TWI582472B - Polarizer and polarizing plate - Google Patents

Description

Polarizing element and polarizing plate

The present invention relates to a polarizing element and a polarizing plate using the same.

The polarizing element is usually produced by adsorbing an iodine complex or a dichroic dye which is a dichroic dye to a polyvinyl alcohol resin film. A protective film containing cellulose triacetate or the like is bonded to at least one surface of the polarizing element via an adhesive layer to form a polarizing plate. Since the polarizing plate has a light penetrating and shielding function, it is a basic component of a display device such as a liquid crystal display (LCD) together with a liquid crystal having a light switching function. The field of application of LCD has also expanded from notebooks, word processors, LCD projectors, LCD TVs, car navigation, mobile phones and indoor and outdoor measuring devices to small devices such as calculators and watches at the beginning. It is used under a wide range of conditions from low temperature to high temperature, low humidity to high humidity, low light quantity to high light quantity. Therefore, a polarizing plate having high polarizing performance and excellent durability is sought. Further, a polarizing plate using an iodine complex as a dichroic dye is referred to as an iodine-based polarizing plate, and a polarizing plate using a dichroic dye as a dichroic dye is referred to as a dye-based polarizing plate. Among these, an iodine-based polarizing plate is often used in terms of excellent optical characteristics. When a dye-based polarizing plate is compared with an iodine-based polarizing plate, if a polarizing plate having the same degree of polarization is compared, there is a problem that the transmittance is low, that is, the contrast is low, but the heat resistance is high, and the heat is high. The characteristics of durability are used in a color liquid crystal projector or the like (Patent Document 1).

Currently, it is used as a light source for LCDs represented by liquid crystal televisions. A light source of a CCFL (Cold Cathode Fluorescent Lamp) or a high-pressure mercury lamp has been widely used in recent years, such as a light-emitting diode (LED) of Patent Document 2 or Patent Document 3, and a white LED is widely used. . Using the polarizing plates of these light sources, a commonly known neutral gray iodine polarizing plate is used. The iodine polarizing plate has a high contrast characteristic in a wide wavelength region, and is used for a CCFL or a high pressure mercury lamp, and a white LED.

Moreover, the function of the liquid crystal panel including the polarizing plate and the liquid crystal not only has a light switching function of penetrating and shielding light, but also a color filter in the liquid crystal panel, and functions as a display image. As a subject of this problem, there is a problem that light leakage occurs depending on the angle of the viewing image due to the alignment direction of the liquid crystal, and the image is not visible, that is, the angle of view is narrow. The types of liquid crystals can be VA type (Vertical Aligned), TN type (Twisted Nematic), IPS (In-Plane Switching), and the like. The difference is different, but any method has a narrow perspective. In order to fill the narrow angle of view, it is widely used to align a PC (polycarbonate) film, a COP (cycloolefin) film, or a disc-shaped liquid crystal in a specific direction and apply TAC (triacetyl cellulose, three An optical compensation film such as a cellulose acetate film.

As a display using a liquid crystal technology, for example, a blue light-emitting diode is used instead of a color filter in a backlight device, and a phosphor having various color lights excited by blue light is known (hereinafter, referred to as a firefly). Light-excited color conversion display). For example, it is disclosed in Patent Document 4. The phosphor-activated color conversion type liquid crystal display device uses a phosphor to be self-backlit device The emitted light is wavelength-converted, and the desired color display is performed using the obtained fluorescent light. This liquid crystal display device differs from the color filter type liquid crystal display device in that it does not have absorption loss of light due to the color filter, and therefore has a feature that light utilization efficiency is high. Further, it is characterized in that there is no problem that the viewing angle as a subject in the prior LCD is narrow, and an image display with high image quality can be obtained. In this light source, a light source of a blue region is used in order to increase the luminous efficiency of the phosphor. In the blue area light source, a blue LED or a blue fluorescent tube with a maximum light output of 440 nm to 470 nm is used.

In general, in a flat panel display, including all images and all viewing angles, the in-screen contrast must be 50 or more. More preferably, the contrast in the screen must be 100 or more. The "intra-screen contrast" refers to the ratio of the brightness of the brightest pixel to the darkest pixel when the state of one image is displayed. Furthermore, the "panel contrast" generally used refers to the ratio of the brightness at the time of full white display to the brightness at the time of full black display. However, an image such as an all-white display or an all-black display does not substantially exist in reality. Moreover, if the contrast becomes too high, the fatigue of the eyes is enhanced. Therefore, the "intra-screen contrast" is recommended to be 50 or more, and more preferably 100 or more, as a requirement for the ergonomic contrast ratio (Non-Patent Document 1).

The required intra-picture contrast varies depending on the illumination of the surrounding area of the flat panel display. That is, the brighter the ambient illuminance, the smaller the contrast within the screen required, and the darker the ambient illuminance, the greater the contrast within the screen required. When the peripheral illuminance changes within 0 to 500 lux, the required intra-screen contrast value is shown in Table 1.

As the average signal level (ASL) of the general television broadcast, or the average brightness level ALL (Average Luminance Level), the average ASL is 40%, the ALL is about 20%, and the range ASL is 20~60. About %, ALL is about 5~40%. When viewing these images on a 65-inch TV, the report is based on the illumination of the general living room at 180 lux, and the viewing distance is 3 H (three times the distance when the height of the TV is counted as H). The maximum brightness is preferably 240 cd/m ² (Non-Patent Document 2). Here, when the ambient illuminance of the general room is 180 lux, in order to make the contrast in the indoor screen 50 or more, it can be seen from Table 1 that the contrast in the dark room screen must be 200 or more.

The condition for minimizing the contrast in the screen is when the entire image is displayed as a dark image. When the darkest image is displayed, the brightness of the brightest pixel in the screen is about 5% of the maximum brightness (Non-Patent Document 3). In the case of a display having a maximum brightness of 240 cd/m ² , the brightness of the brightest pixel in the picture is about 12 cd/m ² . Under these conditions, in order to make the contrast in the screen 200 or more, it is necessary to control the brightness of the darkest pixel in the screen to about 0.06 cd/m ² or less. That is, in order to satisfy the above-described condition that the brightness of the brightest pixel in the screen is 240 cd/m ² and the brightness of the darkest pixel in the screen is 0.06 cd/m ² , the panel contrast must be 4,000. In addition, the panel contrast ratio represents the ratio of the transmittance at the time of light penetration (parallel polarization) when a liquid crystal panel is sandwiched between a pair of polarizing plates and the transmittance at the time of light interruption (orthogonal polarization).

Table 2 shows the relationship between the in-screen contrast, panel contrast, and polarizer contrast of the fluorescent excitation color conversion display.

According to Table 2, when the panel contrast is 4,000, the polarizer contrast must be 6,000. In addition, the contrast of the polarizing plate of Table 2 indicates the light energy transmittance Ep when the light is transmitted (in the case of the passage state/polarized plate when the polarizing plate is polarized), and the light-off state (when the circuit is in a state of being disconnected/polarized by the polarizing plate) The ratio of the light energy penetration rate Ec. The light energy transmittance Ep represents the energy of the amount of light (blue light) incident on the phosphor layer per unit area in a specific wavelength range in the light transmission state. The light energy transmittance Ec in the blocking state indicates the amount of light (blue light) of the incident light per unit area of the phosphor layer in a specific wavelength range in the light blocking state.

In the method of fluorescing the color conversion display, R, G, and B colors are generated by injecting blue light into the phosphor, and the brightness of the display device is multiplied by the spectroscopic radiance of the light emitted by the phosphor. The value determines the spectral radiance of the light emitted from the phosphor and the blue color of the excited phosphor The incident energy of light is proportional. Moreover, even if it is blue light, it will generate similarly by the influence of the depolarization light which penetrates a liquid-crystal panel. For the above reasons, it can be considered that the polarizing plate contrast (Ep/Ec) of the pair of polarizing plates by the necessary energy transmittance is equal to the polarizing plate contrast (Tp/Tc) by the spectral transmittance. In addition, the Tp is a spectral transmittance (transparency at the time of parallel polarization) when the absorption axes of the two polarizing elements are overlapped in parallel, and the Tc is a splitting when the absorption axes of the two polarizing elements are orthogonally overlapped. Transmittance (transmission rate during orthogonal polarization). However, since the wavelength of the light emitted by the phosphor depends on the band structure represented by the phosphor material, it is not necessary to pay attention to the intensity of the excitation light of a specific wavelength, and it is necessary to estimate the energy of the light that excites the phosphor.

According to the above, when the polarizing plate contrast ratio (Ep/Ec) of the light energy transmittance is set to 6,000, especially at any wavelength in the maximum light-emitting output region of the backlight device, the light is penetrated by the splitting light. The polarizing plate contrast ratio (Tp/Tc) must be a value higher than 6,000, preferably a contrast ratio (Tp/Tc) of 8,000. Further, in order to set the contrast (Ep/Ec) of the energy transmittance of light to a higher value, the polarizing plate contrast (Tp/Tc) by the spectral transmittance must also be set to a higher value.

It is considered that it is further preferable that the intra-picture contrast ≧100 is 300 lux. In this case, according to Tables 1 and 2, the contrast in the darkroom is ≧350, and the contrast of the polarizing plate with energy transmittance is ≧15,000, and the contrast of the polarizing plate by the spectral transmittance, especially in the backlight. The contrast must be 20,000 or more between any wavelengths within the maximum illumination output area of the device.

Moreover, the liquid crystal display device of the prior art represents a brightness distribution that roughly reflects the directivity of the backlight device, and the manner in which the fluorescent light activates the color conversion display The use of the isotropic light emission by the phosphor is characterized by a wide viewing angle. On the other hand, the surface brightness directivity is lowered to a low degree. It is considered that when the full-width value of the half-peak is changed from 30 degrees to a full-width half-degree of 45 degrees, the front luminance is roughly reduced by half.

Generally, the video signals of television and video are usually expressed in the 0~255 gray scale which can be expressed in 8 bits, and are expressed by 16~235 gray scale. However, up to 255 gray levels can also be used in the brightness extension mode called the ultra white mode. In the case of all white display, when the brightness of 400 cd/m ^{2 is} obtained with 235 gray scale, the brightness when 255 gray scale is displayed in the super white mode is about 1.2 times 487 cd when the gamma is set to 2.2. m ² . A comparison of the maximum white brightness with the maximum display brightness of the ultra white mode is shown in Table 3. In the method of fluorescing the color conversion display, when the value of the energy transmittance Ep of the light in the light transmission state (in the case of parallel polarization) of the polarizing plate is 30% or more, the optimum brightness is 240 cd/m ^{2 .} . In order to obtain an Ep of 30% or more, the transmittance Tp at the time of parallel polarization by the spectral transmittance must be 30% or more.

Although it is known that a general neutral gray iodine polarizer has a high contrast ratio in a wide wavelength region, in a blue light source region having a maximum light output of 440 nm to 470 nm for use in a fluorescent excitation color conversion display, light leakage occurs. More and less sufficient contrast is not obtained, and the brightness is not sufficient. As for the converter case where the polarizing plate of the display color for fluorescent excitation, has yet to be reached maximum brightness 240 cd / m Ep ² of ≧ 30%, and the maximum brightness of 240 cd / m ² of the darkroom A polarizing plate having a contrast ratio of (Ep/Ec) 6,000 in which the contrast of the screen is 200 or more is obtained.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2001-027708

[Patent Document 2] Japanese Patent No. 3585097

[Patent Document 3] Japanese Patent No. 4686644

[Patent Document 4] Japanese Patent Laid-Open No. 2009-134275

[Non-patent literature]

[Non-Patent Document 1] SID' 03 Digest p. 779

[Non-Patent Document 2] Journal of Electronic Information and Communication Society, J91-A (6), pp. 630-638 (2008)

[Non-Patent Document 3] JJAP vol. 46, 3B, 2007, p. 1358

As described above, as a polarizing plate in a fluorescent excitation color conversion display for use as a light source for a blue LED or a blue fluorescent tube having a maximum light output of 440 nm to 470 nm, it is known in the prior iodine-based polarizing plate. Since there is a problem that the contrast ratio in the wavelength region is low and the transmittance at the time of light leakage or light penetration is low, a sufficient display image cannot be obtained. Therefore the lesson of the present invention The object of the present invention is to provide a polarizing element and a polarizing plate which are suitable for the display and which are characterized by high contrast and low light leakage, and high transmittance when light is transmitted.

In order to solve the above problems, the inventors of the present invention have conducted intensive studies and found that at least a dichroic dye is contained, and the contrast ratio in the wavelength region of 440 nm ≦λ ≦ 470 nm is high and the transmittance at the time of light penetration is high. The polarizing element and the polarizing plate solve the above problems, and the present invention has been achieved.

That is, the present invention relates to

(1) A polarizing element for use in a fluorescent excitation color conversion display using a blue LED or a blue fluorescent tube having a maximum light output of 440 nm to 470 nm as a light source, characterized by: 440 于 at 440 nm In the wavelength region of ≦470 nm, Tp ≧ 30%, and CR ≧ 8,000 in the wavelength region between any successive 20 nm in the wavelength region, CR ≧ 5,000 in the remaining wavelength region, and at least containing dichroic pigment.

Here, λ represents a wavelength, and Tp refers to a spectral transmittance (transparency at the time of parallel polarization) when the absorption axes of the two polarizing elements are overlapped in parallel, and the Tc means that the absorption axes of the two polarizing elements are positive. The spectral transmittance at the time of overlap (transmission ratio at the time of orthogonal polarization), the term "CR" refers to the abbreviation of contrast and indicates the value including Tp/Tc.

(2) The polarizing element of (1), wherein Tp ≧ 30% and CR ≧ 1,500 in a wavelength region of 420 nm ≦ λ < 440 nm.

(3) The polarizing element according to (1) or (2), wherein Tp ≧ 30% and CR ≧ 1,000 in a wavelength region of 470 nm < λ 490 nm.

(4) The polarizing element according to any one of (1) to (3), wherein the dichroic dye Containing at least one of the dichroic dye (A) group and/or the dichroic dye (B) represented by the formula (1):

Dichroic dye (A) group

C.I. Direct Orange 26

C.I. Direct Orange 39

C.I. Direct Orange 107

Dichroic dye (B)

(wherein R ₁ and R ₂ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, and n = 1 to 3).

(5) The polarizing element according to any one of (1) to (4), wherein the transmittance is 2% or less in a wavelength region of 500 nm ≦λ ≦ 560 nm.

(6) The polarizing element according to any one of (1) to (3) wherein the dichroic dye is an iodine complex and Tc(λ460)≦Tc(λ600).

Here, Tc (λ460) refers to the spectral transmittance of 460 nm when the absorption axes of the two polarizing elements are orthogonally overlapped (when parallel polarized light), and Tc (λ600) means that the respective absorption axes of the two polarizing elements are orthogonal. The split transmittance of 600 nm at the time of overlap (when orthogonally polarized).

(7) The polarizing plate according to any one of (1) to (6), wherein the support film is provided on at least one surface of the polarizing element.

(8) The polarizing plate of (7), wherein at least one side of the support film is a PET (polyester) film.

(9) A polarizing plate with an inorganic substrate, characterized in that a polarizing element according to any one of (1) to (6) or a polarizing plate of (7) or (8) is laminated on the inorganic substrate.

The polarizing element of the invention and the polarizing plate using the same have high polarization performance in a wavelength region of 440 nm ≦ λ ≦ 470 nm, and can provide a blue LED or blue fluorite suitable for 440 nm to 470 nm. The light pipe acts as a light source to excite the polarizing plate in the color conversion display.

The polarizing element of the present invention has a Tp ≧ 30% in a wavelength region of 440 nm ≦ λ ≦ 470 nm, and CR ≧ 8,000 in the wavelength region between any successive 20 nm in the wavelength region, and CR ≧ 5,000 in the remaining wavelength region. . By using such a polarizing element of the present invention, sufficient brightness and contrast can be obtained in a fluorescent excitation color conversion display using a blue LED or a blue fluorescent tube having a maximum light output of 440 nm to 470 nm as a light source. . In the display of the display, in the wavelength region of 440 nm ≦ λ ≦ 470 nm, if CR < 8,000 in the wavelength region between any continuous 20 nm and CR < 5,000 in the remaining wavelength region, sufficient contrast cannot be obtained. The tendency is that CR ≧ 8,000 must be in the wavelength region between any successive 20 nm and CR ≧ 5,000 in the remaining wavelength region. Preferably, the wavelength region between at least any successive 20 nm in the wavelength region of 440 nm ≦ λ ≦ 470 nm is CR ≧ 10,000, more preferably CR ≧ 15,000. Further preferably for 450 The wavelength region of nm ≦ λ 460 nm, CR ≧ 20,000. Regarding the contrast value, the CR value can be increased by lowering the single-plate transmittance of the polarizing element, but in this case, the Tp value is also lowered, so that sufficient brightness cannot be obtained. When Tp < 30%, sufficient brightness is not obtained, and Tp ≧ 30% is excellent in light use efficiency, and power consumption can be reduced. It is preferably Tp ≧ 31%, more preferably Tp ≧ 32%.

Further, the polarizing element of the present invention preferably has a Tp ≧ 30% and a CR ≧ 1,500 in a wavelength region of 420 nm ≦ λ < 440 nm. Preferably, the blue LED or the blue fluorescent tube having a maximum light output of 440 nm to 470 nm controls the weak light emission on the short wavelength side. When the display is displayed, if the CR is less than 1,500 in the above wavelength region, there is contrast. The tendency to lower is preferably CR ≧ 1,500, more preferably CR ≧ 3,000, and still more preferably CR ≧ 5,000. Further, similarly to the wavelength region of 440 nm ≦λ ≦ 470 nm, when Tp < 30%, sufficient luminance is not obtained, and when Tp ≧ 30% is excellent in light use efficiency, power consumption can be reduced. It is preferably Tp ≧ 31%, more preferably Tp ≧ 32%.

Further, the polarizing element of the present invention is at 470 nm<λ In the wavelength region of 490 nm, Tp ≧ 30% and CR ≧ 1,000 are preferable. Preferably, the blue LED or the blue fluorescent tube having a maximum light output of 440 nm to 470 nm controls the weak light emission on the long wavelength side. When the display is displayed, if CR<1,000 in the above wavelength region, there is The tendency of the contrast to decrease is preferably CR ≧ 1,000, more preferably CR ≧ 2,500, and still more preferably CR ≧ 4,000. Further, similarly to the wavelength region of 440 nm ≦λ ≦ 470 nm, when Tp < 30%, sufficient luminance is not obtained, and when Tp ≧ 30% is excellent in light use efficiency, power consumption can be reduced. It is preferably Tp ≧ 31%, more preferably Tp ≧ 32%.

The polarizing element of the present invention contains at least a dichroic dye. Examples of the dichroic dye include an iodine complex, a dichroic dye, and the like.

When a dichroic dye is used as the dichroic dye used in the polarizing element of the present invention, it is preferred to use at least one of the dichroic dye (A) group and/or the two colors represented by the formula (1). Sex dye (B).

Dichroic dye (A) group

C.I. Direct Orange 26

C.I. Direct Orange 39

C.I. Direct Orange 107

Dichroic dye (B)

(wherein R ₁ and R ₂ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, and n = 1 to 3).

The dichroic dye (A) group is a dye which exhibits any higher dichroism, and is characterized in that the wavelength (λmax) indicating the maximum contrast value is 420 nm ≦ λ max ≦ 460 nm. Among them, C.I. Direct Orange 39 is better used.

The dichroic dye (B) represented by the formula (1) is a dye which exhibits high dichroism, and is characterized in that the wavelength (λmax) indicating the maximum contrast value is 450 nm ≦ λ max ≦ 470 nm.

In the formula (1), R ₁ and R _{2 are} preferably a hydrogen atom. Further, a mixture of compounds containing n = 1 to 3 is preferable, and the ratio of the weight of the compound of n = 2 to the total weight of the compound of n = 1 and n = 3 is 55% or more, more preferably Preferably, it is 65% or more, further preferably 75% or more, and most preferably 85% or more.

Further, the dichroic dye (B) represented by the formula (1) can be synthesized by the method described in WO2007/138980.

Further, it is preferred to use at least one of the dichroic dye (A) group and the dichroic dye (B) in combination. In general, a polarizing element obtained by using a different dichroic dye in combination has a tendency to lower optical characteristics than a polarizing element obtained by using each dichroic dye alone, and a dichroic dye (A) of the present invention is used in combination. At least one of the groups and the dichroic dye (B) do not hinder the respective characteristics, and as a result, the characteristics of λmax are improved, and a high characteristic in a wide band can be exhibited. It is characterized in that the obtained λmax of the polarizing element is 440 nm ≦ λ max ≦ 470 nm, which is equivalent to the polarizing element obtained by using the dichroic dye (A) group or the dichroic dye (B), respectively. In the case of Tp, a higher contrast value can be obtained, and a higher Tp value can be obtained in the case of the same contrast value. Also, a higher contrast value can be obtained in a wider wavelength region.

When at least one of the dichroic dye (A) group and the dichroic dye (B) are used in combination, the mixing ratio of the dichroic dye (A) group and the dichroic dye (B) is not particularly limited, and usually The dichroic dye (B) is 25 to 400 parts by weight, preferably 100 parts by weight, based on 100 parts by weight of the dichroic dye (A) group, and the dichroic dye (for the dichroic dye (A) group (100 parts by weight) B) is 50 to 200 parts by weight.

The manufacturing method of the polarizing element using the dichroic dye is not particularly limited For example, a film in which a polyvinyl alcohol-based film obtained by adsorbing a dichroic dye is aligned, a film or an element in which a dichroic dye is applied to a rubbed substrate film, and a two-color film a film or a component in which a dye is mixed with a liquid crystal resin and applied to a rubbed substrate film, and a dichroic dye and a liquid crystal resin are mixed and applied to a substrate film for sharing. The film or the element to be aligned, the film which is dyed to the dichroic dye on the film which is oriented at least in the uniaxial direction, the film which mixes the dichroic dye and the resin, and the film which extends at least in the uniaxial direction. It is preferably a film obtained by aligning a polyvinyl alcohol-based film which is adsorbed by a dichroic dye, and the highest contrast value can be obtained.

The method for producing the polyvinyl alcohol-based resin constituting the polarizing element is not particularly limited, and it can be produced by a known method. The method for producing the polyvinyl alcohol-based resin can be obtained, for example, by saponifying a polyvinyl acetate-based resin. Examples of the polyvinyl acetate-based resin include a polyvinyl acetate of a homopolymer of vinyl acetate, and examples thereof include a copolymer of vinyl acetate and another monomer copolymerizable therewith. Examples of the other monomer copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is usually preferably from 85 to 100 mol%, more preferably 95 mol% or more. The polyvinyl alcohol-based resin may be further modified, and for example, an aldehyde-modified polyethylene formaldehyde or a polyvinyl acetal may be used. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually preferably from 1,000 to 10,000, more preferably from 1,500 to 7,000.

The polyvinyl alcohol-based resin is used as a film for the film. The method of forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method can be used. Manufacturing. In this case, the polyvinyl alcohol-based resin film may contain glycerin, ethylene glycol, propylene glycol or low molecular weight polyethylene glycol as a plasticizer. The plasticizing dose is preferably from 5 to 20% by weight, more preferably from 8 to 15% by weight. The film thickness of the original film containing the polyvinyl alcohol-based resin is not particularly limited, and is, for example, preferably 5 to 150 μm, more preferably 10 to 100 μm.

In the polyvinyl alcohol-based resin film, a swelling step is first performed. The swelling step is carried out by immersing the polyvinyl alcohol resin film in a solution of 20 to 50 ° C for 30 seconds to 10 minutes. The solvent is preferably water. When the time for manufacturing the polarizing element is shortened, the swelling step can be omitted because the swelling is performed even during the dyeing treatment of the dye.

The dyeing step is carried out after the swelling step. The dyeing step is carried out by immersing the polyvinyl alcohol-based resin film in a solution containing a dichroic dye. The temperature of the solution in this step is preferably from 5 to 60 ° C, more preferably from 20 to 50 ° C, and particularly preferably from 35 to 50 ° C. The time of immersion in the solution can be appropriately adjusted, preferably from 30 seconds to 20 minutes, more preferably from 1 to 10 minutes. The dyeing method is preferably carried out by immersing in the solution, or by applying the solution to a polyvinyl alcohol-based resin film.

The solution containing a dichroic dye may contain sodium chloride, sodium sulfate, anhydrous sodium sulfate, sodium tripolyphosphate or the like as a dyeing auxiliary. The content may be adjusted at any concentration depending on the dyeing time and temperature of the dye, and is preferably from 0 to 5% by weight, more preferably from 0.1 to 2% by weight, based on the respective contents.

After the dyeing step, a washing step (hereinafter referred to as washing step 1) may be performed before proceeding to the next step. The washing step 1 is a step of washing the dye solvent adhering to the surface of the polyvinyl alcohol-based resin film in the dyeing step. borrow By carrying out the washing step 1, it is possible to inhibit the transfer of the dye into the liquid which is subsequently treated. Water is generally used in the cleaning step 1. The cleaning method is preferably immersed in the solution, and the solution may be washed by applying the solution to a polyvinyl alcohol-based resin film. The washing time is not particularly limited, and is preferably from 1 to 300 seconds, more preferably from 1 to 60 seconds. The temperature of the solvent in the washing step 1 must be a temperature at which the hydrophilic polymer does not dissolve. Generally, it is cleaned at 5~40 °C.

After the dyeing step or the washing step 1, a step of containing a crosslinking agent and/or a water-resistant agent may be carried out. As the crosslinking agent, for example, a boron compound such as boric acid, borax or ammonium borate, a polyvalent aldehyde such as glyoxal or glutaraldehyde, a polyisocyanate compound such as a biuret type, an isocyanurate type or a block type can be used. A titanium-based compound such as titanyl sulfate or the like may be used, and ethylene glycol glycidyl ether or polyamine-epichlorohydrin may be used. Examples of the water resistance agent include peroxysuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ammonium chloride or magnesium chloride, and the like. Boric acid. The step of containing a crosslinking agent and/or a water resistance agent is carried out using at least one of the above-mentioned crosslinking agent and/or water resistance agent. The solvent at this time is preferably water and is not limited. In the step of containing a crosslinking agent and/or a water resistance agent, the concentration of the crosslinking agent and/or the water resistance agent in the solvent is preferably from 0.1 to 6.0 by weight based on the solvent represented by boric acid. %, more preferably 1.0 to 4.0% by weight. The solvent temperature in this step is preferably from 5 to 70 ° C, more preferably from 5 to 50 ° C. The method of containing a crosslinking agent and/or a water-resistant agent in the polyvinyl alcohol-based resin film is preferably immersed in the solution, and the solution may be applied or applied to the polyvinyl alcohol-based resin film. The processing time in this step is preferably from 30 seconds to 6 minutes, more preferably from 1 to 5 minutes. but, It is not necessary to contain a crosslinking agent and/or a water-resistant agent. When it is desired to shorten the time, the treatment step may be omitted when the crosslinking treatment or the water resistance treatment is not required.

After the dyeing step, the washing step 1, or the step of containing a crosslinking agent and/or a water-resistant agent, an extending step is performed. The stretching step refers to a step of stretching the polyvinyl alcohol-based film in a single axis. The stretching method may be any one of a wet stretching method or a dry stretching method.

In the case of the dry stretching method, when the heating medium is an air medium, it is preferred to extend the temperature of the air medium to a normal temperature of -180 °C. Further, it is preferred to carry out the treatment in an environment having a humidity of 20 to 95% RH. Examples of the heating method include an inter-roller region stretching method, a drum heating stretching method, a pressure stretching method, and an infrared heating stretching method. The stretching method is not particularly limited. The extension step can be performed by using one stage or by multi-stage extension of two stages or more.

In the case of the wet stretching method, stretching is carried out in water, a water-soluble organic solvent, or a mixed solution thereof. It is preferred to carry out the stretching treatment while immersing in a solution containing a crosslinking agent and/or a water-resistant agent. As the crosslinking agent, for example, a boron compound such as boric acid, borax or ammonium borate, a polyvalent aldehyde such as glyoxal or glutaraldehyde, a polyisocyanate compound such as a biuret type, an isocyanurate type or a block type can be used. A titanium-based compound such as titanyl sulfate or the like may be used, and ethylene glycol glycidyl ether or polyamine-epichlorohydrin may be used. Examples of the water resistance agent include peroxysuccinic acid, ammonium persulfate, calcium perchlorate, benzoin ethyl ether, ethylene glycol diglycidyl ether, glycerin diglycidyl ether, ammonium chloride or magnesium chloride. Containing at least one or more crosslinking agents as indicated above And/or extending in a solution of the hydrating agent. The crosslinking agent is preferably boric acid. The concentration of the crosslinking agent and/or the water resistance agent in the stretching step is, for example, preferably from 0.5 to 15% by weight, more preferably from 2.0 to 8.0% by weight. The stretching ratio is preferably 2 to 8 times, more preferably 5 to 7 times. It is preferably treated at an extension temperature of 40 to 60 ° C, more preferably 45 to 58 ° C. The extension time is usually 30 seconds to 20 minutes, more preferably 2 to 5 minutes. The wet stretching step can be carried out by one stage or by a plurality of stages of two or more stages.

After the stretching step, a crosslinking agent and/or a water-resistant agent are deposited on the surface of the film, or a foreign matter adheres thereto, so that the cleaning step of the surface of the cleaning film (hereinafter referred to as cleaning step 2) can be performed. The cleaning time is preferably from 1 second to 5 minutes. The cleaning method is preferably immersed in the cleaning solution, and can be washed by applying or applying the solution onto the polyvinyl alcohol resin film. The cleaning process can be performed in one stage, or the multi-stage process in two stages or more. The temperature of the solution in the washing step is not particularly limited and is usually 5 to 50 ° C, preferably 10 to 40 ° C.

Examples of the solvent used in the treatment steps up to this point include water, dimethyl hydrazine, N-methylpyrrolidone, methanol, ethanol, propanol, isopropanol, glycerin, ethylene glycol, propylene glycol, and diethyl ether. An alcohol such as an diol such as diol, triethylene glycol, tetraethylene glycol or trimethylolpropane; or an amine such as ethylenediamine or diethylidenetriamine, but is not particularly limited thereto. Further, a mixture of one or more of these solvents may be used. The best solvent is water.

After the stretching step or the cleaning step 2, a drying step of the film is carried out. The drying treatment can be carried out by natural drying, and in order to further improve the drying efficiency, the surface moisture can be removed by compression with a drum or an air knife or a water suction roller. In addition, and / or can also be air dried. The drying treatment temperature is preferably a drying treatment at 20 to 100 ° C, and more preferably a drying treatment at 60 to 100 ° C. The drying treatment time can be applied for 30 seconds to 20 minutes, preferably 5 to 10 minutes.

Further, in the wavelength region of 500 nm ≦λ ≦ 560 nm, the polarizing element of the present invention preferably has a transmittance of 2% or less. More preferably, the transmittance is 1% or less in the wavelength region of 540 nm ≦ λ ≦ 550 nm. Blue LEDs or blue fluorescent tubes with a maximum luminescence output of 440 nm to 470 nm have a slight luminescence near 550 nm. In this case, since slight light leakage occurs during light shielding, it is preferable to control the light emission. When the transmittance in the wavelength region is 2% or more during display of the display, sufficient contrast is not obtained. The transmittance is preferably 2% or less, more preferably in the wavelength region of 540 nm ≦ λ ≦ 550 nm, and the transmittance is 1% or less.

Further, it is also possible to have polarization characteristics in the above wavelength region. In this case, in the wavelength region of 500 nm ≦λ ≦ 560 nm, Tc ≦ 2% is preferable, and Tc ≦ 1% is preferably in the wavelength region of 540 nm ≦ λ ≦ 550 nm.

The production method is not particularly limited, and a film obtained by aligning a polyvinyl alcohol-based film having a dichroic dye having a polarization characteristic in a wavelength region of 500 nm ≦ λ 560 nm may be used, and a dichroic dye may be coated. a film or element that is aligned on a rubbed substrate film, a film or element that is mixed with a liquid crystal resin and applied to a rubbed substrate film, and is aligned by two colors a film or an element which is mixed with a liquid crystalline resin and applied to a substrate film and shared and aligned, at least in a uniaxial direction a film obtained by dyeing a dichroic dye on an upper extension film, a film obtained by mixing a dichroic dye and a resin such as a plastic, and extending at least in a uniaxial direction, and may be exemplified by 500 nm ≦λ≦. A method of bonding a film having a transmittance of 2% or less in a wavelength region of 500 nm ≦ λ ≦ 560 nm in a polarizing plate having no polarization characteristics in a wavelength region of 560 nm. It is preferably a film in which a polyvinyl alcohol-based film adsorbed by a dichroic dye is aligned, and does not impair the Tp in a wavelength region of 420 nm ≦ λ ≦ 490 nm.

When a dichroic dye is used as the dichroic dye used in the above, the dichroic dye is not particularly limited, and examples thereof include CI Direct Red 79, CI Direct Red 81, CI Direct Violet 9, and CI Direct Purple 35, CI direct purple 57, CI direct blue 67 and so on. These may be used in combination with the dichroic dye (A) group and/or the dichroic dye (B), and may not be used in combination with one or a plurality of them.

The amount of the dichroic dye to be blended is not particularly limited, and is usually 25 to 300 parts by weight based on 100 parts by weight of the total amount of the dichroic dye (A) group and/or the dichroic dye (B).

Further, other dichroic dyes may be used insofar as the dichroic dye of the present invention does not inhibit the polarizing characteristics. The dichroic dye is not particularly limited, and examples thereof include C.I. Direct Yellow 12, C.I. Direct Yellow 28, C.I. Direct Yellow 44, and the like. In addition to the dichroic dyes shown, other organic dyes may be used in combination as needed. The ratio of blending is not particularly limited.

The polarizing element using the dichroic dye thus obtained is suitable as a polarizing element used in the display.

Iodine complex is used in the dichroic dye used in the polarizing element of the present invention In the case, it is preferably Tc(λ460)≦Tc(λ600), more preferably Tc(λ460)<Tc(λ600). A polarizing plate using a well-known iodine complex is usually Tc(λ460)>Tc(λ600), and a higher contrast value cannot be obtained if the wavelength is in the range of 500 nm or less. Further, a higher contrast value can be obtained by increasing the concentration, but if Tp < 30%, sufficient brightness cannot be obtained. For these reasons, a polarizing plate using an iodine complex is not suitable as a polarizing plate used in the display. Therefore, in the case of using an iodine complex, Tc(λ460)≦Tc(λ600) is preferred.

The method for producing the polarizing element of the Tc (λ460) ≦Tc (λ600) is not particularly limited, and examples thereof include a film obtained by aligning a polyvinyl alcohol-based film in which an iodine complex is adsorbed.

The method for producing a polyvinyl alcohol-based resin constituting the polarizing element and the method for forming a polyvinyl alcohol-based resin are the same as those described in the case of using a dichroic dye. Further, the degree of polymerization of the polyvinyl alcohol-based resin is usually preferably from 1,000 to 10,000, more preferably from 1,500 to 5,000.

In the polyvinyl alcohol-based resin film, a swelling step is first performed. The swelling step is the same as that described in the case of using a dichroic dye.

After the swelling step, a dyeing step is carried out. The dyeing step means that the polyvinyl alcohol-based resin film is treated with a solution containing iodine and an iodide. The solvent of the solution is preferably water, and is not particularly limited. The iodide may, for example, be an alkali metal iodide compound such as potassium iodide, ammonium iodide, cobalt iodide or zinc iodide, and is not particularly limited. It is preferably an alkali metal iodide compound, more preferably potassium iodide. . The iodine concentration is preferably 0.0001 to 0.5% by weight, more preferably 0.001 to 0.4% by weight. The concentration of iodide is preferably 0.001~8wt%. The temperature of the solution in this step is preferably 5 to 50 ° C, more preferably 10 to 40 ° C, and particularly preferably 20 to 30 ° C. The time of immersion in the solution can be appropriately adjusted, preferably from 30 seconds to 6 minutes, more preferably from 1 to 5 minutes. The dyeing method is preferably carried out by immersing in the solution, or by coating or coating the solution on a polyvinyl alcohol-based resin film.

When iodine and iodide are treated, a crosslinking agent and/or a water resistance agent may be added to the solution. A crosslinking agent is usually used. The crosslinking agent is not particularly limited, and is usually preferably boric acid. For example, the concentration of boric acid added is preferably from 0.1 to 5.0% by weight, more preferably from 2.0 to 4.0% by weight. Further, in the case of a polyvinyl alcohol resin film containing iodine, an iodide, a crosslinking agent, and/or a water resistance agent, the iodine, the iodide, the crosslinking agent, and/or the water resistance agent may not necessarily be directly contained in the polyvinyl alcohol. The resin film also contains a case where it is contained in the film in the form of a reaction.

Further, as described above, the crosslinking agent treatment step may be carried out simultaneously with the dyeing step, and it is more preferred to carry out the crosslinking agent treatment step after the dyeing step. The treatment method at this time is carried out by treating the film obtained in the dyeing step with a solution containing a crosslinking agent. The treatment method containing the crosslinking agent solution is usually preferably a method of immersing the dyed film in the solution, or a method of coating or coating the solution on the film. The impregnation can also be carried out before the stretching step, or together with the stretching step. In the case where the stretching method is a dry stretching method, it is preferred to carry out the crosslinking agent treatment before stretching, and in the case of the wet stretching method, it is preferably carried out together with the stretching treatment. The crosslinking agent is the same as that described in the crosslinking treatment step of the dichroic dye. Further, the water resistance agent may be coexisted in the solution containing the crosslinking agent. As a water resistance agent, it is described in the water resistance agent treatment step of the dichroic dye. The same. The concentration of the crosslinking agent in the solvent is preferably from 0.1 to 6.0% by weight, more preferably from 1.0 to 4.0% by weight, based on the solvent represented by boric acid. The solvent temperature in the step before the stretching step is preferably from 5 to 60 ° C, more preferably from 5 to 40 ° C before the extension, and from 45 to 58 ° C in the case of the extension. The processing time in this step is preferably from 30 seconds to 6 minutes, more preferably from 1 to 5 minutes.

The stretching step includes a dry stretching method and a wet stretching method, and examples of the method are the same as those described in the step of extending the dichroic dye.

After the stretching treatment, a treatment using a solution containing a halide is carried out. This treatment is a step for the purpose of adjusting the hue and improving the polarization characteristics. The treatment method is preferably a method of immersing the dyed film in the solution, or a method of coating or coating the solution on the film. As the halide, for example, an alkali metal iodide compound such as potassium iodide or sodium iodide, an iodide such as ammonium iodide, cobalt iodide or zinc iodide, an alkali metal chloride compound such as potassium chloride or sodium chloride or chlorine is preferable. A chloride such as zinc is preferably water-soluble. More preferably, it is an iodide, and further preferably an alkali metal iodide compound, particularly preferably potassium iodide. The concentration of the halide is an important element of Tc(λ460)≦Tc(λ600), and the concentration thereof varies depending on the type, but is usually preferably 6.0 to 15.0% by weight, more preferably 7.0 to 12.0% by weight. Further, it is preferably 8.0 to 10.0% by weight. The treatment temperature varies depending on the concentration of the halide, and is, for example, preferably 5 to 55 ° C, more preferably 20 to 40 ° C. The treatment time varies depending on the concentration of the halide, and is, for example, preferably from 1 second to 5 minutes, and is preferably from 5 to 30 seconds in consideration of stability of the in-plane characteristics of the polarizing film. Moreover, in the case of performing the stretching step by the wet stretching method, the halide treatment may be performed together with the stretching step for the elongation treatment. Subsequent halide treatment is preferred in terms of quality stability.

The solvent of the treatment solution in the treatment step up to this point is, for example, water, an alcohol solvent, or a glycol solvent, but is not particularly limited. Further, a mixed solvent of water and a water-soluble solvent may be used, for example, a solution of a mixed water and an alcohol, a mixed solvent of dimethyl hydrazine and water, or the like. The best is water.

After the halide treatment, a drying step of the film is carried out. The drying treatment method is the same as that described in the method for drying the dichroic dye.

The polarizing element using the iodine complex thus obtained is suitable as a polarizing element used in the display.

On the obtained polarizing element, a polarizing plate was produced by providing a transparent protective layer as a support on one side or both sides. The transparent protective layer used for the polarizing element of the film in which the polyvinyl alcohol-based film is aligned can be used as a coating layer using a polymer or a laminated layer of a film. Moreover, the transparent protective layer used for the coating type polarizing element can directly set the base material used for the coating substrate to a transparent protective layer, or can transfer a polarizing element to a film substrate or the like to provide a protective layer.

As the transparent protective layer, a transparent polymer or film having high mechanical strength and good thermal stability is preferred. As a substance used as a transparent protective layer, for example, a cellulose acetate resin such as triacetyl cellulose (TAC) or cellulose diacetate or a film thereof, an acrylic resin or a film thereof, a polyvinyl chloride resin or a film thereof, a polyester resin or a film thereof, a polyarylate resin or a film thereof, such as a drop a cyclic polyolefin resin or a film thereof having a cyclic olefin as a monomer, a polyethylene, a polypropylene, a ring system or a lower The polyolefin of the olefin skeleton or a copolymer thereof, the main chain or the side chain is a resin or polymer of ruthenium and/or guanamine or a film thereof. Further, the resin having a liquid crystal property or a film thereof may be a transparent protective layer. The thickness of the protective film is, for example, about 0.5 to 200 μm. A polarizing plate is produced by providing one or more layers of the same or different kinds of resins or films on one side or both sides.

As the substance used as the transparent protective layer, it is more preferable to use a PET film at least on one side. In the conventional LCD display, since the characteristics of the LCD and the polarizing plate itself display an image, a highly transparent and less birefringent TAC film is mainly used in the transparent protective layer. Further, there is also a case where a retardation film of a viewing angle compensation film is directly used on one side of the transparent protective layer. On the other hand, the polarizing plate in the fluorescent excitation color conversion display used in the polarizing plate of the present invention functions as a light switching function, and it is not necessary to use the polarizing plate of the present invention as an image display surface. Thereby, it is not necessary to use a high-priced film such as a low-birefringence TAC film or a viewing angle compensation film retardation film, and it is more preferable to use a PET film which is inexpensive and has excellent mechanical properties and good workability. Since the PET film has a large birefringence, when it is used as a double-sided support, since the transmittance tends to decrease, it is preferably used on one side of the single-sided support or the double-sided support. The arrangement of the PET film as the polarizing plate support in the display device is preferably disposed on the opposite side of the liquid crystal layer with respect to the polarizing element together with the upper and lower polarizing plates. Further, for the purpose of improving the transmittance and improving the adhesion, it is more preferable to have a PET film having an easy adhesion layer. The PET film to be easily attached is not particularly limited, and a commercially available product can be used, and the adhesive layer is preferably further provided on both sides.

Moreover, if necessary, at least one layer of a material having a lower refractive index than the transparent protective layer may be disposed on the transparent protective layer to form an anti-reflective transparent protective layer. By forming an anti-reflection protective layer, the light penetration efficiency can be improved and higher. Contrast value, and Tp value. The material having a lower refractive index than the transparent protective layer is not particularly limited, and examples thereof include an organic material such as an acrylic resin or a fluorine resin, and an inorganic material such as colloidal cerium oxide. These may be used in combination. Further, it may be a reaction system or a non-reaction system. The processing method is not particularly limited, and examples thereof include a vapor deposition method, a sputtering method, and various coating methods. Further, it is necessary to laminate a plurality of hard coat layers, a high refractive index layer, and the like on the transparent protective layer.

Herein, an adhesive is required in order to bond the transparent protective layer to the polarizing element. The adhesive is not particularly limited, and is preferably a polyvinyl alcohol-based adhesive. Examples of the polyvinyl alcohol-based adhesive include, but are not limited to, Gosenol NH-26 (manufactured by Nippon Synthetic Co., Ltd.) and EXCEVAL RS-2117 (manufactured by Kuraray Co., Ltd.). A crosslinking agent and a water resistance agent may be added to the adhesive. A maleic anhydride-isobutylene copolymer is used for the polyvinyl alcohol-based adhesive, and an adhesive in which a crosslinking agent is mixed may be used as needed. Examples of the maleic anhydride-isobutylene copolymer include: Isobam #18 (manufactured by Kuraray Co., Ltd.), Isobam #04 (manufactured by Kuraray Co., Ltd.), ammonia-modified Isobam #104 (manufactured by Kuraray Co., Ltd.), and ammonia modification. Isobam #110 (manufactured by Kuraray Co., Ltd.), Isobam #304 (manufactured by Kuraray Co., Ltd.), Isobam #310 (manufactured by Kuraray Co., Ltd.), and the like. At this time, a water-soluble polyvalent epoxy compound can be used in the crosslinking agent. Examples of the water-soluble polyvalent epoxy compound include DENACOL EX-521 (manufactured by Nagase Chemical Co., Ltd.), TETRAD-C (manufactured by Mitsui Gas Chemical Co., Ltd.), and the like. Further, as an adhesive other than the polyvinyl alcohol-based resin, a known binder of an urethane-based, acrylic or epoxy-based adhesive can also be used. Again, with the adhesion of the adhesive For the purpose of improving or improving the water resistance, an additive such as a zinc compound, a chloride or an iodide may be contained at a concentration of about 0.1 to 10% by weight. The additive is also not particularly limited. After the transparent protective layer is pasted with an adhesive, the polarizing plate is obtained by drying or heat treatment at an appropriate temperature.

Further, an adhesive may be used when the transparent protective layer is bonded to the polarizing element. The adhesive is not particularly limited, and preferred examples thereof include an acrylic adhesive. The thickness can be arbitrarily selected in terms of characteristics such as adhesion strength, transmittance, and overall thickness, and is usually in the range of 5 to 50 μm, preferably 10 to 30 μm.

The polarizing plate of the present invention can also be formed into a polarizing plate with a support. In order to attach the polarizing plate, the support preferably has a flat portion, and in terms of optical use, a glass molded article is preferable. Examples of the material of the glass include inorganic glass such as soda glass, borosilicate glass, inorganic substrate containing crystal, inorganic substrate containing sapphire, or an organic plastic plate such as acrylic or polycarbonate, and preferably inorganic. glass. As long as the thickness or size of the glass plate is the desired size. Further, in the polarizing plate with glass, in order to further increase the light transmittance of the single plate, an antireflection layer may be provided on the glass surface thereof.

In addition, when the support is bonded to a polarizing element or a polarizing plate, an adhesive, an adhesive, or the like is used, and it is not particularly limited, and a preferred example thereof is an acrylic adhesive. The thickness can be arbitrarily selected in terms of characteristics such as adhesion strength, transmittance, and overall thickness, and is usually in the range of 5 to 50 μm, preferably 10 to 30 μm.

The polarizing element and the polarizing plate of the present invention thus obtained are at 440 In the wavelength region of nm ≦ λ 470 nm, Tp ≧ 30%, and CR ≧ 8,000 in the wavelength region between any continuous 20 nm, CR ≧ 5,000 in the remaining wavelength region, preferably used as the maximum luminescence output of 440 nm A blue LED or blue fluorescent tube up to 470 nm is used as a light source to illuminate the polarizing element and polarizing plate used in the color conversion display.

[Examples]

Hereinafter, the present invention will be described in detail by way of examples, but the invention is not limited thereto. Further, the evaluation of the transmittance shown in the examples was carried out as follows.

When the transmittance is measured using a spectrophotometer [V-7100 manufactured by JASCO Corporation (Company), the transmittance can be corrected based on JIS-Z8701 (C-light source 2° field of view) on the light exit side. 100% of the C source light is incident on the measurement sample.

The C-source light is incident on the two polarizing plates of the present invention, and the parallel (parallel polarized) spectral transmittance obtained by measuring the absorption axis directions of the two polarizing plates is set to be Tp, and two polarizing plates are used. The orthogonal (orthogonal polarization) spectral transmittance obtained by measuring the absorption axis direction is orthogonal to Tc. Further, the contrast is a value including CR=Tp/Tc by the contrast of the spectral transmittance.

Each transmittance was measured using a spectrophotometer ["V-7100" manufactured by JASCO Corporation (Company)].

Example 1

A polyvinyl alcohol-based resin film (VF series manufactured by Kuraray Co., Ltd.) having a saponification degree of 99% or more and a film thickness of 75 μm was immersed in warm water of 40 ° C for 3 minutes. Perform swelling treatment. The swelled film was immersed in an aqueous solution of CI Direct Orange 39 containing a dye of the dichroic dye (A) group at 0.04% by weight, 0.1% by weight of sodium tripolyphosphate, and 0.1% by weight of Glauber's salt at 45° C. to carry out the dye. The dyeing treatment is carried out to adsorb onto a polyvinyl alcohol-based film. The film to which the dye was adsorbed was washed with water, and after washing, the boric acid treatment was carried out for 1 minute with an aqueous solution containing 2% by weight of boric acid at 40 °C. The film obtained by the boric acid treatment was subjected to treatment for 5 minutes while extending 5.0 times on one side in an aqueous solution containing 5 wt% of boric acid at 55 °C. While maintaining the extended state of the film obtained by the boric acid treatment, i5 second treatment was performed using normal temperature water. The film obtained by the treatment was immediately dried at 70 ° C for 9 minutes to obtain a polarizing element having a film thickness of 25 μm. The obtained polarizing element was obtained by using a PET film (COSMOSHINE A4300 manufactured by Toyobo Co., Ltd.) having a double-sided easy-adhesion layer and a polyvinyl alcohol-based adhesive and a 20 μm-thick acrylic adhesive. On a glass substrate having a thickness of 1 mm, a PET/adhesion layer/polarizing element/adhesive layer/glass was laminated to obtain a polarizing plate, and a measurement sample was prepared.

Example 2

As the dye to be adsorbed, a dye represented by the formula (1) of 0.02% by weight of a dichroic dye (B) in which R ₁ and R ₂ are a hydrogen atom, according to HPLC (high performance liquid chromatography) A polarizing plate was prepared in the same manner as in Example 1 except that the ratio of n was 33%, n=2 was 65%, and n=3 was 2%, and a measurement sample was prepared.

Example 3

As the adsorbing dye, a pigment represented by the formula (1) of 0.018 wt% of a dye of the dichroic dye (A) group and a formula (1) of 0.015 wt% of a dichroic dye (B), wherein R ₁ and R are used, ₂ is a hydrogen atom, and a polarizing plate is produced in the same manner as in Example 1 except that n ratio is 33%, n=2 is 65%, and n=3 is 2%. The sample was measured.

Example 4

As the adsorption dye, a pigment represented by the formula (1) of 0.01% by weight of a dye of the dichroic dye (A) group, CI direct orange 39, and 0.01% by weight of a dichroic dye (B), wherein R ₁ and R _{2 are used.} The hydrogen atom is a dye containing n=1 of 33%, n=2 of 65%, n=3 of 2%, and 0.02% by weight of CI Direct Red 81 according to the ratio of n of HPLC. In the same manner as in Example 1, a polarizing plate was produced to prepare a measurement sample.

Example 5

A polyvinyl alcohol-based resin film (VF series manufactured by Kuraray Co., Ltd.) having a saponification degree of 99% or more and having a film thickness of 75 μm was immersed in warm water of 40 ° C for 3 minutes to carry out a swelling treatment. The swelled film was immersed in an aqueous solution containing 30.8% by weight of boric acid, 0.044% by weight of iodine, and 3.13% by weight of potassium iodide, and was subjected to dyeing treatment to adsorb the film on the polyvinyl alcohol film. The dye-dyed film was stretched 5.0 times on one side and treated in an aqueous solution containing 3.0% by weight of boric acid at 50 ° C for 5 minutes. While maintaining the extended state of the film obtained by the boric acid treatment, a color retention treatment was carried out for 20 seconds using an aqueous solution containing 8.0% by weight of potassium iodide at 30 °C. The film obtained by the treatment was immediately dried at 70 ° C for 9 minutes to obtain a polarizing element having a film thickness of 25 μm. The obtained polarizing element was obtained by using a PET film (COSMOSHINE A4300 manufactured by Toyobo Co., Ltd.) having a double-sided easy-adhesion layer and a polyvinyl alcohol-based adhesive and a 20 μm-thick acrylic adhesive. Yu Hou A glass substrate having a degree of 1 mm was laminated with a PET/adhesion layer/polarizing element/adhesive layer/glass, and a polarizing plate was obtained by lamination to prepare a measurement sample.

Comparative example 1

The iodine-based polarizing plate from which a transparent protective layer taken out from a commercially available liquid crystal television (AQUOS/32 type manufactured by Sharp Corporation) was taken out as a double-sided TAC film was bonded to a glass substrate having a thickness of 1 mm using an acrylic adhesive having a thickness of 20 μm. On the top, a measurement sample was prepared.

Comparative example 2

A polarizing plate was prepared in the same manner as in Example 4 except that a coloring treatment was carried out for 20 seconds in an aqueous solution containing 5.0% by weight of potassium iodide at 30 ° C to prepare a measurement sample.

Spectral measurement values Tp for each wavelength of 5 nm obtained by measuring the measurement samples obtained in Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Fig. 1, and Tc is shown in Fig. 2. The Tp of each wavelength of 420 to 490 nm is shown in Table 4, the contrast value is shown in Table 5, and the Tc of each wavelength of 500 to 560 nm is shown in Table 6. Further, the values of Tc (460) and Tc (600) of Example 5 and Comparative Examples 1 and 2 of the iodine-based polarizing plate are shown in Table 7.

According to the results of FIGS. 1 and 2 and Tables 4 to 5, it is understood that the polarizing plates of the dichroic dyes of Examples 1 to 4 have a high Tp and a high contrast ratio in the wavelength region of 420 to 490 nm, particularly at 440. Excellent in the wavelength range of ~470nm. Further, according to Table 6, it is understood that Tc is low in the wavelength region of 500 to 560 nm of Example 4. It can be seen that the polarizing plates of the dichroic dyes (A) and the dichroic dyes (B) of Examples 3 and 4 have a relatively high contrast band. It is excellent in the wavelength range of 440 to 470 nm. Further, according to Table 7, it is understood that the iodine-based polarizing plate of Example 5 is Tc(460)≦Tc(600), and although the polarizing plate using the dichroic dyes of Examples 1 to 3 is inferior, it is at a wavelength of 440 to 470 nm. In the region, the result is higher Tp and higher contrast.

On the other hand, according to Table 7, it is understood that the conventional iodine-based polarizing plates of Comparative Examples 1 and 2 have Tc (460) > Tc (600), and as shown by the results of Figs. 1 to 2 and Tables 4 to 5, In the wavelength region of ~490 nm, especially in the wavelength region below 460 nm, the Tp is low and the contrast is insufficient.

[Industrial availability]

The wavelength range of 440 nm ≦λ≦470 nm is excellent, and it can be used as a fluorescent excitation color conversion display using a blue LED or a blue fluorescent tube with a maximum light output of 440 nm to 470 nm as a light source. Polarizing element and polarizing plate.

Figure 1 shows the spectral measurement value Tp for each wavelength of 5 nm.

Fig. 2 shows the spectral measurement value Tc for each wavelength of 5 nm.

Claims (11)

A polarizing element for use in a fluorescent excitation color conversion display using a blue LED or a blue fluorescent tube having a maximum light output of 440 nm to 470 nm as a light source, characterized in that in a wavelength region of 440 nm ≦ λ ≦ 470 nm, Tp ≧ 30%, and CR ≧ 8,000 in the wavelength region between any successive 20 nm in the wavelength region, CR ≧ 5,000 in the remaining wavelength region, and at least containing dichroic dye; here, λ represents wavelength, so-called Tp It refers to the spectral transmittance (transparency at the time of parallel polarization) when the absorption axes of the two polarizing elements are overlapped in parallel. The so-called Tc is the spectral transmittance when the absorption axes of the two polarizing elements are orthogonally overlapped. "Transmission rate at the time of cross-polarization", CR represents an abbreviation of contrast and represents a value including Tp/Tc, and the dichroic dye contains at least one of the dichroic dye (A) group, and the two represented by the formula (1) Color dye (B): dichroic dye (A) group CI direct orange 26 CI direct orange 39 CI direct orange 107 dichroic dye (B) (wherein R ₁ and R ₂ each independently represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, and n = 1 to 3). The polarizing element of claim 1, wherein the wave at 420 nm ≦ λ < 440 nm In the long region, Tp is 30% and CR is 1,500. The polarizing element of claim 1 or 2, wherein Tp ≧ 30% and CR ≧ 1,000 in a wavelength region of 470 nm < λ 490 nm. The polarizing element of claim 1 or 2, wherein the transmittance is 2% or less in a wavelength region of 500 nm ≦ λ 560 nm. The polarizing element of claim 3, wherein the transmittance is 2% or less in a wavelength region of 500 nm ≦ λ 560 nm. A polarizing element for use in a fluorescent excitation color conversion display using a blue LED or a blue fluorescent tube having a maximum light output of 440 nm to 470 nm as a light source, characterized in that in a wavelength region of 440 nm ≦ λ ≦ 470 nm, Tp ≧ 30%, and CR ≧ 8,000 in the wavelength region between any successive 20 nm in the wavelength region, CR ≧ 5,000 in the remaining wavelength region, and at least containing dichroic dye; here, λ represents wavelength, so-called Tp It refers to the spectral transmittance (transparency at the time of parallel polarization) when the absorption axes of the two polarizing elements are overlapped in parallel. The so-called Tc is the spectral transmittance when the absorption axes of the two polarizing elements are orthogonally overlapped. Transmittance at the time of cross polarization), CR represents the abbreviation of contrast and represents the value of Tp/Tc, the dichroic dye is iodine complex, and Tc( λ 460) ≦Tc( λ 600), where Tc( λ 460) refers to a spectral transmittance of 460 nm when the absorption axes of the two polarizing elements are orthogonally overlapped (when orthogonally polarized), and Tc (λ600) is when the absorption axes of the two polarizing elements are orthogonally overlapped (positive The light transmittance of 600 nm when the light is crossed. The polarizing element of claim 6, wherein Tp ≧ 30% and CR ≧ 1,500 in a wavelength region of 420 nm ≦ λ < 440 nm. The polarizing element of claim 6 or 7, wherein Tp ≧ 30% and CR ≧ 1,000 in a wavelength region of 470 nm < λ 490 nm. A polarizing plate obtained by providing a support film on at least one surface of a polarizing element according to any one of claims 1 to 8. The polarizing plate of claim 9, wherein at least one side of the support film is a PET (polyester) film. A polarizing plate with an inorganic substrate, characterized in that a polarizing element according to any one of claims 1 to 8 or a polarizing plate according to claim 9 or 10 is laminated on the inorganic substrate.