JP2017037151A - Manufacturing method of laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a laminate obtained by laminating a phase difference plate formed of a liquid crystal film and a transfer substrate, the laminate with a further reduced thickness.SOLUTION: According to the present invention, there is provided a manufacturing method of a laminate including the steps of: applying, on an alignment substrate, a liquid crystal composition including a liquid crystal compound and a dichromatic pigment to fix the liquid crystal compound in nematic hybrid alignment; polymerizing the polymerizable liquid crystal composition to fix the nematic hybrid alignment, and thereby forming a liquid crystal film; laminating a transfer substrate on the liquid crystal film to form a laminate with the alignment substrate; and peeling the alignment substrate from the laminate with the alignment substrate.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a method for producing a laminate suitably used for a polarizing plate as a retardation plate.

  The retardation plate is an optical element used to obtain polarized light (linearly polarized light, circularly polarized light, elliptically polarized light), color compensation of liquid crystal display devices, viewing angle improvement applications, and antireflection for organic electroluminescence (EL) display devices. It is used in many applications such as a film, and a reflective polarizing plate that reflects only one of the clockwise and counterclockwise circularly polarized light composed of cholesteric liquid crystal. As the phase difference plate, a plate obtained by thinly cutting an inorganic material (calcite, mica, crystal), a stretched film manufactured using a polymer compound having a high intrinsic birefringence, a liquid crystal film, or the like is used.

  As a typical retardation plate, there are a ¼ wavelength plate having a retardation corresponding to ¼ of a wavelength and a ½ wavelength plate having a retardation corresponding to ½ of a wavelength. The quarter wavelength plate has an optical function of converting linearly polarized light into circularly polarized light, and the half wavelength plate has a function of converting the polarization vibration plane of the linearly polarized light by 90 degrees.

  The retardation plate is usually designed so as to exhibit a necessary optical function with respect to light of a specific wavelength (monochromatic light). However, the above-described color compensation film for liquid crystal display device and organic EL display device Quarter-wave plates used in antireflection films for use convert linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light at a measurement wavelength (λ) of 400 to 780 nm, particularly 400 to 700 nm, in the visible light region. There is a need. In order to realize this with a single retardation plate, it is ideal that the phase difference becomes a quarter wavelength of the measurement wavelength, that is, λ / 4 (nm) at a measurement wavelength of 400 to 780 nm, particularly 400 to 700 nm. .

  In general, as the quarter-wave plate, the above-described retardation plate material or the like is used, but these materials have wavelength dispersion (wavelength dependence) in the retardation. Here, the dispersion characteristic in which the measurement wavelength is shorter and the longer wavelength is smaller is defined as “positive dispersion”, and the dispersion characteristic in which the measurement wavelength is smaller and becomes longer is defined as “negative dispersion”. FIG. 1 shows the wavelength dispersion characteristics of birefringence (Δn (λ)) in the visible light region normalized by setting the birefringence value (Δn (550 nm)) at a measurement wavelength of 550 nm to 1. In general, the birefringence of a polymer film has a “positive dispersion” characteristic in which the measurement wavelength increases as the wavelength decreases and decreases as the wavelength increases, as indicated by the solid line in FIG. On the other hand, the ideal quarter-wave plate described above has a “negative dispersion” characteristic in which the birefringence increases as the measurement wavelength increases, as indicated by the dotted line in FIG. Therefore, it is difficult to obtain an ideal “negative dispersion” characteristic at a measurement wavelength λ = 400 to 700 nm with a general polymer film alone, and it has a “positive dispersion” characteristic made of the polymer film. If the phase difference plate is used for white light in which light having a wavelength in the visible light range is mixed, a distribution of polarization states at each wavelength is generated, and colored polarized light is generated.

  Patent Documents 1 and 2 each disclose a retardation plate obtained by laminating two polymer films having optical anisotropy. The retardation plate described in Patent Document 1 includes a quarter-wave plate in which the phase difference of birefringent light is ¼ wavelength, and a ½ wavelength plate in which the phase difference of birefringent light is ½ wavelength. , And pasted together with their optical axes crossed. The phase difference plate described in Patent Document 2 is formed by laminating at least two phase difference plates having an optical phase difference value of 160 to 320 nm so that their slow axes are not parallel or orthogonal to each other. The retardation plate described in any of the publications requires two birefringent media.

  By adopting the methods described in the above publications, a quarter wavelength plate can be achieved in a wide wavelength region. However, in the manufacture of the phase difference plate described in each of Patent Document 1 and Patent Document 2, in order to adjust the optical orientation (optical axis and slow axis) of the two polymer films, a complicated manufacturing process is required. Need. Since the optical direction of the polymer film generally corresponds to the longitudinal direction or the lateral direction of the sheet or roll film, it is difficult to produce a polymer film having an optical axis or a slow axis in an oblique direction. And in invention of each gazette of patent document 1 and patent document 2, the optical direction of two polymer films is set to the angle which is neither parallel nor orthogonal. Therefore, in order to manufacture the retardation plate described in each of Patent Document 1 and Patent Document 2, it is necessary to cut two types of polymer films at a predetermined angle and bond the obtained chips together. When the retardation plate is manufactured by bonding the chips, the processing is complicated, the quality is likely to deteriorate due to axial misalignment, the yield is reduced, the cost is increased, and deterioration due to contamination is likely to occur. Further, the two polymer films disclosed in these documents are stretched films, and when this is used as a retardation plate for a laminated polarizing plate or a display device, the thickness may be too large.

  Patent Document 3 discloses a retardation film formed by uniaxially stretching a mixture or copolymer film of at least two kinds of organic polymers composed of an organic polymer having positive birefringence and an organic polymer having negative birefringence. Is a retardation plate having “negative dispersion” characteristics with a single film. The retardation film described in Patent Document 3 will be described with reference to a schematic diagram as shown in FIG. 2 and a graph of birefringence wavelength dispersion characteristics as shown in FIG. The extraordinary ray refractive index of an organic polymer having “positive birefringence” (rod-like molecule 1 in FIG. 2) is ne1 (refractive index in a direction parallel to the major axis direction of the rod-like molecule), and the ordinary ray refractive index is no1 (rod-like). Birefringence Δn1 (= ne1−no1)> 0, assuming that the refractive index in the direction perpendicular to the major axis direction of the molecule. Similarly, when an extraordinary ray refractive index of an organic polymer having “negative birefringence” (disc-like molecule 3 in FIG. 2) is ne2, and an ordinary ray refractive index is no2, birefringence Δn2 (= ne2−no2) <0. It becomes. Here, a combination of materials in which the birefringence Δn1 of the organic polymer having “positive birefringence” is larger than the birefringence Δn2 of the organic polymer having “negative birefringence” (when Δn1> Δn2) The total birefringence Δn is Δn1 + Δn2> 0, and the mixture is “positive birefringence”. Further, the wavelength dispersion characteristic D1 of the birefringence Δn1 of the organic polymer having “positive birefringence” is D1 = Δn1 (450) / Δn1 (650), and the birefringence of the organic polymer having “negative birefringence” Δn2 Is defined as D2 = Δn2 (450) / Δn2 (650) (where Δn1 (450) and Δn1 (650) are the birefringence of the polymer film at the measurement wavelengths of 450 nm and 650 nm, respectively) Δn2 (450) and Δn2 (650) are the birefringence of the polymer film at the measurement wavelengths of 450 nm and 650 nm, respectively). As shown in FIG. 3, the organic polymer having “negative birefringence” When the chromatic dispersion characteristic D2 of the organic polymer having “positive birefringence” is designed to be larger than that of the organic polymer (when D2> D1), the mixture may be “positive Retardation plate having a refractive "and" negative dispersion "characteristics.

  However, a retardation film formed by uniaxially stretching a polymer film has a very small birefringence Δn, so that it is necessary to increase the thickness to 50 to 200 μm in order to impart quarter-wave plate characteristics. . In recent years, thinning of liquid crystal display devices and organic EL display devices has been demanded, and improvement of retardation films having a small birefringence Δn is desired.

  Patent Document 4 discloses a liquid crystal film made of a rod-like liquid crystal compound as a retardation film which is a thin film and has a “negative dispersion” characteristic. The retardation plate described in Patent Document 4 is a homogeneous alignment of a liquid crystal composition containing a compound having two or more kinds of mesogenic groups and a rod-like liquid crystal compound, and at least one kind of mesogen group is in the optical axis direction of the rod-like liquid crystal compound. , Making use of orientation in a substantially orthogonal direction. The rod-like liquid crystal compound has a relatively large birefringence Δn compared to the copolymer resin, and therefore has a thickness of several μm, which is advantageous in terms of thinning.

However, the method of combining a compound composed of a positive birefringent material and a negative birefringent material having different birefringence wavelength dispersion characteristics described in Patent Document 3 and Patent Document 4 is a broadband with a measurement wavelength of 400 to 700 nm in the visible light region. In such a region, it is difficult to obtain a characteristic in which the phase difference becomes a quarter wavelength of the measurement wavelength. Generally, as shown in FIG. 4, the long wavelength side tends to deviate from the ideal straight line. This is because, as can be seen from the birefringence wavelength dispersion curve shown in FIG. 1, the slopes of the curve on the shorter wavelength side and the curve on the longer wavelength side than the center wavelength of visible light 550 nm are different. Therefore, in order to approximate the ideal chromatic dispersion curve in the wide-band region of the measurement wavelength 400 to 700 nm, which is the visible light region, the curve on the short wavelength side is maintained in a state close to the ideal straight line, while another method is used. An attempt to bring the wavelength curve closer to the ideal straight line is required.
In addition, the retardation plate described above achieves a quarter-wave plate in a wide wavelength region, so that near-ideal circularly polarized light can be obtained in the light incident from the normal direction of the circularly polarizing plate. The incident light from the light source is converted into elliptically polarized light, which may narrow the viewing angle in a liquid crystal display device or cause light leakage in an oblique direction in an antireflection application in an organic EL display device.

JP-A-10-68816 JP-A-5-027118 JP 2002-48919 A JP 2002-267838 A

  In the previous application (PCT / JP2014 / 069210), the inventors of the present invention mixed an organic polymer with at least one dichroic dye, thereby causing abnormalities in at least a part of the wavelength region of the visible light region. It was found that a novel phase difference plate having a refractive index ne of “negative dispersion” can be realized. In addition, by optimizing the birefringence wavelength dispersion characteristics of the polymerizable liquid crystal compound, the maximum absorption wavelength of the dichroic dye, and the amount of mixing, and by optimizing the film formation conditions, the birefringence Δn is reduced in the visible light region. It has been proposed that a novel retardation plate having “negative dispersion” characteristics can be realized in at least some wavelength regions.

  In producing a polarizing plate having a novel retardation plate having a “negative dispersion” characteristic, the present inventors now attach the alignment substrate after bonding the retardation plate formed on the alignment substrate to the transfer substrate. It was found that a polarizing plate with a thinner film can be realized by peeling. The present invention is based on this finding.

  Accordingly, an object of the present invention is to provide a method for producing a laminate having a thinner film in a laminate in which a retardation plate composed of a liquid crystal film having birefringence Δn having “negative dispersion” characteristics and a transfer substrate are laminated. It is to be.

That is, according to the present invention,
Applying a liquid crystal composition comprising a liquid crystal compound and a dichroic dye on an alignment substrate;
A step of nematic hybrid alignment of the liquid crystal compound;
Fixing the nematic hybrid alignment of the liquid crystal composition to form a liquid crystal film;
A step of bonding a transfer substrate on the liquid crystal film to form a laminate with an alignment substrate;
And a step of peeling the alignment substrate from the alignment substrate-attached laminate.

  In the production method according to the present invention, the nematic hybrid alignment is preferably immobilized by a crosslinking reaction by light or heat.

  In the production method according to the present invention, the birefringence Δn of the liquid crystal film preferably has a “negative dispersion” characteristic in at least a part of the wavelength region of the visible light region.

  In the production method according to the present invention, the transfer substrate is preferably a polarizing plate.

  In the production method according to the present invention, the maximum absorption wavelength of the dichroic dye is preferably in the wavelength region of 380 to 780 nm.

In the method according to the present invention, the retardation ratio in the normal direction of the phase difference plate at a specific wavelength is expressed by the following mathematical formulas (1) and (2):
1.00> Δn · d (500) / Δn · d (550)> 0.80 (1)
1.15> Δn · d (600) / Δn · d (550)> 1.00 (2)
(Here, retardation is represented by the product of birefringence Δn and film thickness d of the retardation plate, and Δn · d (500), Δn · d (550), and Δn · d (600) are respectively wavelengths) Retardation of retardation plate at 500 nm, 550 nm, and 600 nm)
It is preferable to satisfy.

  In the production method according to the present invention, the average tilt angle of the liquid crystal compound of the liquid crystal film is preferably 5 ° to 40 °.

  According to the present invention, a novel retardation plate having a “negative dispersion” characteristic in which the birefringence Δn becomes larger as the measurement wavelength is longer in at least a part of the wavelength region of the visible light region is combined with the transfer substrate to obtain a laminate. When manufacturing the film, a retardation film is once formed on the alignment substrate, and after bonding the transfer substrate to the transfer substrate, the alignment substrate is peeled off to obtain a laminate having a thinner film. The said laminated body can be used suitably for a polarizing plate as a phase difference plate.

  In addition, according to the present invention, the retardation plate constituting the laminate is made of a liquid crystal film with nematic hybrid alignment. Therefore, if a polarizing plate made of the laminate is used in a liquid crystal display device, brightness, contrast ratio, etc. are improved. When used in an organic EL display device, the contrast is greatly improved due to the high prevention performance against specular reflection.

It is a figure which shows the comparison with the wavelength dispersion of a general polymer film and ideal birefringence (DELTA) n. It is a figure which shows the polymer film 2 which consists of the organic polymer (rod-shaped molecule) 1 which has positive birefringence, and the organic polymer (disk-shaped molecule) 3 which has negative birefringence. It is a figure explaining that birefringence expresses a "negative dispersion" characteristic by the polymer film which consists of an organic polymer which has positive birefringence, and an organic polymer which has negative birefringence. It is a figure which shows the comparison with the phase difference plate which has a "negative dispersion | distribution" characteristic, and ideal birefringence wavelength dispersion. It is the schematic which shows one Embodiment of the manufacturing method of the laminated body of this invention. It is a figure which shows the comparison with the absorption spectrum of the long-axis direction (ne direction) and short-axis direction (no direction) of the dye molecule of a dichroic dye. It is a figure which shows the comparison with the wavelength dispersion of the extraordinary ray refractive index ne and the ordinary ray refractive index no before and after adding a dichroic dye to the organic polymer which has anisotropy. It is a figure which shows the comparison with the wavelength dispersion of birefringence (DELTA) n before and after adding a dichroic dye to the organic polymer which has anisotropy. It is a conceptual diagram of the orientation structure of the liquid crystal film by which nematic hybrid orientation was carried out. It is a conceptual diagram for demonstrating the tilt angle and twist angle of a liquid crystal compound. FIG. 4 is a diagram showing wavelength dispersion characteristics of birefringence Δn of the liquid crystal film in Example 1. It is a figure which shows the measurement result of the apparent retardation value measured by inclining the optical film in Example 1 along the orientation direction of a liquid crystal. 1 is a conceptual diagram of a cross-sectional structure of a laminated polarizing plate produced in Example 1. FIG. 10 is a conceptual diagram of a cross-sectional structure of a laminated polarizing plate produced in Example 9. FIG. It is a figure which shows the wavelength dispersion characteristic of the birefringence (DELTA) n of the liquid crystal film in the comparative example 1. It is a figure which shows the wavelength dispersion characteristic of birefringence (DELTA) n of the liquid crystal film in the comparative example 2. FIG. It is a figure which shows the wavelength dispersion characteristic of birefringence (DELTA) n of the PC film in the comparative example 5.

[Manufacturing method of laminate]
The manufacturing method of the laminated body by this invention is demonstrated. FIG. 5 is a schematic view showing each step of the method for manufacturing a laminate according to the present invention.
First, the liquid crystal composition 10 containing a liquid crystal compound and a dichroic dye is applied on the alignment substrate 20 (step 1), and the liquid crystal compound is aligned (step 2).
Next, the liquid crystal film 30 is formed by fixing the nematic hybrid alignment of the liquid crystal composition (step 3).
Thereafter, the transfer substrate 40 is bonded onto the liquid crystal film 30 to form a laminate with an alignment substrate (step 4). The liquid crystal film 30 and the transfer substrate 40 may be bonded via an adhesive or a pressure-sensitive adhesive 50 as described later.
Next, the alignment substrate 20 is peeled from the laminate with the alignment substrate (step 5).
By passing through such a process, the laminated body provided with the liquid crystal film which does not have an orientation substrate, and the transfer substrate can be manufactured. Hereinafter, each step will be described.

[Step 1: Application Step of Liquid Crystal Composition]
About the method of apply | coating a liquid-crystal composition on an orientation board | substrate, if it is a method which can ensure the uniformity of a coating film, it will not specifically limit and a well-known method is employable. For example, a coating liquid obtained by mixing a liquid crystal composition and a solvent can be applied using a spin coating method, a die coating method, a curtain coating method, a dip coating method, a roll coating method, or the like. The coating film formed by coating preferably has a thickness (wet film thickness) of the coating film before drying of 3 to 50 μm, and more preferably 5 to 20 μm. If the wet film thickness is 3 μm or more, it is possible to obtain a uniform liquid crystal film by suppressing the precipitation of solid components (liquid crystal compounds, etc.) in the polymerizable liquid crystal composition in order to obtain desired optical characteristics. By a simple application, a liquid crystal film having sufficient smoothness can be obtained. Moreover, if it is 20 micrometers or less, the drying time after application | coating can be shortened by making solid content in a liquid-crystal composition for setting it as a desired optical characteristic into a comparatively high density | concentration.

<Liquid crystal composition>
The liquid crystal composition applied on the alignment substrate is not particularly limited as long as it contains a liquid crystal compound and a dichroic dye and can fix the nematic hybrid alignment state. In order to fix the nematic hybrid alignment state, the liquid crystal composition in the present invention may contain a polymerizable liquid crystal compound, and contains a mixture of a non-polymerizable liquid crystal compound and a polymerizable compound that does not exhibit liquid crystallinity. And may include a mixture of a polymerizable group liquid crystal compound and a polymerizable compound that does not exhibit liquid crystallinity, or may include a mixture of a polymerizable group compound and a non-polymerizable liquid crystal compound. . The liquid crystal composition may contain a polymerization initiator in order to facilitate the fixing of the alignment state.

<Liquid crystal compound>
In the present invention, a liquid crystal compound having a known polymerizable group can be appropriately used as the liquid crystal compound. As the polymerizable liquid crystal compound, it is preferable to use a polymerizable liquid crystal compound that can be nematic-hybrid aligned on an alignment substrate to fix the alignment state. Furthermore, as the polymerizable liquid crystal compound, for example, a low molecular weight polymerizable liquid crystal compound, a high molecular weight polymerizable liquid crystal compound, and a mixture thereof can be appropriately used.

  The polymerizable liquid crystal compound is preferably a liquid crystal compound having a polymerizable group that reacts with light and / or heat from the viewpoint that the alignment state can be efficiently fixed. The polymerizable group is preferably a vinyl group, a (meth) acryloyl group, a vinyloxy group, an oxiranyl group, an oxetanyl group, an aziridinyl group, or the like. As such a polymerizable group, other polymerizable groups such as an isocyanate group, a hydroxyl group, an amino group, an acid anhydride group, and a carboxyl group may be used depending on the reaction conditions. The polymerizable liquid crystal compound is preferably a (meth) acrylate-based liquid crystal compound having a (meth) acryloyl group as a polymerizable group from the viewpoints of availability, heat resistance, and ease of handling.

  In the present invention, the retardation Δn · d of the liquid crystal film preferably satisfies the above formulas (1) and (2). In particular, as a method of satisfying the above formula (1), two polymerizable liquid crystal compounds are used. A compound having more than one kind of mesogenic group, and by aligning at least one mesogenic group in a direction substantially orthogonal to the slow axis of the parallel (homogeneous) alignment of the liquid crystal layer, the phase difference increases as the wavelength increases. This is described in Japanese Patent Application Laid-Open Nos. 2002-267838 and 2010-31223. Here, the mesogen of the mesogen group is also called an intermediate phase (liquid crystal phase) forming molecule (“Liquid Crystal Dictionary”, Japan Society for the Promotion of Science, 142nd Committee on Organic Materials for Information Science, Liquid Crystal Division, 1989) Year), which is almost synonymous with liquid crystal molecular structure.

  Examples of mesogenic groups include biphenyl, phenylcyclohexyl, cyclohexylphenyl, phenyloxycarbonylphenyl, phenylcarbonyloxyphenyl, phenyloxycarbonylcyclohexyl, cyclohexylcarbonyloxyphenyl, phenylcarbonyloxyphenyloxycarbonylphenyl, phenylcarbonyloxyphenyloxycarbonylphenyl , Phenylcarbonyloxycyclohexyloxycarbonylphenyl, phenyloxycarbonylcyclohexylcarbonyloxyphenyl, phenylcarbonyloxyphenylaminocarbonylphenyl, phenylethenylenephenyl, phenylethynylenephenyl, phenylethynylenephenylethynylenephenyl, phenylethenylenecarbonyloxy Include phenyl and phenyl et tennis alkyleneoxy phenyl ethynylenes phenyl.

  The mesogenic group (a benzene ring or a cyclohexane ring constituting the mesogenic group) may have a substituent. As the substituent, the polymerizable group described above or a derivative thereof is preferable. As a combination of two kinds of mesogenic groups, one mesogenic group is biphenyl, phenylcyclohexyl, cyclohexylphenyl, phenyloxycarbonylphenyl, phenylcarbonyloxyphenyl, phenyloxycarbonylcyclohexyl, cyclohexylcarbonyloxyphenyl, phenylcarbonyloxyphenyloxycarbonyl. Selected from the group consisting of phenyl, phenylcarbonyloxyphenyloxycarbonylphenyl, phenylcarbonyloxycyclohexyloxycarbonylphenyl, phenyloxycarbonylcyclohexylcarbonyloxyphenyl and phenylcarbonyloxyphenylaminocarbonylphenyl, the other mesogenic group is phenylethenylenephenyl Phenylethynylenepheny , Phenyl ethynylene phenyl ethynylene phenyl, particularly preferably selected from the group consisting of phenyl et tennis alkylene carbonyloxy biphenyl and phenyl et tennis alkyleneoxy phenyl ethynylenes phenyl.

Specific examples of the compound having two or more kinds of mesogenic groups include the following compounds.

In order to induce twisted nematic alignment of the liquid crystal compound, a chiral agent is added to the liquid crystal composition, or a liquid crystal compound or a non-liquid crystal compound having at least one chiral structural unit is added to the liquid crystal composition. It is particularly desirable to blend.
Examples of the chiral structural unit include optically active 2-methyl-1,4-butanediol, 2,4-pentanediol, 1,2-propanediol, 2-chloro-1,4-butanediol, and 2-fluoro. -1,4-butanediol, 2-bromo-1,4-butanediol, 2-ethyl-1,4-butanediol, 2-propyl-1,4-butanediol, 3-methylhexanediol, 3-methyl Units derived from adipic acid, naproxen derivatives, camphoric acid, binaphthol, menthol or cholesteryl group-containing structural units or derivatives thereof (for example, derivatives such as diacetoxy compounds) can be used. The diols may be either R-form or S-form, and may be a mixture of R-form and S-form. These structural units are merely examples, and the present invention is not limited thereto. Moreover, even if it is an oligomer and a low molecular liquid crystal, what can be polymerized by means, such as thermal bridge | crosslinking or photocrosslinking, by introduce | transducing a crosslinkable group or mixing a crosslinking agent suitably is also contained in a liquid crystal polymer.

  Moreover, you may utilize a commercial item as said polymeric liquid crystal compound. Furthermore, the polymerizable liquid crystal compound may be used alone or in a mixture of two or more. When two or more polymerizable liquid crystal compounds are combined, it is not necessary for all the liquid crystal compounds to exhibit liquid crystallinity, and the mixture only needs to exhibit liquid crystallinity. For example, a compound having two or more kinds of mesogenic groups may not exhibit liquid crystal properties per se, but a mixture with other liquid crystal compounds may exhibit liquid crystal properties. Furthermore, it is not necessary for all the liquid crystal compounds to have a polymerizable functional group, and it is sufficient that at least one liquid crystal compound has a polymerizable functional group.

  As described above, the polymerizable liquid crystal composition may contain another polymerizable compound that does not exhibit liquid crystallinity. The polymerizable compound is not particularly limited as long as it is compatible with the polymerizable liquid crystal compound and does not cause significant alignment inhibition in the liquid crystal compound. Examples of the polymerizable compound include compounds such as ethylenically unsaturated groups (for example, vinyl group, vinyloxy group, (meth) acryloyl group). The addition amount of the polymerizable compound is preferably 0.5 to 50% by weight, and preferably 1 to 30% by weight, based on the total amount of the polymerizable liquid crystal compound and other polymerizable compounds. Further, the number of polymerizable functional groups of the polymerizable compound is preferably 2 or more from the viewpoint of sufficiently increasing the polymerization rate and imparting sufficient heat resistance to the obtained liquid crystal film.

<Dichroic dye>
A dichroic dye refers to a dye having the property that the absorbance in the major axis direction of a molecule is different from the absorbance in the minor axis direction. The dichroic dye is not particularly limited as long as it has such properties, and may be a dye or a pigment. A plurality of these dyes may be used, a plurality of pigments may be used, or a dye and a pigment may be combined. Furthermore, the dichroic dye may have a polymerizable functional group or may have liquid crystallinity. As the polymerizable functional group, an acrylic group, a methacryl group, a vinyl group, a vinyloxy group, an epoxy group, and an oxetanyl group are preferable, and an acrylic group, an epoxy group, and an oxetanyl group are particularly preferable from the viewpoint of reactivity. As for the liquid crystallinity, those having a nematic phase and a smectic phase are preferable.

  The dichroic dye preferably has a maximum absorption wavelength (λmax) in the range of 380 to 780 nm, more preferably 400 to 750 nm, further preferably 450 to 700 nm, and 540 to 620 nm. Is most preferred. When the laminated polarizing plate obtained by the method of the present invention is applied to a display device such as an image display device, it is preferable to select the maximum absorption wavelength in consideration of the emission spectrum of the light source of the display device.

  When the organic EL display device emits red, blue, and green three colors simultaneously and displays three colors in white, the blue wavelength is about 460 nm, the green wavelength is about 530 nm, and the red wavelength is about 630 nm. have. When the laminated polarizing plate obtained by the method of the present invention is applied to this organic EL display device, light absorption by the dichroic dye is inevitable, but in order to minimize the decrease in transmittance due to this light absorption. It is preferable to select a dichroic dye having a maximum absorption wavelength at a wavelength that deviates from the maximum absorption wavelength of the emission spectrum of these three colors. For example, two colors having a maximum absorption wavelength near 580 nm as shown in FIG. Sex dyes can be applied. The selection criteria for the dichroic dye are the same for other image display devices. For example, in a liquid crystal display device, when an LED is used as a light source, a decrease in transmittance can be suppressed by selecting a dichroic dye having a maximum absorption wavelength that deviates from the maximum value of the emission spectrum of the LED. The difference between the maximum absorption wavelength of the dichroic dye and the maximum wavelength of the emission spectrum of the display device light source is 5 nm or more, preferably 10 nm or more, more preferably 20 nm or more. If it is 5 nm or more, a rate fall can be suppressed.

  The dichroic ratio of the dichroic dye is defined by the ratio of the absorbance at the maximum absorption wavelength in the major axis direction of the dye molecule to the absorbance in the minor axis direction. The absorbance in the orientation direction of the dichroic dye and the direction perpendicular to the orientation direction It can be determined by measuring the absorbance. The dichroic ratio of the dichroic dye is preferably 2 or more and 50 or less, more preferably 5 or more and 30 or less.

  Dichroic dyes include, for example, acridine dyes, azine dyes, azomethine dyes, oxazine dyes, cyanine dyes, merocyanine dyes, squarylium dyes, naphthalene dyes, azo dyes, anthraquinone dyes, benzotriazole dyes, benzophenone dyes, pyrazoline dyes, diphenylpolyenes Examples thereof include dyes, binaphthyl polyene dyes, stilbene dyes, benzothiazole dyes, thienothiazole dyes, benzimidazole dyes, coumarin dyes, nitrodiphenylamine dyes, polymethine dyes, naphthoquinone dyes, perylene dyes, quinophthalone dyes, stilbene dyes, and indigo dyes. Of these, anthraquinone dyes and azo dyes are preferable. Examples of the azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, and preferred examples include bisazo dyes, trisazo dyes, and derivatives of these series of dyes.

The dichroic dye is particularly preferably one represented by the following formula (1) (hereinafter sometimes referred to as “azo dye (1)”).

In formula (1), n is an integer of 1 to 4. Ar ₁ and Ar ₃ are each independently selected from the groups shown below.

Ar ₂ is selected from the following groups, and when n in the formula (1) is 2 or more, Ar ₂ may be the same as or different from each other.

A ₁ and A ₂ are each independently selected from the groups shown below.
(M is an integer of 0 to 10, and when there are two m's in the same group, these two m's may be the same or different from each other.)

The positional isomerism of the azobenzene moiety of the azo dye (1) is preferably trans.
Examples of the azo dye (1) include compounds represented by formulas (1-1) to (1-36).

As the anthraquinone dye, a compound represented by the formula (1-37) is preferable.

In formula (1-37), R ^{1 to} R ⁸ each independently represent a hydrogen atom, —Rx, —NH ₂ , —NHRx, —NRx ₂ , —SRx, —OH, or a halogen atom. Rx represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

As the acridine dye, a compound represented by the formula (1-38) is preferable.

In formula (1-38), R ^{16 to} R ²³ each independently represent a hydrogen atom, —Rx, —NH ₂ , —NHRx, —NRx ₂ , —SRx, or a halogen atom. Rx represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

As the oxazone dye, a compound represented by the formula (1-39) is preferable.

In formula (1-39), R ^{9 to} R ¹⁵ each independently represent a hydrogen atom, —Rx, —NH ₂ , —NHRx, —NRx ₂ , —SRx, —OH or a halogen atom. Rx represents an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

  In the above formula (1-37), formula (1-38) and formula (1-39), the alkyl group having 1 to 6 carbon atoms of Rx is a methyl group, an ethyl group, a propyl group, a butyl group, or pentyl. A aryl group having 6 to 12 carbon atoms, such as a phenyl group, a toluyl group, a xylyl group, and a naphthyl group.

As the cyanine dye, a compound represented by the formula (1-40) and a compound represented by the formula (1-41) are preferable.

In formula (1-40), D ¹ and D ² each independently represent a group represented by any of the following formulas (1-40a) to (1-40d), and n5 is from 1 to 3 Represents an integer.

In Formula (1-41), D ³ and D ⁴ each independently represent a group represented by any of Formula (1-41a) to Formula (1-41h), and n6 is an integer of 1 to 3. Represents.

  As mentioned above, although the preferable example was demonstrated about the dichroic pigment | dye which a liquid crystal film contains, it is preferable that it is an azo pigment | dye (1), and two or more types of azo pigment | dye (1) which has mutually different maximum absorption wavelengths are mentioned. You may contain.

  The content of the dichroic dye in the liquid crystal film can be appropriately adjusted according to the type and the like. For example, the content is preferably 0.1 parts by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the polymerizable liquid crystal composition. More preferably, it is 1 to 20 parts by weight, more preferably 0.1 to 10 parts by weight. If the content of the dichroic dye is within this range, the liquid crystal composition can be formed or polymerized without disturbing the alignment of the liquid crystal compound. Moreover, if content of a dichroic pigment | dye is 50 weight part or less, the fall of the transmittance | permeability of the liquid crystal film by absorption of a pigment | dye can be suppressed. If the content of the dichroic dye is 0.1 parts by weight or more, the refractive index can be controlled and sufficient optical characteristics can be obtained. In addition, when using 2 or more types of dichroic dyes, content of a dichroic dye is content of the sum total of the dichroic dye used.

<Solvent>
The solvent is not particularly limited as long as it can dissolve the liquid crystal compound and the dichroic dye and can be distilled off under appropriate conditions. For example, from the viewpoint of drying speed suitable for applying the solution so as to obtain a uniform film thickness, ease of handling (harmful to the environment), and solubility in liquid crystal compounds and dichroic dyes, propylene glycol 1- Monomethyl ether 2-acetate, 2-methoxyethyl acetate, toluene, xylen, methoxybenzene, 1,2-methoxybenzene, cyclohexanone, cyclopentanone, methyl cellosolve, ethyl cellosolve, butyl cellosolve, γ-butyrolactone are preferred, and propylene glycol 1- Monomethyl ether 2-acetate and γ-butyrolactone are more preferable. The above solvents may be used singly or in combination of two or more. In addition, since the alignment substrate may corrode depending on the type of the solvent, it is preferable to select and use a suitable solvent according to the type of the alignment substrate.

  The content of the solvent can be appropriately adjusted depending on the method of using the composition (for example, when it is used for forming a liquid crystal film, the method of use including the design of the thickness and the coating method). For example, the content of the solvent in the coating liquid is preferably 30 to 98% by weight, more preferably 50 to 95% by weight, and still more preferably 70 to 90% by weight. If the content of the solvent is 30% by weight or more, the amount of the solvent with respect to the mixture of the liquid crystal compound and the dichroic dye is secured, so that the precipitation of the liquid crystal compound during storage is suppressed or the viscosity of the mixture is increased. Therefore, it is possible to prevent the wettability from being lowered and to satisfactorily perform coating during the production of the liquid crystal film. Further, if the content of the solvent is 95% by weight or less, when removing the solvent, the removal time (drying time) is completed in a short time, so that a reduction in work efficiency when producing a liquid crystal film is suppressed, Since the fluidity of the surface when the mixture is coated on the alignment substrate can be suppressed, a uniform retardation plate can be produced. In the mixture, the amount of the mixture of components other than the solvent is preferably 5 to 70% by weight, more preferably 10 to 50% by weight, and still more preferably 10 to 30% by weight. In order to form a uniform coating film on the alignment substrate, a reaction activator, a sensitizer, a surfactant, a dispersant, an antifoaming agent, a leveling agent, and the like may be added to the solution.

<Oriented substrate>
The alignment substrate preferably has a smooth surface, and examples thereof include a film or sheet made of an organic polymer material, a glass plate, and a metal plate. From the viewpoint of cost and continuous productivity, it is preferable to use an organic polymer material. Examples of organic polymer materials include polyvinyl alcohol (PVA), polyimide, polyamide, polyamideimide, polyphenylene sulfide, polyether sulfone, polyphenylene oxide, polyether ketone, polyether ether ketone, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polysulfone, cyclopolyolefin having a cyclic or norbornene structure, diacetyl cellulose, triacetyl cellulose (TAC), cellulose acetate, cellulose propionate, cellulose butyrate, epoxy resin, phenol resin and the like.

  If the alignment substrate has insufficient alignment ability or does not exhibit alignment ability, stretching, rubbing, application of a photo-alignment film, oblique deposition of silicon oxide, etc., or a combination of these means as appropriate Orientation ability may be expressed.

[Step 2: Step of aligning liquid crystal compound]
Next, the coating film is dried, and the liquid crystal compound is aligned by heating as desired. Here, the orientation of the liquid crystal compound indicates a state in which the molecular chains of the liquid crystal compound are aligned in a specific direction, and the retardation (Δn · d: product of birefringence Δn and film thickness d) is measured. I can confirm. The alignment state refers to a state where the retardation is 20 nm or more at a measurement wavelength of 550 nm.

  The conditions for the drying process vary depending on the type of liquid crystal compound and dichroic dye contained in the liquid crystal composition, the type of solvent used, and the like, and cannot be generally described, and are not particularly limited. For example, depending on the type of solvent, the solvent can be removed from the coating film even at room temperature (25 ° C.). Thus, depending on the type of the solvent, it is possible to produce a liquid crystal film in which the liquid crystal compound is nematic-hybrid aligned without particularly performing a heat treatment for aligning the liquid crystal compound. Moreover, it is preferable that it is 15-110 degreeC, and, as for the temperature in a solvent removal process, it is more preferable that it is 20-80 degreeC. If it is in the said numerical range, while not requiring cooling equipment, while being able to manufacture efficiently, it can suppress that an alignment substrate changes an optical characteristic etc. with a heat | fever.

  Moreover, it does not restrict | limit especially as pressure conditions in this drying process, However, It is preferable that it is 600-1400 hPa, and it is more preferable that it is 900-1100 hPa. When the pressure condition is 600 hPa or more, the solvent is slowly dried, and it is possible to suppress the occurrence of drying unevenness. If the pressure condition is 1400 hPa or less, the time required for drying the solvent can be reduced. Although it does not restrict | limit especially as time (drying time) of a solvent removal process, It is preferable to set it as 10 second-60 minutes, and it is more preferable to set it as 1 minute-30 minutes. If the drying time is 10 seconds or more, the drying of the solvent is slow, so that the smoothness of the liquid crystal film can be maintained. Moreover, if it is 60 minutes or less, a manufacturing speed is quick and sufficient productivity can be maintained. In addition, when utilizing a drying apparatus in a drying process, it is preferable to control the relative moving speed of a coating film and a drying apparatus so that a relative wind speed may be 60 m / min-1200 m / min. The drying apparatus is not particularly limited as long as the uniformity of the coating film is maintained, and a known method can be adopted. For example, devices such as a heater (furnace) and a hot air furnace can be mentioned.

  The film thickness in the dry state is 0.1 μm to 50 μm, preferably 0.2 μm to 20 μm. When the film thickness is within the above numerical range, the optical performance of the obtained liquid crystal film can be sufficiently exhibited, and the liquid crystal compound and the dichroic dye can be sufficiently oriented.

  By the drying and / or heat treatment described above, the liquid crystal compound and the dichroic dye are nematic hybrid aligned. The orientation refers to, for example, Δn · d of 20 nm or more at a measurement wavelength of 550 nm. Δn · d is the product of birefringence Δn and film thickness d when a retardation plate is used.

[Step 3: Alignment fixing step of liquid crystal compound]
As a method for fixing the alignment state of the liquid crystal compound, a known method can be appropriately employed depending on the type of the polymerizable compound such as the polymerizable liquid crystal compound and the polymerizable non-liquid crystal compound used, the kind of the polymerization initiator, and the like. . As a method for fixing the alignment state, for example, a method of fixing a nematic hybrid alignment by polymerizing a polymerizable compound by performing light irradiation and / or heat treatment may be employed.

  In this specification, the state of “fixing the nematic hybrid alignment” means that the liquid crystal film obtained after fixing the alignment of the liquid crystal compound is nematic hybrid alignment (the director of the liquid crystal molecules is from the film thickness direction of the film). The state in which the alignment aligned at different angles is confirmed (preferably at every place) is observed, and a component derived from a liquid crystal compound or the like (a component derived from a polymerizable liquid crystal compound, such as a polymerizable liquid crystal compound itself, Any one of the compound formed by decomposition of the polymerizable liquid crystal compound, the polymer of the polymerizable liquid crystal compound, etc.) may be fixed in a nematic hybrid alignment state.

<Polymerization initiator>
The polymerization initiator is not particularly limited, and a known polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator can be appropriately used.

  As the photopolymerization initiator, a commercially available product may be used. For example, a photopolymerization initiator manufactured by Ciba-Geigy (trade name “Irgacure 907”, trade name “Irgacure 651”, trade name “Irgacure 184”) Alternatively, a photopolymerization initiator (trade name “UVI6974”) manufactured by Union Carbide may be used as appropriate. Photopolymerization initiators include those that generate free radicals and those that generate ions upon irradiation with light or an electron beam, but the type of polymerizable liquid crystal compound in the composition, conditions for the polymerization reaction, etc. The photopolymerization initiator that generates free radicals (for example, trade name “Irgacure 651” manufactured by Ciba-Geigy) or the like, or the photopolymerization initiator that generates ions (for example, photopolymerization manufactured by Union Carbide). What is necessary is just to select suitably and use suitably among initiators (brand name "UVI6974").

The method for developing the function of the photopolymerization initiator is not particularly limited. For example, a light source having a spectrum in the absorption wavelength region of the photopolymerization initiator to be used (for example, a metal halide lamp having an illuminance of 10 mW / cm ² or more. And a method of irradiating light from a light source using an intermediate pressure or high pressure mercury lamp (medium pressure or high pressure mercury ultraviolet lamp), an ultrahigh pressure mercury lamp, a low pressure mercury lamp, a xenon lamp, an arc lamp, a laser, or the like. A polymerizable group can be reacted efficiently by light irradiation.

The integrated irradiation dose of light in the light irradiation, the integrated exposure amount at wavelength 365nm is preferably from 10 to 2000 mJ / cm ^2, more preferably 100~1500mJ / cm ^2. However, this is not the case when the absorption region of the polymerization initiator and the spectrum of the light source are significantly different, or when the polymerizable liquid crystal compound itself has the ability to absorb light of the light source wavelength. In these cases, from the viewpoint of fixing the coating film while maintaining the orientation state more efficiently, a suitable photosensitizer or two or more polymerization initiators having different absorption wavelengths are mixed and used. Etc. may be adopted. The temperature condition of the light irradiation is not particularly limited as long as the liquid crystal compound can maintain a nematic hybrid alignment. In addition, a cold mirror or other cooling device may be provided between the substrate and the light source (ultraviolet lamp or the like) so that the temperature of the liquid crystal state can be maintained.

  The atmospheric conditions at the time of light irradiation are not particularly limited, and may be an air atmosphere, or may be an oxygen-blocked atmosphere in order to increase reaction efficiency. Since the oxygen concentration in the atmosphere is related to the degree of polymerization, when the desired degree of polymerization is not reached in the air, it is preferable to perform light irradiation in an atmosphere in which the oxygen concentration is reduced by a method such as nitrogen substitution. In such a case, the oxygen concentration is preferably 10% by volume or less, more preferably 7% by volume or less, and most preferably 3% by volume or less.

  When the polymerization initiator exhibits a function as an initiator by heat, it is preferable to fix the nematic hybrid alignment by heat treatment. The conditions for the heat treatment are not particularly limited, and temperature conditions may be selected so that the orientation state is sufficiently maintained according to the type, and known conditions can be appropriately employed.

  As content of a polymerization initiator, it is preferable that it is 1-10 weight part with respect to 100 weight part of liquid crystal compositions, and it is more preferable that it is 3-5 weight part. If content of a polymerization initiator is in the said numerical range, it can suppress that the obtained liquid crystal film fully hardens | cures and produces a defect in the orientation of a liquid crystal.

  The liquid crystal film manufactured on the alignment substrate by the above alignment process is a sufficiently strong film. Specifically, the mesogen is three-dimensionally immobilized by the polymerization reaction, and not only the heat resistance is improved as compared with that before the polymerization, but also the mechanical strength such as scratch resistance, abrasion resistance, crack resistance, etc. Greatly improved.

  The thickness of the liquid crystal film is preferably 0.1 to 10 μm, more preferably 0.2 to 5 μm, although it varies depending on the application and required characteristics. If the thickness of the liquid crystal film is 0.1 μm or more, a desired phase difference can be expressed, and if it is 10 μm or less, a decrease in the orientation of the liquid crystal compound or a decrease in transmittance due to the dye can be suppressed. it can.

  Although birefringence (DELTA) n of a liquid crystal film changes also with a use or the characteristic calculated | required, 0.005-0.5 are preferable and 0.01-0.3 are further more preferable. If birefringence (DELTA) n is said range, since a film thickness can be 10 micrometers or less when a liquid crystal film is made into desired retardation, it can use suitably as a phase difference plate and a polarizing plate.

In addition, the liquid crystal film according to the present invention preferably has a “negative dispersion” characteristic in which the birefringence Δn becomes larger as the measurement wavelength is longer in at least a part of the wavelength region of the visible light region. Specifically, when the retardation of the liquid crystal film at 500 nm, 550 nm, and 600 nm is Δn · d (500), Δn · d (550), and Δn · d (600),
1.00> Δn · d (500) / Δn · d (550)> 0.80 (1)
And 1.15> Δn · d (600) / Δn · d (550)> 1.00 (2)
Preferably satisfying
0.98> Δn · d (500) / Δn · d (550)> 0.90 (1-1)
And 1.10> Δn · d (600) / Δn · d (550)> 1.02 (2-1)
It is more preferable to satisfy. When the mathematical formula is not satisfied, when linearly polarized light of 400 to 700 nm is incident on this liquid crystal film, a perfect circularly polarized light can be obtained at a specific wavelength, but a circularly polarized light cannot be obtained at other wavelengths. sell.

In the present invention, the retardation at a predetermined wavelength in the normal direction of the liquid crystal film is Δna · da, and the retardation at the predetermined wavelength in the normal direction of the liquid crystal film excluding the dichroic dye is Δnb · db. In this case, it is preferable to satisfy the following formula (3).
Δna · da (580) / Δna · da (550) −Δnb · db (580) / Δnb · db (550)> 0 (3)
(Δna · da (580) and Δna · da (580) are retardations of each liquid crystal film at a wavelength of 580 nm, and Δna · da (550) and Δna · da (550) are retardations of each liquid crystal film at a wavelength of 550 nm. Retardation.)

  The liquid crystal film is required to have a specific Δna · da (550) as well as a film thickness depending on its use. Δna · da (550) is preferably 20 nm to 500 nm, and more preferably 50 nm to 300 nm.

  As a method for confirming the nematic hybrid alignment in the liquid crystal film, the following method may be employed. For example, a liquid crystal film (a state of a laminate with a substrate) between a pair of orthogonal polarizing plates (a pair of polarizing plates bonded so that the deflection direction of one deflection plate and the deflection direction of the other deflection plate are orthogonal) Alternatively, a method of confirming the transmitted light of the sample on which the sample on which the sample is disposed with the naked eye or a method of confirming using a polarizing microscope may be employed. When checking with the naked eye, place the sample on the backlight when viewed from the front, adjust the sample angle so that the transmitted light intensity from the backlight is the weakest, and tilt the slow axis as the axis. It is possible to confirm the presence or absence of nematic hybrid alignment by confirming that the transmitted light intensity becomes strong when observed from above and that the transmitted light intensity remains weak when observed obliquely with the fast axis as the axis. it can. In addition, since the nematic hybrid alignment liquid crystal film has different retardation characteristics depending on the incident angle of light, the retardation in the vertical direction with respect to the surface of the liquid crystal film and the incident angle of light from the vertical direction to a specific angle are set. Using a birefringence measuring apparatus capable of measuring the retardation when tilted (for example, trade name “Axoscan” manufactured by Axo-metrix, trade name “KOBRA-21ADH” manufactured by Oji Scientific Instruments, etc.) The phase difference is measured while appropriately changing the angle from a viewing angle of 0 degrees (perpendicular to the liquid crystal film) to a direction in which the viewing angle becomes larger, and the retardation of the sample is obtained for each of the viewing angles. Retardation is confirmed in the direction perpendicular to the film surface, and the viewing angle is further increased. Deshon is, the viewing angle - the value of the direction and the + direction to exhibit asymmetry, by checking the may be adopted a method of confirming the presence or absence of a nematic hybrid orientation.

<Polymerization initiator>
The polymerization initiator used as desired is not particularly limited, and a known polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator can be appropriately used.

  As the photopolymerization initiator, a commercially available product may be used. For example, a photopolymerization initiator manufactured by Ciba-Geigy (trade name “Irgacure 907”, trade name “Irgacure 651”, trade name “Irgacure 184”) Alternatively, a photopolymerization initiator (trade name “UVI6974”) manufactured by Union Carbide may be used as appropriate. Photopolymerization initiators include those that generate free radicals and those that generate ions upon irradiation with light or an electron beam, but the type of polymerizable liquid crystal compound in the composition, conditions for the polymerization reaction, etc. The photopolymerization initiator that generates free radicals (for example, trade name “Irgacure 651” manufactured by Ciba-Geigy) or the like, or the photopolymerization initiator that generates ions (for example, photopolymerization manufactured by Union Carbide). What is necessary is just to select suitably and use suitably among initiators (brand name "UVI6974").

  Moreover, as content of the polymerization initiator in a polymeric liquid crystal composition, it is preferable that it is 1-10 weight part with respect to 100 weight part of polymeric liquid crystal compositions, and it is more preferable that it is 3-5 weight part. . If content of a polymerization initiator is in the said numerical range, sclerosis | hardenability of the obtained liquid crystal film is enough, and it can suppress producing a defect in the orientation of a liquid crystal.

[Step 4: Transfer substrate bonding step]
A transfer substrate is bonded onto the liquid crystal film formed in the above step to form a laminate with an alignment substrate. The transfer substrate preferably comprises a polarizer, more preferably a linear polarizer. The angle formed by the absorption axis of the polarizer and the slow axis of the liquid crystal film is preferably 40 to 50 degrees, more preferably 42 to 48 degrees, and still more preferably about 45 degrees. If it is in the said range, when the laminated body obtained by the method of this invention is used for an organic electroluminescent display apparatus, sufficient antireflection effect will be acquired. When the liquid crystal film is in a twisted nematic hybrid alignment state, it is necessary to change the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal film depending on the twist angle. difficult.

  In addition, the liquid crystal film and the transfer substrate can be bonded by laminating with an adhesive or an adhesive. In the present specification, the “pressure-sensitive adhesive” refers to a material that exhibits peel resistance without solidifying, and the “adhesive” refers to a material that solidifies and exhibits peel resistance. The adhesive is not particularly limited as long as it is optically isotropic and transparent, and commercially available products such as an acrylic adhesive, an epoxy adhesive, and a urethane adhesive can be used. The pressure-sensitive adhesive is not particularly limited. For example, acrylic pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive, polyurethane-based pressure-sensitive adhesive, polyamide-based pressure-sensitive adhesive, polyether-based pressure-sensitive adhesive, fluorine-based or rubber-based pressure-sensitive adhesive, etc. A base adhesive can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive that is excellent in transparency, exhibits appropriate wettability, cohesiveness, and adhesiveness, and is excellent in weather resistance, heat resistance, and the like is preferably used. Further, a UV curable adhesive or pressure-sensitive adhesive may be used.

  The method of using the pressure-sensitive adhesive or adhesive is not particularly limited. For example, the pressure-sensitive adhesive or the adhesive is dissolved in a solvent composed of an appropriate solvent alone or a mixture such as toluene and ethyl acetate, and cast, Examples thereof include a method of directly attaching on a liquid crystal film by coating or the like, or a method of forming an adhesive layer or an adhesive layer on a separator and transferring it onto the liquid crystal film. The adhesive layer or adhesive layer may be, for example, natural or synthetic resins, in particular, tackifier resins, fillers made of glass fibers, glass beads, metal powders, other inorganic powders, pigments, and coloring. You may contain the additive added to adhesion layers, such as an agent and antioxidant. Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The thickness of the adhesive layer or the adhesive layer is not particularly limited as long as the member to be adhered can be adhered and sufficient adhesion can be maintained, and is appropriately selected depending on the characteristics of the adhesive or the adhesive and the member to be adhered and adhered. Can do. As the thickness of the image display device is reduced, it is highly necessary to reduce the thickness of the elliptically polarizing plate. Therefore, the thickness of the adhesive layer or the adhesive layer is preferably 2 to 80 μm, more preferably 3 to 50 μm, and particularly preferably 5 to 40 μm. .

<Transfer substrate>
The transfer substrate is a substrate for adhering and fixing a single liquid crystal film layer having a phase difference. The transfer substrate preferably includes a polarizer, and more preferably includes a linear polarizer. When a polarizer is used as the transfer substrate, the laminate obtained by the method according to the present invention can be suitably used as the laminated polarizing plate.
The transfer substrate is not particularly limited, and a highly permeable film substrate can be used. Among them, cellulose resin films such as TAC, acrylic films, cycloolefin films, and the like are free from in-plane retardation. A suitable film substrate can be used. The polarizer is not particularly limited, and for example, polyvinyl alcohol resin films such as polyvinyl alcohol (PVA) film, partially formalized polyvinyl alcohol film, ethylene / vinyl acetate copolymer partially saponified film, Examples thereof include a uniaxially stretched film adsorbed and oriented with iodine or a dichroic material, a polyene-based oriented film such as a dehydrated polyvinyl alcohol product or a dehydrochlorinated polyvinyl chloride product, and an oriented film containing a lyotropic liquid crystal. Commercially available polarizers can also be used. Among these, a uniaxially stretched film obtained by stretching a polyvinyl alcohol-based resin film and adsorbing and orienting a dichroic material (iodine, dye) is preferably used. The thickness of the polarizer is not particularly limited, but is generally about 5 to 80 μm.

  The transfer substrate may be provided with a protective film on one side or both sides. As the protective film, a conventionally known film can be used. From the viewpoint of transparency, mechanical strength, thermal stability, moisture shielding property, isotropy, etc., a cellulose resin film such as TAC, an acrylic film, etc. A film, a cycloolefin type film, etc. can be used conveniently.

[Step 5: Step of peeling alignment substrate]
The above-mentioned alignment substrate is not optically isotropic, or is opaque in the wavelength region used, or has a problem that the film thickness is too thick to hinder use, but TAC, acrylic film, cycloolefin type Optical isotropic substrates such as films cannot be used because they have insufficient heat resistance and solvent resistance and cannot withstand the coating process and the alignment process. In addition, since the alignment substrate has poor adhesion to the liquid crystal film, there is a problem that peeling occurs between layers. In the present invention, after a liquid crystal film is bonded to a transfer substrate to form a laminate with an alignment substrate, the alignment substrate is peeled from the laminate with an alignment substrate to produce a laminate having no alignment substrate. Can do. In this way, the above problem can be solved by peeling the alignment substrate. In the present invention, when the liquid crystal film and the transfer substrate are bonded to each other via a pressure-sensitive adhesive or an adhesive, the alignment substrate is preferably peeled after the pressure-sensitive adhesive or the adhesive is cured.

  When the alignment substrate is peeled from the liquid crystal film, one surface of the liquid crystal film is exposed. Therefore, the exposed liquid crystal film surface may be covered with a transparent protective layer. Examples of the transparent protective layer include those obtained by laminating a transparent plastic film such as polyester or TAC directly or via an adhesive, a resin coating layer, an acrylic or epoxy photocurable resin layer, and the like.

<Phase difference plate>
The laminate obtained by the above steps can be suitably used as a retardation plate. The retardation plate obtained by the present invention has a “negative dispersion” characteristic in which the birefringence Δn becomes larger as the measurement wavelength is longer in at least a part of the wavelength region of the visible light region. Conventional retardation plates have “positive dispersion” characteristics in the visible light region due to the effect of absorption in the ultraviolet region. On the other hand, in the present invention, by adding a dichroic dye having absorption in the visible light region to the liquid crystal compound, the birefringence Δn has a “negative dispersion” characteristic in a wavelength region in the visible light region. .

In the retardation plate obtained by the method of the present invention, the birefringence Δn has a “negative dispersion” characteristic in at least a part of the wavelength region of the visible light region. A method for designing birefringence Δn having “negative dispersion” characteristics, which is a feature of the retardation plate of the present invention, will be described.
It is formed by uniaxially stretching a mixture or copolymer film of at least two kinds of organic polymers composed of an organic polymer having positive birefringence and an organic polymer having negative birefringence exemplified in Patent Document 5 described above. In the case of a liquid crystal film comprising a retardation film or a liquid crystal composition comprising a compound having two or more kinds of mesogenic groups exemplified in Patent Document 6 and a rod-like liquid crystal compound, “positive birefringence” and “negative dispersion” A retardation film having characteristics can be obtained.
However, generally, as shown in FIG. 6, the long wavelength side deviates from the ideal straight line due to the difference in slope between the short wavelength side curve and the long wavelength side curve from 550 nm which is the central wavelength of visible light. There is a tendency. Therefore, in order to approximate the ideal chromatic dispersion curve in the wide-band region of the measurement wavelength 400 to 700 nm, which is the visible light region, the curve on the short wavelength side is maintained in a state close to the ideal straight line, while another method is used. An attempt to bring the wavelength curve closer to the ideal straight line is required.

As shown by the thin line in FIG. 7, in general, an organic polymer such as a liquid crystal compound having anisotropy has different anomalous refractive index ne and ordinary ray refractive index no because the kind of dipole differs depending on the axial direction. The dispersion curve. By adding a high dichroic dye having an absorption spectrum having a maximum absorption wavelength at 580 nm as shown in FIG. 6 to this organic polymer, in the wavelength region of 550 to 650 nm, which is near the absorption wavelength, ne A retardation film having a “negative dispersion” characteristic is obtained. Here, the dye exhibiting high dichroism means a dye having a large difference in absorption characteristics between the ne direction and the no direction. FIG. 8 shows the birefringence wavelength dispersion characteristics of a phase difference plate made of an organic polymer before and after the addition of a dichroic dye. It can be seen that by adding a dichroic dye, a phase difference plate having birefringence having “negative dispersion” is obtained in a wavelength region of 550 to 650 nm.
From the above, by adding a dichroic dye having an anomalous dispersion region to a liquid crystal compound whose birefringence has a “positive dispersion” characteristic, in the entire wavelength region of visible light, which is the object of the present invention, It is possible to obtain a phase difference plate having a “negative dispersion” characteristic in which refraction is more ideal.
In addition, when a liquid crystal film having birefringence having a “negative dispersion” characteristic is used, two-color having an anomalous dispersion area may be inferior in the “negative dispersion” characteristic in birefringence in a long wavelength region. By adding a functional dye, the dispersion characteristics in the long wavelength region can be improved, and a retardation film having more ideal “negative dispersion” characteristics in the entire wavelength region of visible light can be obtained.

  FIG. 9 shows the cross-sectional structure of a liquid crystal film comprising the nematic hybrid aligned liquid crystal compound of the present invention, the liquid crystal compound director and the incident angle θ of light incident from the vertical direction with respect to the surface normal of the liquid crystal film. ), The liquid crystal compound director and the incident angle θ (degree) of light incident from the horizontal direction with respect to the normal of the surface of the liquid crystal film (incident angle −θ (degree)), and FIG. 10 shows the tilt of the liquid crystal compound. The definition of angle and twist angle is shown. There are two types of twist directions, but either right twist or left twist may be used. Here, in the liquid crystal film including the liquid crystal compound with nematic hybrid alignment, the director of the liquid crystal compound has different angles at all locations in the film thickness direction of the liquid crystal film. Therefore, the liquid crystal film of the present invention has no optical axis when viewed from the whole film. Note that the tilt direction (axis) of the liquid crystal film is that when the c-plane is viewed from the b-plane side through the liquid-crystal film as shown in FIG. A direction in which the formed angle is an acute angle and parallel to the projection component is defined as a tilt direction (axis).

  In the liquid crystal film according to the present invention, the absolute value of the angle formed by the director of the liquid crystal compound in the vicinity of one film interface of the liquid crystal film and the film plane is preferably 20 degrees to 90 degrees, more preferably 30 degrees to 70 degrees. It is. The absolute value of the angle formed by the director of the liquid crystal compound in the vicinity of the film interface opposite to the liquid crystal film surface and the film plane is preferably 0 ° to 50 °, more preferably 0 ° to 30 °. Further, the absolute value of the average tilt angle of the nematic hybrid orientation in the present invention is preferably 5 to 40 degrees, more preferably 10 to 35 degrees, and most preferably 15 to 30 degrees. If the average tilt angle is within the above numerical range, the reflection viewing angle characteristics can be improved when the liquid crystal display device or the organic EL display device is provided in combination with a polarizer. Here, the average tilt angle is an average value of angles formed by the director of the liquid crystal molecules and the film plane in the film thickness direction of the liquid crystal film.

  Further, the liquid crystal film according to the present invention may contain a liquid crystal compound with twisted nematic hybrid alignment. A liquid crystal film comprising a twisted nematic hybrid aligned liquid crystal compound has a structure in which the optical anisotropic axis of the director of the liquid crystal compound is twisted from one surface to the other surface. Therefore, the liquid crystal film has characteristics equivalent to those obtained by superimposing optically anisotropic layers in multiple layers so that the optical anisotropic axis is continuously twisted, and is a normal TN (twisted nematic). Similar to the liquid crystal cell, STN (super twisted nematic) liquid crystal cell, etc., it has retardation and twist angle when viewed from the normal direction of the film. Further, a liquid crystal film comprising a twisted nematic hybrid aligned liquid crystal compound has a film thickness direction in which the director of the liquid crystal compound is twisted in the in-plane direction from one surface to the other while the optical anisotropic axis is twisted in the in-plane direction. The film is inclined at different angles. The absolute value of the twist angle in the alignment structure is preferably 0 ° to 70 °, more preferably 0 ° to 60 °, and most preferably 0 ° to 59 °. If the twist angle is within the above numerical range, the contrast, the antireflection performance, and the display characteristics seen from the front can be improved when the liquid crystal display device or the organic EL display device is provided in combination with the polarizing plate. .

  When the liquid crystal film obtained by the present invention is used as a retardation plate, since the liquid crystal film has nematic hybrid alignment, the upper and lower sides of the liquid crystal film are not optically equivalent. Accordingly, the display performance varies depending on which side of the liquid crystal film is on the polarizing plate side and in combination with optical parameters such as a liquid crystal cell. In the present invention, it is not limited which side of the liquid crystal film faces the polarizing plate, but it is desirable to determine the arrangement conditions and the like in consideration of required optical characteristics.

<Display device>
The display device in the present invention includes a laminate produced by the above-described process, and the type of the image display device is not particularly limited. For example, a known display device such as a liquid crystal display device, an organic EL display device, or a plasma display can be used as appropriate. In addition, a method for arranging the stacked body in the display device is not particularly limited, and a known method can be appropriately used.

  The liquid crystal display device in the present invention comprises a laminate produced by the above process. A liquid crystal display device is generally a laminate composed of a polarizer, a liquid crystal cell, and a retardation plate, a reflection layer, a light diffusion layer, a backlight, a front light, a light control film, a light guide plate, a prism sheet, and the like. There is no particular limitation on the position of use, and it may be used in one place or in multiple places.

An organic EL display device including the laminate produced in the present invention will be described.
In general, in an organic EL display device, an organic EL light emitter is formed by laminating a transparent electrode, an organic light emitting layer, and a metal electrode in this order on a transparent substrate. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, the light emitting layer and perylene. Structures having various combinations such as a stacked body of electron injection layers made of derivatives or the like, or a stacked body of these hole injection layers, light emitting layers, and electron injection layers are known.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent. Usually, a transparent electrode formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as On the other hand, in order to facilitate electron injection and increase the light emission efficiency, it is important to use a material having a small work function for the cathode. Therefore, a metal electrode such as Mg—Ag or Al—Li is usually used.

In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, external light that is incident from the surface of the transparent substrate when not emitting light, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is emitted again to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror and deteriorates the image visibility.
In such an organic EL display device, a polarizing plate is provided on the surface side of the transparent electrode, and the liquid crystal film obtained by the present invention is provided as a retardation plate between the transparent electrode and the polarizing plate, thereby improving image visibility. Can be improved.

Since the liquid crystal film and the linear polarizer obtained by the present invention have a function of polarizing light incident from the outside and reflected by the metal electrode, external light reflection from the metal electrode is not visually recognized by the polarization action. In particular, when the phase difference plate and the linear polarizer are installed so that the angle between the polarization directions is π / 4, the phase difference plate and the linear polarizer form a circularly polarizing plate and enter the organic EL display device. Only the linearly polarized light component is transmitted through the linear polarizer, and the external light is circularly polarized by the phase difference plate.
This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, is incident on the retardation plate, and becomes linearly polarized light again. Since this linearly polarized light is orthogonal to the polarization direction of the linear polarizer, it cannot be transmitted through the polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

In addition, each analysis method used in the Example is as follows.
(1) Observation of alignment state of liquid crystal The alignment state of the liquid crystal was observed using a polarizing microscope (Olympus Optical Co., Ltd., model number: BH2).
(2) Refractive index The constant light refractive index no and the extraordinary light refractive index ne are spectroscopic ellipsometry (trade name: AUTO-SE, manufactured by Horiba, Ltd.), temperature 20 ° C. ± 2 ° C., relative humidity 60 ± 5%. It calculated by measuring the spectrum of wavelength range 440-1000 nm on condition of this.
(3) Birefringence It measured using the brand name Axoscan by Axometrics.
(4) Polarization absorption spectrum of dichroic dye The measurement was performed using a spectrophotometer (trade name: V-570, manufactured by JASCO Corporation).
(5) Reflection viewing angle The viewing angle of the organic EL display device viewed from the front and oblique directions was measured using a reflection viewing angle measurement device (ELDIM Co., Ltd., trade name: EZ-CONTRAST).

Example 1
[Step 1: Application Step of Liquid Crystal Composition]
A liquid crystal compound (21) represented by the following formula and a liquid crystal compound (22) having a mesogenic group were prepared. In addition, the liquid crystal compound (21) and the liquid crystal compound (22) which has a mesogen group were manufactured by the method described in Unexamined-Japanese-Patent No. 2002-267838.

Next, 17.6 parts by weight of the liquid crystal compound (21) and 2.0 parts by weight of the liquid crystal compound (22) having a mesogenic group were mixed to obtain a liquid crystal composition (A). 0.08 parts by weight of dichroic dye (manufactured by Nagase Sangyo Co., Ltd., trade name: G-241, trisazo dye, maximum absorption wavelength 560 nm) and 100 parts by weight of liquid crystal composition (A), polymerized 3 parts by weight of an initiator (manufactured by BASF, trade name: Irgacure 651) was added to obtain a mixture of the liquid crystal composition (A), the dichroic dye and the polymerization initiator.
Chlorobenzene was added to dissolve the mixture so that the concentration of the mixture was 20% by weight, and a polytetrafluoroethylene (PTFE) filter having a pore size of 0.45 μm (trade name: 25JP050AN, manufactured by Advantech Toyo Co., Ltd.) was used. Insoluble matter was filtered to obtain a mixed solution of the liquid crystal composition (A), the dichroic dye, and the polymerization initiator.

  The PVA alignment substrate was adjusted as follows. A PET film having a thickness of 38 μm (trade name: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.) was cut into a 15 cm square, and 5 weights of alkyl-modified polyvinyl alcohol (PVA, manufactured by Kuraray Co., Ltd., trade name: MP-203). % Solution (a mixed solvent of water and isopropyl alcohol at a weight ratio of 1: 1) was applied by spin coating, dried on a hot plate at 50 ° C. for 30 minutes, and then heated in an oven at 120 ° C. for 10 minutes. Next, rubbing was performed using a rayon rubbing cloth under the condition of a peripheral speed ratio (moving speed of rubbing cloth / moving speed of alignment substrate) of 4 to obtain a PVA alignment substrate. The film thickness of the PVA layer of the obtained alignment substrate was 1.2 μm.

  A mixed solution of the liquid crystal composition (A), the dichroic dye, and the polymerization initiator was applied to the obtained PVA alignment substrate by a spin coating method to form a coating film (wet film thickness: 15.5 μm). .

[Step 2: Step of aligning liquid crystal compound]
The coating film obtained as described above is held under conditions of pressure: 1013 hPa and temperature: 72 ° C. for 3 minutes, and further cooled to room temperature over 20 minutes, whereby the solvent is dried and removed from the coating film. The compound was oriented.

[Step 3: Alignment fixing step of liquid crystal compound]
Using a high-pressure mercury lamp with an illuminance of 15 mW / cm ² , the integrated irradiation amount is 200 mJ / cm ² (light quantity at a wavelength of 365 nm) with respect to the coating film after the solvent is removed by drying and the liquid crystal compound is aligned. Thus, by irradiating with ultraviolet light, the liquid crystal compound was polymerized to fix the alignment state, and a liquid crystal film having the alignment state fixed on the PVA alignment substrate was obtained.

[Step 4: Transfer substrate bonding step]
The PET film used for the PVA alignment substrate has a large birefringence and is not preferable as an optical film. In order to measure the alignment and optical properties of the liquid crystal film, a UV curable adhesive was applied to the liquid crystal film on the alignment substrate so as to have a thickness of 5 μm, and the transfer substrate was laminated with the TAC film by lamination, and PVA alignment A laminate with a substrate was obtained.

[Step 5: Step of peeling alignment substrate]
After irradiating ultraviolet rays from the alignment substrate side of the laminate with the PVA alignment substrate obtained in step 4 to cure the UV curable adhesive, the alignment substrate is peeled off and the laminate (TAC / adhesive layer / liquid crystal film). Got. When the obtained laminate was observed under a polarizing microscope, it was found that there was no disclination and the monodomain was uniformly oriented.

The wavelength dispersion characteristics of the in-plane retardation (Δnd) of the laminate obtained in Step 5 and the TAC film alone, which is the transfer substrate, were measured using an automatic birefringence meter. The wavelength dispersion characteristic of refraction was measured (FIG. 11). As a result, the in-plane retardation Δn · d (550) at 550 nm is 143 nm, Δn · d (500) / Δn · d (550) is 0.974, and Δn · d (580) / Δn · d (550) was 1.012. In particular, it was confirmed that in the region of the measurement wavelength of 400 nm to 630 nm, “negative dispersibility” in which the phase difference increases as the measurement wavelength becomes longer is confirmed. The thickness of the liquid crystal film was 4.0 μm.
Moreover, the retardation when the obtained laminate was tilted in the rubbing direction (the alignment direction of liquid crystal molecules) was measured using an automatic birefringence meter (FIG. 12). As shown in FIG. 12, it was found that the liquid crystal film of the laminate had an asymmetric viewing angle dependency and was tilted. By the method described in the example of JP-A-11-194325, it was confirmed that the alignment was not a uniform tilt alignment but a nematic hybrid alignment. The average tilt angle was 34 degrees.
The laminate was bonded to a glass with a thickness of 1.1 mm using an acrylic pressure-sensitive adhesive and heated at a temperature of 85 ° C. for 120 hours. When the dichroic ratio before and after heating was compared, the dichroic ratio was 6.2 before heating, 5.9 after heating, and the dichroic ratio maintenance ratio was 95%, which was good dichroic ratio retention.

<Manufacture of laminated polarizing plate (A)>
The PVA film was immersed in warm water to swell, then dyed in an iodine / potassium iodide aqueous solution, and then uniaxially stretched in an aqueous boric acid solution to produce a polarizer. This polarizer was examined for single transmittance, parallel transmittance and orthogonal transmittance with a spectrophotometer. The thickness was 20 μm, the transmittance was 43.5%, and the polarization degree was 99.9%. A TAC film (manufactured by Fuji Film Co., Ltd., trade name: T40UZ, thickness 40 μm) as a transparent protective layer is bonded to one surface of this polarizer via an adhesive having a thickness of 5 μm, and a TAC / adhesive layer / The laminated polarizer which consists of polarizers was produced.

The polarizer of the above laminated polarizer and the liquid crystal film of the liquid crystal film (liquid crystal film / PVA / PET) obtained in step 3 are laminated via an acrylic UV curable adhesive having a thickness of 5 μm to obtain a PET film. A UV curable adhesive is cured by irradiating 600 mJ / cm ² from the side to form a laminate composed of TAC / adhesive layer / polarizer / UV curable adhesive / liquid crystal film / PVA / PET. Then, the PVA alignment substrate was peeled off to obtain a laminated polarizing plate (A) (TAC / adhesive layer / polarizer / adhesive layer / liquid crystal film).
At this time, the absorption axis of the polarizer and the slow axis of the liquid crystal film were bonded at an angle of 45 degrees, but the bonding angle between the absorption axis of the polarizer and the slow axis of the liquid crystal film was 135 degrees. It may be appropriately selected depending on the method of using the laminated polarizing plate. A conceptual diagram of a cross-sectional structure of the laminated polarizing plate (A) is shown in FIG. In FIG. 13, only the polarizer 1 and the liquid crystal film 3 are shown, and the other layers are omitted. Further, the orientation of the absorption axis of the polarizer 1 is indicated by 2, and the orientation direction of the liquid crystal film 3 is indicated by 4. In the laminated polarizing plate (A) 5, the surface of the liquid crystal film 3 on which the liquid crystal compound rises is the polarizer 1 side, and the surface on which the liquid crystal compound lies is opposite to the polarizer 1 side. The thickness of the laminated polarizing plate (A) was 74.0 μm.

(Example 2)
<Manufacture of laminated polarizing plate (B)>
Lamination of the polarizer of the laminated polarizer and the liquid crystal film of the liquid crystal film (liquid crystal film / PVA / PET) obtained in Step 3 of Example 1 was performed through an optically isotropic and 15 μm thick adhesive layer. A laminated polarizing plate (B) was produced in the same manner as Example 1 except for the above. The thickness of the laminated polarizing plate (B) was 84.0 μm.

(Example 3)
<Manufacture of laminated polarizing plate (C)>
A TAC film (manufactured by Fuji Film Co., Ltd., trade name: T40UZ, thickness 40 μm) as a transparent protective layer is adhered to the polarizer surface of the laminated polarizer used in Example 1 via an adhesive layer having a thickness of 5 μm. A laminated polarizing plate (C) was obtained in the same procedure as in Example 1 except that the liquid crystal film (liquid crystal film / PVA / PET) obtained in Step 3 of Example 1 was laminated. . The thickness of the laminated polarizing plate (C) was 119.0 μm.

Example 4
<Manufacture of laminated polarizing plate (D)>
Except for laminating the TAC film and the liquid crystal film of the liquid crystal film (liquid crystal film / PVA / PET) obtained in Step 3 of Example 1 through an optically isotropic 15 μm thick adhesive layer. In the same manner as in Example 3, a laminated polarizing plate (D) was produced. The thickness of the laminated polarizing plate (D) was 129.0 μm.

(Example 5)
<Manufacture of laminated polarizing plate (E)>
A 40 μm thick cycloolefin polymer (COP) film (manufactured by Nippon Zeon Co., Ltd., trade name: ZEONOR) is transparently coated on the polarizer surface of the laminated polarizer used in Example 1 through a 5 μm thick adhesive layer. Example 1 except that this COP film and the liquid crystal film (liquid crystal film / PVA / PET) obtained in Step 3 of Example 1 were laminated using the laminated polarizer adhered as A laminated polarizing plate (C) was obtained in the same procedure. The thickness of the laminated polarizing plate (C) was 119.0 μm.

(Example 6)
<Manufacture of laminated polarizing plate (F)>
Lamination of the COP film and the liquid crystal film of the liquid crystal film (liquid crystal film / PVA / PET) obtained in Step 3 of Example 1 was performed via an optically isotropic adhesive layer having a thickness of 15 μm. A laminated polarizing plate (F) was produced in the same manner as Example 5 except for the above. The thickness of the laminated polarizing plate (F) was 129.0 μm.

(Example 7)
<Manufacture of laminated polarizing plate (G)>
A laminate in which an acrylic film (made by Nippon Shokubai Co., Ltd., trade name: Acryviewer) having a thickness of 40 μm is adhered as a transparent protective layer to the polarizer surface of the laminated polarizer used in Example 1 via an adhesive layer having a thickness of 5 μm. A laminated polarizing plate (with the same procedure as in Example 1) except that this acrylic film and the liquid crystal film (liquid crystal film / PVA / PET) obtained in Step 3 were laminated using a polarizer. G) was obtained. The thickness of the laminated polarizing plate (G) was 119.0 μm.

(Example 8)
<Manufacture of laminated polarizing plate (H)>
Lamination of the acrylic film and the liquid crystal film of the liquid crystal film (liquid crystal film / PVA / PET) obtained in step 3 of Example 1 is performed via an optically isotropic adhesive having a thickness of 15 μm. A laminated polarizing plate (H) was produced in the same manner as in Example 7 except that. The thickness of the laminated polarizing plate (H) was 129.0 μm.

Example 9
<Manufacture of laminated polarizing plate (I)>
The liquid crystal film was the same as in Example 1 except that the surface on which the liquid crystal compound lay down was the polarizer 11 side, and the surface on which the liquid crystal compound was raised was on the side opposite to the polarizer 11 side. Thus, a laminated polarizing plate (I) was obtained. The thickness of the laminated polarizing plate (I) was 74.0 μm. A conceptual diagram of a cross-sectional structure of the laminated polarizing plate (I) is shown in FIG. In addition, in the laminated polarizing plate (I) 15 of FIG. 14, only the polarizer 11 and the liquid crystal film 13 are described, and other layers are omitted. Further, the direction of the absorption axis of the polarizer 11 is 12, and the orientation direction of the liquid crystal film 13 is 14.

(Comparative Example 1)
<Manufacture of laminated polarizing plate (J)>
Except not having mixed the dichroic dye, it carried out similarly to Example 1, and obtained the laminated body (liquid crystal film with a PVA orientation substrate) by which the liquid crystal film by which the orientation state was fixed was laminated | stacked on the PVA orientation substrate. . Subsequently, except having used this laminated body instead of the liquid crystal film obtained at the process 3, it carried out similarly to Example 1, and obtained the laminated polarizing plate (J), and the liquid crystal with a PVA alignment board which does not contain a dichroic dye. Δn · d at 550 nm of the film was 143 nm, and Δn · d (500) / Δn · d (550) = 0.981, Δn · d (580) / Δn · d (550) = 1.000. . In particular, it was confirmed that the retardation value was substantially constant at a measurement wavelength of 550 nm or more. The thickness of the laminated polarizing plate (J) was 74.0 μm. FIG. 15 shows the birefringence wavelength dispersion characteristics of the liquid crystal film included in the laminated polarizing plate (J).

(Comparative Example 2)
<Manufacture of laminated polarizing plate (K)>
A laminate was obtained in the same manner as in Example 1 except that Step 3 of Example 1 was changed to pressure: 1013 hPa and temperature: room temperature (25 ° C.). Subsequently, it replaced with the liquid crystal film obtained at the process 3 of Example 1, and obtained the laminated polarizing plate (K) like Example 1 except having used this laminated body. The thickness of the laminated polarizing plate (K) was 74.0 μm.

  When the chromatic dispersion characteristics of the retardation (Δn · d) in the front direction of the liquid crystal film included in the laminate and the average tilt were measured by measuring the phase difference in the oblique direction, Δn · d at a wavelength of 550 nm was 143 nm, and the average tilt angle was measured. Was 0 degrees, and it was found to be homogeneous orientation (so-called parallel orientation). The wavelength dispersion characteristic of birefringence was Δn · d (500) / Δn · d (550) = 0.993, and Δn D (600) / Δn · d (550) = 1.014, and the thickness of the liquid crystal film was 2.5 μm. FIG. 16 shows the birefringence wavelength dispersion characteristics of the liquid crystal film included in the laminated polarizing plate (K).

(Comparative Example 3)
<Manufacture of laminated polarizing plate (L)>
A laminated body (liquid crystal film / PVA / COP) was obtained in the same manner as in Example 1 except that a 40 μm-thick unstretched COP film (manufactured by ZEON Corporation, trade name: ZEONOR) was used instead of the PET film. Obtained. Next, the polarizer of the laminated polarizer used in Example 1 and the liquid crystal film of the laminate were laminated via an acrylic UV curable adhesive having a thickness of 5 μm, and 600 mJ / cm ² from the COP film side. The UV curable adhesive was cured by irradiating ultraviolet rays to obtain a laminated polarizing plate (L) (TAC / adhesive layer / polarizer / adhesive layer / liquid crystal film / PVA / COP). The thickness of the laminated polarizing plate (L) was 115.2 μm.

(Comparative Example 4)
<Manufacture of laminated polarizing plate (M)>
A laminated polarizing plate (M) was produced in the same manner as in Comparative Example 3 except that the polarizer and the liquid crystal film were laminated via an optically isotropic adhesive layer having a thickness of 15 μm. The thickness of the laminated polarizing plate (M) was 125.2 μm.

(Comparative Example 5)
<Manufacture of laminated polarizing plate (N)>
The polarizer of the laminated polarizer used in Example 1 and the PC film were bonded with an optically isotropic adhesive layer having a thickness of 15 μm, and the laminate (TAC / adhesive layer / polarizer / adhesive layer / PC). Film).

  Thereafter, the PC film and the liquid crystal film with a PVA alignment substrate (PVA / adhesive layer / liquid crystal film) produced in the following steps are bonded with an optically isotropic adhesive layer having a thickness of 15 μm, and the PVA alignment substrate is peeled off. Thus, a laminated polarizing plate (N) (TAC / adhesive layer / polarizer / adhesive layer / PC film / adhesive layer / liquid crystal film) was obtained. The thickness of the laminated polarizing plate (N) was 149.0 μm. The PC film is a polycarbonate (PC) film (trade name: Pure Ace WR, manufactured by Teijin Chemicals Ltd.) having a fluorene skeleton having a thickness of 50 μm and a square of 200 mm produced by longitudinal uniaxial stretching. The in-plane retardation value Re (550) at 550 nm of this PC film is 143 nm, the retardation value Rth (550) in the thickness direction is 72 nm, and Δn · d (500) / Δn · d (550). ) = 0.961, Δn · d (580) / Δn · d (550) = 1.015. In particular, in the measurement wavelength range of 500 nm to 600 nm, it was confirmed that the phase difference increases as the measurement wavelength becomes longer. FIG. 17 shows the birefringence wavelength dispersion characteristics of the PC film.

<Manufacture of liquid crystal film>
Polymerizable liquid crystal compounds (acrylate-based polymerizable liquid crystal compounds) represented by the following formulas (110) to (113) were prepared.
Each polymerizable liquid crystal compound represented by the general formulas (110) to (113) was produced by a known method. Specifically, the compound represented by the above general formula (110) (hereinafter sometimes simply referred to as “liquid crystal compound (I)”) was described in British Patent Application Publication No. 2,280,445. A compound produced by the method and represented by the above general formula (111) (hereinafter sometimes simply referred to as “liquid crystal compound (II)”) was published in 1989 (DJ Broer et al., “ Makromol. Chem. ", Vol. 190, 1989, pp. 3201 to 3215), and a compound represented by the above general formula (112) (hereinafter sometimes referred to simply as" liquid crystal compound "). III) ") and (113) (hereinafter sometimes simply referred to as" liquid crystal compound (IV) ") are disclosed in WO 93/22397. It was prepared by placing methods. Moreover, all the polymerizable liquid crystal compounds represented by the general formulas (110) to (113) were solid at room temperature (25 ° C.).

  Next, the liquid crystal compounds (I) to (IV) are mixed with the liquid crystal compound (I): 35% by weight, the liquid crystal compound (II): 23% by weight, the liquid crystal compound (III): 23% by weight, and the liquid crystal compound (IV). ): Mixed at a weight ratio of 19% by weight, and further a polymerization initiator (manufactured by BASF, trade name: Irgacure 907, solid at room temperature (25 ° C.)) of the liquid crystal compounds (I) to (IV) 4.0 parts by weight was added to 100 parts by weight in total. Next, using dichlorobenzene as a solvent, the liquid crystal compounds (I) to (IV) and the polymerization initiator are added so that the total concentration of the liquid crystal compounds (I) to (IV) and the polymerization initiator is 20% by weight. It melt | dissolved and the insoluble part was filtered with the filter made from PTFE with the hole diameter of 0.45 micrometer, and the mixed solution containing the said liquid crystal compounds (I)-(IV), a polymerization initiator, and a solvent was obtained. In the production of such a liquid crystal solution, the total amount of the liquid crystal compounds (I) to (IV) and the polymerization initiator in the liquid crystal solution was adjusted to 20% by weight.

  In a 1 L three-necked flask equipped with a reflux condenser and a stirrer, 24.0 g of PVA (product name: JL-18E, degree of saponification 83-86%, average degree of polymerization 1800) manufactured by Nippon Vinegar Poval Co., Ltd. and deionized water 460.8 g (electrical conductivity value: 1 μS / cm or less) was added, and the mixture was heated to 95 ° C. for 3 hours to be stirred and dissolved, and then cooled to 70 ° C. 115.2 g of isopropyl alcohol (manufactured by Kanto Chemical Co., Inc., deer grade, purity 99% or more) was gradually added and stirred at 65 ° C. to 70 ° C. for 2 hours to obtain a transparent uniform solution. It cooled to room temperature and extracted, filtering the PVA solution from the said tank. For the filtration, a cartridge filter (ADVANTEC TCP-JX-S1FE (1 μm)) capable of collecting particles having an average particle diameter of 1 μm was used to obtain 350 g of a PVA solution having a solid content concentration of about 4% by weight.

A 50 μm thick PET film (manufactured by Toyobo Co., Ltd., trade name: Cosmo Shine A4100) was cut into a 15 cm square and subjected to corona discharge treatment (100 W · min / m ² ). It fixed on the glass substrate and set to the spin coater. The PVA solution obtained as described above was applied by spin coating at 300 rpm for 30 seconds, dried on a 50 ° C. hot plate for 30 minutes, and then heated in an oven at 120 ° C. for 10 minutes to obtain PVA alignment. A substrate (PVA / PET) was obtained. The film thickness of the obtained PVA layer was 1.2 μm.

The liquid crystal solution was applied on the PVA alignment substrate produced as described above by a spin coating method. Subsequently, it dried for 10 minutes with a 55 degreeC hotplate, and orientated the liquid crystal compound by heat-processing for 3 minutes in 100 degreeC oven. Next, the acryloyl group was placed on an aluminum plate heated to 70 ° C. by irradiating 300 mJ / cm ² of ultraviolet light (however, measured at 365 nm) in air with a high-pressure mercury lamp lamp. A liquid crystal film with a PVA alignment substrate / PVA / PET) was obtained by radical polymerization to cure the liquid crystal compound. The thickness of the liquid crystal film was 1.0 μm.

  In order to measure the alignment and optical properties of the liquid crystal film, a UV curable adhesive was applied to the liquid crystal film with a PVA alignment substrate to a thickness of 5 μm, laminated with the TAC film, and then irradiated with ultraviolet rays from the PET film side. After the adhesive was cured, the PVA alignment substrate was peeled off to obtain a TAC substrate-attached liquid crystal film (TAC / adhesive layer / liquid crystal film). When observed under a polarizing microscope with crossed Nicols, the liquid crystal film was found to have homeotropic alignment with a positive uniaxial refractive index structure from conoscopic observation with a uniform monodomain alignment without disclination. . When this film was tilted and light was incident from an oblique direction and observed in the same manner with crossed Nicols, light transmission was observed. As a result of measuring the optical retardation of the liquid crystal film, the in-plane retardation value Re (550) of the second optically anisotropic layer alone was 0 nm, and the retardation value Rth (550) in the thickness direction was −. It was 75 nm.

  The laminated polarizing plates (A) to (O) prepared in Examples 1 to 9 and Comparative Examples 1 to 5 are pasted on an organic EL element transparent glass substrate provided in a commercially available organic EL display via an acrylic pressure-sensitive adhesive. An organic EL display device was prepared by wearing, and the following evaluation was performed.

Evaluation (A): Evaluation of the effect of preventing external light reflection during frontal observation In a state where no voltage is applied to the organic EL element, it is placed in an environment with an illuminance of about 100 lux, and the reflection color blackness of the laminated polarizing plate bonding portion It was classified into the following four levels.
1: There is almost no external light reflection, and the reflection color is black.
Although inferior to 2: 1, the reflection of outside light is sufficiently suppressed, and the reflected color is almost black.
3: A little external light reflection is visually recognized.
4: External light reflection is visually recognized.

Evaluation (B): Evaluation of viewing angle characteristics of the effect of preventing reflection of external light With no voltage applied to the organic EL element, it is placed in an environment with an illuminance of about 100 lux, The black color of the reflected color was classified into the following four levels.
1: Almost no change in external light reflection is seen between the front and diagonal directions.
Although it is inferior to 2: 1, the difference in external light reflection between the front and the diagonal direction is slight.
3: A difference in external light reflection is observed between the front and the diagonal direction.
4: There is a considerable difference in external light reflection between the front and diagonal directions.

As shown in Table 3, it was found that the polarizing plates of Examples 1 to 9 and Comparative Examples 3 to 5 were excellent in the effect of preventing external light reflection during frontal observation and also had good viewing angle characteristics. On the other hand, the polarizing plate (J) of Comparative Example 1 containing no dichroic dye was found to have external light reflection and a bluish tint when viewed from the front and oblique directions.
In addition, the polarizing plate (K) of Comparative Example 2 that does not contain a homeotropic alignment liquid crystal film was found to have an anti-reflection effect on external light during front observation, but a considerable difference was observed in external light reflection between the front and oblique directions. As a result, it was confirmed that the tint change in the oblique direction also increased the bluish tint.
Moreover, as shown in Table 3, when the thickness of the laminate (liquid crystal film / transfer substrate) used for the polarizing plate was compared, all the forms of the examples were significantly thinner than Comparative Examples 3 to 5, and markedly thin It was found that the system was realized.

  In addition, it was found that the laminated polarizing plates of Comparative Examples 3 and 4 have poor adhesion between the PVA layer and the liquid crystal film included in the alignment substrate, and easily peel off during the polarizing plate manufacturing process or during handling after manufacturing. .

Claims (6)

Applying a liquid crystal composition comprising a liquid crystal compound and a dichroic dye on an alignment substrate;
A step of nematic hybrid alignment of the liquid crystal compound;
Fixing the nematic hybrid alignment of the liquid crystal composition to form a liquid crystal film;
A step of bonding a transfer substrate on the liquid crystal film to form a laminate with an alignment substrate;
Separating the alignment substrate from the alignment substrate-attached laminate.   The method for producing a laminate according to claim 1, wherein the nematic hybrid orientation is fixed by a crosslinking reaction by light or heat.   The manufacturing method of the laminated body of Claim 1 or 2 whose said transfer substrate is a polarizing plate.   The manufacturing method of the laminated body as described in any one of Claims 1-3 which has the maximum absorption wavelength of the said dichroic dye in the wavelength range of 380-780 nm. The ratio of retardation in the normal direction of the phase difference plate at a specific wavelength is expressed by the following mathematical formulas (1) and (2):
1.00> Δn · d (500) / Δn · d (550)> 0.80 (1)
1.15> Δn · d (600) / Δn · d (550)> 1.00 (2)
(Here, retardation is represented by the product of birefringence Δn and film thickness d of the retardation plate, and Δn · d (500), Δn · d (550), and Δn · d (600) are respectively wavelengths) Retardation of retardation plate at 500 nm, 550 nm, and 600 nm)
The manufacturing method of the laminated body as described in any one of Claims 1-4 which satisfy | fills.   The manufacturing method of the laminated body as described in any one of Claims 1-5 whose average tilt angles of the liquid crystal compound of the said phase difference plate are 5 degrees-40 degrees.