Polarizing plate and stereolithography apparatus using same

Abstract

A polarizing plate comprising a support and a polarizer, characterized in that the polarizer includes at least two dichroic azo dye compounds having polarization properties in the near ultraviolet light region (wavelength 360-420 nm) and in that the polarizing plate has a dichroic ratio Rd400 of 20 or more at a wavelength of 400 nm and a contrast ratio CR(Tp400 / Tc400) determined from parallel transmittance Tp400 and orthogonal transmittance Tc400 at a wavelength of 400 nm of 1000 or more, and a contrast ratio CR(Yp / Yc) determined from parallel transmittance Yp and orthogonal transmittance Yc in a visibility-corrected visible light region of 10 or more.

Description

Polarizing plate and optical shaping apparatus using the same 【0001】 The present invention relates to a polarizing plate and an optical shaping apparatus using the same. 【0002】 Three-dimensional shaping apparatuses are generally also referred to as three-dimensional (3D) printers and have recently become widely popular as an application of printing technology in various uses such as model manufacturing and architecture. Specifically, a three-dimensional shaping apparatus can form a three-dimensional shaped object by sequentially laminating a resin material or the like using computer-aided design (CAD) data of an object. 【0003】 One type of three-dimensional shaping apparatus method is a shaping method in which a resin is cured with light (hereinafter referred to as a light shaping method, and a three-dimensional shaping apparatus using this light shaping method is also referred to as an optical shaping apparatus). In the light shaping method, generally, light from a light source is made to contain ultraviolet light (ultraviolet rays), and the resin is cured and laminated by intermittently and selectively irradiating the light-curable resin with the light, and this process is repeated to form a shaped object. As the light source, typically, a light-emitting diode having a maximum emission wavelength in the range of 380 to 440 nm is used. 【0004】 In some cases, a liquid crystal shutter is used as a control member for intermittently and selectively irradiating light from a light source. The liquid crystal shutter is composed of a liquid crystal panel provided with a polarizing plate including a liquid crystal cell and a polarizer. An optical shaping apparatus using a liquid crystal shutter is disclosed in, for example, Patent Document 1 and the like. Such an optical shaping apparatus has a simple configuration and is suitable for miniaturization, and can also form a dense and highly accurate three-dimensional shaped object. The liquid crystal shutter of such an optical shaping apparatus generally uses a polarizing plate containing the same iodine-based polarizer as a normal liquid crystal display device, and thus deterioration of the liquid crystal panel due to ultraviolet light irradiation, particularly deterioration of the polarizer, has become a problem. 【0005】To improve the durability (light resistance) of the device's light source, the aforementioned polarizer may use an absorption polarizer employing a dye-based dichroic colorant, which is specialized for polarization characteristics in the near-ultraviolet light range (wavelength 360-420 nm), instead of an iodine-based polarizer. Such polarizers generally contain a dichroic azo dye compound having a monoazo or disazo-based chemical structure, and these polarizers exhibit a yellow or orange color. In particular, they have polarization characteristics suitable for controlling light sources with a maximum emission wavelength of 390-405 nm (Patent Document 2). This is said to improve irradiation efficiency by improving the optical characteristics in this wavelength range, as well as improving the durability (running time) of the liquid crystal panel in the device. 【0006】 Incidentally, in the manufacturing process of polarizing plates, quality inspections of the appearance and other aspects of the polarizing plate products are generally performed. This inspection may be carried out, for example, by placing an iodine-based polarizing plate (which exhibits a grayish color) as a polarizing plate having polarization characteristics across the visible light range on a backlight equipped with a white light-emitting diode (LED) as the light source, and then placing a polarizing plate product manufactured to be perpendicular to the absorption axis of the said polarizing plate on top of it. With this method, these two polarizing plates extinguish the light from the light source, making it easier to detect foreign matter and causes of bright spots present between the polarizing plate on the light source side and the polarizing plate product. This type of inspection method is generally also called transmission inspection. 【0007】 Japanese Patent Publication No. 2018-521341, International Publication No. WO2024 / 143252 【0008】 However, polarizers using dye-based polarizers, which are specialized for polarization characteristics in the near-ultraviolet light range, do not have polarization characteristics in the visible light range, especially above 440 nm. Therefore, even if the above inspection process is performed, such polarizer products cannot extinguish light from the light source, making it difficult to detect foreign matter or the cause of bright spots, and thus making it difficult to perform proper quality inspection. 【0009】Furthermore, while it is desirable to actually use an ultraviolet light source for inspecting and evaluating polarizers that use dye-based polarizers specialized for polarization characteristics in the near-ultraviolet light range, this is not easy, as ultraviolet light sources are harmful to the eyes, and new evaluation methods must be considered to visualize the information obtained from ultraviolet light. 【0010】 Furthermore, conventionally, azo dyes for polarizing plates have been developed primarily with a focus on polarization characteristics in the visible light range, particularly wavelengths of 400 to 700 nm, in order to improve the display performance of display devices equipped with such polarizing plates. As a result, polarization characteristics in the near-ultraviolet light range are usually lost, partly due to the inclusion of ultraviolet absorbers in the support material, and therefore, polarization characteristics in this wavelength range have not been required. Consequently, there has been little discussion about whether known azo dyes other than the yellow and orange dyes mentioned above possess polarization characteristics in this wavelength range. 【0011】 Therefore, the present invention aims to provide a polarizing plate for use in a liquid crystal shutter of a stereolithography apparatus that has high polarization characteristics in the near-ultraviolet light range suitable for stereolithography, while also having good visual inspection properties in the polarizing plate manufacturing process, and a stereolithography apparatus using the same. 【0012】 The present inventors, through diligent research to solve the aforementioned problems, have discovered that by using a dichroic azo dye compound exhibiting a yellowish color with polarization characteristics suitable for near-ultraviolet light (wavelength 360-420 nm) in addition to a dichroic azo dye compound having polarization characteristics in the visible light range (wavelength 380-780 nm) and also having polarization characteristics as a secondary absorption in the near-ultraviolet light range, it is possible to obtain a polarizer that maintains high polarization characteristics in the near-ultraviolet light range while exhibiting polarization quenching in the visible light range, thus completing the present invention. 【0013】 This application relates to, but is not limited to, the following inventions: [Invention 1] A polarizing plate comprising a support and a polarizer, wherein the polarizer contains at least two dichroic azo dye compounds having polarization properties in the near-ultraviolet region (wavelength 360 to 420 nm), and the polarizing plate has a dichroism Rd at a wavelength of 400 nm. ４００ The value is 20 or more, and the parallel transmittance Tp at a wavelength of 400 nm is４００ and the orthogonal transmittance Tc ４００ The contrast ratio CR (Tp ４００ / Tc ４００ ) is 1000 or more, and the contrast ratio CR (Yp / Yc) obtained from the parallel transmittance Yp and the orthogonal transmittance Yc in the visible light region corrected for visual sensitivity is 10 or more. A polarizing plate characterized by this. [Invention 2] Further, the dichroic ratio Rd ３８５ at a wavelength of 385 nm is 17 or more, and the parallel transmittance Tp ３８５ and the orthogonal transmittance Tc ３８５ The contrast ratio CR (Tp ３８５ / Tc ３８５ ) is 1000 or more, the polarizing plate according to Invention 1. [Invention 3] At least two of the dichroic azo dye compounds include at least Compound A and B. Compound A has a maximum absorption wavelength λmax of 370 to 470 nm, and a dichroic ratio Rd ４００ at a wavelength of 400 nm is 42 to 48. Compound B has a maximum absorption wavelength λmax of 660 to 680 nm, and a dichroic ratio Rd ４００ at a wavelength of 400 nm is 17 to 20. The polarizing plate according to Invention 1 or 2. [Invention 4] One of the dichroic azo dye compounds is an azo compound represented by the formula (1) or a salt thereof, and the other one of the dichroic azo dye compounds is an azo compound represented by the formula (2), a salt thereof, or a copper complex salt thereof. The polarizing plate according to Invention 1 or 2: Here, the formula (1) is represented in the form of a free acid, and Q １ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a carboxy group, and Q ２ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a carboxy group, and Q ３ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a hydroxy group, and Q ４ represents a hydrogen atom, a halogen atom, a lower alkyl group, a lower alkoxy group or a hydroxy group, X represents O, S, NH or NCH ３ represents, l represents 0, 1 or 2, m represents 0, 1 or 2, and l + m is 2 or 4. Here, formula (2) is expressed in the form of a free acid, where n represents 0 or 1, X represents a nitro group or an amino group, and R １ , R ２ , R ３ , R ４ Each of these independently represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, or an acetylamino group, R ５ R represents a hydroxyl group or an unsubstituted or substituted amino group. ６ is represented by a hydrogen atom, a hydroxyl group, an unsubstituted or substituted amino group, a methyl group, an ethyl group, a methoxy group, or an ethoxy group. [Invention 5] A stereolithography apparatus comprising a light source and a liquid crystal shutter, wherein a photocurable resin is sequentially cured and laminated by irradiating light controlled by the liquid crystal shutter to form a three-dimensional object, wherein the light source is an LED light source having a maximum emission wavelength in the range of 360 to 420 nm, and the liquid crystal shutter is a liquid crystal panel comprising a pair of polarizing plates as described in Invention 1 or 2. [Invention 6] A stereolithography apparatus comprising a light source and a liquid crystal shutter, wherein a photocurable resin is sequentially cured and laminated by irradiating light controlled by the liquid crystal shutter to form a three-dimensional object, wherein the light source is an LED light source having a maximum emission wavelength in the range of 360 to 420 nm, and the liquid crystal shutter is a liquid crystal panel comprising a pair of polarizing plates as described in Invention 3. [Invention 7] A stereolithography apparatus comprising a light source and a liquid crystal shutter, wherein a photocurable resin is sequentially cured and laminated by irradiating light controlled by the liquid crystal shutter to form a three-dimensional object, wherein the light source is an LED light source having a maximum emission wavelength in the range of 360 to 420 nm, and the liquid crystal shutter is a liquid crystal panel comprising a pair of polarizing plates as described in Invention 4. 【0014】 The present invention provides a polarizing plate that has high polarization characteristics in the near-ultraviolet light range suitable for stereolithography, while also having good visual inspection properties in the polarizing plate manufacturing process, and a stereolithography apparatus using the same. 【0015】Furthermore, by equipping a stereolithography apparatus with a liquid crystal panel using such a polarizing plate, it is possible to provide a stereolithography apparatus that enables stable light irradiation over long periods of time and reduces the frequency of liquid crystal panel replacement. 【0016】 This is an example of a cross-sectional view of the polarizing plate of the present invention. This is an example of the configuration of a stereolithography apparatus equipped with a liquid crystal panel using the polarizing plate of the present invention. This is an example of the wavelength dependence of the illuminance of the apparatus light source used in the stereolithography apparatus. This is the wavelength dependence of the transmittance of the polarizing plate of Example 1. This is the wavelength dependence of the transmittance of the polarizing plate of Comparative Example 1. This is the wavelength dependence of the transmittance of the polarizing plate of Comparative Example 2. This is the wavelength dependence of the transmittance of the polarizing plate of Comparative Example 4. This is a conceptual diagram of a visible light appearance inspection method using a polarizing plate. 【0017】 The following describes embodiments according to the present invention in detail. Note that the following embodiments are examples of some representative embodiments of the present invention, and various modifications can be made within the scope of the present invention. 【0018】 In the claims and specification of this application, the wavelength range of "near ultraviolet light" is defined as the range of wavelengths from 360 to 420 nm. The wavelength range of "visible light" is defined as the range of wavelengths from 380 to 780 nm. 【0019】 In the claims and specification of this application, "substituent" may include a hydrogen atom, and therefore, for convenience, a hydrogen atom may also be described as a "substituent." "May have a substituent" means that it also includes cases where there is no substituent. For example, "phenyl group that may have a substituent" includes an unsubstituted, simple phenyl group and a phenyl group with a substituent. Furthermore, unless otherwise specified, "lower" in the lower alkyl group, lower alkoxy group, etc., of this application indicates that the number of carbon atoms is 1 to 4 (C1 to 4), preferably 1 to 3 (C1 to 3). 【0020】 Examples of "lower (C1-C4) alkyl groups" include linear alkyl groups such as methyl, ethyl, n-propyl, and n-butyl groups, segmented alkyl groups such as sec-butyl and tert-butyl groups, and unsaturated hydrocarbon groups such as vinyl groups. 【0021】Examples of "lower (C1-C4) alkoxy groups" include methoxy, ethoxy, propoxy, n-butoxy, sec-butoxy, and tert-butoxy groups. 【0022】 In this specification, "azo compounds, metal complex compounds thereof, or salts thereof" may be abbreviated as "azo compounds" or "azo compounds or salts thereof." 【0023】 <Polarizing Plate> The polarizing plate of the present invention comprises a support and a polarizer, the polarizer comprises a dichroic azo dye compound, and the polarizing plate has polarization properties in the near-ultraviolet and visible light regions. In the present invention, the statement that the polarizing plate has polarization properties in the near-ultraviolet region includes not only the case in which the support does not absorb near-ultraviolet light, but also the case in which the support contains a component that absorbs near-ultraviolet light, the support comprises another layer that absorbs near-ultraviolet light, or the adhesive layer contains a component that absorbs near-ultraviolet light, as long as the effects of the present invention are achieved. The configuration of the polarizing plate of the present invention is described below, but is not limited to these. 【0024】 In one embodiment of the polarizing plate of the present invention, the polarizing plate 100 includes two supports and a polarizer 20, as shown in Figure 1. The polarizing plate 100 is arranged in the following order from the liquid crystal cell side: adhesive layer 30 / first support 10 / adhesive layer (not shown) / polarizer 20 / adhesive layer (not shown) / second support 11. The polarizing plate 100 also includes a configuration without the adhesive layer 30, where the configuration is first support 10 / adhesive layer (not shown) / polarizer 20 / adhesive layer (not shown) / second support 11. 【0025】 In one embodiment, the polarizing plate of the present invention is a polarizing plate comprising a support and a polarizer, wherein the support does not absorb ultraviolet light, the polarizer contains at least two dichroic azo dye compounds, the dichroic azo dye compounds have polarization properties in the near-ultraviolet region (wavelength 360 to 420 nm), and the polarizing plate has a dichroism ratio Rd at a wavelength of 400 nm. ４００ The value is 20 or more, and the parallel transmittance Tp at a wavelength of 400 nm is ４００ and orthogonal transmittance Tc ４００ The contrast ratio CR(Tp) is determined from this. ４００ / Tc ４００The polarizer has a value of 1000 or more, and a contrast ratio CR (Yp / Yc) calculated from the parallel transmittance Yp and orthogonal transmittance Yc in the visible light range (wavelength 380-780 nm) after luminous efficiency correction is 10 or more. By using such a polarizer, it is possible to impart quenching properties in the visible light range while maintaining high polarization characteristics in the near-ultraviolet light range. 【0026】 In one other embodiment, the polarizing plate of the present invention has a dichromatic ratio Rd at a wavelength of 385 nm. ３８５ The value is 17 or greater, and the parallel transmittance Tp at a wavelength of 385 nm is greater than or equal to 17. ３８５ and orthogonal transmittance Tc ３８５ The contrast ratio CR(Tp) is determined from this. ３８５ / Tc ３８５ The value is 1000 or more. By using such a polarizing plate, a wide polarization characteristic is obtained in the near-ultraviolet light region, thus expanding the selectivity of the device's light source. 【0027】 In one other embodiment of the present invention, one of the dichroic azo dye compounds contained in the polarizer is an azo compound shown in formula (1) or a salt thereof, and the other of the dichroic azo dye compounds is an azo compound shown in formula (2), a salt thereof, or a copper complex salt thereof. By using such a polarizer, it is possible to obtain the optimal dye and the best optical properties in order to maintain high polarization characteristics in the near-ultraviolet region while imparting quenching in the visible light region. 【0028】 (Polarizer) Typical polarizers include dye-oriented polarizing films and dye-coated (also called coated) polarizing films. In particular, PVA-based polarizing films, in which the substrate on which the orientation compound is adsorbed (impregnated) is a polyvinyl alcohol (PVA) resin, can be suitably used. Examples of commercially available PVA-based films include Kuraray's VF-PS#7500 (thickness 75 μm) and VF-PE#4000 (thickness 40 μm). 【0029】The method for producing the PVA-based polarizing film described above can be a known stretching method, in which a dichroic dye is adsorbed onto a polymer film containing PVA or a derivative thereof, and the film is stretched uniaxially by about 2 to 6 times to orient the dye. At this time, the film thickness of the polarizer is generally 5 to 35 μm. Examples of dichroic dyes (colorants) generally include iodine and dyes (dyes). Dichroic dyes are preferred from the viewpoint of heat resistance and light resistance, and in particular, direct dyes (azo dyes) containing azo compounds having a sulfonic acid group are preferred. 【0030】 The polarizer used in the present invention is an absorption-type polarizer containing at least two dichroic azo dye compounds. The wavelength range of the light source of the photopolymerization apparatus is typically such that the emission wavelength range is at least in the range of 380 to 440 nm, as shown in Figure 3, with the maximum emission wavelength being 390 to 410 nm. Here, the emission wavelength range is the region between the wavelength ends that have a predetermined emission illuminance, and the maximum emission wavelength means the wavelength with the strongest emission illuminance in that region. 【0031】 Therefore, it is preferable that one of the dichroic azo dye compounds (also called compound A) contained in the polarizer has a maximum absorption wavelength (λmax) near the emission wavelength so as to have high polarization characteristics in that emission wavelength range. Specifically, the range in which λmax is contained is preferably 370 to 470 nm, more preferably 375 to 465 nm, and even more preferably 380 to 440 nm. Such dyes appear as yellow or orange in polarizers. The hue of the polarizer is determined by spectroscopic measurement, L ＊ a ＊ b ＊ It can be determined using a color system (JIS Z 8781-4). 【0032】As a known dye that is one of the aforementioned dichroic azo dye compounds, dyes having the chemical structure of monoazo, disazo, or biphenyldisazo are preferred, for example, C.I. Direct Yellow 1, C.I. Direct Yellow 4, C.I. Direct Yellow 11, C.I. Direct Yellow 12, C.I. Direct Yellow 26, C.I. Direct Yellow 28, C.I. Direct Yellow 44, C.I. Direct Yellow 50, C.I. Direct Yellow 51, C.I. Examples include Direct Yellow 86, C.I. Direct Yellow 142, C.I. Direct Orange 1, C.I. Direct Orange 10, C.I. Direct Orange 25, C.I. Direct Orange 26, C.I. Direct Orange 39, C.I. Direct Orange 72, etc. 【0033】 One of the dichroic azo dye compounds is the azo compound shown in formula (1) below and / or its salt, and C.I. Direct Yellow 28 can be used particularly preferably. The compound of formula (1) is disclosed, for example, in International Publication WO2005 / 015275. The range of λmax in the polarizer is wavelength 400 to 425 nm, and the dichroism Rd at wavelength 400 nm is ４００ The range is 42 to 48. Therefore, polarizers containing the dye can be suitably used to impart polarization properties to the near-ultraviolet light region. In this specification, when a polarizer containing a certain type of polarizing compound has a certain maximum absorption wavelength λmax and a certain dichroism Rd, the maximum absorption wavelength λmax and dichroism Rd may also be expressed as the maximum absorption wavelength λmax and dichroism Rd of the compound. Here, equation (1) is expressed in the form of a free acid, where Q １ Q represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or carboxyl group. ２ Q represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or carboxyl group. ３Q represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or hydroxyl group. ４ represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or hydroxyl group, and X is O, S, NH, or NCH ３ This represents a value where l represents 0, 1, or 2, m represents 0, 1, or 2, and l + m is 2 or 4. 【0034】 Another type of dichroic azo dye compound used in the polarizer (also called compound B) is an azo compound represented by the following formula (2), its salt, or its copper complex salt, which can be used particularly preferably. This compound is disclosed, for example, in Japanese Patent Application Publication No. 2001-056412. The λmax of this compound is in the wavelength range of 610 to 630 nm, or in the case of the copper complex salt, 660 to 680 nm, and the dichroism (Rd) in this wavelength range is 34 to 38. Furthermore, the range of sub-absorption in this polarizer is the wavelength range of 420 to 440 nm, and the dichroism (Rd) at a wavelength of 400 nm is 34 to 38. ４００ The range is 17-20. Here, formula (2) is expressed in the form of a free acid, where n represents 0 or 1, X represents a nitro group or an amino group, and R １ , R ２ , R ３ , R ４ Each of these independently represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, and an acetylamino group, R ５ R represents a hydroxyl group or an unsubstituted or substituted amino group. ６ The group represents a hydrogen atom, a hydroxyl group, an unsubstituted or substituted amino group, a methyl group, an ethyl group, a methoxy group, or an ethoxy group. Examples of substituted amino groups include methylamino group, carbamoylamino group, and acetylamino group. 【0035】 Furthermore, in order to reduce photodegradation (fading) of the dye due to light irradiation, copper complex salts can be particularly preferably used as the dichroic azo dye compound. 【0036】Polarizers using such dichroic azo dye compounds can maintain polarization characteristics in the near-ultraviolet region while also providing sufficient polarization characteristics in the visible light region to prevent quenching by polarization. "Quenching by polarization" refers to the state in which light is blocked when the transmission axes (or absorption axes) of two polarizers (polarizing plates) are arranged in an orthogonal relationship. Quenching can be determined from the contrast CR (Yp / Yc) obtained from the ratio of Yp and Yc described later. 【0037】 In a method for manufacturing a polarizer, when a PVA-based resin is used as the base material, for example, a polarizer can be manufactured by a step of preparing the base material, a swelling step of immersing the base material in a swelling solution to swell the base material, a dyeing step of impregnating the swollen base material in a dyeing solution containing at least one of the dichroic dyes, a crosslinking step of immersing the base material on which the dichroic dyes have been adsorbed in a boric acid solution to crosslink the dichroic dyes within the base material, a stretching step of uniaxially stretching the base material on which the dichroic dyes have been crosslinked in a certain direction to align (orient) the dichroic dyes in a certain direction, and further, if necessary, a washing step of washing the stretched base material with a washing solution, and / or a drying step of drying the washed base material. 【0038】 Furthermore, in the dyeing process, the dye concentration of the dyeing solution is usually within the range of 0.01 to 0.1% by mass. The amount of dye adsorbed onto the substrate is controlled by adjusting the dyeing time and other factors in addition to the concentration. 【0039】 The optical properties of the polarizer of the present invention will now be described. The optical properties of the polarizer of the present invention preferably have the following conditions. Note that, since there is no significant difference between the optical properties of the polarizer measured in the form of a polarizing plate in this invention, they will be treated as the same. 【0040】 In one of the conditions, the optical properties of a polarizing plate (polarizer) in the near-ultraviolet region are such that, when the light source of the stereolithography apparatus has an illuminance peak around a wavelength of 400 nm, at that wavelength, from the viewpoint of the light utilization efficiency of the liquid crystal shutter in the apparatus, the transmittance of a single polarizing plate is the single-plate transmittance (Ts ４００ ) is 30% or more, and the parallel transmittance (Tp) obtained by aligning the transmission axes (or absorption axes) of the two polarizing plates parallel to each other. ４００) is 20% or more, and the orthogonal transmittance (Tc) obtained by orthogonalizing the transmission axes (or absorption axes) of the two polarizing plates is 20% or more. ４００ ) is 0.01% or less, and the degree of polarization (P ４００ The ratio of ) is preferably 99.5% or higher. In these criteria, it is taken into consideration that existing organic polarizing plates for liquid crystal display devices are also used for stereolithography devices. And in such polarizing plates, the dichromatic ratio Rd at the wavelength is ４００ It is preferable that it be 20 or more, and Tp ４００ and Tc ４００ The contrast ratio CR(Tp) is calculated from the ratio of [the two values]. ４００ / Tc ４００ It is even more preferable that the value is 1000 or more. 【0041】 Furthermore, in one of the conditions, the optical properties of the polarizer in the visible light range (wavelength 380 to 780 nm) are preferably such that, from the viewpoint of obtaining extinction due to polarization, the luminous efficiency-corrected parallel transmittance (Yp) obtained by aligning the transmission axes (or absorption axes) of two polarizers parallel is 30% or more, the luminous efficiency-corrected orthogonal transmittance (Yc) obtained by aligning the transmission axes (or absorption axes) of two polarizers orthogonal is 3% or less, and the luminous efficiency-corrected degree of polarization (Py) is 90% or more. In such a polarizer, the contrast ratio CR (Yp / Yc), which is determined from the ratio of Yp to Yc, is preferably 10 or more. 【0042】 Furthermore, L of a polarizing plate alone ＊ a ＊ b ＊ The hue value according to the color system is a ＊ s is preferably -8 to 8, more preferably -5 to 5, and b ＊ s is preferably -8 to 8, more preferably -5 to 5. In other words, such polarizing plates are close to gray in color and have little tint, so they have good visibility during inspection work. 【0043】 Furthermore, it is even more preferable that the polarizer of the present invention has the following conditions: The optical properties of the polarizing plate (polarizer) in the near-ultraviolet region are such that, when the light source of the stereolithography apparatus has an illuminance peak around a wavelength of 385 nm, the transmittance of a single polarizing plate (Ts) at that wavelength is the transmittance of a single polarizing plate. ３８５) is 28% or more, and the parallel transmittance (Tp) obtained by aligning the transmission axes (or absorption axes) of the two polarizing plates parallel to each other is 28% or more. ３８５ ) is 18% or more, and the orthogonal transmittance (Tc) obtained by orthogonalizing the transmission axes (or absorption axes) of the two polarizing plates is 18% or more. ３８５ ) is 0.1% or less, and the degree of polarization (P ３８５ The ratio of ) is preferably 99.9% or higher. Furthermore, such a polarizing plate has a dichromatic ratio Rd at the relevant wavelength. ３８５ It is preferable that it be 17 or more, and Tp ３８５ and Tc ３８５ The contrast ratio CR(Tp) is calculated from the ratio of [the two values]. ３８５ / Tc ３８５ ) is preferably 1000 or more. Therefore, since the polarizing plate has broad polarization characteristics in the near-ultraviolet light region, it is possible to use light sources of various wavelengths as described later. 【0044】 The wavelength dependence of the polarization characteristics of the polarizer is preferably such that it covers the wavelength range of light from the light source provided in the stereolithography apparatus. For example, if the light from the light source has an illuminance peak around 400 nm and a bandwidth of ±50 nm from that peak, then the polarization characteristics of the polarizer should preferably use a dichroic dye with λmax around 400 nm and have polarization characteristics in the range of at least 350 to 450 nm. Furthermore, by having a polarization characteristic bandwidth of ±10 nm or more, preferably ±30 nm or more, and more preferably ±50 nm or more, relative to the bandwidth of the light source wavelength, a liquid crystal panel without light leakage from the light source can be produced in the stereolithography apparatus. Light leakage from the liquid crystal panel may cause the photocurable resin filled in the resin tray to gel or harden at unintended locations and timings. 【0045】 (Support) In order to improve the physical strength of the polarizer and protect it from scratches, etc., it is preferable to laminate the support described below on one or both sides of the polarizer to form a polarizing plate. 【0046】The support (also called a support plate) is a component for mechanically supporting and protecting the polarizer. The support is preferably made of an optically transparent plastic resin such as a triacetylcellulose (TAC) resin plate (also called a sheet or film), a cycloolefin resin plate, an acrylic resin plate, or a polycarbonate (PC) resin plate. The thickness of the support is preferably 10 μm or more, and more preferably 40 μm or more. When using a PVA resin polarizer, a TAC resin film can be suitably used due to its ease of adhesion. 【0047】 As a support material included in a polarizing plate, it is preferable that it does not contain ultraviolet absorbers in order to allow the polarization function of the polarizer to act without absorbing light in the light source wavelength range. However, the support material of a polarizing plate used in a display device, etc., generally contains an ultraviolet absorber to prevent the degradation of the polarizer and the liquid crystal molecules in the liquid crystal cell due to ultraviolet light contained in ambient light. Examples of ultraviolet absorbers include organic ultraviolet absorbers such as oxybenzophenone compounds, benzotriazole compounds, salicylate ester compounds, benzophenone compounds, cyanoacrylate compounds, and nickel complex salt compounds. These materials are generally added one or more times. A support film containing such an ultraviolet absorber generally has a natural light transmittance of 10 to 1% at a wavelength of 380 nm, a natural light transmittance of 70 to 40% at a wavelength of 400 nm, and a natural light transmittance of 90 to 80% at a wavelength of 410 nm. 【0048】 Examples of commercially available TAC-based resin films that do not contain UV absorbers for use as a support include ZRD60SL (manufactured by Fujifilm Corporation) and 13SG80S-HL (manufactured by Island Polymer Industries GmbH). 【0049】 The support may be provided with known additional functional layers, such as a hard coat layer (HC) for surface protection and an anti-reflective layer (AR, LR) for improving transmittance. 【0050】(Adhesive Layer) The adhesive layer is a layer used to bond a support to a polarizer, a support to another support, a polarizer to a liquid crystal cell, and other polarizers to each other. The adhesive used in the adhesive layer is not particularly limited, but it is preferable to use a material that can absorb (buffer) forces such as thermal stress when they act on the polarizer. Regarding the adhesive layer, if an elastic polymer material is used and it can be bonded by applying pressure and peeled off again, it is generally also called an "adhesive layer (the material is an "adhesive")", and in the present invention, the adhesive layer includes this form. The adhesive layer is generally a composition containing a resin-based material that includes at least a base polymer (hereinafter also called a main component) and a curing aid such as a crosslinking agent, and these are also called adhesives. The adhesive is not particularly limited, but examples include adhesive components that are blended with isocyanate compounds, epoxy compounds, etc. in urethane resin, etc., or adhesive components of acrylic resin, polyester resin, etc. 【0051】 Adhesives are broadly classified into water-based, solvent-based, or solvent-free types based on their diluent components. These systems are appropriately selected according to the surface properties of the adherend and the curing method. 【0052】 Typical water-based adhesives mainly consist of modified or unmodified PVA resin, a crosslinking agent having a dialdehyde structure, and water. Modified PVA resins include those obtained by saponifying a copolymer of a vinyl ester monomer and a copolymerizable monomer, and those obtained by modifying an unmodified PVA resin, such as acetoacetyl-modified PVA resin. Crosslinking agents having a dialdehyde structure include dialdehydes such as glutaraldehyde, succinaldehyde, and malondialdehyde. From the viewpoint of increasing the adhesion between the polarizer and the support, the content of modified or unmodified PVA resin in the total adhesive composition is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more. Furthermore, the content may be, for example, 12% by mass or less, 10% by mass or less, 8% by mass or less, or 6% by mass or less. 【0053】For solvent-based or solvent-free adhesives, transparent photocurable resins or thermosetting resins can be preferably used as the main component, such as acrylic resins, urethane resins, epoxy resins, silicone resins, rubber resins, polyvinyl ether resins, and polyester resins. Examples of solvents include commonly used organic solvents such as ethyl acetate, methyl ethyl ketone, toluene, and isopropanol. 【0054】 When a liquid crystal panel with a polarizing plate is exposed to light containing ultraviolet light for a long period of time, heat generated by this exposure can cause a phenomenon known as light leakage, in which the light transmittance changes due to internal stress in the polarizing plate. When light leakage occurs, the contrast within the panel surface becomes uneven, which may affect the accuracy during stereolithography. In such cases, it is preferable to use an adhesive with adjusted birefringence as disclosed in Japanese Patent Publication No. 2008-144125, Japanese Patent Publication No. 2008-144126, Japanese Patent Publication No. 2010-196000, etc., as the adhesive between the polarizing plate and the liquid crystal cell. 【0055】 There are no special restrictions on the thickness of the adhesive layer; it is preferable to set it to a normal thickness considering the physical properties. For example, the thickness of the adhesive layer is preferably 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 25 μm or less. 【0056】 The method for forming the adhesive layer is not particularly limited. For example, an adhesive composition can be obtained by diluting the solid component of an acrylic or polyester adhesive with a solvent such as toluene or methyl ethyl ketone (MEK), applying the composition to the object to be bonded, laminating it, and then curing the applied adhesive composition. Such an adhesive layer is generally formed on a release film. This release film is typically a polyethylene terephthalate (PET) resin film, which also serves as a surface protection film as described below. 【0057】(Other Layers) The polarizing plate of the present invention may have a surface protective film. The surface protective film is applied to the outer support surface of the polarizing plate mainly to prevent dirt and scratches on the polarizing plate product during the manufacturing process of the polarizing plate, and is generally removed when the polarizing plate product is mounted or used. The surface protective film may include an adhesive layer (tacky layer) for adhesion to the support, as well as various functional layers such as an easy-adhesion layer, an easy-slip layer, an anti-blocking layer, an antistatic layer, an anti-reflective layer, and an oligomer-preventing layer. The surface protective film is made of a thermoplastic resin, and is typically a PET resin film or a polyethylene (PE) resin film. The thickness of these films is, for example, 30 μm to 400 μm. Furthermore, in order to suppress the deterioration of the visual inspectionability of the polarizing plate product, it is preferable that the refractive index (Nz coefficient), slow axis, and phase difference value in the thickness direction of the film of the material are uniformly controlled. By using such a surface protective film, even with a polarizing plate configuration to which the surface protective film is applied, the occurrence of rainbow unevenness during visual inspection can be reduced and inspection can be performed. 【0058】 <Liquid Crystal Panel and Stereolithography Apparatus> The liquid crystal panel and stereolithography apparatus of the present invention will be described in detail below, but are not limited to the following. As shown in Figure 2, the stereolithography apparatus 300 comprises at least a light source 41, a platform 42, a resin tray 44 for holding photocurable resin 40, and a liquid crystal panel 200, and also comprises a processing system for imaging electronic data such as CAD information on the liquid crystal panel. Furthermore, the outer periphery of the stereolithography apparatus 300 may be provided with a protective cover or sheet that cuts ultraviolet light in order to prevent the photocurable resin from hardening due to incident ambient light and to protect the user's eyes from light leakage from the light source 41. Descriptions of the electrical and mechanical aspects related to the driving and control of the stereolithography apparatus 300, and descriptions of the housing for arranging and fixing the above components to form the system will be omitted. 【0059】The liquid crystal panel 200 is a control member in the stereolithography apparatus 300 for intermittently and selectively irradiating light from the light source 41 based on imaged electronic data such as CAD, and in this case, it is also called a liquid crystal shutter. The liquid crystal panel comprises a polarizing plate 100 positioned on the light incidence side of the liquid crystal cell 110 and a polarizing plate 100 positioned on the side where the light from the light source 41 is emitted to the bottom surface of the resin tray 44. The liquid crystal cell 110 and each polarizing plate 100 can be laminated using an adhesive layer. 【0060】 The liquid crystal panel 200 is constructed by sandwiching one polarizing plate 100 between two polarizing plates 100. Generally, the pair of polarizing plates 100 are arranged so that their polarization directions are orthogonal (crossed nicols). By arranging the polarizing plates 100 in this pair and changing the orientation state of the liquid crystal for each pixel in the liquid crystal cell 110 to control the polarization state of the light, it can function as a liquid crystal shutter in the stereolithography apparatus 300 and control the light from the light source 41. 【0061】 A liquid crystal cell 110 (also called a liquid crystal element) generally comprises a liquid crystal layer formed by injecting and sealing liquid crystal material between two alignment films, a transparent electrode for controlling the alignment of the liquid crystal, and a TFT (Thin Film Transistor) substrate on which a driving element for applying voltage to the transparent electrode is formed. By using a TFT driving method, a high-resolution liquid crystal cell can be made, thereby enabling the formation of highly detailed molded objects. The liquid crystal cell 100 can be various types of liquid crystal cells, such as the IPS method (IPS = In Plane Switching), FFS method (FFS = Fringe Field Switching), VA method (VA = Vertical Alignment), and TN method (TN = Twisted Nematic). 【0062】The polarizing plate 100 may include a phase difference layer in accordance with the method of the liquid crystal cell 110. In this case, a phase difference layer designed to be 1 / 4 wavelength or 1 / 2 wavelength with respect to the wavelength range of the light source is used. Alternatively, a phase difference layer for improving the viewing angle may be provided to improve the angle dependence of the emitted light, including ultraviolet light. The phase difference layer for improving the viewing angle varies depending on the type of liquid crystal panel used. In the case of a TN-LCD panel, a phase difference layer with hybrid orientation of discotic liquid crystals can be used; in the case of a VA-LCD panel, a phase difference layer called a negative C-plate can be used; and in the case of an IPS-LCD panel, a combination of two phase difference layers called an A-plate and a positive C-plate can be used. 【0063】 Furthermore, it is desirable that the liquid crystal material used in the liquid crystal cell 110 be capable of polarization control in the wavelength range of 350 to 450 nm, preferably 380 to 440 nm. 【0064】 In a stereolithography apparatus, the liquid crystal cell 110 only needs to be able to control polarization within the aforementioned wavelength range, and therefore does not need to have color filters such as RGB. This type of liquid crystal cell is also called a monocolor cell. 【0065】 The size of the shutter area of ​​a liquid crystal display (LCD) panel ranges from approximately 6 inches to 17 inches, with a typical range of 6 to 9 inches. The effective pixel count of this shutter area is generally in the range of approximately 2 million to 8 million pixels. These designs can be chosen according to the application of the stereolithography equipment and the size of the printed object. 【0066】 The light source 41 is used to photocur the photocurable resin by irradiating it with light containing a specific emission wavelength range. Generally, the light source 41 irradiates with light containing ultraviolet light, and is classified as UV-A (wavelength 315-400 nm), UV-B (wavelength 280-315 nm), and UV-C (wavelength 200-280 nm) depending on its wavelength range. As ultraviolet light becomes shorter in the wavelength range, not only does power consumption increase, but the irradiation energy also becomes stronger, increasing damage to the device and various components. Therefore, it is preferable that the light source 41 be classified as UV-A. 【0067】The light source 41 is generally an LED, and an LED that emits light including ultraviolet (UV) light is also called a "UV-LED". As for the emission characteristics of the UV-LED, one can be used that has an emission wavelength range of 350 to 450 nm, preferably 380 to 440 nm, and whose maximum emission wavelength is in the range of 360 to 420 nm, preferably 380 to 440 nm. Examples of the optical characteristics of commercially available UV-LEDs for the light source 41 include: an emission wavelength range of approximately 355-400 nm with a maximum emission wavelength of approximately 367 nm; an emission wavelength range of approximately 365-420 nm with a maximum emission wavelength of approximately 387 nm; an emission wavelength range of approximately 375-435 nm with a maximum emission wavelength of approximately 397 nm; an emission wavelength range of approximately 380-440 nm with a maximum emission wavelength of approximately 405 nm; an emission wavelength range of approximately 385-450 nm with a maximum emission wavelength of approximately 410 nm, and so on. The term "approximately" takes into account the measurement accuracy of the detection equipment and means that the emission wavelength range and maximum emission wavelength each include a tolerance of 5 nm or less, for example, 1-5 nm. 【0068】 If the light source 41 is, for example, a UV-LED, then, as shown in Figure 2, multiple light-emitting diodes may be arranged directly below the liquid crystal panel 200. In this case, it is preferable that the light-emitting diodes be miniaturized and arranged in a planar manner so as to match the display information of the pixels of the liquid crystal cell, and that they emit light in conjunction with the image information in order to enhance the contrast caused by the on and off of the liquid crystal shutter. Such control technology for liquid crystal displays is generally called local deming or area deming. 【0069】Platform 42 is a base for holding the object 43 that is formed by layering photocured resin. Generally, in the photopolymerization apparatus 300, at the start of the process, the bottom surface of the platform 42 and the bottom surface of the resin tray 44 are in contact, and a mechanism (also called a lift or elevator mechanism) is provided that increases the distance between the bottom surface of the platform 42 and the bottom surface of the resin tray 44 by a stepping motor or the like as the layering process of the object 43 progresses. Light including near ultraviolet light is irradiated onto any surface of the photocurable resin 40 via the liquid crystal panel 200 to harden the light-irradiated surface of the photocurable resin 40 and form a hardened layer of a desired thickness, and then the aforementioned photocurable resin 40 is supplied on top of the hardened layer and hardened in the same way to perform a layering operation to obtain a hardened layer continuous with the aforementioned hardened layer, and a three-dimensional object 43 is obtained by repeating this operation. 【0070】 The photocurable resin 40 is typically a liquid resin (generally also called "resin") that hardens in response to light including near-ultraviolet light, and includes acrylic resins containing (meth)acrylates made of monomers or oligomers, epoxy resins, photopolymerization initiators that generate photoradicals or ions, and photosensitizers. In addition, the photocurable resin 40 may also contain additives such as resin colorants and inorganic or organic fine particles, depending on the texture and design of the molded object. 【0071】 The resin tray 44 stores and holds the photocurable resin 40. The bottom surface of the resin tray 44 is made of a material that transmits light, including near-ultraviolet light, from the liquid crystal panel 200. 【0072】 In addition to the above, the stereolithography apparatus 300 may also be equipped with a filter in the optical path between the light source 41 and the liquid crystal panel that cuts (i.e., prevents transmission of) light in a specific wavelength range. For example, such a filter may be one that cuts wavelengths of 350 nm or less, or one that cuts wavelengths of 380 nm or less. Other options include a lens for focusing light from the light source. 【0073】 <Optical Measurement of Polarizing Plates> Optical measurements of polarizing plates can be performed, for example, using a spectrophotometer UH4150 manufactured by Hitachi High-Tech Science Corporation. 【0074】(Transmittance) Transmittance measurement is performed using natural light as the light source, in the visible light range of 380 nm to 780 nm. The detection conditions for the transmittance of each wavelength are set to a pitch of 10 nm or less, preferably 5 nm or less. Here, one test piece is placed at 0 degrees and 90 degrees relative to the transmission axis or absorption axis and measured separately. The average of these transmittances is taken as the single transmittance (Ts, unit: %), the transmittance obtained by overlapping the transmission axes or absorption axes of two test pieces in parallel is taken as the parallel transmittance (Tp, unit: %), and the transmittance obtained by overlapping the transmission axes or absorption axes of two test pieces orthogonally is taken as the orthogonal transmittance (Tc, unit: %), thereby obtaining the transmittance for each wavelength. The degree of polarization (P, unit: %) for each wavelength can be determined from formula (1). 【0075】 【0076】 From the transmittance obtained by the above measurement, the luminous efficiency-corrected transmittance can be calculated based on JIS Z 8722:2009. In this invention, it is determined as a D65 light source 2-degree field of view and expressed as luminous efficiency-corrected single transmittance (Ys, unit: %), luminous efficiency-corrected parallel transmittance (Yp, unit: %), luminous efficiency-corrected orthogonal transmittance (Yp, unit: %), and luminous efficiency-corrected polarization degree (Py, unit: %), respectively. Py is obtained by replacing Tp and Tc with Yp and Yc, respectively, in formula (1). Formula (2) is for determining Ys, where Ts(λ) is the transmittance of the polarizer alone, S(λ) is the standard light source, and y(λ) is the 2-degree field of view color matching function. Yp and Yc are obtained by replacing Ts(λ) with Tp and Tc, respectively, in formula (2). 【0077】 【0078】(Dichroism of Polarizers) A dichroic dye in a polarizer is a dye that, when oriented on an orientation substrate, exhibits different absorbances in the long axis direction and the short axis direction of its molecule. The dichroism (Rd) is expressed by formula (3) as the ratio of the absorbance in the direction of maximum transmission (Ay) to the absorbance in the direction perpendicular to the direction of maximum transmission (Az) under linearly polarized light incidence. A higher Rd value indicates better polarization characteristics. Rd is usually determined by a spectroscopic measurement method after fabricating a polarizing element in which the dye is oriented under conditions that allow for maximum orientation on the orientation substrate. Typically, a PVA-based resin film can be used as the orientation substrate. 【0079】 【0080】 (Lightfastness Test of Polarizing Plates) The lightfastness test of polarizing plates is a test to evaluate the durability of polarizing plates against ultraviolet light under conditions that simulate actual use in stereolithography equipment, and can be carried out as follows, but is not limited thereto. In this test method, for example, a polarizing plate cut into 5 to 10 cm squares is bonded to a glass plate via an adhesive layer, a UV-LED lamp with a maximum emission wavelength of around 385 nm is used as the light source, and the output of the light source is set to 0.1 to 1.5 W / cm². ２ The light source is set to a range of 1 to 10 cm, and the distance between the light source and the test specimen is set to 1 to 10 cm. The polarizing plate surface of the test specimen is irradiated with light for a predetermined time. The test specimen is evaluated by spectral measurements (particularly the change in transmittance and polarization degree of the polarizing plate near the light source wavelength range) of the test specimen before and after the test, L ＊ a ＊ b ＊ This can be done by calculating the hue value using a color system, visually inspecting the appearance, etc. 【0081】 The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The polarizing plates produced in Examples 1-2 and Comparative Examples 1, 2, and 4-6 should be based on the optical properties of Reference Examples 1-2, with Tp ４００ The percentage was adjusted to be in the 20% range or higher. 【0082】[Example 1] (1) Preparation of polarizer Compound 1 of formula (3) was prepared as the dichroic azo dye compound of formula (1) based on the synthesis method disclosed in Synthesis Example 1 of International Publication WO2005 / 015275. Also, compound 2 of formula (4) was prepared as the dichroic azo dye compound of formula (2) based on the synthesis method disclosed in Synthesis Example 2 of Japanese Patent Application Publication No. 2001-056412. 【0083】 Next, compound 1, compound 2, and sodium sulfate were dissolved in water to prepare a dyeing solution. At this time, the mixing ratio (mass ratio; the same applies hereinafter) of compound 2 to compound 1 was 1:3.5. Next, a PVA resin film (VF-PS#7500 manufactured by Kuraray Co., Ltd.) was immersed in water while being uniaxially stretched to swell it, then immersed in the dyeing solution, and then stretched with an aqueous boric acid solution to orient the dye in the resin film. The total uniaxial stretching ratio from swelling to boric acid treatment was 6 times. After stretching, a polarizer was obtained by drying in a 70°C dryer for 3 minutes while maintaining tension. 【0084】 (2) Fabrication of a polarizing plate The polarizer, the first support, and the second support were bonded together using a water-based adhesive layer containing a PVA resin (Gosenex Z-200 manufactured by Mitsubishi Chemical Corporation) (resin solids content: 2.0 wt%), and the moisture was removed and the plates were bonded by drying at 80°C for 3 minutes, thereby fabricating a polarizing plate with supports on both sides of the polarizer. As the first and second supports, a TAC film (13SG80S-LH manufactured by Island Polymer Industries GmbH, film thickness 80 μm) that does not contain an ultraviolet absorber and was saponified (immersed in a 2 N sodium hydroxide aqueous solution at 40°C for 10 minutes) was used. The optical properties of the obtained polarizing plate were measured using a Hitachi High-Tech Science UH4150 spectrophotometer, and the measurement results of the optical properties in the near-ultraviolet light region and the visible light region are shown in Table 1. Figure 4 shows the wavelength dependence of the transmittance of the polarizing plate. 【0085】 (3) Color of the polarizing plate The color of the polarizing plate was determined by visually observing the color of the manufactured polarizing plate in a room under fluorescent lighting, and a unified opinion was obtained from three persons skilled in the art. 【0086】(4) Visual Inspectability with Visible Light The visual inspection test with visible light was performed as a transmission test based on the configuration shown in Figure 8. Specifically, a white LED high-brightness LED panel power supply (RVC60PT100) manufactured by DSK Dentsu Sangyo Co., Ltd. was used as the light source (backlight) 50, and an iodine-based polarizing plate (SKN-18243P, manufactured by Nippon Kayaku Co., Ltd., Ys=43%, Py=99.9%) was placed on top of it as the standard polarizing plate 101. Furthermore, a small amount of silicon dioxide powder (average particle size 75-150 μm) was sprinkled on the upper surface of the standard polarizing plate 101 to simulate foreign matter between the layers of the polarizing plate (shown as foreign matter 60 in Figure 8). Furthermore, the polarizing plate 100 prepared in (2) above was placed above the standard polarizing plate 101, and the polarizing plate 100 and the standard polarizing plate 101 were positioned so that their absorption axes were perpendicular to each other so that the light from the light source 50 would be extinguished (dimmed). The test was conducted in a darkroom, and the brightness of light source 50 was approximately 1000 cd / m². ２ The polarizer was lit, and three persons skilled in the art observed the appearance of the foreign matter 60 from above the polarizer 100. They evaluated it according to the following criteria and obtained a unified opinion. Under these conditions, the foreign matter between the layers is observed as bright spots. 【0087】 Criteria for evaluation: A: The backlight is dimmed, making the foreign object appear as a bright spot and easily visible. B: Inferior to A, but the backlight is dimmed, making the foreign object appear as a bright spot. C: The backlight is not dimmed, making the foreign object difficult to see. 【0088】 [Example 2] This is the same as Example 1, except that the mixing ratio of compound 2 to compound 1 was 1:8.5. 【0089】 [Comparative Example 1] This is the same as Example 1, except that a polarizer was made using only compound 1 in (1). Figure 5 shows the wavelength dependence of the transmittance of the polarizer. 【0090】 [Comparative Example 2] This is the same as Example 1, except that the polarizer was made using only compound 2 in (1). Figure 6 shows the wavelength dependence of the transmittance of the polarizer. 【0091】[Comparative Example 3] The polarizer was prepared in the same way as in Comparative Example 2, except that the staining time was increased by approximately 1.5 times. 【0092】 [Comparative Example 4] This is the same as Example 1, except that in Example 1 (1), the polarizer was made using only commercially available Direct Red 81 (Red 4BH, manufactured by Nippon Chemical Industries, Ltd.) as the dichroic azo dye compound. Figure 7 shows the wavelength dependence of the transmittance of the polarizer. 【0093】 [Comparative Example 5] This is the same as in Example 1 (1), except that the mixing ratio of compound 2 to compound 1 was 1:35. 【0094】 [Comparative Example 6] The procedure is the same as in Example 1 (1), except that a polarizer containing compound 1 and the compound of Comparative Example 4 in a mixing ratio of 1:3.4 was prepared. 【0095】 [Reference Example 1] To compare with Examples 1-2 and Comparative Examples 1-6, an iodine-based polarizer (SKN-18043P, manufactured by Nippon Kayaku Co., Ltd.) was used as a general organic absorption polarizer having polarization characteristics in the visible light range. This polarizer has a polarizer made of a PVA resin containing iodine, and the polarizer is sandwiched between a TAC film (thickness 80 μm) that does not contain an ultraviolet absorber as a support. This polarizer was evaluated in the same manner as in Examples 1-2 and Comparative Examples 1-6, and the results are shown in Table 1. 【0096】 [Reference Example 2] For comparison with Examples 1-2 and Comparative Examples 1-6, a dye-based polarizer (SHC-13P, manufactured by Nippon Kayaku Co., Ltd.) was used as a general organic absorption polarizer having polarization characteristics in the visible light range. This polarizer has a polarizer made of a PVA resin containing multiple azo dye compounds, and the polarizer is sandwiched between a TAC film (thickness 80 μm) that does not contain an ultraviolet absorber as a support. This polarizer was evaluated in the same manner as in Examples 1-2 and Comparative Examples 1-6, and the results are shown in Table 1. 【0097】 【0098】 The polarizing plates of Examples 1 and 2 have a dichromatic ratio Rd of 400 nm. ４００ 20 or more, contrast ratio CR (Tp４００ / Tc ４００ By setting the polarizer to 1000 or more and the contrast ratio CR(Yp / Yc) value to 10 or more, it was confirmed that the polarizer exhibited excellent polarization characteristics at a wavelength of 400 nm while also having good visual inspection properties in visible light. These polarizers exhibited a dark green color. Furthermore, these polarizers had a CR(Tp ３８５ / Tc ３８５ Since the value is 1000 or more, it has high polarization characteristics over a wide range in the near-ultraviolet light region, and can be applied to light sources with wavelengths of, for example, 385 nm. 【0099】 Comparative Example 1 is a case in which only the dye of formula (1) is used in the polarizing plate. This polarizing plate is CR(Tp ４００ / Tc ４００ The value of ) is 30060, and CR (Tp ３８５ / Tc ３８５ The value of ) is 2813, indicating high optical properties in the near-ultraviolet light range. However, the value of CR(Yp / Yc) is 1, which means that it does not extinguish light due to polarization. Furthermore, in a test of the visual inspection capability of the polarizing plate using visible light, it was confirmed that it could not extinguish light in the visible light range, making inspection difficult. 【0100】 The polarizers in Comparative Examples 2 and 3 were those using only the dye of formula (2). When this dye was used alone, the CR (Yp / Yc) value was improved compared to Comparative Example 1, but the dichromatic ratio in the near-ultraviolet light region was approximately 14 to 18, and it was evaluated that it did not have sufficient performance for use in a stereolithography apparatus compared to Examples 1 and 2. 【0101】 The polarizer in Comparative Example 4 uses Rd as another dye having a relatively high dichroic ratio at a wavelength of 400 nm. ４００ This case involved using only reddish dyes with a value of 16.6. Compared to Reference Examples 1 and 2, such polarizing plates were unable to provide sufficient polarization characteristics in the near-ultraviolet light range. Furthermore, the CR (Yp / Yc) value was lower than that of Comparative Examples 2 and 3, confirming that the visual inspection capability under visible light was not improved. 【0102】Comparative Example 5 uses a combination of the dye of formula (1) and the dye of formula (2), similar to Examples 1 and 2, but with a significantly increased proportion of the dye of formula (2). With this formulation, the optical properties in the near-ultraviolet region were not significantly different from those of Reference Example 2. 【0103】 The polarizing plate of Comparative Example 6 was obtained by combining the dye of formula (1) and the dye of Comparative Example 4. In this case, similar to Examples 1 and 2, excellent optical properties in the near-ultraviolet region were obtained. However, the CR (Yp / Yc) value was 3, resulting in poor visual inspection in visible light, and thus the effects of the present invention were not achieved. 【0104】 The polarizing plate of the present invention possesses high polarization characteristics in the near-ultraviolet light range while also having polarization characteristics in the visible light range. Therefore, this polarizing plate is not only suitable as a polarizing plate for stereolithography equipment, but can also be handled in the same way as existing gray-colored polarizing plate products in the visual inspection process of the polarizing plate manufacturing process without changing any special inspection methods. Furthermore, because the polarizing plate of the present invention has polarization characteristics in the visible light range, it can detect light leakage phenomena in visible light in light leakage tests performed to evaluate the durability of liquid crystal panels, for example, without the need to construct a special method for evaluation. In addition, the inventors have newly discovered that in the manufacture of the polarizing plate, a metal-complexed azo dye compound, such as a copper-based azo dye compound, which has high polarization characteristics in the visible light range and the near-ultraviolet light range, can be used in combination with yellow or orange dye compounds. As a result, polarization characteristics in the visible light range (or partially visible light range) can be imparted to the polarizing plate without complex formulations compared to conventional dye-based polarizing plates designed for the visible light range, and furthermore, an improvement in the light resistance of the polarizing plate to ultraviolet light sources can be expected, which may make it possible to further extend the operating time of the stereolithography equipment. 【0105】10 First support 11 Second support 20 Polarizer 30 Adhesive layer 100 Polarizing plate 40 Photocurable resin 41 Light source (UV-LED) 42 Platform 43 Molded object 44 Resin tray 110 Liquid crystal cell 200 Liquid crystal panel 300 Stereolithography apparatus 50 Backlight 101 Standard polarizing plate 50 Light source (backlight) 51 Light-emitting surface of light source 52 Light from light source 53 Light from extinguished (dimmed) light source 60 Foreign matter 400 Conceptual diagram of transmission inspection

Claims

1. A polarizing plate comprising a support and a polarizer, wherein the polarizer contains at least two dichroic azo dye compounds having polarization properties in the near-ultraviolet region (wavelength 360-420 nm), and the polarizing plate has a dichroism ratio Rd at a wavelength of 400 nm. ４００ The value is 20 or more, and the parallel transmittance Tp at a wavelength of 400 nm is ４００ and orthogonal transmittance Tc ４００ The contrast ratio CR(Tp) is determined from this. ４００ / Tc ４００ A polarizing plate characterized in that the ) is 1000 or more, and the contrast ratio CR(Yp / Yc) obtained from the parallel transmittance Yp and orthogonal transmittance Yc in the visible light range corrected for luminous efficiency is 10 or more.

2. Further, the dichroic ratio Rd at a wavelength of 385 nm ３８５ is 17 or more, and the parallel transmittance Tp at a wavelength of 385 nm ３８５ and the orthogonal transmittance Tc ３８５ The contrast ratio CR (Tp ３８５ / Tc ３８５ ) is 1000 or more. The polarizing plate according to claim 1.

3. The dichroic azo dye compounds include at least two compounds, namely compound A and compound B, wherein compound A has a maximum absorption wavelength λmax of 370 to 470 nm and a dichroism Rd at 400 nm. ４００ The ratio is 42-48, and compound B has a maximum absorption wavelength λmax of 660-680 nm, and a dichromatic ratio Rd at 400 nm. ４００ The polarizing plate according to claim 1 or 2, wherein the value is 17 to 20.

4. The polarizing plate according to claim 1 or 2, wherein one of the dichroic azo dye compounds is an azo compound shown in formula (1) or a salt thereof, and the other of the dichroic azo dye compounds is an azo compound shown in formula (2), a salt thereof, or a copper complex salt thereof: Here, equation (1) is expressed in the form of free acid Q １ Q represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or carboxyl group. ２ Q represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or carboxyl group. ３ Q represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or hydroxyl group. ４ represents a hydrogen atom, halogen atom, lower alkyl group, lower alkoxy group, or hydroxyl group, and X is O, S, NH, or NCH ３ This represents a value where l represents 0, 1, or 2, m represents 0, 1, or 2, and l + m is 2 or 4. Here, formula (2) is expressed in the form of a free acid, where n represents 0 or 1, X represents a nitro group or an amino group, and R １ , R ２ , R ３ , R ４ Each of these independently represents a hydrogen atom, a methyl group, an ethyl group, a methoxy group, an ethoxy group, or an acetylamino group, R ５ R represents a hydroxyl group or an unsubstituted or substituted amino group. ６ The group represents a hydrogen atom, a hydroxyl group, an unsubstituted or substituted amino group, a methyl group, an ethyl group, a methoxy group, or an ethoxy group.

5. A stereolithography apparatus comprising a light source and a liquid crystal shutter, wherein a photocurable resin is sequentially cured and layered by irradiating light controlled by the liquid crystal shutter to form a three-dimensional object, the light source being an LED light source having a maximum emission wavelength in the range of 360 to 420 nm, and the liquid crystal shutter being a liquid crystal panel comprising a pair of polarizing plates as described in claim 1 or 2.

6. A stereolithography apparatus comprising a light source and a liquid crystal shutter, wherein a photocurable resin is sequentially cured and layered by irradiating light controlled by the liquid crystal shutter to form a three-dimensional object, the light source being an LED light source having a maximum emission wavelength in the range of 360 to 420 nm, and the liquid crystal shutter being a liquid crystal panel comprising a pair of polarizing plates as described in claim 3.

7. A stereolithography apparatus comprising a light source and a liquid crystal shutter, wherein a photocurable resin is sequentially cured and layered by irradiating light controlled by the liquid crystal shutter to form a three-dimensional object, the light source being an LED light source having a maximum emission wavelength in the range of 360 to 420 nm, and the liquid crystal shutter being a liquid crystal panel comprising a pair of polarizing plates as described in claim 4.

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