JP6795883B2 - Polarizer manufacturing method - Google Patents

Description

The present invention relates to a method for inspecting and manufacturing a polarizer. More specifically, the present invention relates to a method for inspecting and manufacturing a polarizer having a non-polarizing portion.

Some image display devices such as mobile phones and notebook personal computers (PCs) are equipped with internal electronic components such as cameras. Various studies have been made for the purpose of improving the camera performance of such an image display device (for example, Patent Documents 1 to 7). However, with the rapid spread of smartphones and touch panel type information processing devices, further improvement in camera performance and the like is desired. Further, in order to cope with the diversification and high functionality of the shape of the image display device, a polarizing plate having a partial polarization performance is required. In order to realize these demands industrially and commercially, it is desired to manufacture an image display device and / or its parts at an acceptable cost, and various studies are made to establish such a technique. Matters are left.

Japanese Unexamined Patent Publication No. 2011-81315 Japanese Unexamined Patent Publication No. 2007-241314 U.S. Patent Application Publication No. 2004/0212555 Korean Publication No. 10-2012-0118205 Korean Patent No. 10-1293210 Japanese Unexamined Patent Publication No. 2012-137738 U.S. Patent Application Publication No. 2014/0118826

The present invention has been made to solve the above problems, and its main purpose is to manufacture a polarizer capable of realizing multi-functionality and high-performance electronic devices and having no variation in quality. , To provide a method for inspecting this polarizer with high accuracy.

The method for inspecting a polarizer of the present invention includes a step of irradiating a range including the non-polarized portion of the polarizer having a non-polarized portion with light and imaging a transmitted light image of the polarizer. The contrast ratio (non-polarized part / other part) between the non-polarized part and the other part in the transmitted light image is 1.5 or more.
In one embodiment, the shape and / or characteristics of the non-polarized portion are inspected.
In one embodiment, the image is taken through a surface protective film that protects the polarizer.
In one embodiment, an image is taken between the surface protective film and the image pickup unit without using another optical member.
According to another aspect of the present invention, there is provided a method for producing a polarizer. This manufacturing method includes a step of forming a non-polarizing portion on the polarizer and a step of inspecting by the above inspection method.
In one embodiment, after the formation of the non-polarized portion, the inspection is continuously performed.
In one embodiment, the polarizer is brought into contact with a basic solution to form the unpolarized portion.
In one embodiment, the basic solution is contacted with the polarizer coated with a surface protective film so that at least a part thereof is exposed.

According to the present invention, a polarizer having a non-polarizing portion can be inspected with high accuracy.

It is a top view which shows one specific example of the polarizer which is the object of inspection of this invention. It is the schematic which shows one Embodiment of the inspection method of this invention. It is a schematic plan view which shows the specific example of a long surface protection film. It is the schematic perspective view which shows the specific example of the lamination of the polarizer and the protective material. It is a partial cross-sectional view of the polarizing film laminated body in one Embodiment of this invention. It is a schematic perspective view of the polarizing plate by one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Polarizer FIG. 1 is a plan view showing one specific example of a polarizer to be inspected in the present invention. The polarizer 1 is composed of a resin film containing a dichroic substance. A small circular non-polarizing portion 2 is formed in the polarizer 1 at the center of the upper end portion of the polarizer 1.

The non-polarized portion can be in any suitable form. For example, the non-polarized portion is a partially decolorized decolorized portion. The decolorized portion is formed by, for example, laser irradiation or chemical treatment. As another specific example, the non-polarized part is a through hole. Through holes are formed, for example, by mechanical punching (eg punching, Thomson blade punching, plotters, water jets) or removal of predetermined portions (eg laser ablation or chemical dissolution).

In the illustrated example, the small circular non-polarizing portion 2 is formed in the central portion of the upper end portion of the polarizer 1, but the number, arrangement, shape, size, etc. of the non-polarizing portion can be appropriately designed. For example, it is designed according to the position, shape, size, etc. of the camera unit of the mounted image display device. Specifically, the non-polarized portion is designed so as not to correspond to a portion (for example, an image display unit) other than the camera of the image display device.

The transmittance of the non-polarized portion (for example, the transmittance measured with light having a wavelength of 550 nm at 23 ° C.) is preferably 50% or more, more preferably 60% or more, still more preferably 75% or more. Particularly preferably, it is 90% or more. With such a transmittance, it is possible to prevent an adverse effect on the shooting performance of the camera, for example, when the polarizer is arranged so that the non-polarizing portion corresponds to the camera portion of the image display device.

The polarizer (a portion other than the non-polarizing portion) preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The simple substance transmittance of the polarizer (a portion other than the non-polarizing portion) is preferably 39% or more, more preferably 39.5% or more, still more preferably 40% or more, and particularly preferably 40.5% or more. .. The theoretical upper limit of the simple substance transmittance is 50%, and the practical upper limit is 46%. The single transmittance is a Y value measured by a JIS Z8701 double field of view (C light source) and corrected for luminosity factor. For example, it is measured using a microspectroscopy system (manufactured by Lambdavision, LVmicro). Can be done. The degree of polarization of the polarizer (excluding the non-polarized portion) is preferably 99.9% or more, more preferably 99.93% or more, still more preferably 99.95% or more.

The thickness of the polarizer can be set to any suitable value. The thickness is preferably 30 μm or less, more preferably 25 μm or less, still more preferably 20 μm or less, and particularly preferably 10 μm or less. On the other hand, the thickness is preferably 0.5 μm or more, more preferably 1 μm or more.

Examples of the dichroic substance include iodine and organic dyes. These can be used alone or in combination of two or more. Iodine is preferably used.

Any suitable resin can be used as the resin for forming the resin film. Preferably, a polyvinyl alcohol-based resin is used. Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Polyvinyl alcohol is obtained by saponification of polyvinyl acetate. The ethylene-vinyl alcohol copolymer is obtained by saponifying the ethylene-vinyl acetate copolymer.

B. Inspection Method The inspection method of the present invention includes a step of irradiating a range including the non-polarizing portion of a polarizer having a non-polarizing portion with light and imaging a transmitted light image of the polarizer. In the imaging step, typically, light is irradiated from one side of the polarizer having the non-polarizing portion, and light transmitted through the polarizer is imaged from the other side.

The contrast ratio (non-polarized part / other part) between the non-polarized part and the other part in the transmitted light image is 1.5 or more, preferably 1.8 or more, and more preferably 2.0 or more. .. By imaging with such a contrast ratio, it is possible to inspect the non-polarized portion (for example, the shape and / or characteristic of the non-polarized portion) with high accuracy.

FIG. 2 is a schematic view showing one embodiment of the inspection method of the present invention. As shown in the figure, the inspection device 100 includes a light source unit 110, an image pickup unit 120, and an image processing unit (not shown) for processing an image captured by the image pickup unit 120. The light source unit 110 is arranged so that light is irradiated to a range including the non-polarizing unit 2 of the polarizing element 1 (practically used as a polarizing plate). The image pickup unit 120 is arranged on the side opposite to the side where the light source unit 110 is arranged with respect to the polarizer 1, and images the transmitted light image of the polarizer 1. Although not shown, a polarizing filter may be arranged between the light source unit 110 and the imaging unit 120 depending on the configuration of the polarizing plate.

The light source unit may be configured using any suitable light source. The light source may be a white light source or a monochromatic light source. The light source can be of any suitable shape and can be, for example, a surface light source, a line light source, a point light source or a ring type light source. Specific examples of the light source include fluorescent lamps, halogen lamps, metal halide lamps, LEDs and the like.

The irradiation angle of light on the polarizer (illumination angle of light on the main surface of the polarizer) is preferably 89 ° to 91 °, more preferably 89.5 ° to 90.5 °. According to such an irradiation angle, the roughness of the contour in the thickness direction of the polarizer can be inspected with high accuracy.

The image pickup unit is typically a camera configured by using a lens and an image sensor. As the image sensor, a CCD type image sensor may be used or a CMOS type image sensor may be used.

The number of pixels of the image sensor is preferably 2000 dpi or more, more preferably 4000 dpi to 6000 dpi. By using an image sensor having such a number of pixels, a high-quality image can be captured, so that inspection can be performed with higher accuracy.

As described above, when a polarizing filter is used for imaging, the polarizing filter is arranged so that the absorption axis direction of the polarizing filter is orthogonal to the absorption axis direction of the polarizer to be inspected. Here, "orthogonal" also includes the case where it is substantially orthogonal. Here, "substantially orthogonal" includes the case of 90 ° ± 3.0 °, preferably 90 ° ± 1.0 °, and more preferably 90 ° ± 0.5 °. In the illustrated example, when the polarizing filter is arranged between the polarizer 1 and the imaging unit 120, the light (linearly polarized light) transmitted through the portion other than the non-polarizing portion 2 of the polarizer 1 is absorbed by the polarizing filter. Since a part of the light transmitted through the non-polarizing section 2 can pass through the polarizing filter, the light transmitted through the polarizing filter can be substantially imaged as an image of the non-polarizing section. The polarizing filter may be arranged between the light source unit and the polarizing element to be inspected. Although the details will be described later, whether or not a polarizing filter is used can be determined depending on the form of the polarizing element (polarizing plate) to be inspected.

The quality of the polarizer (eg, the shape and / or characteristics of the unpolarized portion) is inspected based on the image obtained in the imaging step. Specifically, the image processing unit analyzes the image data sent as an electric signal from the imaging unit and inspects the quality of the polarizer. Specific examples of the inspection items include shape accuracy of the non-polarized portion (roundness in the case of a circle), contour roughness, contour steepness, transmittance and the like. The image processing unit preferably detects a non-polarized part that does not satisfy a predetermined criterion as a poor formation.

The analysis of the image data can be performed based on, for example, the luminance information. Specifically, in the obtained image data (transmitted light image data), the brightness of the non-polarized part is relatively high and the brightness of the other parts is low, so that the contrast ratio in the obtained image data is low. It can be specified as a non-polarized part based on. Further, the contour of the specified non-polarized portion is divided into 180 equal parts to obtain the distance from the center to each contour portion, and the value obtained by subtracting the minimum value from the maximum value in the obtained 180 distance data is the roundness. Can be used as an evaluation standard for. For example, when the obtained value is not more than a predetermined value, the roundness of the non-polarized portion can be evaluated as good. Furthermore, the contour of the non-polarized part is divided into 180 equal parts to obtain a reference approximate ellipse, and the maximum value of the distance from the approximate ellipse to the actual contour in each of the 180 equal parts is used as the evaluation standard for the roughness of the contour. can do. For example, when the obtained maximum value is not more than a predetermined value, the roughness of the contour of the non-polarized portion can be evaluated as good. Furthermore, the average brightness of the non-polarized part and other parts (peripheral part of the non-polarized part) is obtained, the average brightness of the non-polarized part is 0%, the average brightness of the other parts is 100%, and 10% and 20%. The maximum value of the distance from the center of the non-polarized portion to each contour divided into 180 equal parts when binarized to black and white with the brightness of can be used as an evaluation standard for the steepness of the contour. For example, when the obtained maximum value is equal to or less than a predetermined value, the steepness of the contour of the non-polarized portion can be evaluated as good.

For the transmittance of the non-polarized part, for example, the average brightness value, the maximum brightness value, and the minimum brightness value of the non-polarized part are obtained, and the maximum brightness value is divided by the average brightness value or the minimum brightness value is divided by the average brightness value. It can be evaluated based on numerical values. Specifically, when the polarization function remains in the non-polarizing portion and the transmittance is low, the obtained value is also low.

C. Method for manufacturing a polarizer having a non-polarizing portion The method for manufacturing a polarizer having a non-polarizing portion of the present invention is to form a non-polarizing portion on the polarizer and inspect the non-polarizing portion by the above inspection method. Including.

C-1. Formation of non-polarized part Polarizer is typically obtained by subjecting the resin film to various treatments such as swelling treatment, stretching treatment, dyeing treatment with the dichroic substance, cross-linking treatment, cleaning treatment, and drying treatment. Be done. When performing various treatments, the resin film may be a resin layer formed on the base material. The formation of the non-polarizing portion can also be performed during the process of manufacturing the polarizer.

Preferably, the non-polarized portion is a decolorized portion. According to such a configuration, cracks and delaminations are formed as compared with the case where a through hole is formed mechanically (for example, by a method of mechanically punching out using a Thomson blade punch, a plotter, a water jet, etc.). Quality problems such as (delamination) and glue squeeze out are avoided. The decolorized portion is preferably formed by bringing a basic solution into contact with a desired position of a polarizer (a resin film containing a dichroic substance). The non-polarized portion formed by such a method can be a low-concentration portion having a lower content of the dichroic substance than other portions (non-contact portions). Since the content of the dichroic substance itself is low in the low-concentration part, the transparency of the non-polarized part is maintained better than in the case where the dichroic substance is decomposed by laser light or the like to form the decolorized part. Will be done.

The content of the dichroic substance in the low concentration portion is preferably 1.0% by weight or less, more preferably 0.5% by weight or less, still more preferably 0.2% by weight or less. The lower limit of the content of the dichroic substance in the low concentration portion is usually below the detection limit. The difference between the content of the dichroic substance in the other portion and the content of the dichroic substance in the low concentration portion is preferably 0.5% by weight or more, more preferably 1% by weight or more. When iodine is used as the bicolor substance, the iodine content is determined, for example, from the X-ray intensity measured by fluorescent X-ray analysis by a calibration curve prepared in advance using a standard sample.

Any suitable compound can be used as the basic compound contained in the basic solution. Examples of the basic compound include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, and inorganic alkali metal salts such as sodium carbonate. , Organic alkali metal salts such as sodium acetate, aqueous ammonia and the like. Among these, hydroxides of alkali metals and / or alkaline earth metals are preferably used, and sodium hydroxide, potassium hydroxide, and lithium hydroxide are more preferably used. The dichroic substance can be efficiently ionized, and the decolorized portion can be formed more easily. These basic compounds may be used alone or in combination of two or more.

Water and alcohol are preferably used as the solvent for the basic solution. The concentration of the basic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N. The temperature of the basic solution is, for example, 20 ° C to 50 ° C. The contact time of the basic solution can be set according to the thickness of the polarizer and the type and concentration of the basic compound contained in the basic solution. The contact time is, for example, 5 seconds to 30 minutes, preferably 5 seconds to 5 minutes.

Any suitable method can be adopted as the contact method for the basic solution. For example, a method of dropping, coating, and spraying a basic solution on a polarizer, and a method of immersing the polarizer in the basic solution can be mentioned. Upon contact with the basic solution, the polarizer may be protected with any suitable protective material so that the basic solution does not come into contact with any part other than the desired site. As such a protective material, for example, a protective film and a surface protective film are used. The protective film can be used as it is as a protective film for the polarizer. The surface protective film is temporarily used during the manufacture of the polarizer. Since the surface protective film is removed from the polarizer at an arbitrary appropriate timing, it is typically attached to the polarizer via an adhesive layer. Another specific example of the protective material is a photoresist or the like. Further, the base material used in the above-mentioned process of producing the polarizer can also be used as a protective material.

Preferably, the surface of the polarizer is coated with a surface protective film so that at least a part thereof is exposed upon contact with the basic solution. The polarizer of the illustrated example is produced, for example, by adhering a surface protective film having a small circular through hole formed to a resin film and bringing a basic solution into contact with the surface protective film. At that time, it is preferable that the other side of the polarizer (the side on which the surface protective film having through holes is not arranged) is also protected.

In one embodiment, a polarizing film laminate obtained by laminating a long surface protective film on a long polarizing element (resin film) is prepared, and a basic solution is brought into contact with the polarizing film laminate. Through holes are formed in the elongated surface protective film at predetermined intervals in the longitudinal direction and / or the width direction thereof, for example. Here, the "long shape" means an elongated shape having a length sufficiently long with respect to the width, and includes, for example, an elongated shape having a length of 10 times or more, preferably 20 times or more with respect to the width. ..

In the elongated polarizer, the absorption axis can be set in any suitable direction depending on the purpose. The direction of the absorption axis may be, for example, a long direction or a width direction. A polarizer having an absorption axis in the long direction has an advantage that, for example, it is excellent in manufacturing efficiency. A polarizer having an absorption axis in the width direction has an advantage that it can be laminated with a retardation film having a slow phase axis in the long direction by roll-to-roll, for example. In one embodiment, the absorption shaft is substantially parallel in the longitudinal or width direction, and both ends of the polarizer in the width direction are slitted parallel to the longitudinal direction. According to such a configuration, it is possible to easily manufacture a plurality of polarizers which can be cut with reference to the end edge of the polarizer, have a non-polarizing portion at a desired position, and have an absorption axis in an appropriate direction. Can be done. The absorption axis of the polarizer may correspond to the stretching direction in the stretching treatment.

FIG. 3 is a schematic plan view showing a specific example of a long surface protective film. The width of the surface protective film 20 is the same as or wider than that of the elongated polarizing elements to be laminated. The surface protective film 20 is formed with small circular through holes 21, 21 ... At substantially equal intervals in both the long direction and the width direction. The placement pattern of the through holes can be determined corresponding to the desired polarizer. For example, when the through hole is cut to a predetermined size (for example, cutting or punching in a long direction and / or a width direction) in order to attach the obtained polarizing element to an image display device of a predetermined size, the image display device is used. It is arranged so as to correspond to the camera unit of. Further, the shape of the through hole can correspond to the shape of the desired non-polarized portion.

As shown in FIG. 4, the lamination of the elongated polarizing element and the elongated protective material (in the illustrated example, the surface protective film having through holes formed) is preferably performed by roll-to-roll. As used herein, the term "roll-to-roll" refers to laminating roll-shaped films while transporting them so that their long directions are aligned with each other.

FIG. 5 is a partial cross-sectional view of the polarizing film laminate according to one embodiment of the present invention. The polarizing film laminate 10 includes a first surface protective film 20 arranged on one surface side (upper surface side in the illustrated example) of the polarizing element 1 and the polarizing element 1, and the other surface side (lower surface side in the illustrated example) of the polarizing element 1. A protective film 30 and a second surface protective film 40 arranged on the side) are provided. The polarizing film laminate 10 has exposed portions 11, 11 ... With the polarizing element 1 exposed on one surface side (upper surface side in the illustrated example). The exposed portion 11 is provided by forming a through hole 21 in the first surface protective film 20.

Examples of the material for forming the surface protective film include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polyethylene and polypropylene, polyamide resins, and polycarbonate resins. Examples include polymer resins. An ester resin (particularly, a polyethylene terephthalate resin) is preferable. This is because the elastic modulus is sufficiently high, and for example, even if tension is applied during transportation and / or bonding, deformation of the through hole is unlikely to occur. The thickness of the surface protective film is typically 20 μm to 250 μm, preferably 30 μm to 150 μm.

As described above, since the surface protective film temporarily protects the polarizer, there is no practical problem even if the orientation of the forming resin varies. For example, the surface protective film may have an in-plane retardation at a wavelength of 590 nm in the range of 500 nm to 3000 nm. The in-plane phase difference Re is obtained by the formula: Re = (nx−ny) × d. Here, "nx" is the refractive index in the direction in which the in-plane refractive index is maximized (slow-phase axis direction), and "ny" is the in-plane direction orthogonal to the slow-phase axis (phase-advance axis direction). It is the refractive index, and "d" is the thickness (nm) of the film. In addition, the surface protective film may have an orientation angle in the range of −40 ° to + 40 °. The orientation angle is the angle formed by the slow axis of the surface protective film with respect to the absorption axis of the polarizer when the surface protective film is laminated on the polarizer.

The first surface protective film has through holes arranged in a predetermined pattern as shown in FIG. The position of the through hole corresponds to the position where the unpolarized portion is formed. The shape of the through hole corresponds to the shape of the desired non-polarized portion. Through holes are formed, for example, by mechanical punching (eg punching, Thomson blade punching, plotters, water jets) or removal of certain parts of the film (eg laser ablation or chemical dissolution).

The surface protective film is peeled off at an arbitrary appropriate timing, for example, after contact with the basic solution.

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. Examples thereof include resins, polyamide resins, polypropylene resins, and copolymer resins thereof. The thickness of the protective film is preferably 10 μm to 100 μm.

The surface of the protective film on which the polarizer is not laminated may be subjected to a hard coat layer, an antireflection treatment, or a treatment for the purpose of diffusion or antiglare as a surface treatment layer. The protective film is typically attached to the polarizer via an adhesive layer.

In one embodiment, the basic solution is removed from the polarizer by any suitable means after contact with the polarizer. According to such an embodiment, for example, it is possible to more reliably prevent a decrease in the transmittance of the non-polarized portion due to the use of the polarizer. Specific examples of the method for removing the basic solution include washing, wiping removal with a waste cloth, suction removal, natural drying, heat drying, blast drying, vacuum drying and the like. Preferably, the basic solution is washed. Examples of the cleaning liquid used for cleaning include water (pure water), alcohols such as methanol and ethanol, and mixed solvents thereof. Preferably water is used. The number of washings is not particularly limited and may be performed a plurality of times. When the basic solution is removed by drying, the drying temperature is, for example, 20 ° C to 100 ° C.

Preferably, after the contact with the basic solution, the alkali metal and / or the alkaline earth metal contained in the resin film is reduced at the contact portion with which the basic solution is contacted. By reducing the amount of alkali metal and / or alkaline earth metal, a non-polarized portion having excellent dimensional stability can be obtained. Specifically, even in a humidified environment, the shape of the non-polarized portion formed by contact with the basic solution can be maintained as it is.

By contacting with a basic solution, hydroxides of alkali metals and / or alkaline earth metals may remain at the contacts. Further, by contacting with a basic solution, a metal salt of an alkali metal and / or an alkaline earth metal (for example, borate) can be formed at the contact portion. These can generate hydroxide ions, and the generated hydroxide ions act (decompose / reduce) on a dichroic substance (for example, an iodine complex) existing around the contact portion to widen the non-polarized region. obtain. Therefore, it is considered that by reducing the alkali metal and / or alkaline earth metal salt, it is possible to suppress the expansion of the non-polarized region over time and maintain the desired non-polarized portion shape.

The non-polarized portion preferably has an alkali metal and / or alkaline earth metal content of 3.6% by weight or less, more preferably 2.5% by weight or less, still more preferably 1.0% by weight. % Or less, particularly preferably 0.5% by weight or less. The content of the alkali metal and / or alkaline earth metal can be determined, for example, from the X-ray intensity measured by fluorescent X-ray analysis by a calibration curve prepared in advance using a standard sample.

As the method for reducing the above, preferably, a method of bringing an acidic solution into contact with a contact portion with the basic solution is used. According to such a method, the alkali metal and / or the alkaline earth metal can be efficiently transferred to the acidic solution to reduce the content thereof. The contact with the acidic solution may be performed after the removal of the basic solution, or may be performed without removing the basic solution.

Any suitable acidic compound can be used as the acidic compound contained in the acidic solution. Examples of the acidic compound include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and hydrogen fluoride, and organic acids such as formic acid, oxalic acid, citric acid, acetic acid and benzoic acid. Among these, the acidic compound contained in the acidic solution is preferably an inorganic acid, and more preferably hydrochloric acid, sulfuric acid, or nitric acid. These acidic compounds may be used alone or in combination of two or more.

Water and alcohol are preferably used as the solvent for the acidic solution. The concentration of the acidic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, and more preferably 0.1N to 2.5N. The liquid temperature of the acidic solution is, for example, 20 ° C to 50 ° C. The contact time of the acidic solution is, for example, 5 seconds to 5 minutes. As the contact method for the acidic solution, the same method as the contact method for the basic solution can be adopted. Also, the acidic solution can be removed from the polarizer. As the method for removing the acidic solution, the same method as the method for removing the basic solution can be adopted.

C-2. Inspection of non-polarized part After forming the non-polarized part, the non-polarized part is inspected by the above inspection method. When performing the inspection, the surface protective film may be laminated on the polarizer, or the surface protective film may be peeled off. Further, when performing the inspection, it is preferable that the polarizer is in the state of a polarizing plate with a protective film bonded to at least one side.

In one embodiment, after the formation of the non-polarized portion, the non-polarized portion is continuously inspected. When the polarizer is long, the non-polarized portion is inspected without winding the polarizer once after the non-polarized portion is formed. For example, after forming a non-polarizing portion on a polarizing film laminate as shown in FIG. 5, the non-polarizing portion is subjected to an inspection step as it is. In this way, by continuously inspecting after the formation of the non-polarized portion (specifically, by determining whether the size of the formed non-polarized portion is larger or smaller than a predetermined size), for example, Problems in the contact step with the basic solution (for example, the state of through holes in the surface protective film, the state of immersion in the basic solution) can be detected at an early stage.

When a surface protective film is laminated on the polarizing element to be inspected (particularly when a surface protective film is laminated on the imaging side), imaging should be performed without using other optical members such as the polarizing filter. Is preferable. As described above, the surface protective film may have variations in the orientation of the forming resin thereof, and conversely, the variations in the contrast ratio can be increased by passing through the polarizing filter. Therefore, the contrast ratio can be stably satisfied by taking an image without using a polarizing filter.

After inspection, the polarizer can be practically provided as a polarizing plate. In one embodiment, the polarizing plate has a pressure-sensitive adhesive layer for bonding to other members. Preferably, a separator is temporarily attached to the surface of the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer until actual use and to form a roll as shown in FIG.

The polarizer obtained by the manufacturing method 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 Non-polarizing part 10 Polarizing film laminate 11 Exposed part 20 Surface protective film 21 Through hole 30 Protective film 40 Surface protective film 100 Inspection device 110 Light source unit 120 Imaging unit

Claims (6)

A step of contacting a basic solution with a polarizer coated with a surface protective film so that at least a part of the surface is exposed to form a non-polarized portion, and
Including the step of inspecting a polarizer having a non-polarized portion
The inspection step includes a step of irradiating a range including the non-polarizing portion of the polarizer having the non-polarizing portion with light and imaging a transmitted light image of the polarizer , and the non-polarizing portion is the contrast of the transmitted light image. are identified based on the ratio, the contrast ratio of the non-polarizing portion and other portions of the transparent over-light image (non-polarization unit / other sites) is 1.5 or more, is performed by the inspection method of the polarizer,
The imaging is performed with the surface protective film side of the polarizer having the non-polarizing portion in the state where the surface protective film is laminated as the imaging side, without passing through a polarizing filter between the surface protective film and the imaging portion. We ,
The in-plane phase difference of the surface protective film at a wavelength of 590 nm is 500 nm to 3000 nm.
A method for manufacturing a polarizer having a non-polarizing portion. The manufacturing method according to claim 1, wherein the inspection is continuously performed after the formation of the non-polarized portion. The production method according to claim 1 or 2 , wherein the surface protective film contains a polyethylene terephthalate resin. The formation of the non-polarizing portion is performed by bringing a basic solution into contact with a polarizing film laminate obtained by laminating a long surface protective film having a through hole on a long polarizing element. Item 8. The production method according to any one of Items 1 to 3 . The manufacturing method according to claim 4 , wherein through holes are formed at predetermined intervals in the longitudinal direction and / or the width direction of the surface protective film. The manufacturing method according to any one of claims 1 to 5 , wherein in the step of inspecting a polarizer having a non-polarizing portion, the shape and / or characteristics of the non-polarizing portion are inspected.