JP2016197219A - Laminate and optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate that has an optical anisotropic layer in which a polymerizable liquid crystal compound is immobilized in a state of homeotropic alignment, homogeneous alignment, or cholesteric alignment, the optical anisotropic layer being provided on an intermediate layer or a lower layer, and an optical film including the laminate; and achieve both good durability of the optical anisotropic layer and good film characteristics of an upper layer of the optical anisotropic layer.SOLUTION: A laminate 10 is formed through photopolymerization of a polymerizable composition including a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light to create a photopolymerization active spot of the polymerizable liquid crystal compound, and includes at least an optical anisotropic layer 12 in which the polymerizable liquid crystal compound is immobilized in a state of homeotropic alignment, homogeneous alignment, or cholesteric alignment, and an upper layer 13 that is laminated adjacent on the optical anisotropic layer. The compound creating a photopolymerization active spot includes at least two photopolymerization initiators in which frequencies of ultraviolet light to be absorbed are different from each other or at least one photopolymerization initiator and at least one sensitizer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminate and an optical film comprising an optically anisotropic layer formed by fixing a polymerizable liquid crystal compound in a homeotropic alignment, homogeneous alignment, or cholesteric alignment in an intermediate layer or a lower layer.

  Liquid crystal display devices are widely used for liquid crystal televisions, liquid crystal panels such as personal computers, mobile phones, and digital cameras. Usually, a liquid crystal display device has a liquid crystal panel member provided with polarizing plates on both sides of a liquid crystal cell, and display is performed by controlling light from the backlight member with the liquid crystal panel member.

  In recent years, studies for increasing the size and definition of liquid crystal display devices have been promoted. For example, backlight members are required to have higher luminance and lower power consumption. As a high-brightness and power-saving backlight system, the so-called luminance that shows the characteristics of transmitting linearly polarized light with a predetermined polarization axis or circularly polarized light with a predetermined direction and reflecting light other than transmitted light on the exit side to the liquid crystal cell A configuration with an enhancement film has been proposed.

  For example, Patent Document 1 includes a circularly polarized light separation element including a plurality of cholesteric liquid crystal layers having different reflection bandwidths and reflection center wavelengths on a film substrate, an optically anisotropic element, and a periodic structure. An integrated brightness enhancement film is disclosed.

An optically anisotropic layer in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state by polymerizing a polymerizable liquid crystal compound as an optical film utilizing liquid crystal alignment. Is known (Patent Document 2).
Since such an optically anisotropic layer has a high surface energy, there is a problem that a so-called “repellency phenomenon” tends to occur when the upper layer is formed, and the wettability of the coating film is poor.
In particular, when a film containing a liquid crystal compound is applied as an upper layer, when a repellency phenomenon occurs, a non-adherent portion is formed at the interface, and in the vicinity thereof, the alignment regulating force of the base is difficult to act on the coating film. There is a problem that alignment defects are likely to occur in the obtained alignment film.

  In order to suppress the repellency phenomenon of the coating solution during the upper layer deposition, it has been proposed to add a surfactant to the coating solution used for the upper layer deposition. In Patent Document 3, as a liquid crystal alignment accelerator capable of aligning liquid crystal molecules in a uniform manner up to the upper part in the film thickness direction by mixing with a composition containing a liquid crystal compound, fluorine-substituted aliphatic in one molecule. A compound having a hydrophobic group such as a group or an oligosiloxanoxy group and a group having an excluded volume effect containing at least two cyclic structures has been proposed. Patent Document 3 describes that a liquid crystal compound includes a rod-shaped liquid crystal compound or a disk-shaped liquid crystal compound.

  In Patent Document 4, a specific amount of an additive made of a (meth) acrylic copolymer having a side chain containing a fluorine group and a group compatible with liquid crystal molecules in a specific ratio is added to the liquid crystal composition. By doing so, it is described that alignment defects can be suppressed.

International Publication No. 2008-016056 JP 2008-40309 A JP 2000-345164 A JP 2006-16599 A

  Additives described in Patent Document 4, so-called fluoropolymer surfactants and silicone surfactants, are unevenly distributed on the surface of the coating film using their hydrophobic groups, and reduce the surface tension of the coating solution. This suppresses the repellency phenomenon (hereinafter abbreviated as “repellency”) of the coating solution and contributes to forming a coating film with good adhesion to the base.

  However, the liquid crystal molecules contained in the optical film vary in polymerizability and shape depending on the application, and it is difficult to obtain the same adhesion regardless of the type of liquid crystal molecules. Even if the adhesion is improved, the surface-active agent on the base may inhibit the alignment regulating force.

  On the other hand, by reducing the amount of light irradiation during the photopolymerization of the optically anisotropic layer, the surface energy of the optically anisotropic layer can be lowered and the repellency of the upper coating film can be suppressed. However, a laminate such as an optical film obtained by this method has a problem that the durability of the optically anisotropic layer is not good.

The present invention has been made in view of the above circumstances, and an intermediate layer or a lower layer is provided with an optically anisotropic layer in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state. Thus, an object of the present invention is to provide a laminate that has both good durability of the optically anisotropic layer and good film characteristics of the upper layer.
The present invention also includes an optically anisotropic layer in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state in an intermediate layer or a lower layer, and the optically anisotropic layer is excellent. An object of the present invention is to provide an optical film provided with a laminate that achieves both excellent durability and good film properties on the upper layer.

The laminate of the present invention is
It is formed by photopolymerizing a polymerizable composition containing a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light and generates a photopolymerization active site of the polymerizable liquid crystal compound,
An optically anisotropic layer in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment;
Including an upper layer laminated adjacently on the optically anisotropic layer,
The compound that generates the photopolymerization active site is at least two photopolymerization initiators having different wavelengths of ultraviolet light to be absorbed, or at least one photopolymerization initiator having different wavelengths of ultraviolet light to be absorbed and at least one kind of increase. And a sensitizer.

  In this specification, ultraviolet light means light having a wavelength of 10 to 400 nm.

  “The wavelength of ultraviolet light to be absorbed is different” means that the peak wavelength of the absorption spectrum of the photopolymerization initiator or the sensitizer is different.

  Further, in this specification, “a compound that absorbs ultraviolet light to generate a photopolymerization active site of a polymerizable liquid crystal compound” means a compound that absorbs ultraviolet light to directly generate an active site and indirectly an active site. The resulting compound is meant to be included.

Among the compounds that generate photopolymerization active sites, it is preferable that at least one of the compounds has a maximum absorption wavelength of ultraviolet light of 300 nm or less, and at least one compound has a maximum absorption wavelength of ultraviolet light of 320 nm or more.
The compound that generates a photopolymerization active site preferably contains at least one photopolymerization initiator and at least one sensitizer having different wavelengths of ultraviolet light to be absorbed.

  In the polymerizable composition, the content of the compound that generates a photopolymerization active point having a maximum ultraviolet light absorption wavelength of 320 nm or more with respect to the polymerizable liquid crystal compound is preferably 2 weight percent or less.

  In the optically anisotropic layer, the polymerizable liquid crystal compound is preferably fixed in a cholesteric alignment state. The polymerizable liquid crystal compound is preferably a discotic liquid crystal compound or a rod-shaped liquid crystal compound.

  Moreover, as a laminated body of this invention, the aspect which further comprises the optically anisotropic layer adjacent to the upper layer on the opposite side to the optically anisotropic layer is mentioned.

The optically anisotropic layer preferably contains a surfactant having a molecular weight of 15000 or less composed of a fluorine-containing compound or a compound having a polysiloxane structure. The surfactant is preferably composed of a fluorine-containing compound. In this case, the liquid crystal layer preferably contains 0.001% by mass or more and less than 0.10% by mass of fluorine atoms.
Further, the surfactant preferably has a polyalkylene oxide group and / or a hydroxyl group.

In the present specification, the molecular weight of the surfactant when the surfactant is a polymer compound having a molecular weight of 1500 or more means a weight average molecular weight. In this specification, a weight average molecular weight (hereinafter abbreviated as Mw) means a polystyrene equivalent value by gel permeation chromatography (GPC), and is a weight average molecular weight measured under the following conditions.
Solvent Tetrahydrofuran Equipment Name TOSOH HLC-8320GPC
Three columns TOSOH TSKgel Super HZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ4000 are connected and used.
Column temperature 25 ° C
Sample concentration 0.1% by mass
Flow rate 0.35ml / min
Calibration curve TSK standard polystyrene made by TOSOH Mw = 2800000-1050 calibration curves with 7 samples are used.

  The optical film of the present invention includes a support and the laminate of the present invention provided on the support.

  As a preferred embodiment of the optical film of the present invention, the present invention comprises a support and a surfactant having a molecular weight of 15000 or less comprising the above-mentioned fluorine-containing compound or compound having a polysiloxane structure provided on the support. In which a surfactant is present on the surface on the upper layer side of the optically anisotropic layer. In such an optical film, it is preferable that a λ / 4 plate is provided between the support and the optically anisotropic layer.

  The laminate of the present invention comprises an optically anisotropic layer in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state, and an optically anisotropic layer laminated adjacently. And an optically anisotropic layer, the polymerizable liquid crystal compound, at least two kinds of photopolymerization initiators that absorb different wavelengths of ultraviolet light, or at least different wavelengths of absorbed ultraviolet light. It is formed by photopolymerizing a polymerizable composition containing one kind of photopolymerization initiator and at least one kind of sensitizer. According to such a configuration, the durability of the optically anisotropic layer in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state, and excellent film characteristics of the upper layer are obtained. Both can be achieved.

It is a schematic sectional drawing of the laminated body of one Embodiment which concerns on this invention. It is a schematic sectional drawing of the optical film of one Embodiment concerning this invention. It is the schematic which shows the structure of the liquid crystal display device of one Embodiment of this invention. It is the schematic which shows the structure of the backlight system of one Embodiment of this invention.

  The following description may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  As described in the section of “Background Art”, an optically anisotropic layer in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state by polymerizing the polymerizable liquid crystal compound. Because of its high surface energy, repelling of the coating liquid is likely to occur during film formation of the upper layer, and the non-adhered portion between the optically anisotropic layer and the upper layer formed by the repelling is the film characteristics (orientation) of the upper layer in the vicinity. Said that there is a problem of lowering. In addition, the laminate produced by suppressing the repellency of the upper coating layer by lowering the light irradiation amount during photopolymerization of the optically anisotropic layer has a problem that the durability of the optically anisotropic layer is not good. I also mentioned that.

  The present inventor has intensively studied a method for solving the above-described problem of reducing the surface energy of the optically anisotropic layer and suppressing the repellency of the upper coating film without reducing the durability of the optically anisotropic layer. . The inventor of the present invention has the reason that the durability of the optically anisotropic layer of the laminate produced by lowering the light irradiation amount during the photopolymerization of the optically anisotropic layer is low. Therefore, it was considered that the residual monomer in the optically anisotropic layer increased and the polymerization was not carried out at a sufficient conversion rate during the photopolymerization of the upper layer in the subsequent step.

  When forming the optically anisotropic layer by photopolymerization, the inventor increases the use efficiency of light used for polymerization, that is, uses more light irradiated to the coating film to generate photopolymerization active sites. In consideration of this, it was considered that the polymerization of monomers and oligomers remaining in the optically anisotropic layer during the photopolymerization of the upper layer can be facilitated and the conversion of the optically anisotropic layer in the resulting laminate can be increased. .

  The light source used for photopolymerization mainly uses a light source having a broad ultraviolet line spectrum such as a high-pressure mercury lamp, but in recent years, an ultraviolet light-emitting diode (UV-LED) which is a relatively narrow-band single peak light source. , Ultraviolet-Light Emitting Diode) is also being used.

  In photopolymerization, a polymerization initiator or sensitizer that is a starting point for generating a polymerization active site is usually selected such that its absorption wavelength matches the spectral shape and band of a light source used for polymerization as much as possible. In order to utilize more light irradiated to the coating film during photopolymerization for the generation of photopolymerization active sites, the present inventor, as a polymerization initiator or sensitizer that is the starting point for the generation of polymerization active sites, Attempts have been made to use two or more absorption wavelengths within the spectrum shape and band of the light source. As a result, as shown in the examples described later, the repelling at the time of forming the upper layer of the optically anisotropic layer in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state is prevented. It was found that both the good durability of the optically anisotropic layer and the good film properties of the upper layer can be achieved.

  When a high-pressure mercury lamp is used as the light source, for example, when the peak wavelength (bright line wavelength) with high relative intensity is 245 nm, 313 nm, 365 nm (main wavelength), 405 nm, 436 nm, the absorption wavelength includes these wavelengths. Preferably, two or more polymerization initiators or sensitizers having an absorption peak are selected. By using two or more kinds of polymerization initiators or sensitizers, the decomposition of the initiator proceeds with higher efficiency than in the case of using one kind of polymerization initiator, and more polymerization active sites are made highly efficient. It can produce | generate and can superpose | polymerize an optically anisotropic layer.

  Even when a UV-LED or the like, which is a relatively narrow band single peak light source, is used as a light source, two kinds of polymerization initiators or sensitizers having different absorption peak wavelengths within the band range (for example, 365 to 385 nm). By using the above, it is possible to generate the polymerization active sites with high efficiency as compared with the case of one kind.

  Thus, by generating the polymerization active sites with high efficiency, the generation efficiency of the polymerization start points per unit time is increased, and the start points are increased as compared with the case where only one polymerization initiator or sensitizer is used. Polymerization of the polymerizable liquid crystal compound proceeds. When the polymerization proceeds from many polymerization starting points, the molecular weight (weight average, number average) tends to decrease, and in the middle of the polymerization reaction, many polymerization active sites together with unpolymerized monomers are present in the layer. Will exist. If the upper coating liquid is applied on the optically anisotropic layer in such a state, the polymer conversion rate of the optically anisotropic layer is low, so that the coating liquid is less likely to be repelled, and during the subsequent photopolymerization of the upper layer It is considered that the polymerization of unconverted monomers or oligomers in the optically anisotropic layer also proceeds with high efficiency by UV irradiation.

  From the viewpoint of suppressing repellency, the difference between the surface energy of the optically anisotropic layer during coating of the upper layer and the surface energy of the coating solution is preferably in the range of 0 to 10 mN / m. Smaller is preferable. Accordingly, the upper layer coating film is formed so that the difference between the surface energy of the optically anisotropic layer and the surface energy of the coating liquid during the upper layer coating film formation is within the above range, preferably within the above range. The light irradiation amount of the photopolymerization of the previous optically anisotropic layer is adjusted, and after the upper layer is applied, an unconverted monomer is polymerized during the photopolymerization of the upper layer. As described above, since many polymerization active sites exist together with unconverted monomers in the optically anisotropic layer at the time of photopolymerization of the upper layer, the optical difference is obtained by utilizing light irradiation in the photopolymerization of the upper layer. The isotropic layer can be polymerized with high conversion.

That is, in the polymerizable composition preparation step of preparing a polymerizable composition comprising a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light and generates a photopolymerization active site of the polymerizable liquid crystal compound, The compound that generates the photopolymerization active site is at least one photopolymerization initiator having a different wavelength of ultraviolet light to be absorbed, or at least one photopolymerization initiator having a different wavelength of ultraviolet light to be absorbed. And a sensitizer.
An optically anisotropic layer forming step of irradiating the polymerizable composition with ultraviolet light to form an optically anisotropic layer in which the polymerizable liquid crystal compound is fixed in a homeotropic, homogeneous, or cholesteric orientation; ,
After forming the coating film of the photopolymerizable composition on the optically anisotropic layer, the coating film is irradiated with ultraviolet light to cure the coating film and to convert the unconverted polymerizable liquid crystal compound in the optically anisotropic layer. And an upper layer forming step for carrying out at least one part polymerization to form an upper layer of the optically anisotropic layer in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state. It is believed that repellency during film formation can be suppressed, and that both good durability of the optically anisotropic layer and good film characteristics of the upper layer can be achieved.

  JP 2011-247934 A includes one or more polymerization initiators in a polymerizable composition that easily expands the wavelength range of selective reflection of a cholesteric reflective film and can be produced with high productivity. Is disclosed. However, this document only describes that two or more kinds of polymerization initiators can be used, and does not describe the effect of using two or more kinds. There are examples in which two or more kinds of initiators having different absorption wavelengths are used, but there is no example in which an upper layer is formed, and a cholesteric liquid crystal layer containing two or more kinds of initiators and an upper layer are applied. There is no mention or suggestion of suitability and durability. In the present invention, when a coating film is further provided on the cholesteric liquid crystal layer, the cholesteric liquid crystal layer contains two or more initiators, so that the cholesteric liquid crystal has a small change in Re before and after the durability condition, It is considered that the change in the thickness of the cholesteric liquid crystal layer can be suppressed and the change in the reflection center wavelength can be controlled by blocking the entry of the diffusion component from the coating layer in contact with the layer over time.

  Hereinafter, an embodiment of the laminate of the present invention obtained by the above production method will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the configuration of the laminate 10 of the present embodiment. In the drawings of this specification, the scale of each part is appropriately changed and shown for easy visual recognition.

A laminate 10 shown in FIG. 1 includes a polymerizable composition containing a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light and generates a photopolymerization active point of the polymerizable liquid crystal compound on a surface 11 s of a support 11. Formed by photopolymerization,
An optically anisotropic layer 12 in which a polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment;
An upper layer 13 laminated adjacently on the optically anisotropic layer 12;
The compound that generates the photopolymerization active site is at least two photopolymerization initiators having different wavelengths of ultraviolet light to be absorbed, or at least one photopolymerization initiator having different wavelengths of ultraviolet light to be absorbed and at least one kind of increase. And a sensitizer.

  In FIG. 1, the homogeneous alignment of the discotic liquid crystal compound is schematically shown in the embodiment in which the optically anisotropic layer 12 is a layer in which the discotic liquid crystal compound is fixed by homogeneous alignment with respect to the support surface 11s. It is shown.

  The optically anisotropic layer 12 may not be formed on the support 11, but the layer in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment is used as the support. 11 can be easily formed by utilizing the orientation regulating force of the surface 11s of the surface 11.

  The homeotropic alignment in the case where the polymerizable liquid crystal compound is a rod-like liquid crystal compound means that the major axis direction of the rod-like liquid crystal compound is aligned at an elevation angle of 90 degrees with respect to the support surface 11s, and is a homogeneous alignment. The term “major axis direction of the rod-like liquid crystal compound” means that the long axis direction is oriented in a state horizontal to the support surface 11s. The homeotropic alignment when the polymerizable liquid crystal compound is a discotic liquid crystal compound means that the plane of the discotic liquid crystal compound is aligned in a horizontal state with respect to the support surface 11s, and the homogeneous alignment is a disc. This means that the plane of the liquid crystal compound is aligned at an elevation angle of 90 degrees with respect to the support surface 11s. The fluctuation width of each angle is less than plus or minus 5 degrees at an arbitrary position of the optically anisotropic layer. The alignment state in the present invention can be confirmed using Axo Scan (0 PMF-1, manufactured by Axometrics).

<Support>
The support 11 shown in FIG. 1 includes an alignment layer 11b on a base material 11a, and the alignment layer 11b has an alignment regulating force on the surface 11s.

  As the substrate 11a, glass or a polymer film can be used. Examples of polymer film materials used as the substrate include cellulose acylate films (for example, cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film). Polyolefins such as polyethylene and polypropylene, polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic resin films such as polymethyl methacrylate, polyurethane resin films, polyester films, polycarbonate films, polysulfone films , Polyether film, polymethylpentene film, polyetherketone film, (meth) active Runitrile film, polyolefin, polymer having an alicyclic structure (norbornene resin (trade name “ARTON (registered trademark)”, manufactured by JSR Corporation, amorphous polyolefin (trade name “ZEONEX (registered trademark)”, ZEON CORPORATION) Among them, triacetyl cellulose, polyethylene terephthalate (PET), and polymers having an alicyclic structure are preferable, and triacetyl cellulose is particularly preferable.

  The film thickness of the substrate 11a may be about 5 μm to 1000 μm, preferably 10 μm to 250 μm, and more preferably 15 μm to 90 μm. The substrate 11 may be a temporary support that is finally peeled off.

  The alignment layer 11b can be provided on the substrate 11a by means such as a rubbing treatment of an organic compound (preferably a polymer), oblique vapor deposition of an inorganic compound such as silicon oxide, or formation of a layer having microgrooves. Furthermore, an alignment layer in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

  Hereinafter, a rubbing alignment layer and a photo alignment layer used by rubbing the surface as a preferred example will be described.

-Rubbing treatment orientation layer-
Examples of the polymer that can be used for the rubbing treatment oriented layer include, for example, a methacrylate copolymer, a styrene copolymer, a polyolefin, polyvinyl alcohol, and the like described in paragraph No. [0022] of JP-A-8-338913. Examples include modified polyvinyl alcohol, poly (N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, and polycarbonate. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. .
The thickness of the alignment layer 11b is preferably in the range of 0.1 to 10 μm.

--Rubbing process--
The rubbing treatment can be generally performed by rubbing the surface of a film mainly composed of a polymer with paper or cloth in a certain direction. A general method of rubbing is described in, for example, “Liquid Crystal Handbook” (issued by Maruzen, October 30, 2000).

As a method for changing the rubbing density, a method described in “Liquid Crystal Handbook” (published by Maruzen) can be used. The rubbing density (L) is quantified by the following formula (A).
Formula (A) L = Nl (1 + 2πrn / 60v)
In the formula (A), N is the number of rubbing, l is the contact length of the rubbing roller, r is the radius of the roller, n is the number of rotations (rpm) of the roller, and v is the stage moving speed (second speed).

  In order to increase the rubbing density, the rubbing frequency should be increased, the contact length of the rubbing roller should be increased, the radius of the roller should be increased, the rotation speed of the roller should be increased, and the stage moving speed should be decreased, while the rubbing density should be decreased. To do this, you can reverse this. In addition, the description in Japanese Patent No. 4052558 can also be referred to as conditions for the rubbing process.

-Photo-alignment layer-
A large number of documents describe the photo-alignment material used for the photo-alignment layer formed by light irradiation. For example, JP 2006-285197 A, JP 2007-76839 A, JP 2007-138138 A, JP 2007-94071 A, JP 2007-121721 A, JP 2007-140465 A, Azo compounds described in JP 2007-156439 A, JP 2007-133184 A, JP 2009-109831 A, Patent 3888848, Patent 4151746, and Fragrance described in JP 2002-229039 A. Group ester compounds, maleimide and / or alkenyl-substituted nadiimide compounds having a photo-alignment unit described in JP-A No. 2002-265541 and JP-A No. 2002-317013, light described in Japanese Patent No. 4205195 and Japanese Patent No. 4205198 Crosslinkable silane derivatives, special table 003-520878, JP-T-2004-529220 and JP-mentioned as photocrosslinkable polyimide, polyamide or ester are preferable examples described in Japanese Patent No. 4162850. Particularly preferred are azo compounds, photocrosslinkable polyimides, polyamides, or esters.

The photo-alignment layer formed from the above material is irradiated with linearly polarized light or non-polarized light to produce a photo-alignment layer.
In this specification, “linearly polarized light irradiation” is an operation for causing a photoreaction in a photo-alignment material. The wavelength of light used varies depending on the photo-alignment material used, and is not particularly limited as long as it is a wavelength necessary for the photoreaction. Preferably, the peak wavelength of light used for light irradiation is 200 nm to 700 nm, more preferably ultraviolet light having a peak wavelength of light of 400 nm or less.

  The light source used for light irradiation is a commonly used light source such as a tungsten lamp, a halogen lamp, a xenon lamp, a xenon flash lamp, a mercury lamp, a mercury xenon lamp, a carbon arc lamp, or various lasers (eg, semiconductor laser, helium). Neon laser, argon ion laser, helium cadmium laser, YAG laser), light emitting diode, cathode ray tube, and the like.

  As means for obtaining linearly polarized light, a method using a polarizing plate (eg, iodine polarizing plate, dichroic dye polarizing plate, wire grid polarizing plate), reflection using a prism-based element (eg, Glan-Thompson prism) or Brewster angle A method using a type polarizer or a method using light emitted from a laser light source having polarization can be employed. Moreover, you may selectively irradiate only the light of the required wavelength using a filter, a wavelength conversion element, etc.

In the case of linearly polarized light, a method of irradiating light from the top surface or the back surface to the alignment layer surface perpendicularly or obliquely with respect to the alignment layer is employed. The incident angle of light varies depending on the photo-alignment material, but is, for example, 0 to 90 ° (vertical), and preferably 40 to 90 °.
When non-polarized light is used, the non-polarized light is irradiated obliquely. The incident angle is 10 to 80 °, preferably 20 to 60 °, particularly preferably 30 to 50 °.
The irradiation time is preferably 1 minute to 60 minutes, more preferably 1 minute to 10 minutes.

  As mentioned above, although the aspect provided with the orientation layer 11b on the base material 11a as the support body 11 was demonstrated, the method in particular of providing the orientation control force to the surface 11s is not restrict | limited, The surface of the base material 11a is directly orientated ( For example, a rubbing process) may be used. In that case, the alignment layer 11b may not be provided. Examples of the substrate 11a that can be directly oriented include a PET substrate film.

<Optically anisotropic layer>
The optically anisotropic layer 12 is formed by photopolymerizing a polymerizable composition containing a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light and generates a photopolymerization active point of the polymerizable liquid crystal compound. In this layer, the liquid crystalline compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment.

  The optically anisotropic layer 12 is formed by applying the polymerizable composition to the rubbing-treated surface of the alignment layer 11b of the support 11 and forming a coating film in which the molecules of the polymerizable liquid crystal compound are aligned in a desired alignment state. The film is cured by photopolymerization to fix the alignment state of the molecules of the liquid crystal compound. In the present embodiment, the curing by photopolymerization includes an optically anisotropic layer forming step before forming a coating film of the upper layer 13 formed on the optically anisotropic layer 12, and photopolymerization after forming the coating film of the upper layer 13. Is implemented.

  Application of the polymerizable composition on the support surface 11s can be performed by a method such as a roll coating method, a gravure printing method, or a spin coating method. Furthermore, it can be performed by various methods such as a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method. Alternatively, the coating film can be formed by ejecting the composition from a nozzle using an inkjet apparatus.

  After forming the coating film, the coating film may be dried before photopolymerization. Drying may be performed by standing or may be performed by heating. In the drying step, an optical function derived from the liquid crystal component may be expressed. For example, the liquid crystal phase may be formed in the process of removing the solvent contained in the polymerizable composition by drying. The liquid crystal phase may be formed by setting the transition temperature to the liquid crystal phase by heating. For example, the liquid crystal phase can be stably formed by heating to the temperature of the isotropic phase and then cooling to the liquid crystal phase transition temperature. The liquid crystal phase transition temperature is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C. from the viewpoint of production suitability and the like. When the temperature is lower than 10 ° C., a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a liquid crystal phase. When the temperature exceeds 200 ° C., a high temperature is required to make the isotropic liquid state higher than the temperature range once exhibiting the liquid crystal phase, which is disadvantageous from waste of heat energy, deformation of the substrate, and alteration.

  In the photopolymerization, light irradiation may be performed under heating conditions in order to promote the photopolymerization reaction. Also, since the oxygen concentration in the atmosphere is related to the degree of polymerization, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less.

  Moreover, after superposing | polymerizing once, the method of hold | maintaining at a temperature higher than superposition | polymerization temperature and advancing reaction further by thermal polymerization reaction, or the method of irradiating an ultraviolet light again can also be used. The reaction rate can be measured by comparing the absorption intensity of the infrared vibration spectrum of a reactive group (for example, a polymerizable group) before and after the reaction proceeds.

(Polymerizable composition)
The polymerizable composition that is a raw material liquid for the optically anisotropic layer 12 includes a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light to generate a photopolymerization active point of the polymerizable liquid crystal compound, and has a photopolymerization active point. The resulting compound contains at least two photopolymerization initiators having different wavelengths of absorbing ultraviolet light, or at least one photopolymerization initiator having different wavelengths of absorbing ultraviolet light and at least one sensitizer. It is out.

-Polymerizable liquid crystal compounds-
The polymerizable liquid crystal compound contained in the polymerizable composition is not particularly limited as long as it is capable of homeotropic alignment, homogeneous alignment, or cholesteric alignment, but is preferably a rod-like liquid crystal compound or a disk-like liquid crystal compound. Examples of the polymerizable group include an acryloyl group, a methacryloyl group, an epoxy group, and a vinyl group. The orientation of the liquid crystal compound can be fixed by curing the polymerizable liquid crystal compound. The liquid crystal compound having a polymerizable group is preferably a monomer or a relatively low molecular weight liquid crystal compound having a polymerization degree of less than 100.

  Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

As the rod-like liquid crystal compound which is a polymerizable liquid crystal compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), U.S. Pat. Nos. 4,683,327, 5,622,648, 5,770,107, WO 95/22586, 95/24455, 97/97. JP-A Nos. 0600, 98/23580, 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and Japanese Patent Application No. 2001-64627 Etc. can be used. Further, as the rod-like liquid crystal compound, for example, compounds described in JP-A-11-513019 and JP-A-2007-279688 can be preferably used.
Table 1 below illustrates suitable rod-like liquid crystal compounds as the optically anisotropic layer 12.

Examples of the discotic liquid crystal compound include compounds described in JP-A-2007-108732 and JP-A-2010-244038. Table 2 below illustrates disk-like liquid crystal compounds suitable for the optically anisotropic layer 12 used in the examples described later.

-A compound that generates a photopolymerization active site of a polymerizable liquid crystal compound (photopolymerization initiator or sensitizer)-
The polymerizable composition includes at least two photopolymerization initiators having different wavelengths of ultraviolet light to be absorbed, or at least one having different wavelengths of ultraviolet light to be absorbed as a compound that generates a photopolymerization active point of the polymerizable liquid crystal compound. It contains a seed photopolymerization initiator and at least one sensitizer.

  At least two kinds of photopolymerization initiators having different wavelengths of absorbing ultraviolet light, or at least one kind of photopolymerization initiators having different wavelengths of absorbing ultraviolet light and at least one sensitizer are polymerization initiations shown below. Depending on the spectral characteristics of the light source for photopolymerization, the polymerization initiator preferably has an absorption wavelength including a peak wavelength with a high relative intensity of the light source (emission line wavelength), preferably an absorption peak. It is preferable that two or more sensitizers are selected and contained.

  Of the compounds that generate photopolymerization active sites, it is preferable that at least one of the compounds has a maximum absorption wavelength of ultraviolet light of 300 nm or less, and at least one of the compounds has a maximum value of 320 nm or more. The content of the compound having at least one compound having an ultraviolet absorption wavelength of 320 nm or more in the polymerizable composition is preferably 2 percent by weight or less based on the polymerizable liquid crystal compound.

  Examples of the photopolymerization initiator or sensitizer include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbons. A substituted aromatic acyloin compound (described in US Pat. No. 2,722,512), a polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of a triarylimidazole dimer and p-aminophenyl ketone ( U.S. Pat. No. 3,549,367), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (described in U.S. Pat. No. 4,221,970), acyl Phosphine oxide compounds (SHO 6) No. 3-40799, JP-B-5-29234, JP-A-10-95788, JP-A-10-29997) and the like.

The photopolymerization initiator or sensitizer has a maximum absorption wavelength within a range of about 200 nm to 400 nm (more preferably 250 nm to 380 nm), and the maximum value has a molar extinction coefficient of at least 5000 or more. It is preferable to contain at least one compound. The molar extinction coefficient was determined by measuring the absorption wavelength of a photopolymerization initiator or sensitizer dissolved in methanol and calculating the molar extinction coefficient from the following equation. The absorption wavelength can be measured with an ultraviolet-visible spectrophotometer (UV3150, manufactured by Shimadzu Corporation).
log (I ₀ / I) = e · c · d
e is the molar extinction coefficient [L / (mol · cm)], c is the molar concentration [mol / L], and d is the cell length [cm].

  The photopolymerization initiator or sensitizer that can be used is preferably a compound having at least an aromatic group. For example, an acylphosphine compound, an acetophenone compound, an α-aminoketone compound, a benzophenone compound, a benzoin ether compound, Ketal derivative compounds, thioxanthone compounds, oxime compounds, hexaarylbiimidazole compounds, trihalomethyl compounds, azo compounds, organic peroxides, diazonium compounds, iodonium compounds, sulfonium compounds, azinium compounds, benzoin ether compounds, ketal derivative compounds, metallocenes Examples thereof include onium salt compounds such as compounds, organic boron salt compounds, and disulfone compounds.

  Of these, oxime compounds, acetophenone compounds, α-aminoketone compounds, trihalomethyl compounds, hexaarylbiimidazole compounds, thioxanthone compounds, and thiol compounds are preferable from the viewpoint of sensitivity.

Specific examples of the oxime compound include compounds described in JP-A No. 2001-233842, compounds described in JP-A 2000-80068, and compounds described in JP-A 2006-342166.
Examples of oxime compounds such as oxime derivatives that are suitably used as photopolymerization initiators or sensitizers include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, and 3-propionyloxy. Iminobutan-2-one, 2-acetoxyiminopentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3- ( 4-toluenesulfonyloxy) iminobutan-2-one and 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one.

  Further, as oxime ester compounds other than those described above, compounds described in JP-T 2009-519904, in which an oxime is linked to the N-position of carbazole, compounds described in US Pat. No. 7,626,957 in which a hetero substituent is introduced into the benzophenone moiety, A compound described in Japanese Patent Application Laid-Open No. 2010-15025 and US Patent Publication No. 2009-292039 in which a nitro group is introduced into the dye moiety, a ketoxime compound described in International Patent Publication No. 2009-131189, the triazine skeleton and the oxime skeleton are identical A compound described in US Pat. No. 7,556,910 contained in the molecule, a compound described in JP 2009-221114 A having an absorption maximum at 405 nm and good sensitivity to a g-ray light source may be used.

In a commercial item, IRGACURE (registered trademark) -OXE01 and IRGACURE-OXE02 are preferably used.
As acetophenone-based initiators, commercially available products IRGACURE-907, IRGACURE-369, and IRGACURE-379 (trade names: all manufactured by BASF Japan Ltd.) can be used. As the acylphosphine initiator, commercially available products such as IRGACURE-819 and DAROCUR (registered trademark) -TPO (trade names: all manufactured by BASF Japan Ltd.) can be used.

  Furthermore, as the thioxanthone compound, the following exemplary compounds can be used. For example, thioxanthone sensitizers such as 2,4-diethylthioxanthone, 2-isopropylthioxanthone and 4-isopropylthioxanthone can be mentioned. Representative examples of commercially available thioxanthone sensitizers include KAYACURE (registered trademark) -DETX (trade name: manufactured by Nippon Kayaku Co., Ltd.), Speedcure (registered trademark) -ITX (manufactured by Lambson), Esacure (registered trademark). -ITX (made by Lamberti) etc. are mentioned.

  The content of the compound (photopolymerization initiator or sensitizer) that generates the photopolymerization active point of the polymerizable liquid crystal compound in the composition with respect to 100 parts by mass of the total amount of the polymerizable liquid crystal compound is 0.5 from the viewpoint of curability. It is preferably ˜15 parts by mass, more preferably 1 to 10 parts by mass, and further preferably 2 to 8 parts by mass.

  In addition, the mass ratio of the polymerizable liquid crystal compound that generates the photopolymerization active point for each type of compound is not particularly limited, but when two kinds of compounds that generate the photopolymerization active point are included, the initiator having the higher content is started. When the smaller amount of the initiator 1 is used as the initiator 2, the (initiator 1 content) / (initiator 2 content) is preferably 1 to 20, more preferably 1 to 10. 3 to 8 is particularly preferable.

The compounds used in Examples and Comparative Examples below are shown in the following table as examples of polymerization initiators and sensitizers.

―Surfactant―
The polymerizable composition preferably contains a surfactant. As a surfactant, a fluorine-containing compound or a compound having a polysiloxane structure, a surfactant having a molecular weight of 15000 or less, preferably a surfactant having a molecular weight of 10,000 or less, can suppress the repelling of the upper layer. Can be increased. Accordingly, repelling can be effectively suppressed even when the conversion ratio of the optically anisotropic layer 12 is high as compared with the case where such a surfactant is not included. The durability of the anisotropic layer can be increased.

  Since a compound having a fluorine or siloxane structure has a property of being unevenly distributed on the surface, it has a fluorine-containing compound or a polysiloxane structure contained in the coating film by including a surfactant for the polymerizable composition. A surfactant having a molecular weight of 15000 or less, which is composed of a compound, moves toward the surface in the coating film during the drying process of the coating film and the alignment aging process of the liquid crystal molecules. Accordingly, the optically anisotropic layer 12 having such a surfactant on the surface can be formed. Moreover, if molecular weight is 10,000 or less, the repelling phenomenon and the generation | occurrence | production of an orientation defect can be suppressed more favorably.

  In particular, in the case of using a coating liquid made of a liquid crystal composition containing a rod-like liquid crystal compound or a disk-like liquid crystal compound for forming the upper layer, a liquid crystal composition containing the rod-like liquid crystal compound or the disk-like liquid crystal compound by adjusting the molecular weight to the above range. An alignment layer in which alignment defects are suppressed by satisfactorily suppressing the repellency phenomenon of a coating solution made of a material and aligning liquid crystal molecules in a direction parallel or perpendicular to the surface 10s of the laminate. Can do. Although the mechanism is not clear, the present inventor has found that a surfactant within such a molecular weight range improves the wettability at the time of application of the coating solution and suppresses the repellency phenomenon of the coating solution, thereby improving the coating. Since the film is formed and the coating film moves to the coating film surface due to the uneven distribution of fluorine or siloxane structure, there is little adverse effect on the alignment regulating force of the surface 10s, and the rod-like liquid crystal compound or disk shape in the coating film It is believed that an alignment layer can be formed while suppressing alignment defects in the liquid crystal compound. A surfactant composed of large molecules having a molecular weight exceeding 15000 is not easily extracted from the coating film to the air interface side and remains in the vicinity of the surface 10 s, so that the orientation defect suppressing effect cannot be sufficiently obtained. Inferred.

  Therefore, the surfactant should have a relatively small molecular weight, preferably 10,000 or less, more preferably 5000 or less. In addition, the surfactant is preferably one that is easily compatible or soluble in a solvent contained in a coating solution to be formed on the surface 10 s of the laminate 10. Here, dissolution means that the transmittance of the solution exhibits 99% or more when the surfactant is mixed with the solvent so as to have a solid content concentration of 10%. The solubility parameter (SP value) of the surfactant is preferably as close as possible to the SP value of the rod-like liquid crystal compound or disk-like liquid crystal compound contained in the upper layer preparation coating solution, and the difference between these SP values is 5 or less. Is preferably 4, or less, more preferably 4 or less, and particularly preferably 2 or less. The solubility parameter is a numerical value of how easily soluble in a solvent or the like, and has the same concept as the polarity often used in organic compounds. The larger the solubility parameter, the greater the polarity. In this specification, SP values are the values of p. Of Hideki Yamamoto, SP Value Basics / Applications and Calculation Methods (Information Organization, published on March 31, 2005). 66, the value calculated by Fedor's estimation method is used.

  When a cholesteric liquid crystal layer is formed as an upper layer, it is necessary to apply a twisting force due to a chiral agent in addition to a normal alignment regulating force. Therefore, it is considered preferable that the action of the surfactant present on the surface 10s of the laminate is less. As described above, it is considered that the larger the molecular weight, the greater the influence on the alignment regulating force. Therefore, in order to obtain a sufficient twisting force by the chiral agent, the alignment regulating force of the laminate surface 10s is higher. Is required. Therefore, it is preferable that the surfactant on the surface 10s of the laminate is more easily extracted by the solvent in the coating solution when the upper layer coating solution is applied, so the molecular weight of the surfactant is smaller than 10,000. It is inferred that it is necessary.

  Although it is a fluorine-containing compound or a compound having a polysiloxane structure, the surfactant having a molecular weight of 15000 or less is not particularly limited, but is preferably a compound having a polyalkylene oxide group and / or a hydroxyl group.

The surfactant is preferably made of a fluorine-containing compound. In this case, the optically anisotropic layer 12 preferably contains 0.001% by mass or more and less than 0.10% by mass of fluorine atoms (described later). See Examples). The fluorine-containing compound is such that the polarizability of the polymerizable liquid crystal compound and the fluorine-containing compound contained in the optically anisotropic layer 12 is not too far apart, maintains a compatible state, and improves the repelling phenomenon suppressing ability and the orientation of the liquid crystal compound. From the viewpoint, the weight ratio of the fluorine part is preferably 20% to 98%, more preferably 30% to 95%, and particularly preferably 35% to 90%. The fluorine part is a repeating unit containing a fluorine atom in a polymer. If the fluorine element is contained in the main chain or part of the side chain, it is regarded as a fluorine part (that is, does not contain a fluorine element). The repeating unit is defined as the non-fluorine part.)
Also, the fluorine part contains a lot of ω-fluorine parts (eg, C ₄ F ₉ and C ₆ F ₁₃ groups in the compounds in Table 3 below) and contains high molecular weight (molecular weight of 10,000 or more) fluorine content. Polymers tend to horizontally align a discotic liquid crystal compound or a rod-shaped liquid crystal compound. On the contrary, a fluorine-containing compound having a large number of highly polar functional groups such as OH groups, COOH groups, and NH groups in the non-fluorine part tends to vertically align the disc-shaped liquid crystal compound or the rod-shaped liquid crystal compound.

  The content of the surfactant in the polymerizable composition is preferably 5% by mass or less with respect to the total mass of the composition, from the viewpoint of uneven distribution at the interface in the coating film and surface improvement. 4 mass% or less is more preferable, and it is still more preferable that it is 3 mass% or less.

Below, a compound suitable as a surfactant contained in a polymerizable composition is illustrated.
Examples of the fluorine-containing compound include those containing fluorine among the compounds described as alignment control agents described in paragraphs 0028 to 0034 of JP2011-191582A, and fluorine-based surfactants described in Japanese Patent No. 2841611. And fluorine-based surfactants described in paragraphs 0017 to 0019 of JP-A-2005-272560.

  Examples of the compound having a polysiloxane structure include polymethylphenylsiloxane, polyether-modified silicone oil, polyether-modified dimethylpolysiloxane, dimethylsilicone, diphenylsilicone, hydrogen-modified polysiloxane, vinyl-modified polysiloxane, and hydroxy-modified polysiloxane. , Amino modified polysiloxane, carboxyl modified polysiloxane, chloro modified polysiloxane, epoxy modified polysiloxane, methacryloxy modified polysiloxane, mercapto modified polysiloxane, fluorine modified polysiloxane, long chain alkyl modified polysiloxane, phenyl modified polysiloxane, silicone modified Examples thereof include low molecular compounds containing silicon atoms such as copolymers.

  Commercially available silicone surfactants include KF-96, X-22-945 manufactured by Shin-Etsu Chemical, Toray Silicone DC3PA, DC7PA, SH11PA, SH21PA, SH28PA, SH29PA, SH30PA, and FS. -1265-300 (above, manufactured by Toray Dow Corning Silicone Co., Ltd.), TSF-4300, -4440, -4445, -4446, -4442, -4442 (above, GE Toshiba Silicon Co., Ltd.) )), Polysiloxane polymer KP341 (manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-301, BYK-302, BYK-307, BYK-325, BYK-331, BYK-333, BYK-341 BYK-345, BYK-346, BYK-348, BYK-375 (Bic Chemie Alon GS-30 (manufactured by Japan Co., Ltd.), Silicone L-75, Silicone L-76, Silicone L-77, Silicone L-78, Silicone L-79, Silicone L-520 and Silicone L- 530 (manufactured by Nippon Unika Co., Ltd.).

Table 4 illustrates suitable surfactants.

-solvent-
The polymerizable composition preferably contains a solvent. The solvent may be a low surface tension solvent or a standard surface tension solvent. Especially, it is preferable that the composition for forming a liquid-crystal layer contains a low surface tension solvent.

The surface tension of the low surface tension solvent is 10 to 22 mN / m (10 to 22 dyn / cm), preferably 15 to 21 mN / m, and more preferably 18 to 20 mN / m. The surface tension of the standard surface tension solvent is larger than 22 mN / m, preferably 23 to 50 mN / m, and more preferably 23 to 40 mN / m.
The difference between the surface tension of the low surface tension solvent and the surface tension of the standard surface tension solvent is preferably 2 mN / m or more, more preferably 3 mN / m or more, and 4 to 20 mN / m or more. More preferably, it is 5-15 mN / m.

  In addition, in this specification, the surface tension of a solvent is a value as described in a solvent handbook (Kodansha, 1976 issuance). The surface tension of the solvent is a physical property value that can be measured by, for example, an automatic surface tension meter CBVP-A3 manufactured by Kyowa Interface Science Co., Ltd. The measurement may be performed at 25 ° C.

  As the solvent, an organic solvent is preferably used, and a low surface tension solvent and a standard surface tension solvent can be selected from these. Examples of organic solvents include alcohols (eg, ethanol, tert-butyl alcohol), amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (Eg, heptane, cyclopentane, toluene, hexane, tetrafluoroethylene), alkyl halides (eg, chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate, isopropyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone) ), Ether (eg, tetrahydrofuran, 1,2-dimethoxyethane), and amine (eg, triethylamine). Two or more organic solvents may be used in combination. These solvents can be used as the solvent of the composition without removing those used as a solvent during polymerization (for example, toluene).

  Examples of low surface tension solvents include tert-butyl alcohol (19.5 mN / m), tetrafluoroethylene (TFE, 20.6 mN / m), triethylamine (20.7 mN / m), cyclopentane (21.8 mN / m). m), heptane (19.6 mN / m), and a mixed solvent composed of a combination of any two or more of these solvents. The numerical value indicates the surface tension. Among these, tert-butyl alcohol, tetrafluoroethylene, triethylamine, and cyclopentane are preferable from the viewpoint of safety, tert-butyl alcohol or tetrafluoroethylene is more preferable, and tert-butyl alcohol is more preferable.

  Examples of standard surface tension solvents include methyl ethyl ketone (MEK, 23.9 mN / m), methyl acetate (24.8 mN / m), methyl isobutyl ketone (MIBK, 25.4 mN / m), cyclohexanone (34.5 mN / m). ), Acetone (23.7 mN / m), isopropyl acetate (0.0221 mN / m), and a mixed solvent composed of a combination of any two or more of these solvents. The numerical value indicates the surface tension. Of these, methyl ethyl ketone, a mixed solvent of cyclohexanone and another solvent, a mixed solvent of methyl acetate and methyl isobutyl ketone, and the like are preferable.

The concentration of the solvent with respect to the total mass of the polymerizable composition is preferably 95 to 50% by mass, more preferably 93 to 60% by mass, and still more preferably 90 to 75% by mass.
In the drying step in forming the liquid crystal layer, the solvent of the polymerizable composition is preferably removed by 95% by mass or more, more preferably by 98% by mass or more, and 99% by mass with respect to the total amount of the solvent. It is more preferable to remove the above, and it is particularly preferable to remove substantially 100% by mass.

―Chiral agent―
When the optically anisotropic layer 12 formed from the polymerizable composition is a layer in which a cholesteric liquid crystal phase is fixed, the liquid crystal component preferably contains a chiral agent (also referred to as a chiral agent).
The chiral agent is known various chiral agents (for example, described in Liquid Crystal Device Handbook, Chapter 3-4-3, TN, chiral agent for STN, page 199, edited by Japan Society for the Promotion of Science, 42nd Committee, 1989) You can choose from. A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound containing no asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When the chiral agent has a polymerizable group, a repeating unit derived from the polymerizable liquid crystal compound and a repeating unit derived from the chiral agent by a polymerization reaction between the chiral agent having a polymerizable group and the polymerizable liquid crystal compound Can be formed. In this embodiment, the polymerizable group possessed by the chiral agent having a polymerizable group is preferably the same group as the polymerizable group possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Particularly preferred.
The chiral agent may be a liquid crystal compound.

  Examples of the chiral agent exhibiting a strong twisting force include JP 2010-181852 A, JP 2003-287623 A, JP 2002-80851 A, JP 2002-80478 A, and JP 2002-302487 A. The chiral agent described in the publication can be mentioned and can be preferably used. Furthermore, isosorbide compounds having a corresponding structure can be used for isosorbide compounds described in these publications, and isosorbide compounds having a corresponding structure can be used for isomannide compounds described in these publications. It can also be used.

The structural formulas of suitable chiral agents are illustrated below.

  The optically anisotropic layer 12 may be a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase. As the cholesteric liquid crystal layer and the method for producing the cholesteric liquid crystal layer, for example, the descriptions in JP-A-1-133003, JP-A-3416302, JP-A-3363565, and JP-A-8-271731 can be referred to.

  The optical properties of the optically anisotropic layer 12 based on the orientation of the liquid crystal compound molecules, for example, the optical properties of the cholesteric liquid crystal phase are sufficient if they are retained in the layer, and the liquid crystal composition of the liquid crystal layer after curing is sufficient. No longer need to exhibit liquid crystallinity. For example, the liquid crystal compound molecules may become high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

<Upper layer>
The upper layer 13 laminated adjacently on the optically anisotropic layer 12 is not particularly limited. Like the optical anisotropic layer 12, the upper layer may be an optical anisotropic layer in which the orientation of the polymerizable liquid crystal compound is fixed, as in the optical film 1 described later, or the optical anisotropic layer 12 A layer such as a protective layer may be used.

  The polymerizable composition (coating liquid) used for forming the upper layer 13 includes a polymerizable compound selected according to the function required for the upper layer 13, and photopolymerization activity of the polymerizable compound that absorbs ultraviolet light. If it contains the compound which produces a point, it will not restrict | limit in particular. In the polymerizable composition of the upper layer 13, at least two types of photopolymerization initiators having different wavelengths of ultraviolet light to be absorbed, or at least one type of light having different wavelengths of ultraviolet light to be absorbed It may contain a polymerization initiator and at least one sensitizer. By adopting such a configuration, even when a polymer layer formed adjacently on the upper layer 13 is provided, the upper layer can be formed by applying the above-described manufacturing method of the optically anisotropic layer 12 to the formation of the upper layer 13. It is possible to achieve both the durability of 13 and the good film properties of the polymer layer formed adjacent thereto.

  For example, the optical film 1 schematically shown in FIG. 2 includes an optically anisotropic layer 12a of this embodiment in which a polymerizable discotic liquid crystal compound is fixed in a homeotropic alignment state, and the optically anisotropic layer 12a. And an optically anisotropic layer 12b of the present embodiment in which a polymerizable discotic liquid crystal compound is fixed in a cholesteric alignment state, and adjacently stacked on the optically anisotropic layer 12b. Thus, a laminated body 10 including the upper layer 13 of this embodiment in which a polymerizable rod-like liquid crystal compound is fixed in a cholesteric alignment state is provided on a support 11.

  Since the optical film 1 having such a configuration is configured to include the laminate 10 of the present embodiment on the support 11, the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state. Even if the optically anisotropic layer is formed in a plurality of layers, the effect of the laminated body 10 is obtained.

  As described above, the laminate 10 includes the optically anisotropic layer 12 in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state, and the optically anisotropic layer 12 on the optically anisotropic layer 12. And an optically anisotropic layer 12 that includes a polymerizable liquid crystal compound and at least two types of photopolymerization initiators that absorb different wavelengths of ultraviolet light, or an absorption layer. It is formed by photopolymerizing a polymerizable composition containing at least one photopolymerization initiator and at least one sensitizer having different wavelengths of ultraviolet light. According to this configuration, the optically anisotropic layer 12 in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment state has good durability, and the upper layer 13 has good film characteristics. Can be made compatible.

The use of the optical film 1 is not particularly limited. Examples of the optical film include a retardation film, a reflective film, and a light absorbing film. More specifically, examples include an optical compensation film, a polarizing film, a brightness enhancement film, a heat shielding film, and a projection film used for liquid crystal display devices.
The optical film 1 may be a support film for producing a laminated film other than the aspect of the optical film 1 of the above embodiment.

  As a suitable aspect of the optical film 1, an aspect in which the signs of Rth (550) of the optically anisotropic layer 12b and Rth (550) of the upper layer 13 are different may be mentioned. The optical film 1 having such a configuration can be suitably used as a brightness enhancement film for a backlight system of a liquid crystal display device. Details of the backlight system and the liquid crystal display device provided with such a brightness enhancement film are described in Japanese Patent Application No. 2013-174971 (not disclosed at the time of this application).

[Liquid Crystal Display]
The optical film of the present invention can be used as a brightness enhancement film used for a backlight of a liquid crystal display device. Hereinafter, a liquid crystal display device according to an embodiment of the present invention will be described. FIG. 3 is a schematic diagram showing the configuration of the liquid crystal display device 20 according to an embodiment of the present invention. FIG. 4 is a schematic sectional view of the backlight unit 40.
As shown in FIG. 3, the liquid crystal display device 20 includes a pair of polarizing plates (an upper polarizing plate 21 and a lower polarizing plate 28), a liquid crystal cell 30 sandwiched between them, and a liquid crystal of the lower polarizing plate 28. The liquid crystal cell 30 includes a liquid crystal 25 and a liquid crystal cell upper electrode substrate 23 and a liquid crystal cell lower electrode substrate 26 which are arranged above and below the liquid crystal cell 25. doing. In addition, since the backlight unit 40 includes a polarized light-emitting film, the lower polarizing plate 28 can be omitted.

  When the liquid crystal display device 20 is used as a transmission type, the upper polarizing plate 21 is a front side (viewing side) polarizing plate and the lower polarizing plate 28 is a rear side (backlight side) polarizing plate, which is not shown. 25 and the upper polarizing plate 21 is provided with a color filter. In FIG. 3, 22 and 29 indicate the directions of the absorption axes of the polarizing plates substantially orthogonal to each other, and 24 and 27 indicate the orientation control directions of the electrode substrates.

  As shown in FIG. 4, the backlight unit 40 is provided on the light guide plate 43, a light source 42 that emits white light, a light guide plate 43 that guides and emits primary light emitted from the light source 42. A brightness enhancement film 44 and a reflection plate 41 disposed opposite to the brightness enhancement film 44 with the light guide plate 43 interposed therebetween. The brightness enhancement film 44 has the optical film 1 of the present invention. In the backlight unit 40, the optical film 1 is arranged so that the upper layer 13 side is the light guide plate 43 side.

  The light source 42 includes blue light having an emission center wavelength in the wavelength band of 430 nm to 480 nm, green light having an emission center wavelength in the wavelength band of 500 nm to 600 nm, and at least a peak of emission intensity in the wavelength band of 600 nm to 4700 nm. The light source is not particularly limited as long as it is a light source that emits a part of red light. As such a light source, a blue light emitting diode (LED) that emits blue light, a light source having a fluorescent material that emits green light and red light when the light of the blue light emitting diode is incident, and light emission in a wavelength band of 300 nm to less than 430 nm. A UV light emitting diode that emits UV light having a center, a light source having a fluorescent material that emits blue light, green light, and red light when the light from the UV light emitting diode is incident, a blue light emitting diode that emits blue light, and blue light A light source (pseudo white LED) having a fluorescent material (yellow phosphor, etc.) that emits light with a wide peak from green light to red light when light from the light emitting diode is incident, a light source having a light emitting diode of each color, etc. are preferable Illustrated.

The reflection plate 41 converts the polarization state of the light emitted from the light source and reflected by the brightness enhancement film, and reflects it. There is no restriction | limiting in particular as such a reflecting plate 41, A well-known thing can be used, and it is described in the patent 3416302, the patent 3363565, the patent 4091978, the patent 348656, etc.
As the light guide plate 43, a known one can be used without any limitation.

The brightness enhancement film 44 includes a λ / 4 plate between the support 11 and the optically anisotropic layer 12 in the optical film 1 of the above embodiment, and one of the optically anisotropic layer 12 and the upper layer 13 is provided. A light reflection layer having a reflectance peak having a reflection center wavelength of 380 nm to less than 500 nm and a half width of 100 nm or less, and the other having a reflectance peak having a reflection center wavelength of 500 nm to 750 nm and a half width of 200 nm or less This is a layer having an aspect in which Rth (550) of the optically anisotropic layer 12 and Rth (550) of the upper layer 13 are different. In this embodiment, the brightness enhancement film reflects blue light (L _B ) at the liquid layer 110 and reflects at least one of right circularly polarized light and left circularly polarized light of green light (L _G ) and red light (L _R ) at the upper layer 13. The λ / 4 plate can convert light of wavelength λ from circularly polarized light to linearly polarized light. With this configuration, circularly polarized light in the first polarization state (for example, right circularly polarized light) is substantially reflected by the optically anisotropic layer 12 and the upper layer 13, while circularly polarized light in the second polarization state (for example, left circularly polarized light). ) Is substantially transmitted through the optically anisotropic layer 12 and the upper layer 13, and the transmitted light is converted into linearly polarized light by the λ / 4 plate and emitted. The reflected right circularly polarized light is randomized in its direction and polarization state by the reflector 41 or the like, is incident on the brightness enhancement film 44 again, and the left circularly polarized light is transmitted and emitted. In this way, the light utilization efficiency can be increased by recirculating the reflected light in the polarization state, and the intensity of the light Lw emitted from the backlight can be increased.

  In addition, the backlight unit 40 preferably includes a known diffusion plate, diffusion sheet, prism sheet (for example, BEF series manufactured by Sumitomo 3M Limited), and a light guide. Other members are also described in Japanese Patent No. 3416302, Japanese Patent No. 3363565, Japanese Patent No. 4091978, Japanese Patent No. 3448626, and the contents of these publications are incorporated in the present invention.

  In the liquid crystal display device provided with the backlight unit, the driving mode of the liquid crystal cell is not particularly limited, and twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), and in-plane switching. Various modes such as (IPS) and optically compensated bend cell (OCB) can be used. The liquid crystal cell is preferably VA mode, OCB mode, IPS mode, or TN mode, but is not limited thereto. As an example of the configuration of the VA mode liquid crystal display device, the configuration shown in FIG. 2 of Japanese Patent Application Laid-Open No. 2008-262161 is given as an example. However, the specific configuration of the liquid crystal display device is not particularly limited, and a known configuration can be adopted.

  When the brightness enhancement film of the backlight unit includes the optical film of the present invention, the wavelength conversion range of red and green is particularly widened, and a high-brightness backlight and liquid crystal display device can be obtained.

  The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following examples.

"Main compounds used"
The compounds used in the following examples and comparative examples are as follows.
<Polymerizable liquid crystal compound>
As the rod-like liquid crystal compound and the disk-like liquid crystal compound, those already shown in Table 1 and Table 2 were used.
<Surfactant>
As the surfactant having a molecular weight of 15000 or less, those already shown in Table 4 were used.
As the surfactant used in the pitch gradient layer (PG layer), those described in the explanation part of the PG layer were used, and the other surfactants shown in Table 6 were used.
<Polymerization initiator and sensitizer>
As the polymerization initiator and the sensitizer, those already shown in Table 3 were used.

<Chiral agent>
The one shown in Table 5 above was used.
<Alignment aid>
The alignment aids shown in Table 7 below were used. In the alignment aids OA1 to OA3, in the following structural formula, a mixture of two types of compounds having different methyl group substitution positions in the trimethyl-substituted benzene ring (mixing mass ratio 50:50)

<Support>
Cellulose acylate film T1 (“TD40UL” (manufactured by FUJIFILM Corporation) is passed through a dielectric heating roll at a temperature of 60 ° C., and the film surface temperature is raised to 40 ° C., and then the composition shown below on one side of the film Was applied at a coating amount of 14 ml / m ² using a bar coater and heated to 110 ° C. It was transported for 10 seconds under a steam far infrared heater manufactured by Noritake Company Limited. Using a bar coater, pure water was applied at a rate of 3 ml / m ^2. Next, washing with a fountain coater and draining with an air knife were repeated three times, followed by transporting to a drying zone at 70 ° C. for 10 seconds to dry, An alkali saponified cellulose acylate film was prepared and used as a support.

<Alignment layer Y1>
On the long cellulose acetate film saponified as described above, an alignment layer coating solution having the following composition was continuously applied with a # 14 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds. The obtained coating film was continuously rubbed. At this time, the longitudinal direction of the long film and the conveying direction were parallel, and the rotation axis of the rubbing roller with respect to the longitudinal direction of the film was 45 ° clockwise (hereinafter referred to as rubbing direction A).

<Alignment layer Y2>
An alignment layer Y2 was formed in the same manner as the alignment layer Y1, except that the rotation axis of the rubbing roller with respect to the film longitudinal direction was set to a direction of 75 ° clockwise (hereinafter referred to as the rubbing direction B).

<Hard coat layer HC>
The following composition was put into a mixing tank and stirred to obtain a hard coat layer coating solution.
To 900 parts by mass of methyl ethyl ketone, 100 parts by mass of cyclohexanone, 750 parts by mass of partially caprolactone-modified polyfunctional acrylate (DPCA-20, manufactured by Nippon Kayaku Co., Ltd.), silica sol (MIBK-ST, manufactured by Nissan Chemical Industries, Ltd.) ) 200 parts by mass and 50 parts by mass of photopolymerization initiator IN7 (Irgacure 184, manufactured by Ciba Specialty Chemicals) were added and stirred. A coating solution A for a hard coat layer was prepared by filtering through a polypropylene filter having a pore size of 0.4 μm.

On the underlayer (support, alignment layer, liquid crystal layer, etc.), the coating liquid A for hard coat layer was applied using a gravure coater. After drying at 100 ° C., an irradiance of 400 mW / cm using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) of 160 W / cm while purging with nitrogen so that the oxygen concentration becomes 1.0 vol% or less. ^2. The ultraviolet ray having an irradiation amount of 150 mJ / cm ² was irradiated to cure the coating layer, thereby forming a hard coat layer HC having a thickness of 12 μm.

<Λ / 2 layer (HWP) 1>
The following composition was put into a mixing tank and stirred to obtain a coating solution for λ / 2 layer (HWP) 1. On the alignment layer Y2, it was continuously applied with a # 5.0 wire bar. The conveyance speed (V) of the film was 26 m / min. For drying the solvent of the coating solution and orientation ripening of the discotic liquid crystalline compound (hereinafter also referred to as DLC compound), heating was performed with warm air of 115 ° C. for 90 seconds, followed by heating with warm air of 80 ° C. for 60 seconds, UV irradiation was performed at 80 ° C. to fix the alignment of the liquid crystal compound. The thickness of the optically anisotropic layer HWP1 was 2.0 μm. The average inclination angle of the disk surface of the DLC compound with respect to the film surface was 90 °, and it was confirmed that the DLC compound was oriented perpendicular to the film surface. The angle of the slow axis was parallel to the rotation axis of the rubbing roller when forming the alignment layer Y2, and was 15 ° when the film longitudinal direction was 90 ° (film width direction was 0 °).

<Λ / 2 layer (HWP) 2>
Coating having the same composition as the composition for forming HWP1 except that 3.00 parts by mass of polymerization initiator IN2 and 1.00 parts by mass of polymerization initiator IN5 are blended as polymerization initiators, and no sensitizer is added. The solution was used as a coating solution for forming HWP2. Using this coating solution, a λ / 2 layer (HWP) 2 was formed in the same manner as HWP1.

<Λ / 2 layer (HWP) 3>
Coating having the same composition as the composition for forming HWP1 except that 3.00 parts by mass of polymerization initiator IN2 and 1.00 parts by mass of polymerization initiator IN4 are blended as a polymerization initiator and no sensitizer is added. The solution was used as a coating solution for forming HWP3. Using this coating solution, a λ / 2 layer (HWP) 3 was formed in the same manner as HWP1.

<Λ / 2 layer (HWP) 4 for comparative example>
A coating solution having the same composition as the composition for forming HWP2 except that only 3.00 parts by mass of IN2 was blended as a polymerization initiator was used as a coating solution for forming HWP4 for comparative examples. Using this coating solution, a λ / 2 layer for comparative example (HWP) 4 was formed in the same manner as HWP1.

<Λ / 2 layer for comparison example (HWP) 5>
A coating solution having the same composition as the composition for forming HWP1 except that only 1.00 parts by mass of sensitizer IN6 used for HWP1 was blended without using a polymerization initiator, and a coating solution for forming HWP5 for Comparative Example did. Using this coating solution, a λ / 2 layer for comparative example (HWP) 5 was formed in the same manner as HWP1.

<Λ / 4 layer (QWP) 1>
The following composition was put into a mixing tank and stirred to obtain a coating solution for λ / 4 layer (QWP) 1. In Examples 1, 3 to 5, and 8 to 12, the coating was continuously applied on the alignment layer Y1 and in Comparative Example 5 on the hard coat layer with a # 3.2 wire bar. The conveyance speed (V) of the film was 40 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the discotic liquid crystal compound, it was heated with hot air at 60 ° C. for 80 seconds. Subsequently, UV irradiation was performed at 70 ° C. to fix the orientation of the liquid crystal compound and form an optically anisotropic layer. At this time, the UV irradiation amount was 300 mJ / cm ² .

<Λ / 4 layer (QWP) 13>
A coating solution having the same composition as the QWP1 forming composition except that no surfactant was added was used as a QWP13 forming coating solution. Using this coating solution, a λ / 4 layer (QWP) 13 was formed in the same manner as QWP 1 (Example 13).

<Λ / 4 layer (QWP) 14>
Instead of the surfactants SF1 and SF5, a coating solution having the same composition as the QWP1 forming composition was used except that 0.15 parts by mass of the surfactant SF9 was added. Using this coating solution, a λ / 4 layer (QWP) 14 was formed in the same manner as QWP 1 (Example 14).

<Λ / 4 layer (QWP) 15>
Instead of the surfactants SF1 and SF5, a coating solution having the same composition as the QWP1 forming composition was used except that 0.15 parts by mass of the surfactant SF11 was added. Using this coating solution, a λ / 4 layer (QWP) 15 was formed in the same manner as QWP 1 (Example 15).

<Λ / 4 layer (QWP) 0 for upper layer>
The following composition was charged into a mixing tank and stirred to obtain a coating solution for λ / 4 layer (QWP) 0 for upper layer. The surface of the λ / 2 layer (HWP) as a base was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction are parallel, and the angle formed between the longitudinal direction of the film and the rotation axis of the rubbing roller is −75 ° (counterclockwise) (the longitudinal direction of the film is 90 °). Then, the rotation axis of the rubbing roller is 165 ° and the rubbing direction C).

The prepared coating solution for λ / 4 layer (QWP) 0 for the upper layer was continuously coated on the rubbed surface with a # 2.2 wire bar. The conveyance speed (V) of the film was 26 m / min. In order to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound, the solution was heated with warm air of 60 ° C. for 60 seconds and irradiated with UV at 60 ° C. to fix the alignment of the liquid crystal compound. The thickness of λ / 4 layer (QWP) 0 was 0.8 μm. The average inclination angle of the long axis of the rod-like liquid crystalline compound with respect to the film surface was 0 °, and it was confirmed that the liquid crystalline compound was aligned horizontally with respect to the film surface. The angle of the slow axis was orthogonal to the rotation axis of the rubbing roller, and was 75 ° when the film longitudinal direction was 90 ° (film width direction was 0 °).
In this way, retardation plates in which a λ / 2 plate and a λ / 4 plate were laminated on a support were obtained (Examples 2, 6, 7 and Comparative Examples 1 and 2).

<Λ / 4 layer (QWP) 2>
A coating solution having the same composition as the QWP1 forming composition except that only 3.00 parts by mass of IN2 was added as a polymerization initiator was used as a QWP2 forming coating solution. Using this coating solution, a λ / 4 layer (QWP) 2 was formed in the same manner as QWP 1 (Comparative Examples 3, 4, 6).

<Disc-shaped cholesteric liquid crystal (B-DLC) layer 1 for reflecting blue light>
The following composition was put into a mixing tank and stirred to obtain a coating solution for a disc-shaped cholesteric liquid crystal layer (B-DLC) 1 for reflecting blue light. The prepared coating solution was continuously applied to the surface of the λ / 4 layer (QWP) 1 serving as a base with a wire bar so as to have a film thickness of 3.0 μm.
Subsequently, the solvent was dried at 70 ° C. for 2 minutes, and after evaporating the solvent, heat aging was performed at 107 ° C. for 2 minutes to obtain a uniform alignment state. Thereafter, this coating film is kept at 50 ° C., and irradiated with ultraviolet light (150 mJ / cm ² ) using a high-pressure mercury lamp in a nitrogen atmosphere, so that a disc-shaped cholesteric liquid crystal (B-DLC) layer 1 for reflecting blue light is formed. Formed (Example 3).

<Disc cholesteric liquid crystal (B-DLC) layer 2 for reflecting blue light>
A coating solution having the same composition as the composition for forming the B-DLC layer 1 except that the polymerization initiator IN4 was used in place of the sensitizer IN6 was prepared, and a blue light reflecting discotic cholesteric liquid crystal layer (B- DLC) 2 forming coating solution. Using this coating solution, a disc-shaped cholesteric liquid crystal (B-DLC) layer 2 for reflecting blue light was formed in the same manner as the B-DLC layer 1 (Example 8).

<Disc-shaped cholesteric liquid crystal (B-DLC) layer 3 for reflecting blue light>
A coating liquid having the same composition as the composition for forming the B-DLC layer 2 except that the blending ratio of the polymerization initiator IN2 and the polymerization initiator IN4 was changed was prepared, and a disc-shaped cholesteric liquid crystal layer (B- DLC) 3 forming coating solution (3 parts by mass of polymerization initiator IN2 and 0.5 parts by mass of polymerization initiator IN4). Using this coating solution, a disc-shaped cholesteric liquid crystal (B-DLC) layer 3 for reflecting blue light was formed in the same manner as in the B-DLC layer 1 (Example 9).

<Disc cholesteric liquid crystal (B-DLC) layer 4 for reflecting blue light>
A coating solution having the same composition as the composition for forming the B-DLC layer 1 except that the polymerization initiator IN3 (3 parts by mass) was used in place of the sensitizer IN6 was prepared, and a disc-shaped cholesteric for blue light reflection was prepared. A coating liquid for forming a liquid crystal layer (B-DLC) 4 was obtained. Using this coating solution, a disc-shaped cholesteric liquid crystal (B-DLC) layer 4 for reflecting blue light was formed in the same manner as the B-DLC layer 1 (Example 10).

<Disc cholesteric liquid crystal (B-DLC) layer 5 for reflecting blue light>
A coating liquid having the same composition as the composition for forming the B-DLC layer 1 was prepared except that the blending ratio of the polymerization initiator IN2 and the sensitizer IN6 was changed, and a disc-shaped cholesteric liquid crystal layer for blue light reflection (B- DLC) 5 forming coating solution (3 parts by mass of polymerization initiator IN2 and 3 parts by mass of sensitizer IN6). Using this coating solution, a disc-shaped cholesteric liquid crystal (B-DLC) layer 5 for reflecting blue light was formed in the same manner as the B-DLC layer 1 (Example 11).

<Disc cholesteric liquid crystal (B-DLC) layer 6 for reflecting blue light>
Composition similar to the composition for forming B-DLC layer 1 except that sensitizer IN5 (3 parts by mass) and polymerization initiator IN4 (1 part by mass) were used instead of polymerization initiator IN2 and sensitizer IN6. Was prepared as a coating solution for forming a disc-shaped cholesteric liquid crystal layer (B-DLC) 6 for reflecting blue light. Using this coating solution, a disc-shaped cholesteric liquid crystal (B-DLC) layer 6 for reflecting blue light was formed in the same manner as the B-DLC layer 1 (Example 11).

<Disc cholesteric liquid crystal (B-DLC) layer 7 for reflecting blue light>
A coating liquid having the same composition as the composition for forming the B-DLC layer 1 was prepared except that the sensitizer IN6 was not added and the polymerization initiator IN2 was changed to 3 parts by mass, and a disc-shaped cholesteric liquid crystal for blue light reflection was prepared. The coating liquid for forming the layer (B-DLC) 7 was used. The prepared coating solution was continuously applied to the surface of the λ / 4 layer (QWP) 2 serving as a base with a wire bar so as to have a film thickness of 3.0 μm. Subsequently, the solvent was dried at 70 ° C. for 2 minutes, and after evaporating the solvent, heat aging was performed at 107 ° C. for 2 minutes to obtain a uniform alignment state. Then holding the coating film 50 ° C., this ultraviolet light irradiation using a high-pressure mercury lamp under a nitrogen atmosphere (Comparative Example 3 In 300 mJ / cm ^2, Comparative Example 4, 150 mJ / cm ^2, Comparative Example 6 In 50 mJ / cm ² ) to form a disc-shaped cholesteric liquid crystal (B-DLC) layer 7 for reflecting blue light.

<Disc-shaped cholesteric liquid crystal layer (B-DLC) 13 for reflecting blue light>
A coating solution having the same composition as the composition for forming B-DLC layer 1 except that no surfactant was added was prepared, and a coating solution for forming a disc-shaped cholesteric liquid crystal layer (B-DLC) 13 for reflecting blue light was used. did. Similarly, a disc-shaped cholesteric liquid crystal (B-DLC) layer 13 for reflecting blue light is used on the surface of the λ / 4 layer QWP 13 to which no surfactant is added, using the prepared coating solution in the same manner as the B-DLC layer 1. (Example 13).

<Blue Light Reflecting Disc Cholesteric Liquid Crystal (B-DLC) Layer 14>
Instead of surfactants SF1 and SF5, a coating solution having the same composition as the composition for forming B-DLC layer 1 except that 0.15 parts by mass of surfactant SF9 is added is applied for forming B-DLC layer 14 A liquid was used.
Similarly, a disc-shaped cholesteric liquid crystal (B-DLC) layer 14 for reflecting blue light is applied to the surface of the λ / 4 layer QWP 14 in which the surfactant is SF9 in the same manner as the B-DLC layer 1 using the prepared coating liquid. Formed (Example 14).

<Blue Light Reflecting Disc Cholesteric Liquid Crystal (B-DLC) Layer 15>
Instead of surfactants SF1 and SF5, a coating solution having the same composition as the composition for forming B-DLC layer 1 except that 0.15 parts by mass of surfactant SF11 is added is applied for forming B-DLC layer 15 A liquid was used.
Similarly, a disc-shaped cholesteric liquid crystal (B-DLC) layer 15 for reflecting blue light is applied to the surface of the λ / 4 layer QWP 15 in which the surfactant is SF11 in the same manner as the B-DLC layer 1 using the prepared coating liquid. Formed (Example 15).

<Disc-shaped cholesteric liquid crystal layer (R-DLC) for reflecting red light>
The following composition was charged into a mixing tank and stirred to obtain a coating solution for a red light reflecting disc-shaped cholesteric liquid crystal layer (R-DLC). The prepared coating solution was continuously applied to the surface of the λ / 4 layer (QWP) 1 serving as a base with a wire bar so as to have a film thickness of 3.0 μm.
Subsequently, the solvent was dried at 70 ° C. for 2 minutes, and after evaporating the solvent, heat aging was performed at 107 ° C. for 2 minutes to obtain a uniform alignment state. Thereafter, this coating film is kept at 50 ° C., and irradiated with ultraviolet light (150 mJ / cm ² ) using a high-pressure mercury lamp in a nitrogen atmosphere to form a disc-shaped cholesteric liquid crystal (R-DLC) layer for reflecting red light. (Example 4). As a result of confirming the region where the transmittance was 60% or less from the light transmittance measured with Axometry manufactured by Axometric, it had a reflection band of 450 nm to 510 nm on the short wave side, and the center wavelength was 480 nm.

<Pitch gradient cholesteric liquid crystal (PG) layer>
The following composition was charged into a mixing tank and stirred to obtain a coating solution for a pitch gradient cholesteric liquid crystal (PG) layer. The prepared coating solution is formed on the disc-shaped cholesteric liquid crystal (B-DLC) layer for reflecting blue light (B-DLC) (1 (Example 3), 2 to 6 (Examples 8 to 12) so as to have a film thickness of 5.5 μm. The film was conveyed continuously (V) at 20 m / min, and heated for 120 seconds with hot air at 110 ° C. to dry the solvent of the coating solution and to mature the alignment of the rod-like liquid crystal compound. Subsequently, UV irradiation was performed at 100 ° C. with an irradiation amount of 20 mJ / cm ^2. Further, as alignment ripening, heating was performed with warm air at 80 ° C. for 120 seconds, followed by irradiation at 70 ° C. with an irradiation amount of 800 mJ / cm ² . UV irradiation was performed at cm ² to form a pitch gradient cholesteric liquid crystal (PG) layer.

<Pitch gradient cholesteric liquid crystal (PG) layer 1>
A coating solution having the same composition as that of the PG layer except that 3.00 parts by mass of polymerization initiator IN2 and 1.00 parts by mass of sensitizer IN6 were blended as a polymerization initiator was used as a coating solution for forming PG layer 1. The prepared coating solution was adjusted to a film thickness of 5.5 μm on the QWP layer 1 and continuously applied to form the PG layer 1 in the same manner as the PG layer (Example 5).

<Pitch gradient cholesteric liquid crystal (PG) layer 2>
A coating solution having the same composition as that of the PG layer was used as the coating solution for forming PG layer 2 except that the blending amount of the chiral agent CH1 was 4.5 parts by mass. The prepared coating solution was adjusted to a thickness of 5.5 μm on the red light reflecting disc-shaped cholesteric liquid crystal (R-DLC) layer, and continuously applied. Layer 2 was formed (Example 4).

<Evaluation>
(Haze evaluation)
The obtained optical film sample 40 mm × 80 mm was measured according to JISK-7136 (2000) using a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH. A or B is preferable, and A is more preferable.
Evaluation index A 1.0% or less
B More than 1.0% to 2.0% or less
C Over 2.0% to 3.0% or less
D> 3.0%

(Repel evaluation)
The obtained 1 m width of the optical film was inspected at a length of 3 m, and a failure that appeared to be circular or oval in a color different or missing was regarded as a repellency, and the repellency failure was visually confirmed.
Evaluation index A Quantity: 0
B Number: 1-3
C Number: 4-6
D Number of 7 or more

(Adhesion)
A cross-cut test (cross cut tape peeling test) based on JIS D0202-1988 was performed. Based on the number of squares peeled off by applying and removing cellophane tape (“CT24”, manufactured by Nichiban Co., Ltd.) out of 100 squares formed by grid-like cutting, the adhesion was evaluated according to the following criteria. did. A is preferred.
Evaluation index A Number of Hagaremas 30 or less
B Hagaremas 31 or more

(durability)
―Evaluation Method A―
Re (550) was measured at a wavelength of 550 nm using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.) in film form, and the measured film was placed in an 80 ° C. cellco for 500 hours. After leaving it to be taken out and adjusting the humidity for 24 hours in an environment of 25 ° C. and 60% RH, the retardation value of the same portion was measured again with an automatic birefringence meter. ΔRe (550) before and after heat treatment was calculated and classified according to the following indices.
The evaluation index is preferably A or B, and more preferably A.
Evaluation index A Δ0 nm or more to less than 5 nm
B Δ5 nm or more and less than 10 nm
C Δ10 nm to less than 15 nm
D Δ15nm or more

―Evaluation Method B―
In film form, the film was left in an 80 ° C. cellco for 500 hours, taken out, conditioned at 25 ° C. and 60% RH for 24 hours, and then light transmittance was measured with Axometry manufactured by Axometric. At this time, the change Δ after the heat treatment of the reflection band on the short wave side (450 nm) in the reflection band of 450 to 510 nm before the heat treatment was calculated. The evaluation index is preferably A or B, and more preferably A.
Evaluation index A More than Δ0nm to 2nm or less
B Δ2nm to 5nm or less
C Δ5 nm to 10 nm or less
D> 10nm

Table 8 shows the layer structure and evaluation results of each example.

In the embodiment in which the cholesteric liquid crystal layer is the fourth layer, in addition to the above effects, it was also found that the change in the reflection center wavelength can be controlled.
In Comparative Examples 3, 4 and 6, the film was left to stand in an 80 ° C. environment for 500 hours and then taken out, and the amount of change in the reflection center wavelength after adjusting for humidity for 24 hours in an environment of 25 ° C. and 60% RH was 10 nm. On the other hand, in the examples of the present invention in which the cholesteric liquid crystal layer was the fourth layer, all were less than 3 nm. They measure the transmission spectrum of each sample using a spectrophotometer (UV3150, manufactured by Shimadzu Corporation), and have two wavelengths that are the highest transmittance divided by the sum of the smallest transmittance and the baseline transmittance. Among them, the wavelength value on the short wave side is λ1 (nm) and the wavelength value on the long wave side is λ2 (nm).
Reflection center wavelength = (λ1 + λ2) / 2

DESCRIPTION OF SYMBOLS 1 Optical film 10 Laminated body 11 Support body 11a Base material 11b Orientation layer 12 Optical anisotropic layer 13 Upper layer

Table 4 illustrates suitable surfactants.

Claims (14)

It is formed by photopolymerizing a polymerizable composition containing a polymerizable liquid crystal compound and a compound that absorbs ultraviolet light and generates a photopolymerization active site of the polymerizable liquid crystal compound,
An optically anisotropic layer in which the polymerizable liquid crystal compound is fixed in a homeotropic alignment, homogeneous alignment, or cholesteric alignment;
And an upper layer laminated adjacently on the optically anisotropic layer,
The compound that generates the photopolymerization active site is at least two photopolymerization initiators having different wavelengths of ultraviolet light to be absorbed, or at least one photopolymerization initiator having different wavelengths of ultraviolet light to be absorbed and at least one kind of photopolymerization initiator. A laminate comprising a sensitizer.   2. The laminate according to claim 1, wherein among the compounds that generate the photopolymerization active sites, at least one of the compounds has a maximum absorption wavelength of the ultraviolet light of 300 nm or less, and at least one of the compounds has a maximum value of 320 nm or more.   3. The laminate according to claim 2, wherein, in the polymerizable composition, the content of the compound that generates the photopolymerization active site having the maximum value of 320 nm or more with respect to the polymerizable liquid crystal compound is 2 weight percent or less.   The laminate according to any one of claims 1 to 3, wherein the polymerizable liquid crystal compound is fixed in a state of cholesteric alignment in the optically anisotropic layer.   The laminate according to any one of claims 1 to 4, wherein the polymerizable liquid crystal compound is a discotic liquid crystal compound.   The laminate according to any one of claims 1 to 5, wherein the polymerizable liquid crystal compound is a rod-like liquid crystal compound.   The laminate according to any one of claims 1 to 6, further comprising the optically anisotropic layer adjacent to the optically anisotropic layer on the side opposite to the upper layer.   The laminate according to any one of claims 1 to 7, wherein the compound that generates the photopolymerization active site contains at least one photopolymerization initiator and at least one sensitizer having different wavelengths of ultraviolet light to be absorbed.   The laminate according to any one of claims 1 to 8, wherein the optically anisotropic layer includes a surfactant made of a fluorine-containing compound or a compound having a polysiloxane structure, and the molecular weight of the surfactant is 15000 or less. .   The laminate according to claim 9, wherein the surfactant comprises a fluorine-containing compound, and the optically anisotropic layer contains 0.001% by mass or more and less than 0.10% by mass of fluorine atoms.   The laminate according to claim 9 or 10, wherein the surfactant has a polyalkylene oxide group and / or a hydroxyl group.   The optical film containing a support body and the laminated body of any one of Claims 1-11 provided on this support body.   A support and a laminate according to any one of claims 9 to 11 provided on the support, wherein the surfactant is present on the surface of the optically anisotropic layer on the upper layer side An optical film.   The optical film according to claim 13, comprising a λ / 4 plate between the support and the optically anisotropic layer.