} and Y ³ in the general formula (IV) are hydrogen. Atom, Cl, -COOCH ₃ are preferred, and other groups are appropriately selected.
This norbornene-based resin can also be a commercially available product. Specifically, it is sold by JSR Corporation under the trade name of Arton G or Arton F, and by ZEON CORPORATION, Zeonor. ) ZF14, ZF16, Zeonex 250 or Zeonex 280 is commercially available, and these can be used.

The cycloolefin polymer used in the present invention preferably has a mass average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 5,000 to 1,000,000 in terms of polystyrene molecular weight. It is more preferably 000 to 500,000, and even more preferably 50,000 to 300,000. The molecular weight distribution (Mw / Mn; Mn is a number average molecular weight measured by GPC) is preferably 10 or less, more preferably 5.0 or less, still more preferably 3.0 or less.

The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is preferably in the range of 50 to 350 ° C, more preferably 80 to 330 ° C, still more preferably 100 to 300 ° C. is there.

The cycloolefin-based polymer used in the present invention may contain additives as long as the gist of the present invention is not deviated, and the description in paragraphs 0025 to 0074 and 0083 to 0091 of JP2009-114303A is described. These contents can be taken into consideration and are incorporated in the specification of the present application.

{Water contact angle of polymer film}
The polymer film of the optical film of the present invention is surface-treated so that the water contact angle on the surface adjacent to the liquid crystal layer is 5 ° to 65 °, as shown in the method for producing the optical film of the present invention described later. It is preferable to have. The water contact angle of the polymer film is more preferably 5 ° to 55 °, and particularly preferably 5 ° to 50 °.

<< Measurement method of water contact angle >>
In the present invention, the water contact angle refers to a value measured by the following method.
The water contact angle is measured based on the intravenous drop method of JIS R 3257: 1999.
Further, LSE-ME1 (software 2win mini) manufactured by Nick Co., Ltd. is used for the measurement. Specifically, 2 μl of droplets are dropped on the surface of a polymer film kept horizontal at room temperature of 20 ° C. using pure water, and the contact angle is measured 20 seconds after the drops.

{Optical properties of polymer film}
The optical properties of the polymer film of the optical film of the present invention are the following formulas (2) and (3) because the display performance is improved when the polarizing plate of the present invention described later is used in an image display device. It is preferable that the following formulas (2-1) and the following formulas (3-1) are satisfied, and the following formulas (2-2) and (3-2) are satisfied. Is even more preferable.
Equation (2) 5 nm ≤ Re1 (550) ≤ 300 nm
Equation (3) 10 nm ≤ Rth1 (550) ≤ 240 nm

Equation (2-1) 40 nm ≤ Re1 (550) ≤ 200 nm
Equation (3-1) 20 nm ≤ Rth1 (550) ≤ 200 nm

Equation (2-2) 80 nm ≤ Re1 (550) ≤ 150 nm
Equation (3-2) 40 nm ≤ Rth1 (550) ≤ 150 nm

{Stretching of polymer film}
Various properties of the polymer film of the optical film of the present invention can be adjusted by stretching. Specifically, by stretching (uniaxially or biaxially stretching) the polymer film in the longitudinal direction (conveyance direction) and the lateral direction (width direction), in-plane retardation (Re), thickness direction retardation (Rth) and Any film thickness can be developed.

Stretching and relaxation may be combined to adjust the properties. For example, each process described in the following (a) to (k) can be carried out.
(A) Horizontal stretching (b) Vertical stretching (c) Horizontal stretching → relaxation treatment (d) Vertical stretching → relaxation treatment (e) Vertical stretching → horizontal stretching (f) Vertical stretching → horizontal stretching → relaxation treatment (g) Vertical stretching → Relaxation treatment → Lateral stretching → Relaxing treatment (h) Lateral stretching → Vertical stretching → Relaxing treatment (i) Lateral stretching → Relaxing treatment → Vertical stretching → Relaxing treatment (j) Vertical stretching → Horizontal stretching → Vertical stretching (k) Vertical stretching → Transverse stretching → Longitudinal stretching → Relaxation treatment Of these, the transverse stretching step (a) and the longitudinal stretching step (b) are particularly important.

<Vertical extension>
When the polymer film is stretched in the vertical direction, for example, after preheating the polymer film with a plurality of preheating rollers, the polymer film can be stretched in the vertical direction by giving a difference in peripheral speed to the pair of stretching rollers.

In this longitudinal stretching step, as described in [0036] to [0045] of JP-A-2008-213332, in order to prevent the occurrence of wrinkles, a plurality of preheating rollers and an upstream stretching roller are used. The peripheral speed may be gradually increased toward the downstream based on the temperature change before and after the film contact with each roller to apply an appropriate tension between the preheating rollers.

Further, as described in Japanese Patent Application Laid-Open No. 2011-207168 [0022] to [0031], the film may be rapidly cooled by a cooling roller after longitudinal stretching in order to suppress the occurrence of scratches.

<Horizontal stretching>
When the polymer film is stretched laterally, it can be stretched in the lateral direction by using, for example, a tenter. That is, both ends of the polymer film in the width direction are gripped by clips and stretched by widening in the lateral direction. At this time, the stretching temperature can be controlled by blowing air at a desired temperature into the tenter. In the present specification, the "stretching temperature" (hereinafter, also referred to as "transverse stretching temperature") is specified by the polymer film film surface temperature.
It is preferable to control the stretching temperature so that it is Tg-40 ° C to Tg + 40 ° C. That is, the transverse stretching temperature in the transverse stretching step is preferably Tg-40 ° C. to Tg + 40 ° C., more preferably Tg-20 ° C. to Tg + 20 ° C., and even more preferably Tg-10 ° C. to Tg + 10 ° C. Here, the transverse stretching temperature in the transverse stretching step means the average temperature between the stretching start point and the stretching end point.

The stretching time in the transverse stretching step is preferably 1 second to 10 minutes, more preferably 2 seconds to 5 minutes, and even more preferably 5 seconds to 3 minutes. By controlling the stretching temperature and stretching time within the above ranges, the Re, Rth, and film thickness can be adjusted within the preferred ranges of the present invention.

The transverse stretching ratio is preferably 1.01 to 4 times, more preferably 1.03 to 3.5 times, and even more preferably 1.1 to 3.0 times. The transverse stretching ratio is particularly preferably 1.51 to 3.0 times.

<Simultaneous biaxial stretching>
When the polymer film is biaxially stretched at the same time, the clip is widened in the horizontal direction and at the same time stretched and contracted in the vertical direction, thereby simultaneously stretching in the vertical and horizontal directions, as in the normal transverse stretching method. be able to. Specifically, Japanese Patent Application Laid-Open No. 55-93520, Japanese Patent Application Laid-Open No. 63-247021, Japanese Patent Application Laid-Open No. 6-210726, Japanese Patent Application Laid-Open No. 6-278204, Japanese Patent Application Laid-Open No. 2000-334832, Japanese Patent Application Laid-Open No. 2004-106434, Kai 2004-195712, JP-A-2006-142595, JP-A-2007-210306, JP-A-2005-22087, JP-A-2006-517608, JP-A-2007-210306, whichever is described. The methods described in the publication can also be referred to.

By performing preheating before stretching and heat fixing after stretching, the Re and Rth distributions after stretching can be reduced, and the variation in orientation angle due to Boeing can be reduced. Either preheating or heat fixing may be performed, but it is more preferable to perform both. These preheating and heat fixing are preferably performed by gripping with a clip, that is, they are preferably performed continuously with stretching.

The preheating can be performed at a temperature higher than the stretching temperature by about 1 ° C. to 50 ° C., preferably 2 ° C. to 40 ° C. or lower, and more preferably 3 ° C. or higher and 30 ° C. or lower. The preferable preheating time is 1 second or more and 10 minutes or less, more preferably 5 seconds or more and 4 minutes or less, and further preferably 10 seconds or more and 2 minutes or less. During preheating, it is preferable to keep the width of the tenter substantially constant. Here, "almost" refers to ± 10% of the width of the unstretched film.

The heat fixation can be performed at a temperature lower than the stretching temperature by 1 ° C. or higher and 50 ° C. or lower, more preferably 2 ° C. or higher and 40 ° C. or lower, and further preferably 3 ° C. or higher and 30 ° C. or higher. More preferably, it is below the stretching temperature and below Tg. The preferable preheating time is 1 second or more and 10 minutes or less, more preferably 5 seconds or more and 4 minutes or less, and further preferably 10 seconds or more and 2 minutes or less. At the time of heat fixing, it is preferable to keep the width of the tenter substantially constant. Here, "almost" refers to 0% to -10% (the same width as the tenter width after stretching) to -10% (10% reduction from the tenter width after stretching = reduced width) after the completion of stretching. If the width is wider than the stretch width, residual strain is likely to occur in the polymer film and the time variation of Re and Rth is likely to increase, which is not preferable.

By such stretching, the variation of Re and Rth in the width direction and the longitudinal direction can be further reduced to 5% or less, more preferably 4% or less, still more preferably 3% or less.
The high-speed stretching treatment may be performed, and the stretching treatment can be preferably performed at 20 m / min or more, more preferably 25 m / min or more, and further preferably 30 m / min or more.

In the present invention, the polymer film has a slow axis parallel to the transport direction. The degree of parallelism is that the angle formed by the transport direction and the slow axis is 0 ° ± 8 ° or less, preferably 0 ° ± 5 ° or less, more preferably 0 ° ± 3 ° or less, and further preferably 0. It can be ° ± 1 ° or less.

The thickness of the polymer film of the present invention is 30 μm or less. It is preferably 5 μm to 30 μm, more preferably 7 μm to 25 μm, and even more preferably 10 μm to 20 μm.

[Protect film]
In the polymer film of the present invention, a protective film can be provided on the side opposite to the surface to be coated from the viewpoint of preventing blocking at the time of winding and stabilizing the transportation. It can also be provided on the coated surface side after coating. The protective film is peeled off when it is no longer needed, for example, during polarizing plate processing. As the material of the protective film, polyethylene-based resin, polypropylene-based resin, polystyrene-based resin, polyethylene terephthalate-based resin, etc., which are easy to handle, can be preferably used, and one or more of these can be used as a single layer or many. A film formed into layers can be used as a protective film. Among them, a self-adhesive protective film that has adhesiveness to a polarizing film by itself is convenient because it does not need to protect the adhesive layer on the surface of the protective film, and can be used more preferably. Examples of commercially available self-adhesive resin films include Tretec (manufactured by Toray Industries, Inc.) made of polyethylene resin.

[Liquid crystal layer]
The liquid crystal layer of the optical film of the present invention is a layer provided adjacent to the polymer film described above, and is a liquid crystal layer formed by using a liquid crystal composition containing a liquid crystal compound described later. Further, in the liquid crystal composition, the compound represented by the formula (I) described later may be contained in an amount of 0.5 to 7.0% by mass with respect to the mass of the liquid crystal compound.

{Optical characteristics of liquid crystal layer}
The optical characteristics of the liquid crystal layer of the optical film of the present invention include the following equations (4) and (5), because the display performance is improved when the polarizing plate of the present invention described later is used in an image display device. Alternatively, it is preferable to satisfy the following formula (6) and the following formula (7).
Equation (4) 0 nm ≤ Re2 (550) ≤ 10 nm
Equation (5) -360 nm ≤ Rth2 (550) ≤ -50 nm
Equation (6) 10 nm ≤ Re2 (550) ≤ 220 nm
Equation (7) −110 nm ≤ Rth2 (550) ≤ -5 nm

Further, the optical characteristics of the liquid crystal layer of the optical film of the present invention are the following formulas (4-1) and the following formulas (5-1), or the following formulas (6-1) and the following formulas (7-1). It is more preferable to satisfy the following formulas (4-2) and the following formula (5-2), or it is further preferable to satisfy the following formulas (6-2) and the following formulas (7-2).

Equation (4-1) 0 nm ≤ Re2 (550) ≤ 5 nm
Equation (5-1) -270 nm ≤ Rth2 (550) ≤ -50 nm
Equation (6-1) 20 nm ≤ Re2 (550) ≤ 200 nm
Equation (7-1) -100 nm ≤ Rth2 (550) ≤ -10 nm

Equation (4-2) 0 nm ≤ Re2 (550) ≤ 1 nm
Equation (5-2) -180 nm ≤ Rth2 (550) ≤ -100 nm
Equation (6-2) 60 nm ≤ Re2 (550) ≤ 160 nm
Equation (7-2) -80 nm ≤ Rth2 (550) ≤ -30 nm

In the present invention, the thickness of the liquid crystal layer is not particularly limited, but is preferably 0.1 μm to 10 μm, more preferably 0.3 μm to 8 μm, and even more preferably 0.5 μm to 5 μm.

{Liquid crystal compound}
The liquid crystal composition forming the liquid crystal layer of the optical film of the present invention contains a liquid crystal compound. The liquid crystal compound is preferably a rod-shaped liquid crystal compound or a discotic liquid crystal compound, and is a rod-shaped liquid crystal compound because the display performance is improved when the polarizing plate of the present invention described later is used in an image display device. More preferably.

The rod-shaped liquid crystal compounds that can be used are described in, for example, Japanese Patent Application Laid-Open No. 2009-217256 [0045] to [0066], and these contents are incorporated in the present specification.

Examples of the discotic liquid crystal compound include [0025] to [0153] of JP-A-2006-301614, [0020]-[0122] of JP-A-2007-108732, and JP-A-2010-244038. [0012] to [0108], and these contents are incorporated in the present specification.

The liquid crystal compound used in the present invention is preferably immobilized in a vertically oriented state in order to adjust the optical characteristics of the liquid crystal layer. For example, a layer in which a rod-shaped liquid crystal compound is immobilized in a vertically oriented state can function as a positive C-plate. In addition, the layer in which the discotic liquid crystal compound is immobilized in a vertically oriented state can function as a negative A-plate.

In the present invention, the vertical orientation means the normal direction of the layer and the long axis direction of the liquid crystal molecule in the case of a rod-shaped liquid crystal compound, and the normal direction of the layer and the liquid crystal molecule in the case of a discotic liquid crystal compound. It is an oriented state in which the disk surfaces of the above are parallel. It is particularly preferable that the long axis direction of the liquid crystal molecules and the disk surface of the liquid crystal molecules are parallel to the normal direction of the layer, but the liquid crystal molecules may have an inclination depending on the orientation state. This inclination is preferably within 3.5 °.

Here, when the rod-shaped liquid crystal compound is vertically oriented, it is preferable to satisfy the above formulas (4) and (5), and when the discotic liquid crystal compound is vertically oriented, the above formula (6) is satisfied. And (7) are preferably satisfied.

In the present invention, there is a backup roller that supports a surface of the film having the coating layer opposite to the side of the coating layer when the coating layer is irradiated with ultraviolet rays to cure the liquid crystal compound. The temperature is set to 30 ° C to 80 ° C. It is preferably 35 ° C. to 70 ° C., and more preferably 35 ° C. to 50 ° C. If the temperature of the backup roller is lower than 30 ° C., the degree of polymerization of the coating layer does not increase, and the durability of the completed optical film is significantly deteriorated. On the other hand, when the temperature is set higher than 30 ° C., the above-mentioned creases and uneven phase difference occur in a polymer film having a slow phase axis parallel to the transport direction and having a thickness of 30 μm or less. Therefore, as a result of diligent studies, immediately before the backup roller, there is a guide roller that supports the surface of the film having the coating layer on the side opposite to the side of the coating layer, and the film having the coating layer on the guide roller. If the distance from the separation point to the landing point of the film having the coating layer on the backup roller is 0.5 m or less, the durability of an optical film having a slow phase axis parallel to the transport direction and having a thickness of 30 μm is impaired. It was found that no creases or uneven phase difference occurred.

It is preferable that a plurality of units in which the backup roller and the ultraviolet irradiation light source are paired are provided in series on the film transport line. When two or more are installed, in the present invention, by increasing the set temperature from the first half to the second half of the backup roller, it is possible to satisfy all the quality requirements of durability, creases, and phase difference unevenness. It will be easier. The temperature difference between the backup rollers is 0 ° C. to 50 ° C., preferably 0 ° C. to 20 ° C., and more preferably 0 ° C. to 5 ° C. Further, a plurality of ultraviolet irradiation light sources may be mounted on one backup roller.

The backup roller includes a columnar body and rotating shafts arranged at both ends of the body. The main body of the backup roller has, for example, a length of 1000 mm or more and 5000 m or less in the width direction and a radius R of 150 mm or more and 1000 mm or less, but there is no limitation on the length and radius in the width direction. A temperature controller is attached to the main body of the backup roller. If there are multiple backup rollers, it is preferable that each has a temperature controller.

The transparent polymer film, which has a slow axis parallel to the transport direction, originally has a slight deformation that is parallel to the transport direction without a tin-like permanent deformation, which is further exacerbated during transport and is further deteriorated during UV irradiation. It grows into creases that become permanently deformed on the backup roller.
In the present invention, immediately before the backup roller, there is a guide roller that supports a surface of the film having the coating layer on the side opposite to the side of the coating layer, and a separation point of the film having the coating layer on the guide roller. The distance between the landing points of the film having the coating layer on the backup roll is 0.5 m or less. The mechanism is unknown, but it was found that wrinkles worsened dramatically when the length was longer than 0.5 m, and improved dramatically when the length became shorter. Further, it is preferably 0.3 m or less, and more preferably 0.1 m or less. However, it is necessary to install each roller so that the UV irradiation backup roller and the immediately preceding guide roller do not come into contact with each other. In the following description, for the sake of simplicity, the distance between the rollers is abbreviated as the distance between the ultraviolet irradiation backup roller and the immediately preceding guide roller, or the distance between the UV backup roller and the guide roller.

In the present invention, the temperature of the film having the coating layer between the landing point on the backup roller and the detachment point on the guide roller is measured by a radiation thermometer with respect to the temperature of the backup roller. It is preferable to adjust the temperature of the film having the coating layer so as to be in the range of 15 ° C. to + 15 ° C. for the improvement of creases and wrinkles. More preferably, it is −10 ° C. to + 10 ° C. More preferably, it is −5 ° C. to + 5 ° C. In the present invention, the distance between the backup roller and the guide roller is 0.5 m or less. It was clarified that the small temperature difference between the film and the backup roller when the polymer film comes into contact with the backup roller is good for suppressing wrinkles, but the temperature is measured within 0.5 m before contacting the backup roller. It was found that there is no problem if the result is within the above temperature range. It is difficult to measure without a radiation thermometer, and at the time of measurement, select a place where there is no object with a temperature higher than room temperature, such as a roller, on the background of the polymer film. In order to set the film temperature in this way, it is effective to adjust the temperature before entering the ultraviolet irradiation zone, and methods such as blowing warm air on the film, irradiating an infrared heater, and raising the room temperature are available. However, the method is not limited to these.

The UV irradiation light source closest to the application and the guide roller that supports the film just before reaching the backup roller wrap the tape on the side closer to both ends than the center of the straight roller so that the diameters on both sides are larger than the concave roller or the center part. Combining the use of the existing rollers with the above method is more effective in suppressing breakage and wrinkles. The tape used at this time is not limited to a specific one.

{Compound represented by formula (I)}
The liquid crystal composition forming the liquid crystal layer of the optical film of the present invention preferably contains a compound represented by the following formula (I).
Equations (I) (Z) _n − L ¹⁰⁰ − (Q) _m
Here, in the formula (I), Z represents a substituent having a polymerizable group, n represents an integer of 0 to 4, and when n is an integer of 2 to 4, 2 or more Z represents. They may be the same or different.
Further, Q represents a substituent containing at least one boron atom, m represents 1 or 2, and when m is 2, the two Qs may be the same or different.
Further, L ¹⁰⁰ represents a linking group having an n + m valence. However, when n represents 0 and m represents 1, L ¹⁰⁰ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituent. Alternatively, it represents an unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

In the above formula (I), examples of the substituent having a polymerizable group represented by Z include (meth) acrylate group, styryl group, vinyl ketone group, butadiene group, vinyl ether group, oxylanyl group, aziridinyl group and oxetane group. Examples include substituents.
Of these, a substituent containing a (meth) acrylate group, a styryl group, an oxylanyl group or an oxetane group is preferable, and a substituent containing a (meth) acrylate group or a styryl group is more preferable.

In particular, the substituent containing the (meth) acrylate group is preferably a group having an ethylenically unsaturated double bond represented by the following general formula (V).

In the above general formula (V), R ³ is a hydrogen atom or a methyl group, and a hydrogen atom is preferable.
Further, in the above general formula (V), L ¹ is a single bond, or -O-, -CO-, -NH-, -CO-NH-, -COO-, -O-COO-, an alkylene group. It is a divalent linking group selected from the group consisting of an arylene group, a heterocyclic group, and a combination thereof, preferably a single bond, -CO-NH- or -COO-, and a single bond or -CO-NH- is preferable. Especially preferable.

In the above formula (I), n represents an integer of 0 to 4, preferably 0 or 1, and more preferably 1.
Further, m represents 1 or 2, and preferably represents 1.
Further, as L ¹⁰⁰ , for example, as a divalent linking group, a single bond or -O-, -CO-, -NH-, -CO-NH-, -COO-, -O-COO-, alkylene Examples thereof include a divalent linking group selected from a group, an arylene group, a heteroaryl group, and a combination thereof.
Of these, a substituted or unsubstituted arylene group is more preferable.
The alkyl group, alkenyl group, alkynyl group, aryl group and heteroaryl group represented by L ^{100 are synonymous with R 1} and R ² in the following general formula (VI), and the preferred range is also the same.
In addition, examples of the substituents contained in these groups include the substituents described in paragraph [0046] of JP2013-054201A.

In the above formula (I), Q is a substituent containing at least one boron atom, and is preferably a group that can be adsorbed and bonded to the polymer film.
For example, when the polymer film has a hydroxyl group or a carboxyl group on the surface by surface treatment or the like, a group capable of binding to the hydroxyl group or the carboxyl group of the polymer film is preferable. The "group that can be adsorbed and bonded to the polymer film" means a group that can be chemically adsorbed to the polymer film by interacting with the structure of the material constituting the polymer film.

Examples of the substituent containing at least one boron atom include a substituent represented by the following general formula (VI).

In the above general formula (VI), R ¹ and R ² are independently hydrogen atoms, substituted or unsubstituted aliphatic hydrocarbon groups, substituted or unsubstituted aryl groups, or substituted or unsubstituted heteroaryl groups, respectively. Represents. Further, R ¹ and R ² in the general formula (VI), the alkylene groups R ¹ and R ² are linked, an aryl group or may form a linking group comprising a combination thereof.

In the above general formula (VI), the ^{substituted or unsubstituted aliphatic hydrocarbon group represented by R 1} and R ² , respectively, includes a substituted or unsubstituted alkyl group, an alkenyl group and an alkynyl group.
Specific examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, a dodecyl group, a tridecyl group and a hexadecyl group. Octadecyl group, eicosyl group, isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, isopentyl group, neopentyl group, 1-methylbutyl group, isohexyl group, 2-methylhexyl group, cyclopentyl group, cyclohexyl group, 1- Examples thereof include linear, branched or cyclic alkyl groups such as adamantyl group and 2-norbornyl group.
Specific examples of the alkenyl group include linear and branched groups such as vinyl group, 1-propenyl group, 1-butenyl group, 1-methyl-1-propenyl group, 1-cyclopentenyl group and 1-cyclohexenyl group. , Or a cyclic alkenyl group.
Specific examples of the alkynyl group include an ethynyl group, a 1-propynyl group, a 1-butynyl group, a 1-octynyl group and the like.
Specific examples of the aryl group include those in which one to four benzene rings form a fused ring and those in which a benzene ring and an unsaturated five-membered ring form a fused ring. Specific examples thereof include those in which a fused ring is formed. Examples thereof include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, an indenyl group, an acenabutenyl group, a fluorenyl group, a pyrenyl group and the like.

Further, in the above general formula (VI), in ^{the example of the substituted or unsubstituted heteroaryl group represented by R 1} and R ² , respectively, one hetero atom selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom is used. A heteroaryl group obtained by removing one hydrogen atom on the heteroaromatic ring containing the above is included.
Specific examples of a heteroaromatic ring containing one or more heteroatoms selected from the group consisting of nitrogen atom, oxygen atom and sulfur atom include pyrol, furan, thiophene, pyrazole, imidazole, triazole, oxazole, isoxazole and oxazole. , Thiazol, thiazazole, indol, carbazole, benzofuran, dibenzofuran, thianaften, dibenzothiophene, indazole benzimidazole, anthranil, benzisoxazole, benzoxazole, benzothiazole, purine, pyridine, pyridazine, pyrimidine, pyrazine, triazine, quinoline, acrydin, Examples thereof include isoquinolin, phthalazine, quinazoline, quinoxalin, naphthylidine, phenanthrolin, pteridine and the like.

^{R 1} and R ² in the above general formula (VI) are preferably hydrogen atoms.

^{Further, R 1} and R ² in the above general formula (VI) ^{and L 100} in the above formula (I) may be further substituted with one or more substituents, if possible. One or more of these hydrocarbon groups may be substituted with any substituent. Examples of the substituent include monovalent non-metal atomic groups excluding hydrogen.

The molecular weight of the compound represented by the above formula (I) is preferably 120 to 1200, more preferably 180 to 800.

Specific examples of the compound represented by the above formula (I) include the following compounds in addition to the compounds exemplified in the specific examples described in paragraphs [0035] to [0040] of JP-A-2007-219193. These contents are incorporated herein by reference. Of course, the present invention is not limited to these specific examples.

As described above, the compound represented by the above formula (I) contains 0.5% to 7% by mass and 1 to 5% by mass with respect to the mass of the liquid crystal compound in the liquid crystal composition. It is preferably contained, and more preferably 3 to 5% by mass is contained.
Adhesion can be improved by setting the compounding amount of the compound represented by the above formula (I) to 0.5% by mass or more, and orientation can be improved by setting it to 7% by mass or less. When a plurality of liquid crystal compounds are contained, it is a ratio to the total.

In the present invention, the compound represented by the above formula (I) is preferably unevenly distributed in the liquid crystal layer on the side closer to the polymer film in the film thickness direction. The term "uneven distribution" as used herein includes not only the case where the compound itself is unevenly distributed, but also the case where the liquid crystal layer is a polymer of a liquid crystal composition and the distribution is unevenly distributed as a reaction product after polymerization. It is a concept.

{Other additives}
The liquid crystal layer or the liquid crystal composition forming the liquid crystal layer of the optical film of the present invention may contain other additives as long as the gist of the present invention is not deviated.
Other additives include, for example, vertical alignment agents. As the vertical alignment agent, it is preferable to use a pyridinium compound or an onium compound, and by containing these compounds, the liquid crystal compound acts as a vertical alignment agent that promotes the vertical orientation at the polymer film interface of the liquid crystal compound, and the liquid crystal compound. It also contributes to improving the adhesion of the interface between the liquid crystal layer and the polymer film in which the orientation state of the compound is fixed. Pyridine compounds are described in, for example, [0030] to [0052] of JP-A-2007-0938664, and onium compounds are described in, for example, JP-A-2012-208397, [0027] to [0058]. These contents are incorporated herein.
Further, the liquid crystal layer in which the orientation state of the liquid crystal compound is fixed is a copolymer containing an air interface side orientation control agent (for example, a repeating unit having a fluoroaliphatic group) for controlling the orientation on the air interface side, if necessary. ) May be contained.
Further, the liquid crystal composition can contain, for example, a polymerization initiator. As the polymerization initiator, the descriptions in paragraphs [0099] to [0100] of JP-A-2010-84032 and paragraphs [0065]-[0067] of JP-A-2007-219193 can be referred to, and these contents are described in the present application. Incorporated into the specification.
Examples of commercially available products include IRGACURE907, 184, 819, TPO, OXE01, OXE02, 127, 2959 (manufactured by BASF), and two or more kinds of polymerization initiators may be used in combination. Further, various sensitizers such as benzophenones and thioxanthones and various chain transfer agents can be used in combination. Examples of the chain transfer agent include thiols, and commercially available products include Karenz MT (R) PE1, BD1, NR1 (manufactured by Showa Denko) and the like.
Further, the liquid crystal composition may contain a non-liquid crystal polymerizable monomer. As the polymerizable monomer, a compound having a vinyl group, a vinyloxy group, an acryloyl group or a methacryloyl group is preferable. Specifically, a polyfunctional monomer having two or more polymerizable reactive functional groups, for example, an ester of a polyhydric alcohol and (meth) acrylic acid [for example, ethylene glycol di (meth) acrylate, butanediol di (meth)). Acrylate, hexanediol di (meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra (meth) acrylate], pentaerythritol tri (meth) acrylate, trimethylolpropanthry (meth) acrylate, trimethylol ethanetri (meth) ) Acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane poly Acrylate, polyester polyacrylate], the above-mentioned ethylene oxide modified product, vinylbenzene and its derivatives (for example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloyl ethyl ester, 1,4-divinylcyclohexanone), vinylsulfone. (Eg divinyl sulfone), acrylamide (eg methylenebis acrylamide) and methacrylamide. Two or more kinds of the above-mentioned monomers may be used in combination.

<Manufacturing method of optical film>
The method for producing an optical film of the present invention (hereinafter, also simply abbreviated as "the production method of the present invention") has a water contact angle of 5 with respect to the surface of a polymer film containing a cycloolefin polymer and a cellulose polymer. A liquid crystal that forms a liquid crystal layer after a surface treatment step in which the surface treatment is performed so as to be ° to 65 ° and a liquid crystal composition containing a liquid crystal compound and a solvent are brought into contact with the surface treated surface. It has a layer forming step.
Further, the liquid crystal composition may contain the compound represented by the above formula (I) in an amount of 0.5 to 7.0% by mass with respect to the mass of the liquid crystal compound.

[Surface treatment process]
The surface treatment step of the production method of the present invention is a step of surface-treating the surface of the polymer film so that the water contact angle is 5 ° to 65 °. The method for measuring the water contact angle is as described above.

Further, the surface treatment step is preferably a step of adding a hydroxyl group or a carboxyl group to the surface of the polymer film. As a specific means, various known means can be used, but corona treatment is preferable.

{Corona processing}
The corona treatment can be performed by, for example, the treatment methods described in JP-A-39-12838, JP-A-47-19824, JP-A-48-28067, and JP-A-52-42114. it can. As the corona treatment apparatus, a solid state corona treatment machine manufactured by Pillar, a LEPEL type surface treatment machine, a VETAPHON type treatment machine and the like can be used. The treatment can be performed at normal pressure in air. The gap transparent lance between the electrode and the dielectric roll is 0.1 mm to 10 mm, more preferably 1.0 mm to 2.0 mm. The discharge is processed above the dielectric support roller provided in the discharge band, and the processing amount is 10 W · min / m2 to 1000 W · min / m ² , preferably 20 W · min / m ^{2 to} 500 W · min / m ^2. , more preferably ^{30W · min / m 2 ~250W ·} min / m 2.

[Liquid crystal layer forming process]
The liquid crystal layer forming step of the production method of the present invention is a step of forming a liquid crystal layer after contacting a liquid crystal composition containing a liquid crystal compound and a solvent with a surface treated surface.
The method of contacting the liquid crystal composition is not particularly limited, and various known methods such as coating can be used. Moreover, the compound represented by the above formula (I) can be added.

Here, from the viewpoint of controlling the soaked layer described above, it is preferable that the solvent is a solvent having neither a dissolving ability nor a swelling ability with respect to the polymer film. The solvent having neither the dissolving ability nor the swelling ability to the polymer film means a solvent having low compatibility with the polymer film, and can be used properly according to the dissolving ability and the swelling ability to the polymer film.

The solvent having the solubility in the polymer film is taken out by immersing the polymer film having a size of 24 mm × 36 mm (thickness 80 μm) in a 15 cm ³ bottle containing the solvent at room temperature (25 ° C.) for 60 seconds. After that, when the immersed solution is analyzed by gel permeation chromatography (GPC), it means a solvent in which the peak area of the polymer film component is 400 mV / sec or more.

The solvent having a swelling ability for the polymer film is a polymer film having a size of 24 mm × 36 mm (thickness 80 μm), which ^{is vertically placed in a 15 cm 3} bottle containing the solvent, immersed at 25 ° C. for 60 seconds, and appropriately immersed in the bottle. It means a solvent that is bent or deformed when observed while shaking. In addition, the size of the swollen portion of the polymer film changes, and it is observed as bending or deformation. No change such as bending or deformation is observed with a solvent that does not have swelling ability.

Examples of the solvent preferably used in the present invention include methanol, ethanol, cyclohexanone, acetone, methyl isobutyl ketone, methyl acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, toluene and the like. These can be used alone or in combination of two or more.

On the other hand, whether or not the solvent has a dissolving ability or a swelling ability with respect to the polymer film depends not only on the combination of the components of the polymer film and the solvent but also on the production method when producing the polymer film. It is preferable to select the solvent according to the film. An ester solvent such as methyl acetate and an ether solvent such as propylene glycol monomethyl ether can be preferably used because they have an excellent balance between the dissolving ability or swelling ability for a polymer film and the dissolution stability of a liquid crystal compound.

<Polarizer>
The polarizing plate of the present invention has the above-mentioned optical film of the present invention and a polarizer.
An optical film may be separately provided on the side of the polarizer opposite to the optical film, a cured resin layer may be arranged, or the polarizing element may be directly bonded to another member of an image display device described later.
In the optical film of the present invention, the polymer film side may be arranged as the polarizer side, or the liquid crystal layer side may be arranged as the polarizer side.

An adhesive can be used for laminating the polarizer and the optical film.
The thickness of the adhesive layer between the polarizer and the polarizing plate protective films on both sides is preferably about 0.01 to 30 μm, more preferably 0.01 to 10 μm, still more preferably 0.05 to 5 μm. Is. When the thickness of the adhesive layer is within this range, floating or peeling does not occur between the laminated optical film and the polarizer, and a practically acceptable adhesive force can be obtained.

As one of the preferable adhesives, a water-based adhesive, that is, an adhesive in which the adhesive component is dissolved or dispersed in water can be mentioned, and an adhesive composed of a polyvinyl alcohol-based resin aqueous solution is preferably used. In an adhesive composed of an aqueous solution of a polyvinyl alcohol-based resin, the polyvinyl alcohol-based resin includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and a copolymer with vinyl acetate. There are vinyl alcohol-based copolymers obtained by saponifying copolymers with other polymerizable monomers, and modified polyvinyl alcohol-based polymers in which their hydroxyl groups are partially modified. A polyhydric aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, a glyoxyphosphate or the like may be added to this adhesive as a cross-linking agent. When a water-based adhesive is used, the thickness of the adhesive layer obtained from the water-based adhesive is usually 1 μm or less.

As another preferable adhesive, a curable adhesive composition containing a cationically polymerizable compound, which is cured by irradiation or heating with active energy rays, a curable adhesive composition containing a radically polymerizable compound, and the like can be mentioned. Be done. Examples of the cationically polymerizable compound include compounds having an epoxy group and an oxetanyl group. The epoxy compound is not particularly limited as long as it has at least two epoxy groups in the molecule, and for example, a compound described in detail in JP-A-2004-245925 can be used.
The radically polymerizable compound is not particularly limited as long as it is a radically polymerizable compound having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and is a monofunctional radically polymerizable compound, or two or more in the molecule. Examples thereof include polyfunctional radically polymerizable compounds having a polymerizable group, (meth) acrylates having a hydroxyl group, acrylamide, acryloylmorpholine and the like, and these compounds may be used alone or in combination. For example, a compound described in detail in Japanese Patent Application Laid-Open No. 2015-11094 can be used. Further, a radically polymerizable compound and a cationically polymerizable compound can be used in combination.

When a curable adhesive is used, the film is bonded using a bonding roller, dried as necessary, and the curable adhesive is cured by irradiating or heating with active energy rays. .. The light source of the active energy ray is not particularly limited, but an active energy ray having an emission distribution at a wavelength of 400 nm or less is preferable, and specifically, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, and a black light lamp. , Microwave-excited mercury lamp, metal halide lamp and the like are preferably used.

Further, when the optical film and the polarizer are bonded together with an adhesive, the surface of the optical film is surfaced on the surface of the optical film facing the polarizer for the purpose of improving the adhesive strength and the wettability of the adhesive on the surface of the optical film. Treatment (for example, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment), easy-adhesion layer formation, and the like may be performed. The materials and forming methods of the easy-adhesive layer described in JP-A-2007-127893, JP-A-2007-127893 and the like can be used.

When the liquid crystal layer side of the optical film and the polarizer are bonded with an adhesive made of a polyvinyl alcohol-based resin aqueous solution, the surface of the liquid crystal layer is subjected to glow discharge treatment, corona discharge treatment, and the liquid crystal layer has a high affinity with polyvinyl alcohol. It is preferable to add an additive to improve the adhesive strength.

When the liquid crystal layer side of the optical film and the polarizer are bonded to each other using an adhesive that is cured by irradiation with active energy rays or heating, the surface of the liquid crystal layer is subjected to glow discharge treatment or corona discharge treatment. This is preferable from the viewpoint of improving the adhesive strength and the wettability of the adhesive on the surface of the optical film. Further, a high adhesiveness can be obtained by producing an optical film in a state where the liquid crystal layer is half-cured and then fully curing the optical film by irradiation with active energy rays or heating when the liquid crystal layer is adhered and bonded to the polarizer.

Further, the polarizing plate of the present invention may have a protective film.
When the protective film is provided, it may be arranged between the polarizing element and the optical film, on the side opposite to the polarizing element of the optical film, or the like via an adhesive or an adhesive.

[Polarizer]
The polarizing plate of the polarizing plate of the present invention is not particularly limited, and may be a so-called linear polarized light having a function of converting natural light into specific linearly polarized light. The polarizer is not particularly limited, but an absorption type polarizer can be used.

The material of the polarizer used in the present invention is not particularly limited, and commonly used polarizers can be used, for example, an iodine-based polarizer, a dye-based polarizer using a dichroic dye, and a polyene. Any of the system polarizers can be used.

In the present invention, the thickness of the polarizer is not particularly limited, but is preferably 3 μm to 60 μm, more preferably 5 μm to 30 μm, and even more preferably 5 μm to 15 μm.

〔Protective film〕
The material of the protective film is not particularly limited, and is a polyacrylic type such as a cellulose acylate film (for example, a cellulose triacetate film, a cellulose diacetate film, a cellulose acetate butyrate film, a cellulose acetate propionate film), a polymethyl methacrylate, or the like. Resin film, polyolefin such as polyethylene and polypropylene, polyester resin film such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone film, polyurethane resin film, polyester film, polycarbonate film, polysulfone film, polyether film, polymethylpentene film , Polyether ketone film, (meth) acrylic nitrile film, polyolefin, polymer with alicyclic structure (norbornen resin (Arton: trade name, manufactured by JSR), amorphous polyolefin (Zeonex: trade name, manufactured by Nippon Zeon) )), Etc. can be mentioned.

The optical characteristics of the protective film preferably satisfy the following formulas (8) and (9) because the display performance is improved when the polarizing plate of the present invention is used in an image display device.
Equation (8) 0 nm ≤ Re3 (550) ≤ 10 nm
Equation (9) -40 nm ≤ Rth3 (550) ≤ 40 nm

In particular, when a protective film is provided between the optical film of the present invention and the polarizer, or on the side opposite to the polarizer of the optical film, it is used as an optical compensation film while being attached to the transparent polymer film. The protective film is preferably a wavelength dispersion compensating layer that satisfies the optical characteristics of the following formulas (10) and (11).
Equation (10) 3 nm ≤ | Rth (450) -Rth (550) | ≤ 30 nm
Equation (11) 0 nm ≦ | Rth (450) | <30 nm or 0 nm ≦ | Rth (550) | <30 nm

By forming a polarizing plate in which a polarizing element, a protective film satisfying the above formulas (10) and (11), and an optical film of the present invention are laminated, the wavelength dispersibility of the refractive index is corrected, and the entire visible light wavelength range is obtained. Ideal optical compensation can be achieved over a wide range.

<Image display device>
The image display device of the present invention includes the above-mentioned polarizing plate of the present invention and an image display element.
Further, the image display device of the present invention includes the above-mentioned polarizing plate of the present invention, an image display element, and a counter-polarizing plate, the image display element is a liquid crystal cell, and the counter-polarizing plate is a polarizing element. An image display device having an opposing polarizing plate having a protective film (wavelength dispersion compensating layer) satisfying the above formula (10) and the above formula (11), and the protective film is arranged so as to be on the liquid crystal cell side. Is preferable.
Equation (10) 3 nm ≦ | Rth3 (450) -Rth3 (550) | ≦ 30 nm
Equation (11) 0 nm ≦ | Rth3 (450) | <30 nm or 0 nm ≦ | Rth3 (550) | <30 nm

[Image display element]
The image display element used in the present invention is not particularly limited, and examples thereof include a liquid crystal cell, an organic electroluminescence (hereinafter abbreviated as “EL”) display panel, and a plasma display panel.
Of these, a liquid crystal cell or an organic EL display panel is preferable, and a liquid crystal cell is more preferable. That is, the image display device of the present invention is preferably a liquid crystal display device using a liquid crystal cell as an image display element and an organic EL display device using an organic EL display panel as an image display element, and is a liquid crystal display device. Is more preferable.

{LCD cell}
The liquid crystal cell used in the liquid crystal display device is preferably a VA (Vertical Optical) mode, an OCB (Optical Compensated Bend) mode, an FFS or IPS (In-Plane-Switching) mode, or a TN (Twisted Nematic) mode. However, it is not limited to these.

In the liquid crystal cell in the TN mode, the rod-shaped liquid crystal molecules are substantially horizontally oriented when no voltage is applied, and are further twisted to 60 to 120 °. The TN mode liquid crystal cell is most often used as a color TFT (Thin Film Transistor) liquid crystal display device, and has been described in many documents.

In the VA mode liquid crystal cell, the rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied. In the VA mode liquid crystal cell, (1) a VA mode liquid crystal cell in a narrow sense in which rod-shaped liquid crystal molecules are oriented substantially vertically when no voltage is applied and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. 2-). In addition to (described in Japanese Patent Application Laid-Open No. 176625), (2) a liquid crystal cell (SID97, Digital of technique. Papers (Proceedings) 28 (1997) 845 in which the VA mode is multi-domainized for expanding the viewing angle). ), (3) Liquid crystal cells in a mode (n-ASM mode) in which rod-shaped liquid crystal molecules are substantially vertically oriented when no voltage is applied and twisted and multi-domain oriented when a voltage is applied. (1998)) and (4) SURVIVAL mode liquid crystal cells (presented at LCD International 98). Further, it may be any of PVA (Patternized Vertical Alignment) type, optical alignment type (Optical Alignment), and PSA (Polymer-Sustained Alignment). Details of these modes are described in Japanese Patent Application Laid-Open No. 2006-215326 and Japanese Patent Application Laid-Open No. 2008-538819.

In the liquid crystal cell in the IPS mode, the rod-shaped liquid crystal molecules are oriented substantially parallel to the substrate, and the liquid crystal molecules respond in a plane by applying an electric field parallel to the substrate surface. In the IPS mode, the display is black when no electric field is applied, and the absorption axes of the pair of upper and lower polarizing plates are orthogonal to each other. Methods for reducing leakage light when displaying black in an oblique direction and improving the viewing angle by using an optical compensation sheet are described in JP-A-10-54982, JP-A-11-202323, and JP-A-9-292522. It is disclosed in JP-A-11-133408, JP-A-11-305217, JP-A-10-307291, and the like.

{Organic EL display panel}
The organic EL display panel used as the image display element used in the present invention is a display configured by using an organic EL element having an organic light emitting layer (organic electroluminescence layer) sandwiched between electrodes (between the cathode and the anode). It is a panel. The configuration of the organic EL display panel is not particularly limited, and a known configuration is adopted.

Hereinafter, the present invention will be specifically described based on Examples. The materials, reagents, amounts of substances and their ratios, operations, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the present invention is not limited to the following examples.

[Example 1]
<Manufacturing of optical film>
One side of a cycloleolefin polymer film (trade name: Arton Film, Re = 124 nm, Nz = 1.0, film thickness 25 μm) manufactured by JSR Corporation is corona-treated with a ^{discharge amount of 125 W ・ min / m 2.} The liquid crystal layer forming composition 1 prepared with the following composition was applied onto the support by a die coating method using a slot die under the conditions of a coating amount of 4.6 cc / m2 and a transport speed of 20 m / min. It was applied. Next, for drying the solvent of the composition and aging the orientation of the liquid crystal compound, the first was heated with warm air at 70 ° C. for 120 seconds and further kept at 35 ° C. at an oxygen concentration of about 0.01% by volume under a nitrogen purge. After irradiating with 100 mJ / cm2 ultraviolet rays while wrapping with the UV backup roller of the above, irradiating with 300 mJ / cm2 ultraviolet rays while wrapping with a second UV backup roller kept at 40 ° C. After forming, it was wound up.
At this time, the film was heated with a heater so that the film temperature immediately before reaching the first UV backup roller was 35 ° C. Further, a capton tape was wrapped around a guide roller that supports the film immediately before reaching the first UV backup roller so that the amount of engagement from both ends of the film was 20 mm and the thickness was 0.5 mm. The Re of the produced optical film was 124 nm, and the Rth was −36 nm.

The cycloolefin polymer film used in the present invention is optically a positive A plate having an Nz coefficient of 1.0, and has in-plane refractive indexes of nx and ny in the slow axis direction and the phase advance axis direction, respectively. Assuming that the refractive index in the thickness direction is nz, there is a relationship of nx> ny = nz. The in-plane retardation Re and the Nz coefficient have the following relationships, respectively.

Re = (nx-ny) x d
Nz = (nx-nz) / (nx-ny)
However, d represents the thickness.

In the present invention, the description of "ny = nz" in the positive A plate does not necessarily mean that the in-plane refractive index ny and the refractive index nz in the thickness direction completely match. Therefore, if the Nz coefficient is in the range of 0.99 to 1.10, it may be regarded as a positive A plate of Nz = 1.0 of ny = nz of the present invention, and preferably 0.95 to 1. It is 0.05.

―――――――――――――――――――――――――――――――――
Liquid crystal layer forming composition 1
Liquid liquid compound R1 100.0 parts by mass Orientation aid (A1) 2.0 parts by mass Compound B1 represented by the above formula (I) 4.5 parts by mass ATMMT 8.0 parts by mass Polymerization initiator (P1) 2. 0 parts by mass polymerization initiator (P2) 5.0 parts by mass surfactant (S1) 0.3 parts by mass surfactant (S2) 0.5 parts by mass acetone 425.6 parts by mass propylene glycol monomethyl ether acetate 48.9 Parts by mass Methanol 14.7 parts by mass ――――――――――――――――――――――――――――――――――

-Liquid crystal compound R1
A mixture of the following liquid crystal compounds (RA) (RB) (RC) at 83: 15: 2 (mass ratio)

・ Orientation aid A1

-Compound B1 represented by the formula (I)

-Polymerization initiator (P1): OXE-01 (manufactured by BASF)
-Polymerization initiator (P2): IRGACURE127 (manufactured by BASF)

-Surfactant S1

-Surfactant S2 (weight average molecular weight: 11,200)

The optical films of Examples 2 to 5, Comparative Examples 1 and 2, and Reference Examples 1 and 2 were produced in the same manner as in Example 1 except that the conditions shown in Table 1 were changed. With respect to the produced optical film, Re and Nz were measured according to the method described above. The results are shown in Table 1 below.

<Evaluation; film form>
In the form of an optical film, fold wrinkles (UV wrinkles), adhesion, and durability are evaluated.

[Evaluation of broken wrinkles (UV wrinkles)]
The polarizing plate was arranged in a cross Nicol arrangement, the obtained optical film was placed between the polarizing plates arranged in a cross Nicol arrangement, a backlight light source was arranged under the polarizing plate, and wrinkles were observed.
A: Wrinkles are not visible B: Wrinkles are slightly visible, but not noticeable C: Strong wrinkles are visible

[Evaluation of adhesion]
Eleven notches were made vertically and horizontally at 1 mm intervals on the liquid crystal layer side of the produced optical film to make 100 1 mm square grids.
Cellotape (registered trademark) manufactured by Nichiban Co., Ltd. was crimped, left for 1 minute, and then vigorously peeled off. The presence or absence of peeling of the liquid crystal layer is visually observed, and the one in which the area of 1/4 or more (0.25 mm ² or more) in each box is peeled is regarded as a peeling box, and the number of peeling boxes is counted to obtain the liquid crystal. The adhesion between the layer and the polymer film was evaluated according to the following criteria. The results are shown in Table 1 below.
A: 80 to 100 squares B: 51 to 79 squares C: 0 to 50 squares

[Evaluation of durability]
The Rth change was measured when the produced optical film was exposed to 500 hr in an environment of 85 ° C. and 85%.
A: Δ3 nm or less B: Δ5 nm or less C: Greater than Δ5 nm

<Evaluation; Polarizing plate / display device form>
The produced optical film is used as a polarizing plate, and further mounted on a liquid crystal display device to evaluate the display quality of retardation unevenness and oblique light leakage.

<Preparation of protective film 1>
[Preparation of core layer cellulose acylate dope 1]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a core layer cellulose acylate dope 1.
――――――――――――――――――――――――――――――
Core layer Cellulose acylate dope 1
――――――――――――――――――――――――――――――
100 parts by mass of cellulose acetate with an acetyl substitution degree 2.88 parts by mass of the following ester oligomer A 10 parts by mass of the following polarizer durability improver 4 parts by mass of the following ultraviolet absorber 2 parts by mass of methylene chloride (first solvent) 430 parts by mass of methanol (second) Solvent) 64 parts by mass ――――――――――――――――――――――――――――――

-Ester oligomer A (molecular weight MW: 750)

・ Polarizer durability improver

・ UV absorber

[Preparation of outer layer cellulose acylate dope 1]
The following matting solution was added to 90 parts by mass of the core layer cellulose acylate dope 1 by 10 parts by mass to prepare an outer layer cellulose acylate dope 1.
――――――――――――――――――――――――――――――
Outer layer cellulose acylate dope 1
――――――――――――――――――――――――――――――
Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
2 parts by mass methylene chloride (first solvent) 76 parts by mass methanol (second solvent) 11 parts by mass Core layer Cellulose acylate dope 1 1 part by mass ―――――――――――――――――― ――――――――――――

[Preparation of Cellulose Achillate Film 1]
Three layers of the core layer cellulose acylate dope 1 and the outer layer cellulose acylate dope 1 on both sides thereof were simultaneously flowed from the flow port onto a drum at 20 ° C. The film was peeled off with a solvent content of about 20% by mass, both ends in the width direction of the film were fixed with tenter clips, and the film was dried while being stretched 1.1 times in the lateral direction with a residual solvent of 3 to 15%. Then, it was further dried by transporting it between the rolls of the heat treatment apparatus to prepare a cellulose acylate film 1 having a thickness of 40 μm, which was used as a protective film 1. As a result of measuring the phase difference of the protective film 1, Re = 2 nm and Rth = 7 nm.

<Preparation of protective film 2>
[Preparation of core layer cellulose acylate dope 2]
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a core layer cellulose acylate dope 2.
――――――――――――――――――――――――――――――――
Core layer Cellulose acylate dope 2
――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.88 100 parts by mass 12 parts by mass of the following polyester 4 parts by mass of the above-mentioned polarizer durability improver Methylene chloride (first solvent) 430 parts by mass Methanol (second solvent) 64 parts by mass --- ――――――――――――――――――――――――――――

-Polyester (number average molecular weight 800)

[Preparation of outer layer cellulose acylate dope 2]
The following matting solution was added to 90 parts by mass of the core layer cellulose acylate dope 2 by 10 parts by mass to prepare an outer layer cellulose acylate dope 2.
―――――――――――――――――――――――――――――――
Matte solution ――――――――――――――――――――――――――――――――
Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
2 parts by mass methylene chloride (first solvent) 76 parts by mass methanol (second solvent) 11 parts by mass Core layer Cellulose acylate dope 1 part by mass ――――――――――――――――――― ――――――――――――

[Preparation of Cellulose Achillate Film 2]
After filtering the core layer cellulose acylate dope 2 and the outer layer cellulose acylate dope 2 with a filter paper having an average pore diameter of 34 μm and a sintered metal filter having an average pore diameter of 10 μm, the core layer cellulose acylate dope 2 and outer layer cellulose on both sides thereof are filtered. Three layers of acylate dope 2 were simultaneously cast on a drum at 20 ° C. from the casting port (band casting machine).
Then, the film was peeled off with a solvent content of about 20% by mass, both ends of the film in the width direction were fixed with tenter clips, and the film was dried while being stretched in the lateral direction at a stretching ratio of 1.1 times.
Then, it was further dried by transporting it between the rolls of the heat treatment apparatus to prepare a cellulose acylate film 2 having a thickness of 40 μm, which was used as a protective film 2. As a result of measuring the phase difference of the protective film 2, Re = 1 nm and Rth = -5 nm.

<Saponification treatment of protective film>
The protective films 1 and 2 prepared above were immersed in a 2.3 mol / L sodium hydroxide aqueous solution at 55 ° C. for 3 minutes. It was washed in a water washing bath at room temperature and neutralized at 30 ° C. with 0.05 mol / L sulfuric acid. The film was washed again in a water-washing bath at room temperature, further dried with warm air at 100 ° C., and the surface of the protective film was saponified.

<Manufacturing of polarizing plate>
The saponified protective film 1, the polyvinyl alcohol-based polarizer, and the optical film of Example 1 were subjected to the liquid crystal layer of the optical film so that the absorption axis of the polarizer and the slow axis of the optical film were parallel to each other. The side and the polarizer were bonded together using an adhesive to prepare an upper polarizing plate. As the adhesive, a 3% aqueous solution of PVA (manufactured by Kuraray Co., Ltd., PVA-117H) was used. The lower polarizing plate was prepared by similarly laminating a saponified protective film 1, a polyvinyl alcohol-based polarizing element, and a saponified protective film 2. At this time, the polarizer and the optical film had sufficient adhesiveness for practical use.

<Manufacturing of liquid crystal display device>
The upper polarizing plate and the lower polarizing plate are attached to the prepared liquid crystal cell using SK2057 manufactured by Soken Kagaku Co., Ltd. so that the optical film and the protective film 2 are on the liquid crystal cell side, respectively, and the liquid crystal display of Example 1 is performed. The device was made. At this time, they were bonded so that the slow axis of the liquid crystal in the cell and the absorption axis of the upper polarizing plate were orthogonal to each other, and the slow axis of the liquid crystal in the cell and the absorption axis of the lower polarizing plate were parallel to each other.

FIG. 2 showing an example of the layer structure of the liquid crystal display device will be described in detail. The arrows on each layer indicate the absorption axis direction for the polarizer and the slow axis direction for the other layers. In this embodiment, the protective film 1 produced above is used for a and d of FIG. 2, and the protective film 2 is used for c of FIG. B in FIG. 2 is not used in this embodiment. 1 and 2 in FIG. 2 are the optical films of the present invention.

《Measurement of light leakage and color in black display》
The manufactured liquid crystal display device is placed on a diffused light source, and using a measuring machine "EZ-Contrast XL88" (manufactured by ELDIM), the azimuth angle is 0 ° (horizontal direction) to 359 ° counterclockwise in 1 ° increments. , And the brightness in the black display in 1 ° increments from a polar angle of 0 ° (front direction) to 88 ° was measured. Light leakage at a polar angle of 60 ° was evaluated according to the following evaluation criteria.
A: Very little light leakage, especially excellent B: Little light leakage, excellent C: Many light leakage, unacceptable

In Comparative Example 1, strong UV wrinkles are observed, but in Example 2, the distance between the guide roller and the ultraviolet backup roller is greatly improved to an unnoticeable quality by adopting the aspect of the present invention. Further, in Example 1, it can be seen that the UV wrinkles are completely healed by setting the temperature difference between the first and second lamps of the ultraviolet backup roller. Further, Examples 3, 4 and 5 also have a large effect on UV wrinkles, but as compared with Example 1, the temperature of the polymer film is raised by the pre-ultraviolet heater, and both ends of the guide roller are made larger than the center. And the effect of the protective film on UV wrinkles is clear. Further, in Comparative Example 2 in which the temperature of the ultraviolet backup roller was lower than that of the present invention, the durability was poor.

In Reference Examples 1 and 2, it can be seen that the adhesion is poor unless the compound B1 of the present invention is added, and that the transversely stretched COP having the slow phase axis perpendicular to the transport direction has poor oblique light leakage.

10 Optical film 1 Polymer film 2 Liquid crystal layer 3, 5 Polarizer 4 Liquid crystal cell 6 Backlight a Protective film a
b Protective film b
c Protective film c
d Protective film d

11 Guide roller immediately before the UV irradiation backup roller 12 UV irradiation backup roller 13 Polymer film transport direction 14 Film detachment point on the guide roller 15 Film landing point on the backup roller 16 UV irradiation device

Claims (7)

A coating liquid containing a liquid crystal compound having a crosslinkable functional group is applied onto a transparent polymer film having a slow axis parallel to the transport direction and having a thickness of 30 μm or less, and dried to form a coating layer. There is a backup roller that supports the surface of the film having the coating layer on the side opposite to the side of the coating layer when the layer is irradiated with ultraviolet rays to cure the liquid crystal compound, and the temperature of the backup roller is set to 30 ° C. to 80 ° C. At ° C., immediately before the backup roller, there is a guide roller that supports the surface of the film having the coating layer on the side opposite to the side of the coating layer, and from the separation point of the film having the coating layer on the guide roller. A method for producing an optical film in which the landing point distance of the film having the coating layer on the backup roller is 0.5 m or less. A plurality of units in which the backup roller and the ultraviolet irradiation light source are paired are provided in series on the film transport line, and the temperature of the backup roller on the side far from the coating is the same as that of the backup roller on the side closer to the coating. The method for producing an optical film according to claim 1, wherein the temperature is higher than that. The temperature of the film having the coating layer between the landing point on the backup roller and the detachment point on the guide roller measured by a radiation thermometer is −15 ° C. to +15 with respect to the temperature of the backup roller. The method for producing an optical film according to claim 1 or 2, wherein the temperature of the film having the coating layer is adjusted so as to be in the range of ° C. The one according to any one of claims 1 to 3, wherein the guide roller is a concave roller or a roller in which tape is wound on a side closer to both ends than the center of the straight roller so that the diameters on both sides are larger than the center portion. the method for producing an optical film. The optical according to any one of claims 1 to 4, wherein a protective film is previously attached to the transparent polymer film on the side opposite to the side on which the coating layer is applied via an adhesive. method of producing a film. The method for producing an optical film according to any one of claims 1 to 5, wherein the liquid crystal compound is a rod-shaped liquid crystal compound. The invention according to any one of claims 1 to 6, wherein the coating liquid contains 0.5 to 7.0% by mass of the compound represented by the following (I) with respect to the mass of the liquid crystal compound. A method for manufacturing an optical film.
Equations (I) (Z) _n − L ¹⁰⁰ − (Q) _m
In the formula (I),
Z represents a substituent having a polymerizable group, n represents an integer of 0 to 4, and when n is an integer of 2 to 4, two or more Zs are different even if they are the same. May be good.
Q represents a substituent containing at least one boron atom, m represents 1 or 2, and when m is 2, the two Qs may be the same or different, respectively.
L ¹⁰⁰ represents a linking group having an n + m valence. However, when n represents 0 and m represents 1, L ¹⁰⁰ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituent. Alternatively, it represents an unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.

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