JP2014081482A - Polarizer and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device having excellent camera performance.SOLUTION: A polarizer 1 of the present invention is formed of a resin film containing a dichroic substance, and has a decolorized part 2 that is partially decolorized.

Description

  The present invention relates to a polarizer and an image display device.

  An image display device such as a mobile phone or a notebook personal computer (PC) is usually equipped with a camera. Various studies have been made for the purpose of improving the camera performance of such an image display device (for example, Patent Document 1). However, with the rapid spread of smartphones and touch panel type information processing devices, further improvement in camera performance is desired.

JP 2011-81315 A

  The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide an image display device having excellent camera performance.

  The inventors of the present invention have focused on the polarizer mounted on the image display device, found that the above object can be achieved by forming a decoloring part in the polarizer, and have completed the present invention.

The polarizer of the present invention is composed of a resin film containing a dichroic substance and has a decolorized part that is partially decolored.
In preferable embodiment, the transmittance | permeability of the said decoloring part is 46% or more.
In a preferred embodiment, the decolorization part is formed by irradiating a laser beam including light having a wavelength of at least 1500 nm.
In a preferred embodiment, the decoloring section corresponds to a camera hole section of an image display device to be mounted.
In a preferred embodiment, the dichroic material is iodine.
In a preferred embodiment, the thickness is 30 μm or less.
According to another aspect of the present invention, a method for producing a polarizer is provided. This manufacturing method of a polarizer has a process of forming a decoloring part by irradiating a resin film containing a dichroic substance with a laser beam.
In a preferred embodiment, the laser light includes light having a wavelength of at least 1500 nm.
In a preferred embodiment, the laser is a solid state laser.
According to still another aspect of the present invention, an image display device is provided. The image display device includes the polarizer.
According to another situation of this invention, the manufacturing method of the said image display apparatus is provided. This manufacturing method includes a step of irradiating a laser beam onto an image display panel laminated so that a resin film containing a dichroic material is on the surface side to form the decolorized portion.

  According to the present invention, by forming a decoloring part in a resin film containing a dichroic substance, it is possible to ensure the transparency of the camera hole part and contribute to the improvement of the camera performance of the obtained image display device. . Thus, according to the present invention, not only receiving electronic devices such as images and monitors (for example, camera devices having a photographing optical system), but also transmitting electronic devices such as LED lights and infrared sensors, and the naked eye. It is also possible to provide an image display device that ensures the transparency of the image.

1 is a plan view of a polarizer according to a preferred embodiment of the present invention.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

A. Polarizer FIG. 1 is a plan view of a polarizer according to a preferred embodiment of the present invention. The polarizer 1 is made of a resin film and has a decoloring part 2 that is partially decolored. According to such a configuration, compared to a case where a hole is formed in the resin film mechanically (specifically, by a method of mechanically pulling out using an engraving blade punching, a plotter, a water jet, or the like) It is possible to avoid quality problems such as cracks, delamination (delamination), and paste sticking.

  The resin film contains a dichroic substance. Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. Preferably, iodine is used.

  Arbitrary appropriate resin may be used as resin which forms the said resin film. Preferably, polyvinyl alcohol resin (hereinafter referred to as “PVA resin”) is used. Examples of the PVA resin include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer can be obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA resin is usually 85 mol% or more and less than 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. is there. The saponification degree can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a saponification degree, a polarizer having excellent durability can be obtained. If the degree of saponification is too high, there is a risk of gelation.

  The average degree of polymerization of the PVA-based resin can be appropriately selected according to the purpose. The average degree of polymerization is usually 1000 to 10000, preferably 1200 to 4500, more preferably 1500 to 4300. The average degree of polymerization can be determined according to JIS K 6726-1994.

  The polarizer (excluding the decolorization part) preferably exhibits absorption dichroism in the wavelength range of 380 nm to 780 nm. The single transmittance (Ts) of the polarizer (excluding the decolorized part) is preferably 40% or more, more preferably 41% or more, still more preferably 42% or more, and particularly preferably 43% or more. The theoretical upper limit of the single transmittance is 50%, and the practical upper limit is 46%. Further, the single transmittance (Ts) is a Y value measured with a 2 degree visual field (C light source) of JIS Z8701 and corrected for visibility, for example, using a microspectroscopic system (Lambda Vision, LVmicro). Can be measured. The degree of polarization of the polarizer (excluding the decolorization part) is preferably 99.8% or more, more preferably 99.9% or more, and further preferably 99.95% or more.

  The thickness of the polarizer can be set to any appropriate value. The thickness is typically about 1 μm to 80 μm, preferably 30 μm or less. The thinner the thickness, the better the decolorization part can be formed. For example, in laser light irradiation described later, the absorbance per unit film thickness is high, and a decolorized portion can be formed efficiently.

  In the illustrated example, the small-color decoloring part 2 is formed at the center of the upper end of the resin film, but the arrangement, shape, size, etc. of the decoloring part can be designed as appropriate. Preferably, it is designed according to the position, shape, size, etc. of the camera hole part of the mounted image display device. Specifically, it is designed so that the decoloring part does not correspond to the display screen of the mounted image display device.

  The transmittance of the decolorized part (for example, transmittance measured with light having a wavelength of 550 nm at 23 ° C.) is preferably 46% or more, more preferably 60% or more, still more preferably 75% or more, and particularly preferably 90% or more. It is.

  The polarizer of the present invention can be used in any suitable form. Typically, a polarizer is used by laminating a protective film on at least one side thereof (as a polarizing film). Examples of the material for forming the protective film include cellulose resins such as diacetyl cellulose and triacetyl cellulose, (meth) acrylic resins, cycloolefin resins, olefin resins such as polypropylene, and ester resins such as polyethylene terephthalate resins. , Polyamide resins, polycarbonate resins, copolymer resins thereof, and the like.

  The surface of the protective film where the polarizer is not laminated may be subjected to a treatment for the purpose of a hard coat layer, antireflection treatment, diffusion or antiglare as a surface treatment layer. For example, the surface treatment layer is preferably a layer having a low moisture permeability for the purpose of improving the humidification durability of the polarizer. The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing film. The hard coat layer can be formed by, for example, a method of adding a cured film excellent in hardness, slipping properties, etc., to an appropriate ultraviolet curable resin such as acrylic or silicone. The hard coat layer preferably has a pencil hardness of 2H or more. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing film, and is based on the interference of light as disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-248173. Such as a thin layer type that prevents reflection by using a canceling effect of reflected light, or a structure type that exhibits low reflectivity by imparting a fine structure to the surface as disclosed in JP 2011-2759 A, etc. This can be achieved by forming a low reflective layer. Anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing film and obstructing the visibility of the light transmitted through the polarizing film. For example, a roughening method using a sandblasting method or an embossing method. Or by applying a fine concavo-convex structure to the surface of the protective film by an appropriate method such as a blending method of transparent fine particles. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing film to expand the viewing angle.

  The thickness of the protective film is preferably 20 μm to 100 μm. The protective film is typically laminated on the polarizer via an adhesive layer (specifically, an adhesive layer or an adhesive layer). The adhesive layer is typically formed of a PVA adhesive. The pressure-sensitive adhesive layer is typically formed of an acrylic pressure-sensitive adhesive.

B. Method for Producing Polarizer The polarizer is preferably produced by subjecting a resin film containing a dichroic material to a decolorization treatment to form the decolorization part.

  The resin film containing the dichroic substance is preferably produced by subjecting the resin film to a treatment such as dyeing. The resin film may be a resin layer (PVA resin layer) formed on a resin base material. According to such a form, a thin polarizer (for example, 10 micrometers or less) can be obtained.

B-1. Dyeing The dyeing is preferably performed by adsorbing iodine to the resin film. Examples of the adsorption method include a method of immersing a resin film in a staining solution containing iodine, a method of applying the staining solution to a resin film, and a method of spraying the staining solution onto the resin film. Preferably, the resin film is immersed in the dyeing solution. This is because iodine can be adsorbed well.

  The staining solution is preferably an iodine aqueous solution. The blending amount of iodine is preferably 0.04 to 5.0 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add an iodide to the aqueous iodine solution. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and titanium iodide. Etc. Among these, potassium iodide is preferable. The blending amount of iodide is preferably 0.3 to 15 parts by weight with respect to 100 parts by weight of water.

  The liquid temperature during staining of the staining liquid is preferably 20 ° C to 50 ° C. When the PVA resin film is immersed in the staining solution, the immersion time is preferably 5 seconds to 5 minutes.

B-2. Other treatments In addition to dyeing, the resin film may be appropriately subjected to treatment for making a polarizer. Examples of the treatment for obtaining a polarizer include stretching treatment, insolubilization treatment, crosslinking treatment, washing treatment, and drying treatment. In addition, the frequency | count, order, etc. of these processes are not specifically limited.

  Any appropriate method can be adopted as the stretching method of the stretching treatment. Specifically, free end stretching or fixed end stretching may be used.

  The stretching direction can be appropriately set. In one embodiment, it extends in the longitudinal direction of the long resin film. In this case, typically, a method of stretching through a resin film between rolls having different peripheral speeds is employed. In another embodiment, it extends | stretches in the width direction of an elongate resin film. In this case, typically, a method of stretching using a tenter stretching machine is employed. The stretching direction can correspond to the absorption axis direction of the obtained polarizer.

  The stretching method is not particularly limited, and may be wet or dry. The stretching temperature can be appropriately set according to the stretching method, for example.

  The draw ratio is typically 3 to 7 times. Stretching may be performed in one stage or in multiple stages. When performing in multiple stages, for example, the free end stretching and fixed end stretching may be combined, or the wet stretching and dry stretching may be combined. In addition, when performing by multistep, the said draw ratio is a product of the draw ratio of each step.

  As described above, when the resin film is a resin layer (PVA resin layer) formed on a resin substrate, it is preferable to combine dry stretching and wet stretching. More specifically, it is preferable to dry-stretch a laminate of a resin base material and a resin layer (resin film), and further wet-stretch in a boric acid aqueous solution. In addition, as a specific example of a resin base material and detailed extending | stretching conditions, it describes in the patent 4804588 gazette, for example. The description is incorporated herein by reference.

  The insolubilization treatment and the crosslinking treatment are typically performed by immersing a resin film in an aqueous boric acid solution. The cleaning treatment is typically performed by immersing a resin film in an aqueous potassium iodide solution. The drying temperature in the drying treatment is preferably 30 ° C to 100 ° C.

B-3. Decolorization The decolorization part is preferably formed by irradiating the resin film containing the dichroic substance with laser light. According to laser light irradiation, a decoloring part having a desired shape can be formed satisfactorily. Further, as described above, even in a state where the protective film is laminated on the resin film, the decolorized portion can be formed. Furthermore, it can be excellent in mass productivity.

  The laser beam preferably includes light having a wavelength of at least 1500 nm. With a laser beam including such a wavelength, a decoloring part can be formed. More preferably, it contains light with a wavelength of at least 1000 nm, more preferably contains light with a wavelength of 800 nm or less, and particularly preferably contains light with a wavelength of 600 nm or less. According to the laser light including such a wavelength, the decoloring part can be formed while achieving surface uniformity. Specifically, the decoloring part can be formed without damaging (for example, thermal deformation) the polarizer peripheral optical member (for example, the protective film). Note that the damage to the polarizer peripheral optical member is considered to be one of the factors because the difference in absorbance between the polarizer and the peripheral optical member becomes large. Moreover, a decoloring part can be favorably formed without damaging the resin film itself. As a result, the flatness of the obtained image display device (image display panel) can be ensured, and a good module design can be achieved. Furthermore, according to the laser beam including the wavelength, the transmittance of the decoloring part can be achieved satisfactorily.

  Examples of the laser include a solid laser such as a YAG laser, a YLF laser, and a YVO4 laser, a gas laser including an argon ion laser, and a krypton ion laser, a fiber laser, and a semiconductor laser. Preferably, a solid laser (particularly a YAG laser) is used.

  As the laser, a short pulse laser (a laser that emits light having a pulse width of 1 nanosecond or less, such as a picosecond laser or a femtosecond laser) is preferably used. In order to suppress thermal damage to the resin film, a pulse width of 500 picoseconds or less is particularly preferable.

  The irradiation condition of the laser beam can be set to any appropriate condition. For example, when a solid laser (YAG laser) is used, the pulse energy is preferably 25 μJ to 71 μJ. The scanning speed is preferably 10 mm / second to 100 mm / second. The number of repetitive pulses is preferably 100 Hz to 12480 Hz. According to such conditions, a decoloring part can be satisfactorily formed without damaging the polarizing film peripheral member and the resin film itself. Moreover, the transmittance can be achieved satisfactorily.

  Preferably, the laser beam includes polarized light substantially coaxial with the absorption axis of the resin film (polarizer). According to such a laser beam, the difference in absorbance between the polarizer and its peripheral optical member can be further increased, and the decolorization part can be formed more satisfactorily.

  In the irradiation, for example, a laser may be scanned and positioned by driving a galvanometer mirror. Further, for the purpose of obtaining the surface uniformity of the decolorized portion, a homogenizer (DOE: Diffractive Optical Element) that uniformizes the laser light intensity mainly having a Gaussian distribution may be used.

  In addition, the said decoloring part can be formed favorably, achieving surface uniformity also by irradiating X-rays. In addition to this, for example, the decoloring portion can also be formed by a light source (for example, a Xe lamp) that emits light having a wavelength of 100 pm to 1500 nm, a heating means such as a heating plate for barcode printing, or the like.

C. Image Display Device An image display device of the present invention includes the polarizer. Examples of the image display device include a liquid crystal display device and an organic EL device. Specifically, the liquid crystal display device includes a liquid crystal panel including a liquid crystal cell and the polarizer disposed on one side or both sides of the liquid crystal cell. The organic EL device includes an organic EL panel in which the polarizer is disposed on the viewing side. The polarizer is arranged so as to correspond to the camera hole part of the image display device on which the decoloring part is mounted.

D. Method for Manufacturing Image Display Device In one embodiment, the image display device includes an image display panel (for example, a liquid crystal panel or an organic EL panel) laminated such that the resin film containing the dichroic material is on the surface side. ) Is irradiated with a laser beam (from the front surface side) to form the decoloring part. According to such a method, positioning of the decoloring part can be facilitated.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. In addition, the measuring method of the transmittance | permeability is as follows.
[Transmissivity (Ts)]
Measurement was performed using a microspectroscopic system (Lambda Vision Co., Ltd., LVmicro). Note that Ts is a Y value measured by a two-degree field of view (C light source) of JIS Z8701 and corrected for visibility.

[Example 1]
Using a solid-state laser (wavelength: 532 nm), a glued polarizing film (adhesive layer (thickness 20 μm) / second) with a total thickness of 129 μm under irradiation conditions of a pulse energy of 40 μJ, a scanning speed of 100 mm / sec, and a repetition pulse number of 3120 Hz The protective film (thickness 58 μm) / polarizer (thickness 5 μm) / first protective film (thickness 46 μm)) was irradiated with laser light from the viewing side (first protective film side).
In this way, the decoloring part was formed in the polarizing film (polarizer).

Only the area irradiated with laser light could be decolorized. The transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 66.2%.
Moreover, when the surface shape of the irradiation area was confirmed by WYKO (manufactured by Bruker AXS Co., Ltd.), there were no noticeable steps or irregularities and the surface uniformity was excellent. Furthermore, when the inside of the polarizing film was visually observed, no break such as a crack was confirmed.

[Example 2]
A decolorized portion was formed in the same manner as in Example 1 except that the laser beam was irradiated under irradiation conditions of a pulse energy of 71 μJ, a scanning speed of 100 mm / sec, and a repetition pulse number of 6240 Hz.

Only the area irradiated with laser light could be decolorized. The transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 80.2%.
Moreover, when the surface shape of the irradiation area was confirmed by WYKO, there was no conspicuous step or unevenness, and the surface uniformity was excellent. Furthermore, when the inside of the polarizing film was visually observed, no break such as a crack was confirmed.

[Example 3]
A decolorized portion was formed in the same manner as in Example 1 except that laser light was irradiated under irradiation conditions of a pulse energy of 71 μJ, a scanning speed of 100 mm / sec, and a repetition pulse number of 12480 Hz.

Only the area irradiated with laser light could be decolorized. The transmittance of the unirradiated portion was 44.0%, and the transmittance of the irradiated portion was 92.0%.
Moreover, when the surface shape of the irradiation area was confirmed by WYKO, there was no conspicuous step or unevenness, and the surface uniformity was excellent. Furthermore, when the inside of the polarizing film was visually observed, no break such as a crack was confirmed.

[Example 4]
Using a semiconductor laser (wavelength: 940 nm), a decolorized portion was formed in the same manner as in Example 1 except that laser light was irradiated under irradiation conditions of continuous wave energy of 30 W, scanning speed of 10 mm / sec, and spot diameter of 2 mmφ. .

The area irradiated with the laser beam was slightly discolored, the transmittance of the irradiated portion was 44.0%, and the transmittance of the irradiated portion was 49.2%.
When observed inside, no crack-like fracture was confirmed, but when the surface shape of the irradiated area was confirmed, noticeable unevenness (thickness change) that can be seen with the touch of the finger occurred, and the surface uniformity It was inferior.

(Comparative Example 1)
A part of the glued polarizing film was removed by press working with an engraving blade.
A crack having a length of 1 mm or more was generated in the peripheral portion that was removed.

(Comparative Example 2)
A part of the glued polarizing film was removed by press working with a heated engraving blade.
Although cracks were not confirmed in the peripheral portion that was removed, a step due to thermal deformation occurred, and surface uniformity could not be obtained.

(Comparative Example 3)
A CO ₂ gas laser (wavelength: 10.6 μm) was used in the same manner as in Example 1 except that laser light was irradiated under irradiation conditions of a pulse energy of 0.8 mJ, a scanning speed of 300 mm / sec, and a repetition pulse number of 3000 Hz. An attempt was made to form a decoloring part.

The area irradiated with the laser beam was not decolorized, and the transmittance (44.0%) of the unirradiated portion and the transmittance of the irradiated portion were the same.
Moreover, when the surface shape of the irradiation area was confirmed, the remarkable unevenness | corrugation (thickness change) enough to understand by finger touch has generate | occur | produced, and the surface uniformity was not acquired. In addition, as a result of internal observation, no break such as a crack was confirmed.

  The polarizer of the present invention is suitably used for an image display device with a camera (liquid crystal display device, organic EL device) such as a mobile phone such as a smartphone, a notebook PC, or a tablet PC.

1 Polarizer 2 Decolorizing part

Claims (11)

Consists of a resin film containing a dichroic substance,
A polarizer having a partially decolorized decolorizing part.   The polarizer of Claim 1 whose transmittance | permeability of the said decoloring part is 46% or more.   The polarizer according to claim 1 or 2, wherein the decolorization part is formed by irradiating a laser beam including light having a wavelength of at least 1500 nm.   The polarizer according to claim 1, wherein the decoloring unit corresponds to a camera hole unit of an image display device to be mounted.   The polarizer according to claim 1, wherein the dichroic substance is iodine.   The polarizer in any one of Claim 1 to 5 whose thickness is 30 micrometers or less. Having a step of irradiating a resin film containing a dichroic substance with a laser beam to form a decoloring part,
A method for producing a polarizer.   The manufacturing method according to claim 7, wherein the laser light includes light having a wavelength of at least 1500 nm or less.   The manufacturing method according to claim 7 or 8, wherein the laser is a solid-state laser.   An image display device comprising the polarizer according to claim 1. Irradiating the image display panel laminated so that the resin film containing the dichroic substance is on the surface side, and forming the decoloring part,
The manufacturing method of the image display apparatus of Claim 10.