JP7128228B2 - long polarizing film laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a long polarizing film laminate. More particularly, the present invention relates to laminates of polarizers and surface protective films.

2. Description of the Related Art 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 with the aim of improving the camera performance of such image display devices (for example, Patent Documents 1 to 7). However, with the rapid spread of smart phones and touch panel type information processing devices, there is a demand for further improvements in camera performance and the like. In addition, a polarizing plate having partial polarizing performance is required in order to cope with the diversification of the shape and high functionality of image display devices. In order to industrially and commercially realize these demands, it is desired to manufacture an image display device and/or its parts at an acceptable cost. matter is left.

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

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to realize multi-functionality and high-performance electronic devices such as image display devices, and to improve the quality of the final product. To provide a long polarizing film laminate with which a polarizer can be manufactured with no variation in polarizing properties and excellent yield in manufacturing.

The polarizing film laminate of the present invention includes a long polarizer and a surface protective film disposed on one surface side of the polarizer, and has an exposed portion where the polarizer is exposed on the one surface side. The exposed portions are arranged at predetermined intervals in the longitudinal direction and/or width direction of the polarizer.
In one embodiment, the exposed portions are arranged at predetermined intervals in the longitudinal direction.
In one embodiment, the exposed portions are arranged at substantially equal intervals in at least the longitudinal direction.
In one embodiment, the exposed portions are arranged at substantially equal intervals in the longitudinal direction and the width direction of the polarizer.
In one embodiment, when the polarizer is cut to a predetermined size for attachment to an image display device of a predetermined size, the exposed portion is arranged at a position corresponding to the camera portion of the image display device. .
In one embodiment, the direction of the straight line connecting the adjacent exposed portions is within a range of ±10° with respect to the longitudinal direction and/or the width direction of the polarizer.
In one embodiment, the thickness of the polarizer is 10 μm or less.
In one embodiment, the degree of polarization of the portion corresponding to the exposed portion of the polarizer is 99.9% or more.
In one embodiment, the polarizing film laminate is subjected to a step of decolorizing the portion corresponding to the exposed portion of the polarizer while being conveyed in the longitudinal direction.
In one embodiment, the portion corresponding to the exposed portion of the polarizer is a non-polarized portion formed by decolorizing the polarizer.
In one embodiment, the non-polarizing portion has a transmittance of 90% or more.
In one embodiment, the portion corresponding to the exposed portion of the polarizer includes a concave portion in which the surface of the polarizer on one side is concave.
In one embodiment, the non-polarized portion is a low-concentration portion having a lower content of the dichroic substance than other portions.
In one embodiment, the content of alkali metal and/or alkaline earth metal in the low concentration portion is 3.6% by weight or less.
In one embodiment, the low-concentration portion is formed by bringing a basic solution into contact with the polarizer.
In one embodiment, the basic solution is an aqueous solution containing hydroxides of alkali metals and/or alkaline earth metals.
In one embodiment, a through hole is formed in the surface protective film, and a portion corresponding to the through hole is the exposed portion.
In one embodiment, the surface protective film is detachably laminated on the polarizer.
In one embodiment, the polarizing film laminate includes a protective film arranged on the other side of the polarizer.
In one embodiment, the protective film has a thickness of 80 µm or less.
In one embodiment, the polarizing film laminate includes a second surface protection film arranged on the other side of the polarizer.
In one embodiment, the exposed portions are arranged in dots.
In one embodiment, the planar view shape of the exposed portion is substantially circular or substantially rectangular.
In one embodiment, the polarizing film laminate is wound into a roll.
In one embodiment, the polarizing film laminate is used to manufacture a plurality of polarizers having non-polarizing portions.

According to the present invention, a long polarizer and a surface protective film disposed on one side thereof are provided, and the one side has an exposed portion where the polarizer is exposed, and the exposed portion is the polarizer. Provided is a polarizing film laminate that is arranged at predetermined intervals (that is, in a predetermined pattern) in the longitudinal direction and/or width direction. For example, such a polarizing film laminate can be satisfactorily chemically treated, and a polarizer having non-polarizing portions arranged in a predetermined pattern can be produced with very high production efficiency. In such a polarizer, the position of the non-polarizing portion can be set according to the size of the polarizer to be cut and mounted on the image display device and the position of the camera portion of the image display device, so that a polarizer of a predetermined size can be obtained. The actual yield is extremely excellent. Furthermore, since the position of the non-polarizing portion can be accurately set, the position of the non-polarizing portion in the obtained polarizer of a predetermined size can also be well controlled. As a result, variations in the position of the non-polarizing portion for each obtained polarizer of a predetermined size are reduced, so that final products (polarizers of a predetermined size) with no variation in quality can be obtained. As a result, the polarizing film laminate of the present invention can contribute to multifunctionality and high functionality of electronic devices such as image display devices. Furthermore, according to the polarizing film laminate of the present invention, the positional relationship between the non-polarizing portion and the absorption axis can be uniformly controlled in the entire long polarizer, so that the axis accuracy is excellent (therefore, the optical characteristics (excellent) final product can be obtained.

1 is a schematic perspective view of a polarizing film laminate according to one embodiment of the invention; FIG. FIG. 2 is a partial cross-sectional view of the polarizing film laminate shown in FIG. 1; It is a schematic plan view explaining an example of an arrangement pattern of an exposed part in a polarizing film layered product by an embodiment of the present invention. It is a schematic plan view explaining another example of the arrangement pattern of the exposed part in the polarizing film laminated body by embodiment of this invention. FIG. 5 is a schematic plan view illustrating still another example of the arrangement pattern of the exposed portions in the polarizing film laminate according to the embodiment of the present invention; It is a schematic perspective view explaining lamination|stacking of a polarizer and a surface protection film in the manufacturing method of the polarizing film laminated body by embodiment of this invention. It is the schematic explaining formation of the non-polarization part of the polarizing film laminated body by embodiment of this invention. (a) is a diagram showing evaluation results of surface smoothness of Example 1, and (b) is a diagram showing evaluation results of surface smoothness of Example 2. FIG.

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

A. Polarizing Film Laminate FIGS. 1 and 2 are schematic diagrams of a polarizing film laminate according to one embodiment of the present invention, FIG. 1 is a perspective view of the polarizing film laminate, and FIG. FIG. 4 is a partial cross-sectional view of a film laminate; The polarizing film laminate 100 includes a polarizer 10, a surface protective film 20 arranged on one surface side of the polarizer 10 (the upper surface side in the illustrated example), and a surface protection film 20 disposed on the other surface side of the polarizer 10 (the lower surface side in the illustrated example). A protective film 30 and a second surface protective film 40 are provided. The polarizing film laminate 100 has exposed portions 11, 11 . In the illustrated example, the exposed portion 11 is provided by forming a through hole 21 in the surface protective film 20 arranged on one side of the polarizer 10 (for convenience, the surface protective film having the through hole is referred to as a second surface protective film). 1). A portion of the polarizer 10 corresponding to the exposed portion 11 may be made a non-polarizing portion by any appropriate treatment.

The surface protection film 20 is used for the purpose of temporarily protecting the polarizer 10 during manufacturing, and is removed from the polarizer 10 at any appropriate timing. Therefore, the surface protection film 20 is detachably laminated on the polarizer 10 . Although not shown, the surface protective film 20 is typically adhered to the polarizer 10 via any appropriate adhesive. In this specification, the term "protective film" simply means a polarizer protective film such as the protective film 30, and is different from a surface protective film temporarily used during manufacturing.

The polarizer 10 is elongated, and typically, the polarizing film laminate 100 is wound into a roll as shown in FIG. As used herein, the term "long shape" means an elongated shape whose length is sufficiently long relative to its width, for example, an elongated shape whose length is 10 times or more, preferably 20 times or more, its width. include. In the illustrated example, the longitudinal direction of the elongated surface protective film 20 and the longitudinal direction of the polarizer 10 are substantially parallel. In one embodiment, the width dimension of the elongated surface protective film 20 is designed to be substantially the same as or larger than the width dimension of the polarizer 10 .

The exposed portions 11 are arranged at predetermined intervals (that is, in a predetermined pattern) in the longitudinal direction and/or width direction of the polarizer 10 . The arrangement pattern of the exposed portions 11 can be appropriately set according to the purpose. Typically, the exposed portion 11 is formed when the polarizer 10 is cut into a predetermined size (for example, cut in the longitudinal direction and/or the width direction, punched out) in order to attach the polarizer 10 to an image display device of a predetermined size. It is arranged at a position corresponding to the camera section of the image display device.

When obtaining only one size polarizer piece from one long polarizer 10 by cutting, as shown in FIG. may also be substantially equally spaced. With such a configuration, it is easy to control the cutting of the polarizer into a predetermined size that matches the size of the image display device, and the yield can be improved. Furthermore, it is possible to suppress variation in the position of the non-polarized portion (exposed portion) in the cut sheet of the polarizer (polarizing film laminate). In addition, "substantially equal intervals in both the longitudinal direction and the width direction" means that the intervals in the longitudinal direction are equal and the intervals in the width direction are equal. The longitudinal spacing and the widthwise spacing need not be equal. For example, when the interval in the longitudinal direction is L1 and the interval in the width direction is L2, L1=L2 or L1≠L2. A "polarizer piece" means a polarizer obtained by cutting a long polarizer. In this specification, for context, the polarizer pieces may be simply referred to as polarizers.

When obtaining polarizer pieces of a plurality of sizes from one elongated polarizer 10 by cutting, the distance between the exposed portions 11 in the longitudinal direction and/or the width direction of the polarizer 10 is the size of the polarizer to be cut. can be changed according to For example, the exposed portions 11 may be arranged at substantially equal intervals in the longitudinal direction and arranged at different intervals in the width direction; The directions may be substantially evenly spaced. When the exposed portions 11 are arranged at different intervals in the longitudinal direction or width direction, the intervals between adjacent exposed portions may all be different, or only a portion (specific adjacent exposed intervals) may be different. good. Alternatively, a plurality of regions may be defined in the longitudinal direction of the polarizer 10, and the intervals between the exposed portions 11 in the longitudinal direction and/or the width direction may be set for each region. As described above, it is one of the features of the present invention that the exposed portions (non-polarized portions) can be formed in any appropriate arrangement pattern according to the purpose in the elongated polarizer.

FIG. 3A is a schematic plan view illustrating an example of an arrangement pattern of exposed portions in a polarizing film laminate according to an embodiment of the present invention, and FIG. 3B is a schematic plan view illustrating another example of the arrangement pattern of exposed portions. , and FIG. 3C is a schematic plan view illustrating still another example of the arrangement pattern of the exposed portions. In one embodiment, as shown in FIG. 3A, straight lines connecting adjacent exposed portions 11 in the longitudinal direction of the polarizer 10 are substantially parallel to the longitudinal direction. , and straight lines connecting adjacent exposed portions 11 in the width direction of the polarizer 10 are arranged substantially parallel to the width direction. This embodiment corresponds to the arrangement pattern of the exposed portions 11 in the polarizing film laminate 100 shown in FIG. In another embodiment, as shown in FIG. 3B, in the exposed portions 11, straight lines connecting adjacent exposed portions 11 in the longitudinal direction of the polarizer 10 are substantially parallel to the longitudinal direction. , and straight lines connecting adjacent exposed portions in the width direction of the polarizer 10 are arranged to have a predetermined angle θ _W with respect to the width direction. In still another embodiment, as shown in FIG. 3C, the exposed portion 11 has a straight line connecting adjacent exposed portions in the longitudinal direction of the polarizer 10 at a predetermined angle θ _L with respect to the longitudinal direction. and a straight line connecting adjacent exposed portions in the width direction of the polarizer 10 is arranged to have a predetermined angle θ _W with respect to the width direction.

The above θ _L and/or θ _W is preferably greater than 0° and equal to or less than ±10°. Here, "±" means including both clockwise and counterclockwise directions with respect to the reference direction (longitudinal direction or width direction of the polarizer). The embodiments shown in FIGS. 3B and 3C have the following advantages: Depending on the image display device, the absorption axis of the polarizer may be arranged at maximum with respect to the long side or short side of the device in order to improve display characteristics. It may be required to displace them by about 10°. As will be described later, the absorption axis of the polarizer is expressed in the longitudinal direction or the width direction. Therefore, in such a case, if the configuration is as described above, in such a case, the cut polarizing film laminate (polarizer) The direction of the absorption axis of 101 can be precisely controlled at a desired angle, and the variation in the direction of the absorption axis of each polarizing film laminate (polarizer) 101 can be significantly suppressed. Needless to say, the arrangement pattern of the exposed portions is not limited to the illustrated example. For example, in the exposed portions, a straight line connecting adjacent exposed portions in the longitudinal direction of the polarizer has a predetermined angle _θL with respect to the longitudinal direction, and exposed portions adjacent in the width direction of the polarizer may be arranged so as to be substantially parallel to the width direction. Alternatively, a plurality of regions may be defined along the longitudinal direction of the polarizer, and θ _L and/or θ _W may be set for each region.

The planar view shape of the exposed portion 11 (the shape viewed from one side of the polarizing film laminate 100) is any appropriate shape as long as it does not adversely affect the camera performance of the image display device in which the polarizer is used. can be Examples of the planar shape of the exposed portion include a substantially circular shape and a substantially rectangular shape. Specifically, circles, ovals, squares, rectangles, and rhombuses are mentioned. By appropriately setting the shape of the through-holes of the surface protection film, which will be described later, the exposed portion having a desired plan view shape can be formed.

A-1. Polarizer The polarizer 10 is typically composed of a resin film containing a dichroic substance. The resin film is, for example, a polyvinyl alcohol-based resin (hereinafter referred to as "PVA-based resin") film.

Examples of the dichroic substance include iodine and organic dyes. These may be used alone or in combination of two or more. Iodine is preferably used. For example, when the non-polarizing portion is formed by decolorization by chemical treatment, the iodine complex contained in the resin film (polarizer) is appropriately reduced, so the non-polarizing portion having properties suitable for use in the camera portion. This is because it is possible to form

Any appropriate resin may be used as the PVA-based resin forming the PVA-based resin film. Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymer. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. An ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The degree of saponification of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% to 99.95 mol%, more preferably 99.0 mol% to 99.93 mol%. . The degree of saponification can be determined according to JIS K 6726-1994. By using a PVA-based resin having such a degree of saponification, a polarizer with excellent durability can be obtained. If the degree of saponification is too high, gelation may occur.

The average degree of polymerization of the PVA-based resin can be appropriately selected depending on the purpose. The average degree of polymerization is usually 1,000 to 10,000, preferably 1,200 to 4,500, more preferably 1,500 to 4,300. The average degree of polymerization can be determined according to JIS K 6726-1994.

The polarizer (excluding the non-polarizing portion) preferably exhibits absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance (Ts) of the polarizer (excluding 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 single transmittance is 50%, and the practical upper limit is 46%. In addition, the single transmittance (Ts) is a Y value measured with a JIS Z8701 2-degree field of view (C light source) and corrected for visibility. can be measured. The degree of polarization of the polarizer (excluding the non-polarized portion) is preferably 99.9% or higher, more preferably 99.93% or higher, and even more preferably 99.95% or higher.

The non-polarizing portion is preferably a bleached portion formed by bleaching a polarizer. 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, and still more preferably 75% or more, Especially preferably, it is 90% or more. With such a transmittance, the desired transparency of the non-polarizing portion can be ensured. As a result, when the polarizer is arranged such that the non-polarizing portion corresponds to the camera portion of the image display device, it is possible to prevent adverse effects on the photographing performance of the camera.

Preferably, the non-polarized portion is a low concentration portion having a relatively low dichroic substance content. Specifically, it is a low-density portion having a lower dichroic substance content than other portions. According to such a configuration, compared to the case where the non-polarized portion is formed mechanically (for example, by a method of mechanically punching out using an engraving blade punching, plotter, water jet, etc.), cracks, Quality problems such as delamination (delamination of layers) and paste extrusion are avoided. In addition, since the content of the dichroic substance itself is low in the low-density portion, the transparency of the non-polarized portion is higher than in the case where the non-polarized portion is formed by decomposing the dichroic substance with a laser beam or the like. well maintained.

The low concentration portion is a portion having a lower dichroic substance content than the other portion. 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, and even more preferably 0.2% by weight or less. If the content of the dichroic substance in the low-density portion is within this range, the desired transparency can be sufficiently imparted to the low-density portion. For example, when the low-density portion corresponds to the camera portion of the image display device, extremely excellent shooting performance can be achieved in terms of both brightness and color. On the other hand, the lower limit of the content of the dichroic substance in the low-concentration part is usually below the detection limit. When iodine is used as the dichroic substance, the iodine content can be obtained from, for example, a calibration curve prepared in advance using standard samples from X-ray intensities measured by fluorescent X-ray analysis.

The difference between the content of the dichroic substance in the other portion and the content of the dichroic substance in the low-density portion is preferably 0.5% by weight or more, more preferably 1% by weight or more. If the content difference is within such a range, a low-concentration portion having desired transparency can be formed.

The low-concentration part 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, and still more preferably 1.0% by weight. % or less, particularly preferably 0.5 wt % or less. If the content of the alkali metal and/or alkaline earth metal in the low-concentration part is within such a range, the shape of the low-concentration part formed by contact with the basic solution described below can be maintained satisfactorily. (ie, a low density portion with excellent dimensional stability can be achieved). The content can be obtained, for example, from a calibration curve prepared in advance using standard samples from X-ray intensities measured by fluorescent X-ray analysis. Such a content can be achieved by reducing the alkali metal and/or alkaline earth metal in the contact portion in contact with the basic solution described below.

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 less than 10 μm. On the other hand, the thickness is preferably 0.5 μm or more, more preferably 1 μm or more. With such a thickness, a polarizer having excellent durability and optical properties can be obtained. Also, the thinner the thickness, the better the non-polarizing portion can be formed. For example, when the non-polarized portion is formed by chemical decolorization, the contact time between the decolorizing solution and the resin film (polarizer) can be shortened. Specifically, it is possible to form a non-polarizing portion with a higher transmittance in a shorter time.

The thickness of the portion contacted with the decolorizing solution (eg, basic solution) can be thinner than other portions. This tendency can become stronger as the transmittance of the non-polarized portion obtained by decolorization is increased. By making the resin film thinner, it is possible to achieve a high transmittance (preferably 90% or more) in the non-polarizing portion while reducing the step between the non-polarizing portion and other portions. In this way, problems that may occur due to steps can be prevented. Problems include, for example, when a long polarizer is wound into a roll, the difference in level between the non-polarized portion and other portions is transferred as winding marks to the overlapped portion, and the protective film, etc. It is conceivable that air bubbles may be generated due to the difference in level between the non-polarizing portion and other parts when the non-polarizing portion is bonded to the constituent members of (1), and the difference in level may be visible in the final product. It is thought that preventing such problems can also contribute to suppressing variations in the quality of the polarizer that is finally used and obtained by cutting the polarizer of the present invention. It is considered that such an effect can become remarkable, for example, when the transmittance of the non-polarizing portion is 90% or more and/or when the content of the dichroic substance is 0.2% by weight or less. The high transmittance of 90% or more in the non-polarizing portion can also contribute to suppressing variations in the quality of the polarizer that is finally used. Specifically, when the non-polarized portion is formed by contact with the decolorizing liquid, the transmittance of the non-polarized portion obtained is likely to vary if the degree of decolorization is weak, but the transmittance is 90% or more and / or the dichroic substance is 0.2% by weight or less (by increasing the degree of decolorization), the decolorization state can be stably controlled.

In one embodiment, the non-polarized portion is a thin portion that is thinner than other portions. For example, the surface of the polarizer on one side is formed with a recessed portion to form a thin portion. In this case, the step (depth of the recess) between the non-polarizing portion and the other portion is, for example, 0.02 μm or more. On the other hand, the step is preferably 2 μm or less, more preferably 1 μm or less. When the non-polarizing portion is formed by decolorization described later (for example, when the transmittance of the non-polarizing portion is 90% or more and/or when the content of the dichroic substance is 0.2% by weight or less), such However, if the upper limit of the step is in such a range, it is considered that problems due to the step such as winding marks due to roll formation can be suppressed satisfactorily. As a result, it is possible to remarkably suppress variations in the quality of the finally used polarizer obtained by cutting the polarizer of the present invention. In this specification, the term "step (depth of recess)" refers to the depth of the deepest portion of the recess.

The above-mentioned recesses in which the surface on the one side is recessed are formed, for example, by applying a decolorizing liquid only from the one side of the polarizer. By setting the depth of the recesses formed after the decolorization treatment within the above range, the post-decolorization treatment described below can be performed uniformly. In addition, it is thought that by forming the concave portion only on one surface side, it is possible to prevent the occurrence of defects due to steps such as winding marks due to roll formation, and to suppress variations in the quality of the polarizer that is finally used. .

The absorption axis of the polarizer can be set in any appropriate direction depending on the purpose. The direction of the absorption axis may be, for example, the longitudinal direction or the width direction. A polarizer having an absorption axis in the longitudinal direction has the advantage of being excellent in manufacturing efficiency. A polarizer having an absorption axis in the width direction has the advantage that it can be laminated, for example, with a retardation film having a slow axis in the longitudinal direction in a so-called roll-to-roll manner. In this specification, the term “roll to roll” refers to stacking a roll of film while aligning the longitudinal directions of each film while transporting the film.

The resin film (typically, PVA-based resin film) constituting the polarizer may be a single film, and a resin layer (typically, PVA-based resin layer). The PVA-based resin layer may be formed by applying a coating liquid containing the PVA-based resin onto the resin substrate, or may be formed by laminating a PVA-based resin film on the resin substrate. A case where the polarizer is a PVA-based resin layer formed on a resin substrate will be specifically described below. Here, a case where a PVA-based resin layer is formed by coating will be described, but the same applies to a case where a PVA-based resin film is laminated. In addition, when the polarizer is a single PVA-based resin film, the polarizer can be produced by a method well known and commonly used in the art, so detailed description thereof is omitted.

A-1-1. Production of Laminate First, a coating liquid containing a PVA-based resin is applied onto a resin substrate and dried to form a PVA-based resin layer, thereby producing a laminate of resin substrate/PVA-based resin layer. do.

Any appropriate thermoplastic resin may be employed as a material for forming the resin base material. Examples of thermoplastic resins include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. is mentioned. Among these, norbornene-based resins and amorphous polyethylene terephthalate-based resins are preferred.

In one embodiment, an amorphous (not crystallized) polyethylene terephthalate resin is preferably used. Among them, amorphous (difficult to crystallize) polyethylene terephthalate resin is particularly preferably used. Specific examples of amorphous polyethylene terephthalate resins include copolymers further containing isophthalic acid as a dicarboxylic acid and copolymers further containing cyclohexanedimethanol as a glycol.

When the underwater stretching method is adopted for the stretching described later, the resin substrate absorbs water, and the water acts like a plasticizer to plasticize the substrate. As a result, the stretching stress can be greatly reduced, and the film can be stretched at a high draw ratio, resulting in better stretchability than during stretching in the air. As a result, a polarizer having excellent optical properties can be produced. In one embodiment, the resin substrate preferably has a water absorption of 0.2% or more, more preferably 0.3% or more. On the other hand, the water absorption rate of the resin substrate is preferably 3.0% or less, more preferably 1.0% or less. By using such a resin base material, it is possible to prevent problems such as deterioration of the appearance of the obtained polarizer due to a significant decrease in dimensional stability during production. In addition, it is possible to prevent breakage of the base material and peeling of the PVA-based resin layer from the resin base material during stretching in water. The water absorption rate of the resin base material can be adjusted, for example, by introducing a modifying group into the forming material. The water absorption is a value determined according to JIS K7209.

The glass transition temperature (Tg) of the resin substrate is preferably 170° C. or lower. By using such a resin base material, it is possible to sufficiently secure the stretchability of the laminate while suppressing the crystallization of the PVA-based resin layer. Furthermore, considering the plasticization of the resin base material with water and the excellent stretching in water, the temperature is more preferably 120° C. or less. In one embodiment, the glass transition temperature of the resin substrate is preferably 60° C. or higher. By using such a resin base material, problems such as deformation of the resin base material (for example, occurrence of unevenness, sag, wrinkles, etc.) can be prevented when applying and drying the coating liquid containing the PVA-based resin. By doing so, a laminate can be produced satisfactorily. Moreover, the PVA-based resin layer can be satisfactorily stretched at a suitable temperature (for example, about 60°C). In another embodiment, the glass transition temperature may be lower than 60° C. as long as the resin substrate is not deformed when the coating liquid containing the PVA-based resin is applied and dried. The glass transition temperature of the resin base material can be adjusted, for example, by heating using a crystallization material that introduces a modifying group into the forming material. The glass transition temperature (Tg) is a value determined according to JIS K7121.

The thickness of the resin substrate before stretching is preferably 20 μm to 300 μm, more preferably 50 μm to 200 μm. If the thickness is less than 20 μm, it may be difficult to form the PVA-based resin layer. If it exceeds 300 μm, for example, in stretching in water, it may take a long time for the resin substrate to absorb water, and an excessive load may be required for stretching.

The PVA-based resin forming the PVA-based resin layer is as described in section A-1 above.

The coating liquid is typically a solution obtained by dissolving the PVA-based resin in a solvent. Examples of solvents include water, dimethylsulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine. These can be used alone or in combination of two or more. Among these, water is preferred. The concentration of the PVA-based resin in the solution is preferably 3 to 20 parts by weight with respect to 100 parts by weight of the solvent. With such a resin concentration, it is possible to form a uniform coating film in close contact with the resin substrate.

Additives may be added to the coating liquid. Examples of additives include plasticizers and surfactants. Examples of plasticizers include polyhydric alcohols such as ethylene glycol and glycerin. Surfactants include, for example, nonionic surfactants. These can be used for the purpose of further improving the uniformity, dyeability and stretchability of the obtained PVA-based resin layer.

Any appropriate method can be adopted as a method for applying the coating liquid. Examples thereof include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (comma coating, etc.).

The coating/drying temperature of the coating liquid is preferably 50° C. or higher.

The thickness of the PVA-based resin layer before stretching is preferably 3 μm to 40 μm, more preferably 3 μm to 20 μm.

Before forming the PVA-based resin layer, the resin substrate may be surface-treated (for example, corona treatment), or an easy-adhesion layer may be formed on the resin substrate. By performing such a treatment, the adhesion between the resin substrate and the PVA-based resin layer can be improved.

A-1-2. Stretching of Laminate Any appropriate method can be adopted as a method for stretching the laminate. Specifically, fixed-end stretching or free-end stretching (for example, a method of uniaxially stretching a laminate by passing it between rolls having different peripheral speeds) may be used. Free end drawing is preferred.

The stretching direction of the laminate can be appropriately set. In one embodiment, the laminate is stretched in the longitudinal direction. As a result, the absorption axis of the resulting polarizer can be developed in the longitudinal direction. In this case, typically, a method is adopted in which the laminate is passed through rolls with different peripheral speeds and stretched. In another embodiment, the elongated laminate is stretched in the width direction. As a result, the absorption axis of the obtained polarizer can be developed in the width direction. In this case, a method of drawing using a tenter drawing machine is typically adopted.

The stretching method is not particularly limited, and may be an air stretching method or an underwater stretching method. An underwater drawing method is preferable. According to the underwater stretching method, stretching can be performed at a temperature lower than the glass transition temperature (typically, about 80° C.) of the resin base material and the PVA-based resin layer, and the crystallization of the PVA-based resin layer can be suppressed. However, it can be stretched to a high magnification. As a result, a polarizer having excellent optical properties can be produced.

The laminate may be stretched in one step or in multiple steps. When performing in multiple steps, for example, the free end stretching and the fixed end stretching may be combined, or the underwater stretching method and the air stretching method may be combined. Moreover, when carrying out in multiple steps, the draw ratio (maximum draw ratio) of the laminate described later is the product of the draw ratios in each step.

The stretching temperature of the laminate can be set to any appropriate value depending on the material for forming the resin substrate, the stretching method, and the like. When the in-air stretching method is employed, the stretching temperature is preferably the glass transition temperature (Tg) of the resin substrate or higher, more preferably the glass transition temperature (Tg) of the resin substrate + 10°C or higher, particularly preferably Tg + 15°C. That's it. On the other hand, the stretching temperature of the laminate is preferably 170° C. or lower. By stretching at such a temperature, it is possible to suppress rapid crystallization of the PVA-based resin and suppress problems caused by the crystallization (for example, hindrance of orientation of the PVA-based resin layer due to stretching). can.

When the underwater stretching method is employed, the liquid temperature of the stretching bath is preferably 40°C to 85°C, more preferably 50°C to 85°C. At such a temperature, the film can be stretched at a high magnification while suppressing dissolution of the PVA-based resin layer. Specifically, as described above, the glass transition temperature (Tg) of the resin substrate is preferably 60° C. or higher in relation to the formation of the PVA-based resin layer. In this case, if the stretching temperature is lower than 40° C., it may not be possible to stretch well even if the plasticization of the resin base material by water is considered. On the other hand, the higher the temperature of the stretching bath, the higher the solubility of the PVA-based resin layer, which may make it impossible to obtain excellent optical properties. The immersion time of the laminate in the stretching bath is preferably 15 seconds to 5 minutes.

When the underwater stretching method is employed, it is preferable to stretch the laminate by immersing it in an aqueous boric acid solution (stretching in boric acid water). By using an aqueous boric acid solution as the stretching bath, the PVA-based resin layer can be imparted with rigidity to withstand tension applied during stretching and water resistance that does not dissolve in water. Specifically, boric acid can form a tetrahydroxyborate anion in an aqueous solution and crosslink with a PVA-based resin through hydrogen bonding. As a result, rigidity and water resistance can be imparted to the PVA-based resin layer, which can be satisfactorily stretched, and a polarizer having excellent optical properties can be produced.

The boric acid aqueous solution is preferably obtained by dissolving boric acid and/or a borate salt in water as a solvent. The boric acid concentration is preferably 1 to 10 parts by weight with respect to 100 parts by weight of water. By setting the boric acid concentration to 1 part by weight or more, dissolution of the PVA-based resin layer can be effectively suppressed, and a polarizer with higher properties can be produced. In addition to boric acid or borate salts, an aqueous solution obtained by dissolving a boron compound such as borax, glyoxal, glutaraldehyde, or the like in a solvent can also be used.

When a dichroic substance (typically iodine) is previously adsorbed on the PVA-based resin layer by dyeing, which will be described later, iodide is preferably added to the stretching bath (boric acid aqueous solution). By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. Examples of iodides 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 preferred. The concentration of iodide is preferably 0.05 to 15 parts by weight, more preferably 0.5 to 8 parts by weight, per 100 parts by weight of water.

The draw ratio (maximum draw ratio) of the laminate is preferably 5.0 times or more with respect to the original length of the laminate. Such a high draw ratio can be achieved, for example, by adopting an underwater drawing method (boric acid solution drawing). In this specification, the "maximum draw ratio" refers to the draw ratio immediately before the laminate breaks, and the draw ratio at which the laminate breaks is confirmed separately, and the value is 0.2 lower than that value. .

In a preferred embodiment, the laminate is stretched in air at a high temperature (for example, 95° C. or higher), then stretched in boric acid solution and dyed as described later. Such in-air stretching can be positioned as a preliminary or supplementary stretching for stretching in boric acid solution, and hence is hereinafter referred to as "auxiliary in-air stretching".

In some cases, the laminate can be stretched at a higher draw ratio by combining the in-air auxiliary stretching. As a result, a polarizer with better optical properties (eg degree of polarization) can be produced. For example, when a polyethylene terephthalate-based resin is used as the resin substrate, the orientation of the resin substrate is suppressed more by combining the auxiliary stretching in the air and the stretching in boric acid water than by stretching in boric acid water alone. It can be stretched while As the orientation of the resin base material improves, the drawing tension increases, making stable drawing difficult or breaking the base material. Therefore, by stretching while suppressing the orientation of the resin base material, the laminate can be stretched at a higher magnification.

In addition, by combining auxiliary stretching in the air, the orientation of the PVA-based resin can be improved, thereby improving the orientation of the PVA-based resin even after stretching in boric acid solution. Specifically, by improving the orientation of the PVA-based resin in advance by auxiliary stretching in the air, the PVA-based resin is easily crosslinked with boric acid during stretching in boric acid water, and boric acid acts as a node. It is presumed that the orientation of the PVA-based resin is enhanced even after the stretching in the boric acid solution by stretching in the flat state. As a result, a polarizer having excellent optical properties (eg degree of polarization) can be produced.

The draw ratio in the in-air auxiliary drawing is preferably 3.5 times or less. The stretching temperature of the in-air auxiliary stretching is preferably equal to or higher than the glass transition temperature of the PVA-based resin. The stretching temperature is preferably 95°C to 150°C. In addition, the maximum draw ratio when the in-air auxiliary drawing and the boric acid solution drawing are combined is preferably 5.0 times or more, more preferably 5.5 times or more, still more preferably 5.5 times or more, relative to the original length of the laminate. is 6.0 times or more.

A-1-3. Dyeing The dyeing is typically performed by adsorbing a dichroic substance (preferably iodine) to the PVA-based resin layer. Examples of the adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of coating the PVA-based resin layer with the dyeing solution, and a method of applying the dyeing solution to the PVA-based resin layer. A spraying method and the like can be mentioned. A preferred method is to immerse the laminate in a dyeing solution. This is because iodine can be well adsorbed.

The staining solution is preferably an iodine aqueous solution. The amount of iodine compounded is preferably 0.1 to 0.5 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 iodine aqueous solution. Specific examples of iodides are as described above. The amount of iodide compounded is preferably 0.02 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, per 100 parts by weight of water. The liquid temperature of the dyeing liquid during dyeing is preferably 20° C. to 50° C. in order to suppress the dissolution of the PVA-based resin. When the PVA-based resin layer is immersed in the dyeing solution, the immersion time is preferably 5 seconds to 5 minutes in order to ensure the transmittance of the PVA-based resin layer. In addition, the dyeing conditions (concentration, liquid temperature, immersion time) can be set so that the degree of polarization or single transmittance of the finally obtained polarizer falls within a predetermined range. In one embodiment, the immersion time is set so that the obtained polarizer has a degree of polarization of 99.98% or more. In another embodiment, the immersion time is set so that the single transmittance of the obtained polarizer is 40% to 44%.

Dyeing treatment can be performed at any appropriate timing. When the underwater stretching is performed, it is preferably performed before the underwater stretching.

A-1-4. Other Treatments In addition to stretching and dyeing, the laminate may be appropriately treated to make the PVA-based resin layer into a polarizer. Examples of the treatment for forming a polarizer include insolubilization treatment, cross-linking treatment, washing treatment, drying treatment, and the like. Note that the number of times, order, etc. of these processes are not particularly limited.

The insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. Water resistance can be imparted to the PVA-based resin layer by performing the insolubilization treatment. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20°C to 50°C. Preferably, the insolubilization treatment is performed before the above-mentioned stretching in water and the above-mentioned dyeing treatment.

The cross-linking treatment is typically performed by immersing the PVA-based resin layer in an aqueous solution of boric acid. The cross-linking treatment can impart water resistance to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 5 parts by weight with respect to 100 parts by weight of water. Moreover, when cross-linking treatment is carried out after the dyeing treatment, it is preferable to further add an iodide. By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The amount of iodide compounded is preferably 1 to 5 parts by weight per 100 parts by weight of water. Specific examples of iodides are as described above. The liquid temperature of the cross-linking bath (boric acid aqueous solution) is preferably 20°C to 60°C. Preferably, the cross-linking treatment is performed before the underwater stretching. In a preferred embodiment, dyeing treatment, cross-linking treatment and stretching in water are performed in this order.

The cleaning treatment is typically performed by immersing the PVA-based resin layer in an aqueous solution of potassium iodide. The drying temperature in the drying treatment is preferably 30°C to 100°C.

A-2. Surface Protection Film The surface protection film 20 has through holes 21 arranged in a predetermined pattern. The position where the through-hole is provided corresponds to the position where the exposed portion (non-polarized portion) of the polarizer is formed. The arrangement pattern of the through holes shown in FIG. 4 corresponds to the arrangement pattern of the exposed portions (non-polarized portions) shown in FIG. 3A. A through-hole may have any suitable shape. The shape of the through-hole corresponds to the planar view shape of the formed exposed portion (non-polarized portion). Through-holes are formed, for example, by mechanical punching (eg, punching, engraving blade punching, plotter, water jet) or removal of predetermined portions (eg, laser ablation or chemical dissolution).

The surface protection film is preferably a film with high hardness (for example, elastic modulus). This is because deformation of the through-holes during transportation and/or lamination can be prevented. Materials for forming the surface protective film include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. etc. Ester-based resins (especially polyethylene terephthalate-based resins) are preferred. Such a material is advantageous in that it is inexpensive, has a sufficiently high elastic modulus, and the through holes are less likely to deform even when tension is applied during transportation and/or lamination.

The thickness of the surface protective film is typically 20 μm to 250 μm, preferably 30 μm to 150 μm. With such a thickness, there is an advantage that deformation of the through-holes is less likely to occur even if tension is applied during transportation and/or lamination.

The elastic modulus of the surface protective film is preferably 2.2 kN/mm ² to 4.8 kN/mm ² . If the elastic modulus of the surface protection film is within such a range, there is an advantage that deformation of the through-holes is unlikely to occur even if tension is applied during transportation and/or lamination. The elastic modulus is measured according to JIS K6781.

The tensile elongation of the surface protective film is preferably 90% to 170%. If the tensile elongation of the surface protective film is within such a range, it has the advantage of being less likely to break during transportation. The tensile elongation is measured according to JIS K 6781.

As one embodiment, as shown in FIG. 4, a long polarizer 10 is coated with a surface protective film 20 having through holes 21 arranged in a predetermined pattern in a roll-to-roll manner. Lamination by By using a surface protection film having through-holes, the exposed portions (non-polarized portions) of the polarizer can be formed satisfactorily.

When laminating a polarizer and a surface protective film by roll-to-roll, the surface protective film is unwound from a surface protective film roll in which a long surface protective film is wound into a roll, and laminated on the polarizer. Alternatively, after forming the through holes in the surface protective film, the surface protective film may be continuously laminated on the polarizer (without once winding up the surface protective film).

As described above, surface protection film 20 is typically releasably attached to polarizer 10 via any appropriate adhesive. Preferably, through holes are formed in advance in the surface protection film on which the pressure-sensitive adhesive layer is formed, and this is attached to the polarizer. As the adhesive used for laminating the surface protection film, for example, an acrylic resin, a styrene resin, a silicone resin, or the like is used as a base resin, and the base resin is crosslinked selected from isocyanate compounds, epoxy compounds, aziridine compounds, and the like. and a pressure-sensitive adhesive composition containing a silane coupling agent or the like. The thickness of the adhesive layer is usually 1 μm to 60 μm, preferably 3 μm to 30 μm. If the pressure-sensitive adhesive layer is too thin, there is a risk that problems such as reduced adhesiveness and that air bubbles will easily enter may occur. Acrylic pressure-sensitive adhesives are preferably used from the viewpoints of chemical resistance, adhesion (for example, for preventing solution from penetrating during immersion, which will be described later), and degree of freedom to adherends.

A-3. Others Materials for forming the protective film 30 include, for example, cellulose-based resins such as diacetyl cellulose and triacetyl cellulose, (meth)acrylic-based resins, cycloolefin-based resins, olefin-based resins such as polypropylene, and esters such as polyethylene terephthalate-based resins. system resins, polyamide system resins, polycarbonate system resins, copolymer resins thereof, and the like. The thickness of the protective film is typically 10 μm to 100 μm. In one embodiment, the protective film has a thickness of 80 μm or less. Use of a protective film having such a thickness can contribute to thinning of the obtained polarizing plate. On the other hand, when a long polarizing plate in which a protective film having such a thickness is disposed on the other side of the polarizer in which the recesses are formed on the one side is wound into a roll, the above It is conceivable that problems due to steps, such as the concave portions being transferred to the protective film as winding marks, are likely to occur. In such an embodiment, the merit of reducing the step of the recess can be obtained remarkably.

The protective film may have an optical compensation function (that is, it may have an appropriate refractive index ellipsoid, in-plane retardation, and thickness direction retardation depending on the purpose). A protective film is typically laminated on a polarizer via an adhesive layer (specifically, an adhesive layer, an adhesive layer). The adhesive layer is typically formed of a PVA-based adhesive or an active energy ray-curable adhesive. The adhesive layer is typically formed with an acrylic adhesive.

When the polarizer 10 is a resin layer formed on a resin substrate, lamination of the protective film 30 and/or peeling of the resin substrate may be performed. In one embodiment, a protective film is laminated on the surface of a polarizer of a resin substrate/polarizer laminate by roll-to-roll, and then the resin substrate is peeled off.

The second surface protection film 40 may be the same film as the first surface protection film except that it does not have through holes. Furthermore, a soft (for example, low elastic modulus) film such as a polyolefin (for example, polyethylene) film can also be used as the second surface protection film. In one embodiment, the second surface protection film 40 is laminated on one side of the polarizer 10 by roll-to-roll. Specifically, the second surface protection film 40 is releasably attached to the polarizer 10 or the protection film 30 via any appropriate adhesive. By using the second surface protective film, the polarizer or polarizing plate (polarizer/protective film) can be appropriately protected during the chemical treatment described below. The second surface protective film may be laminated on the polarizer or polarizing plate at the same time as the first surface protective film, may be laminated before laminating the first surface protective film, and may be laminated on the first surface protective film. It may be laminated after laminating the film. Preferably, the second surface protection film is laminated before laminating the first surface protection film to the polarizer or polarizing plate. With such a procedure, the protective film is prevented from being damaged, and the through holes formed in the first surface protective film are prevented from being transferred to the protective film as marks during winding. have advantages. When laminating the second surface protective film before laminating the first surface protective film, for example, a laminate of the protective film and the second surface protective film is produced, and this laminate is used as a resin base material. / After lamination on the laminate of the polarizer, the resin substrate can be peeled off, and the first surface protective film can be laminated on the peeled surface.

Although not shown, the polarizing film laminate of the present invention may further have any suitable optical function layer depending on the purpose. Representative examples of the optical functional layer include a retardation film (optical compensation film) and a surface treatment layer.

B. Formation of Non-Polarizing Portion The non-polarizing portion can be formed by any appropriate method as long as the desired optical properties are obtained. In one embodiment, the non-polarizing portion is formed by decolorizing the polarizer by chemical treatment. When performing chemical treatment, it is preferable that the other surface side of the polarizer 10 is protected by any suitable film material in addition to the protection by the first surface protective film. As this film material, for example, when the protective film 30, the second surface protective film 40, and the polarizer 10 are resin layers formed on a resin substrate, the resin substrate is used.

The formation of the non-polarizing portion will be specifically described below. As a representative example, the case of forming a non-polarizing portion in the polarizer by chemical decolorization (hereinafter also referred to as chemical decolorization treatment) in the illustrated polarizing film laminate 100 will be described. It is obvious to those skilled in the art that the same procedure can be applied to configurations different from the illustrated example.

The chemical decolorization treatment includes contacting the polarizing film laminate with a basic solution. When iodine is used as the dichroic substance, the iodine content of the contact portion can be easily reduced by contacting the desired portion of the resin film with a basic solution.

Contact with a polarizing film laminated body and a basic solution can be performed by arbitrary appropriate means. Typical examples include immersion of the polarizing film laminate in a basic solution, or application or spraying of a basic solution onto the polarizing film laminate. Immersion is preferred. This is because, as shown in FIG. 5, the decolorization treatment can be performed while transporting the polarizing film laminate in the longitudinal direction, so that the production efficiency is remarkably high. Immersion is possible by using the first surface protection film (and the second surface protection film if necessary). Specifically, by immersing the polarizer in the basic solution, only the portions of the polarizer corresponding to the through-holes of the first surface protection film come into contact with the basic solution. For example, when the polarizer contains iodine as a dichroic substance, the iodine concentration in the contact portion of the polarizer with the basic solution is reduced by bringing the polarizer into contact with the basic solution, and as a result, the contact A non-polarizing portion can be selectively formed only in a portion (which can be set by the through holes of the first surface protective film). As described above, according to the present embodiment, it is possible to selectively form a non-polarizing portion in a predetermined portion of the polarizer with extremely high manufacturing efficiency without complicated operations. Note that when iodine remains in the polarizer, even if the iodine complex is destroyed to form the non-polarizing portion, the iodine complex is formed again as the polarizer is used, and the non-polarizing portion has the desired characteristics. It may disappear. In this embodiment, the iodine itself is removed from the polarizer (substantially, the non-polarization portion) by removing the basic solution, which will be described later. As a result, it is possible to prevent the characteristics of the non-polarized portion from changing due to the use of the polarizer.

Formation of the non-polarized portion with a basic solution will be described in more detail. After contact with the predetermined portion of the polarizer, the basic solution permeates into the predetermined portion. The iodine complex contained in the predetermined portion is reduced by the base contained in the basic solution to become iodine ions. By reducing the iodine complex to iodine ions, the polarizing performance of the portion is substantially lost, and a non-polarizing portion is formed in the portion. Moreover, the reduction of the iodine complex improves the transmittance of the relevant portion. The iodine converted to iodine ions migrates from this portion into the solvent of the basic solution. As a result, iodide ions are also removed from the portion along with the basic solution by the removal of the basic solution, which will be described later. In this manner, a non-polarized portion (low-density portion) is selectively formed in a predetermined portion of the polarizer, and the non-polarized portion is stable without aging. By adjusting the material, thickness and mechanical properties of the first surface protective film, the concentration of the basic solution, and the immersion time of the polarizing film laminate in the basic solution, etc., the portion where the basic solution is not desired permeation up to (resulting in the formation of a non-polarized portion in an undesired portion) can be prevented.

Any appropriate basic compound can be used as the basic compound contained in the basic solution. Basic compounds include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, inorganic alkali metal salts such as sodium carbonate, and acetic acid. Examples include organic alkali metal salts such as sodium, aqueous ammonia, and the like. Among these, alkali metal and/or alkaline earth metal hydroxides are preferably used, and sodium hydroxide, potassium hydroxide and lithium hydroxide are more preferably used. The iodine complex can be efficiently ionized, and the non-polarized portion can be formed more easily. These basic compounds may be used alone or in combination of two or more.

Any appropriate solvent can be used as the solvent for the basic solution. Specific examples include water, alcohols such as ethanol and methanol, ethers, benzene, chloroform, and mixed solvents thereof. As the solvent, water and alcohol are preferable because the iodide ions transfer well to the solvent and the iodide ions can be easily removed in the subsequent removal of the basic solution.

The concentration of the basic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, more preferably 0.1N to 2.5N. If the concentration of the basic solution is within this range, the iodine concentration inside the polarizer can be efficiently reduced, and the ionization of the iodine complex at desired portions can be prevented.

The liquid temperature of the basic solution is, for example, 20°C to 50°C. The contact time between the polarizing film laminate (substantially, a predetermined portion of the polarizer) and the basic solution depends on the thickness of the polarizer, the type of basic compound contained in the basic solution used, and the basic compound. can be set according to the concentration of , for example, 5 seconds to 30 minutes.

A polarizer (resin film) may contain boric acid. For example, boric acid can be included by bringing a boric acid solution (eg, boric acid aqueous solution) into contact during the stretching treatment, cross-linking treatment, or the like. The boric acid content of the polarizer (resin film) is, for example, 10% by weight to 30% by weight. Also, the boric acid content in the contact portion with the basic solution is, for example, 5% to 12% by weight.

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

By bringing the basic solution into contact with the resin film, hydroxides of alkali metals and/or alkaline earth metals can remain in the contact area. Also, by bringing a basic solution into contact with the resin film, metal salts of alkali metals and/or alkaline earth metals can be generated at the contact portion. These can generate hydroxide ions, and the generated hydroxide ions act (decompose/reduce) dichroic substances (e.g., iodine complexes) present around the contact area, resulting in non-polarized regions (low concentration range) can be widened. Therefore, it is thought that by reducing the alkali metal and/or alkaline earth metal salt, the expansion of the non-polarized region over time can be suppressed, and the desired shape of the non-polarized portion can be maintained.

（式中、Ｘはアルカリ金属またはアルカリ土類金属を表す） Examples of metal salts capable of generating hydroxide ions include borates. The borate can be produced by neutralizing the boric acid contained in the resin film with a basic solution (alkali metal hydroxide and/or alkaline earth metal hydroxide solution). Borate (metaborate) can be hydrolyzed to generate hydroxide ions as shown in the following formula when the polarizer is placed in a humidified environment, for example.

(Wherein, X represents an alkali metal or alkaline earth metal)

Preferably, the content of alkali metal and/or alkaline earth metal in the contact portion is 3.6% by weight or less, preferably 2.5% by weight or less, more preferably 1.0% by weight or less, still more preferably 0.5% by weight or less. The content is reduced to 5% by weight or less.

The resin film may contain an alkali metal and/or an alkaline earth metal in advance by being subjected to various treatments for forming a polarizer. For example, the resin film can contain potassium by contacting with a solution of iodide such as potassium iodide. Thus, it is generally believed that alkali metals and/or alkaline earth metals contained in the polarizer do not adversely affect the dimensional stability of the low-concentration portion.

As the above-mentioned reduction method, a method of contacting the treatment liquid to the contact portion with the basic solution is preferably used. According to such a method, the alkali metal and/or alkaline earth metal can be transferred from the resin film to the treatment liquid to reduce the content thereof.

Any appropriate method can be adopted as the method of contacting the treatment liquid. Examples thereof include a method of dropping, coating, or spraying the treatment liquid onto the portion in contact with the basic solution, and a method of immersing the portion in contact with the basic solution in the treatment liquid.

When the resin film is protected with any appropriate protective material when it comes into contact with the basic solution, it is preferable to contact the treatment liquid in that state (especially when the temperature of the treatment liquid is 50° C. or higher). According to such a configuration, it is possible to prevent deterioration of the polarizing properties due to the treatment liquid at the portion other than the contact portion with the basic solution.

The treatment liquid may contain any suitable solvent. Examples of solvents include water, alcohols such as ethanol and methanol, ethers, benzene, chloroform, and mixed solvents thereof. Among these, water and alcohol are preferably used from the viewpoint of efficiently transferring alkali metals and/or alkaline earth metals. Any appropriate water can be used as the water. Examples include tap water, pure water, and deionized water.

The temperature of the treatment liquid during contact is, for example, 20° C. or higher, preferably 50° C. or higher, more preferably 60° C. or higher, and even more preferably 70° C. or higher. At such a temperature, the alkali metal and/or alkaline earth metal can be efficiently transferred to the processing liquid. Specifically, it is possible to significantly improve the swelling rate of the resin film and physically remove alkali metals and/or alkaline earth metals in the resin film. On the other hand, the temperature of water is substantially below 95°C.

The contact time can be appropriately adjusted according to the contact method, the temperature of the treatment liquid (water), the thickness of the resin film, and the like. For example, when immersed in warm water, the contact time is preferably 10 seconds to 30 minutes, more preferably 30 seconds to 15 minutes, even more preferably 60 seconds to 10 minutes.

In one embodiment, an acidic solution is used as the treatment liquid. The alkali metal and/or alkaline earth metal hydroxide remaining in the resin film is neutralized by using an acidic solution to chemically remove the alkali metal and/or alkaline earth metal in the resin film. be able to.

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

Preferably, an acidic compound having stronger acidity than boric acid is suitably used as the acidic compound. This is because it can also act on metal salts (borates) of the alkali metals and/or alkaline earth metals. Specifically, boric acid can be liberated from the borate to chemically remove alkali metals and/or alkaline earth metals in the resin film.

An example of the index of acidity is the acid dissociation constant (pKa), and an acidic compound having a pKa smaller than the pKa of boric acid (9.2) is preferably used. Specifically, the pKa is preferably less than 9.2, more preferably 5 or less. The pKa may be measured using any appropriate measuring device, and the values described in literature such as Kagaku Binran, Basic Edition, Revised 5th Edition (Edited by The Chemical Society of Japan, Maruzen Publishing) may be referred to. Also, in an acidic compound that dissociates in multiple steps, the pKa value may change at each step. When such an acidic compound is used, one whose pKa value at each step is within the above range is used. In addition, in this specification, pKa means the value in 25 degreeC aqueous solution.

The difference between the pKa of the acidic compound and the pKa of boric acid is, for example, 2.0 or more, preferably 2.5-15, more preferably 2.5-13. Within such a range, the alkali metal and/or alkaline earth metal can be efficiently transferred to the treatment liquid, resulting in the desired alkali metal and/or alkaline earth metal content in the low concentration portion. can be realized.

Examples of acidic compounds that can satisfy the above pKa include hydrochloric acid (pKa: −3.7), sulfuric acid (pK ₂ : 1.96), nitric acid (pKa: −1.8), hydrogen fluoride (pKa: 3 .17), inorganic acids such as boric acid (pKa: 9.2), formic acid (pKa: 3.54), oxalic acid (pK ₁ : 1.04, pK ₂ : 3.82), citric acid (pK ₁ : 3.09, pK ₂ : 4.75, pK ₃ : 6.41), acetic acid (pKa: 4.8), benzoic acid (pKa: 4.0), and the like.

The solvent of the acidic solution (treatment liquid) is as described above, and physical removal of the alkali metal and/or alkaline earth metal in the resin film does not occur even in the present embodiment in which the acid solution is used as the treatment liquid. obtain.

The concentration of the acidic solution is, for example, 0.01N to 5N, preferably 0.05N to 3N, 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 with the acid solution can be set according to the thickness of the resin film, the type of acid compound, and the concentration of the acid solution, and is, for example, 5 seconds to 30 minutes.

The resin film may be further subjected to any appropriate other treatment in addition to the above treatments. Other treatments include removal of basic and/or acidic solutions, washing, and the like.

Specific examples of the method for removing the basic solution and/or the acidic solution include wiping removal with a waste cloth or the like, suction removal, natural drying, heat drying, air drying, and reduced pressure drying. The drying temperature is, for example, 20°C to 100°C. The drying time is, for example, 5 seconds to 600 seconds.

Washing treatment is performed by any suitable method. Examples of solutions used for the cleaning process include pure water, alcohols such as methanol and ethanol, acidic aqueous solutions, and mixed solvents thereof. Washing is typically carried out while conveying the polarizing film laminate as shown in FIG. The washing process can be performed at any suitable stage. The washing treatment may be performed multiple times. In the illustrated example, after contact with the basic solution, washing with water, contact with the acid solution, and washing with water are performed in this order.

Typically, after the non-polarized portion is formed as described above (preferably after the alkali metal and/or alkaline earth metal content is reduced), the first surface protective film and the second surface protective film are It can be peeled off. According to the polarizing film laminate of the present invention, lamination of the polarizer and the surface protection film, decolorization, and peeling of the surface protection film can be performed (continuously) while conveying in the longitudinal direction.

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

[Example 1]
As the resin substrate, a long amorphous isophthalic acid-copolymerized polyethylene terephthalate (IPA-copolymerized PET) film (thickness: 100 μm) with a water absorption of 0.75% and a Tg of 75° C. was used. One side of the substrate was subjected to corona treatment, and the corona-treated side was coated with polyvinyl alcohol (degree of polymerization: 4,200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization: 1,200, degree of acetoacetyl modification: 4.6). %, degree of saponification 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOSEFIMER Z200") at a ratio of 9:1. A PVA-based resin layer was formed to produce a laminate.
The resulting laminate was uniaxially stretched 2.0 times at the free end in the machine direction (longitudinal direction) between rolls with different peripheral speeds in an oven at 120° C. (in-air auxiliary stretching).
Next, the laminate was immersed in an insolubilizing bath (an aqueous boric acid solution obtained by blending 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30° C. for 30 seconds (insolubilizing treatment).
Then, it was immersed in a dyeing bath at a liquid temperature of 30° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was added to 100 parts by weight of water, and 1.5 parts by weight of potassium iodide was added to the resulting iodine aqueous solution for 60 seconds (dyeing treatment). .
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 30°C (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking treatment).
After that, the laminate is immersed in an aqueous solution of boric acid having a liquid temperature of 70° C. (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). Meanwhile, the film was uniaxially stretched in the machine direction (longitudinal direction) between rolls with different circumferential speeds so that the total draw ratio was 5.5 (underwater stretching).
After that, the laminate was immersed in a cleaning bath having a liquid temperature of 30° C. (aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
Subsequently, a PVA-based resin aqueous solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “GOSEFIMER (registered trademark) Z-200”, resin concentration: 3% by weight) was applied to the surface of the PVA-based resin layer of the laminate. A protective film (thickness: 25 μm) was attached to the substrate by hand, and heated in an oven maintained at 60° C. for 5 minutes. After that, the substrate was peeled off from the PVA-based resin layer to obtain a long polarizing plate (5 μm thick polarizer (single transmittance 42.3%)/protective film) having a width of 1200 mm and a length of 43 m.

An adhesive (acrylic adhesive) was applied to one surface of an ester resin film (thickness: 38 μm) having a width of 1,200 mm and a length of 43 m so as to have a thickness of 5 μm. Through-holes having a diameter of 2.8 mm were formed in this adhesive-attached ester resin film at intervals of 250 mm in the longitudinal direction and at intervals of 400 mm in the width direction using a Pycnal blade.

On the polarizer side of the resulting polarizing plate having a total thickness of 30 μm, the adhesive-attached ester resin film was laminated by roll-to-roll, and this was immersed in a 1 mol/L (1N) sodium hydroxide aqueous solution for 30 seconds. Then, it was immersed in 1 mol/L (1N) hydrochloric acid for 10 seconds. After that, it was dried at 60° C. to form a transparent portion on the polarizer.

[Example 2]
A PVA film (manufactured by Kuraray Co., Ltd., PE6000) having a thickness of 60 μm was immersed in an aqueous solution at 30° C. for 30 seconds (swelling step).
Next, the PVA film was immersed in a dyeing bath having a liquid temperature of 30° C. while adjusting the iodine concentration and the immersion time so that the obtained polarizing plate had a predetermined transmittance. In this example, 0.15 parts by weight of iodine was mixed with 100 parts by weight of water, and 1.0 parts by weight of potassium iodide was mixed and immersed for 60 seconds in an aqueous iodine solution (dyeing treatment). .
Next, it was immersed for 30 seconds in a cross-linking bath at a liquid temperature of 30°C (an aqueous boric acid solution obtained by blending 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water). (crosslinking treatment).
After that, the PVA film is immersed in an aqueous solution of boric acid at a liquid temperature of 70° C. (an aqueous solution obtained by blending 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). The film was uniaxially stretched 5.5 times in the machine direction (longitudinal direction) between rolls having different peripheral speeds (underwater stretching).
Thereafter, the PVA film was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with 100 parts by weight of water) at a liquid temperature of 30° C. (washing treatment).
After washing, one side of the PVA film was coated with an aqueous solution of PVA-based resin (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “GOSEFIMER (registered trademark) Z-200”, resin concentration: 3% by weight), followed by triacetyl cellulose. A film (manufactured by Konica Minolta, trade name “KC4UY”, thickness 40 μm) is laminated, heated in an oven maintained at 60 ° C. for 5 minutes, and has a 22 μm thick polarizer (single transmittance 42.5%). A polarizing plate having a width of 1200 mm and a length of 43 m was produced.

The polarizer surface of the obtained polarizing plate was laminated with the adhesive-attached ester resin film having the through holes formed thereon by roll-to-roll, and this was immersed in a 1 mol/L (1N) sodium hydroxide aqueous solution for 180 seconds. Then, it was immersed in 1 mol/L (1N) hydrochloric acid for 60 seconds. After that, it was dried at 60° C. to form a transparent portion on the polarizer.

The following items were evaluated for the transparent portion of the polarizing plate of each example.
1. Transmittance (Ts)
It was measured using a spectrophotometer (manufactured by Murakami Color Research Laboratory Co., Ltd., product name “DOT-3”). The transmittance (T) is the Y value corrected for visual sensitivity using the 2-degree field of view (C light source) of Jls Z 8701-1982.
2. Iodine Content The iodine content in the transparent portion of the polarizer was determined by fluorescent X-ray analysis. Specifically, the iodine content of the polarizer was obtained from the X-ray intensity measured under the following conditions, using a calibration curve prepared in advance using a standard sample.
・ Analysis device: Rigaku Denki Kogyo Fluorescent X-ray analyzer (XRF) Product name “ZSX100e”
・Anticathode: rhodium ・Analyzing crystal: lithium fluoride ・Excitation light energy: 40 kV-90 mA
・ Iodine measurement line: I-LA
・ Quantitative method: FP method ・ 2θ angle peak: 103.078 deg (iodine)
・Measurement time: 40 seconds

The transparent portions (before immersion in hydrochloric acid) of the polarizing plates obtained in Examples 1 and 2 had transmittances of 90.3% (Example 1) and 90.2% (Example 2), respectively, and contained iodine. The amounts were 0.08% by weight (Example 1) and 0.12% by weight (Example 2). The iodine content of the portion other than the transparent portion of the polarizer is about 5% by weight, and the content of the dichroic substance is lower than that of the other portion in any of the examples. was formed.

3. Sodium Content The sodium content in the transparent portion of the polarizer was determined by fluorescent X-ray analysis. Specifically, the sodium content of the polarizer was obtained from the X-ray intensity measured under the following conditions, using a calibration curve prepared in advance using a standard sample. Measurements of sodium content were made before and after immersion in hydrochloric acid.
・ Analysis device: Rigaku Denki Kogyo Fluorescent X-ray analyzer (XRF) Product name “ZSX100e”
・Anticathode: rhodium ・Analyzing crystal: lithium fluoride ・Excitation light energy: 40 kV-90 mA
・Sodium measurement line: Na-KA
・Quantitative method: FP method ・Measurement time: 40 seconds

In the polarizing plate of Example 1, the sodium content in the transparent portion was 4.0% by weight before immersion in hydrochloric acid and 0.04% by weight after immersion. In the polarizing plate of Example 2, the sodium content in the transparent portion was 4.1% by weight before immersion in hydrochloric acid and 0.05% by weight after immersion.

In addition, when the polarizing plate obtained in each example was placed in an environment of 65°C/90% RH for 500 hours, no significant change in the size of the transparent portion was observed before and after the humidification test in any of the examples. . A similar humidification test was performed on the polarizing plates prepared in the same manner as in Examples 1 and 2, except that they were not immersed in hydrochloric acid. was getting bigger.

Furthermore, the surface smoothness near the transparent portion was measured using an optical measuring instrument "ZYGO New View 7300" manufactured by Canon Inc. 6(a) and 6(b) show the evaluation results of surface smoothness (size of unevenness) in the vicinity of the transparent portion of Examples 1 and 2. FIG. In Example 1 in which the thickness of the polarizer was 5 μm, the difference in level between the transparent portion (concave portion) and other portions was as small as 0.8 μm or less, and the surface was smoother.

The polarizing film laminate of the present invention is suitably used for manufacturing camera-equipped image display devices (liquid crystal display devices, organic EL devices) such as mobile phones such as smartphones, notebook PCs, and tablet PCs.

10 polarizer 11 exposed part (non-polarized part)
20 Surface protection film (first surface protection film)
30 protective film 40 second surface protective film 100 polarizing film laminate

Claims (4)

Equipped with a long polarizer and a surface protective film peelably laminated on one side of the polarizer via an adhesive layer,
Having a plurality of exposed portions where the polarizer is exposed on the one surface side,
The plurality of exposed portions are arranged at predetermined intervals in the longitudinal direction and the width direction over the entire length of the elongated polarizer, and the length of the exposed portions is predetermined for attaching the elongated polarizer to an image display device of a predetermined size. When cut into polarizer pieces of a size, each exposed portion is arranged in each polarizer piece at a position corresponding to the camera portion of the image display device,
Through holes are formed in the surface protective film and the pressure-sensitive adhesive layer, and portions corresponding to the through holes are the exposed portions.
Polarizing film laminate. The surface protection film has a thickness of 20 μm to 250 μm,
The polarizing film laminate according to claim 1. The surface protection film has an elastic modulus of 2.2 kN/mm ² to 4.8 kN/mm ² ,
The polarizing film laminate according to claim 1 or 2. The surface protection film has a tensile elongation of 90% to 170%,
The polarizing film laminate according to any one of claims 1 to 3.

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