JP7316297B2 - LASER CUTTING METHOD FOR POLARIZING OPTICAL FUNCTION FILM LAMINATED BODY - Google Patents

Description

The present invention relates to a laser cutting method for a polarizing optical functional film laminate. More specifically, the polarizing optical function film laminate having at least a polarizing film in which a protective film is laminated on at least one side of a polarizer is not limited to a rectangular shape, and may be formed into a desired shape such as curved edges or holes. The present invention relates to a method of laser cutting to have. A polarizing film that is a polarizing optical functional film laminate or a part thereof that has been subjected to laser cutting is then mounted on an optical display device such as a liquid crystal display device or an organic EL display device, and is also used as a plasma display panel (PDP ), etc., by laminating them to an optical display panel.

In recent years, a polarizing film, which is a polarizing optical functional film laminate or a part thereof, has been used in many types of image display devices such as automobile meter displays, smart watches, goggles, smartphones, laptop computers, note pads, and monitors. It is used. In addition, in these image display devices, from the viewpoint of design, these polarizing films and the like can be processed into various shapes such as not only a rectangular shape but also a curved shape, a notched shape, or a shape with a hole. In order to meet such requirements, punching with blades such as Thomson blades and pinnacle blades, end face processing using full back and end mills, and laser cutting using laser light. and other methods have been proposed (see, for example, Patent Document 1).

Furthermore, recently, due to the demand for maximizing the display area of image display devices, designs with narrow frame widths have become mainstream. Demands and dimensional accuracy requirements are becoming more stringent.

On the other hand, as described above, image display devices equipped with polarizing films are used in a wide range of applications, so they are often used for long periods of time in high-temperature, high-humidity environments. This causes a phenomenon in which moisture enters and exits from the cut end surface of the polarizing film to which the heat is applied. In general, most polarizers are of a type in which a stretched film made of a PVA-based resin material is impregnated with iodine to form a PVA-polyiodine ion complex, thereby exhibiting polarizing performance. When the cut end face of such a PVA-iodine-based polarizer is exposed to a high-temperature and high-humidity environment, the PVA-polyiodine ion complex in the PVA film is denatured due to the influence of moisture flowing in and out from the cut end face, resulting in a loss of fluidity. This results in a problem of quality in that the tarnishing and passing out (bleaching) impairs the polarizing function of the end portion. In the following, we refer to this phenomenon as "depolarization".

In order to solve the above-mentioned problems, a method has been proposed in which the outer peripheral cut surface of a polarizing film that has been cut into a desired shape is coated with a resin coating (Patent Document 2). However, in order to form a film, it is necessary to apply a solution obtained by dissolving a resin in a solvent to the cut surface of the polarizing film using a roll coater or the like, and then dry it. creates another problem of increasing the Further, in Patent Document 3, by forming the protective layers arranged on both the front and back surfaces of the polarizer larger than the polarizer, groove-like gaps are provided between these protective layers, and the gaps are filled with a sealing material. However, the method according to this proposal, like the case of Patent Document 2, requires a long and complicated manufacturing process. Furthermore, when forming a coating using a universal coating means such as a roll coater or a slot die coater on the cut end face of a polarizing film cut into a non-linear shape with a curved outer periphery, the coater It is necessary to maintain a uniform gap between the liquid discharge part and the cut end surface of the polarizing film, but such gap adjustment is extremely difficult, and it is difficult to form a coating with a uniform thickness on the cut end surface. . It is also conceivable to use a spray coater to form the resin film, but in this method, a solution in which the resin material is dissolved in an organic solvent is used as the coating liquid. The coating liquid may permeate between the layers of the polarizing film, and the coating liquid permeating between the layers causes a problem that the interlaminar adhesive strength is lowered. Moreover, in this method, it is conceivable that the organic solvent for dilution contained in the coating liquid may erode the constituent base material of the polarizing film. In order to avoid this problem, it is possible to spray coat a solvent-free UV curable resin. In addition, it becomes difficult to form a thin film, and the film becomes so thick that it affects the dimensional accuracy of products cut into non-linear shapes.
There is also a drip coating method along the cutting shape, such as inkjet printing or dispenser method, but even by this type of method, it is difficult to thin the film, and splashes on the surface of the polarizing film accompanying film formation It is technically difficult to apply due to problems such as contamination.
Incidentally, the optical film generally has, on one or both sides thereof, a surface protective film and a release liner that are peeled off when mounted on a device. When the coating is formed as taught in , the coating is also formed on the cut end surfaces of the surface protective film and the release liner at the same time. The coating covering the cut ends keeps them fixed together, making it difficult to remove the surface protective film and release liner. Further, if the surface protection film and the release liner are forcibly peeled off, a problem arises that the coating formed on the cut edges falls off from the optical film. Furthermore, there arises a problem that part of the film that has fallen off causes foreign matter contamination in the manufacturing process.

Vapor deposition, CVD (Chemical Vapor Deposition), and other so-called vacuum dry coating methods are also conceivable. With respect to CVD, although it is possible to deposit an organic monomer in a reaction furnace and form a film by plasma CVD or the like, it takes too much time to form a film with a thickness of 100 nm or more, resulting in low productivity. , is practically difficult to apply.

In addition, by adopting a cutting method using a laser beam having an infrared wavelength, the protective film, which is one component of the polarizing film, is melted, and the melted product forms a coating layer covering the cut end face of the polarizer. A method for improving the reliability of the cut end face by using the above method has also been proposed (Patent Document 4). This document teaches that a protective film, which is originally made of a material with low moisture permeability, is melted by heat during cutting, and the melted material covers the laser-cut polarizer end faces. Patent Document 4 states that this method can improve the reliability of the polarizing film processed edge in a high-temperature and high-humidity environment. According to this method, the coating layer can be formed at the same time as the laser cutting process, so that the outer peripheral coating process after shape processing can be omitted.

Furthermore, in the laser cutting process, an optical laminate roll is prepared by winding a long optical laminate comprising a long optical film and protective sheets laminated on both sides of the optical film into a roll. A method has also been proposed in which the optical layered body is subjected to laser cutting processing while the optical layered body is paid out (Patent Document 5). According to the teaching of Patent Document 5, among the protective sheets laminated on both sides of the optical film, the lower protective sheet can function as a conveying base material. In this case, it can be understood that the lower protective sheet is half-cut by laser irradiation.

Japanese Unexamined Patent Application Publication No. 2018-22140 JP-A-8-146219 Japanese Utility Model Publication No. 7-34415 Japanese Patent No. 5558026 JP 2017-207585 A

However, even if the method taught in Patent Document 4 is adopted, the cut end surface of the polarizer cannot be sufficiently protected by coating only the melt from the protective film provided on one surface of the polarizer. It is difficult. The reason for this is that the thickness of the polarizer and the protective film that constitute the polarizing film varies widely, and the volume of the melt from the protective film provided on one surface of the polarizer is the thickness of the polarizer over the entire thickness of the polarizer. This is because there is no guarantee that a coating having a width sufficient to cover the cut surface and having a thickness sufficient to prevent permeation of moisture from the cut end surface is sufficient.

Patent Document 4 teaches that the protective film of the polarizer is made of a resin material having a predetermined low moisture permeability. There is no guarantee that the resulting melt from the protective film will be sufficient in quantity to form a coating covering the cut end face of the polarizer, and a coating having a thickness sufficient to block the transmission of moisture from the cut end face is provided. difficult to form.
As described above, the conventionally proposed methods described above have not been able to obtain a polarizing film that satisfies recent strict quality requirements for "depolarization" due to color loss from the cut edge of the polarizer.

The present inventors have recognized the above-described problems in the prior art, and as a result of extensive studies aimed at solving the problems, have found that a polarizer having at least a polarizing film in which a protective film is laminated on at least one side of a polarizer In the optically polarizing film laminate, a sheet material separate from the polarizing optically functional film laminate is superimposed on one surface of the polarizing optically functional film laminate, and the polarizing optically functional film is obtained. A laser is irradiated in the thickness direction of the polarizing optical function film laminate from the other surface located opposite to the sheet material of the laminate, and the laser irradiation position is aligned along a predetermined shape within the plane of the laminate. By performing a moving laser cutting process, the polarizing optical function film laminate is cut into a predetermined shape, and under the laser irradiation, the sheet material component present in a part of the thickness direction is cut by the laser energy. Scattered as droplets, at least part of the droplets of the sheet material components are deposited on the laser-cut end surface formed on the polarizer of the polarizing optical function film laminate, thereby removing the components of the sheet material. To find a phenomenon that a coating layer containing at least is formed so as to cover a laser-cut end surface of a polarizer, and to form a protective coating that suppresses permeation of moisture on the cut end surface of a polarizing film by using this phenomenon. I came up with the idea. The film thus formed can enhance the protection function of the cut end surface of the polarizing film in a high-temperature and high-humidity environment, and improve the reliability of the polarizing film.

That is, the present invention provides a cutting method for laser cutting a polarizing optical functional film laminate containing, as a minimum component, a polarizing film in which a protective film is laminated on at least one side of a polarizer.
A laser cutting method for a polarizing film according to one aspect of the present invention is a cutting method for laser cutting a polarizing optical functional film laminate having at least a polarizing film in which a protective film is laminated on at least one side of a polarizer. a sheet material separate from the polarizing optical function film laminate is placed on one surface of the polarizing optical function film laminate, and the sheet material of the polarizing optical function film laminate and is a laser cutting process in which a laser is irradiated in the thickness direction of the polarizing optical functional film laminate from the other surface located on the opposite side, and the laser irradiation position is moved along the predetermined shape in the plane of the laminate. By doing so, the polarizing optical function film laminate is cut into the predetermined shape, and the sheet material is irradiated with a laser, and the sheet material components present in a part of the thickness direction are splashed by the laser energy. so that at least part of the droplets of the sheet material components are deposited on the laser-cut end surface formed on the polarizer of the polarizing optical function film laminate, and the components of the sheet material are at least and a coating layer containing the polarizer so as to cover the laser-cut end surface of the polarizer.

According to the present invention, in the shape processing of a polarizing optically functional film laminate or the like, a coating layer that contributes to improved reliability in a high-temperature, high-humidity environment can be formed on the cut end surface of the polarizing film at the same time as the laser cutting processing. It becomes possible.

1 is a schematic cross-sectional view showing an example of a polarizing optical functional film laminate that can be used in a laser cutting method according to an embodiment of the present invention; FIG. FIG. 2 is a schematic cross-sectional view showing an example of a state in which the polarizing optical function film laminate of FIG. 1 is cut into a desired shape by laser irradiation. FIG. 4 is a schematic cross-sectional view of the laminate showing the state of the laminate with the sheet material being cut by laser irradiation. FIG. 10 is an optical microscope image showing depolarization of a cut end face perpendicular to the light absorption axis of a polarizer observed under crossed Nicols transmitted illumination, showing an example in which depolarization due to color loss does not occur. FIG. 10 is an optical microscope image showing depolarization observed on a cut end face perpendicular to the light absorption axis of a polarizer under crossed Nicols transmitted illumination, showing an example of depolarization due to color loss. The figure which shows an example of the SEM image in the cut cross section of the laminated body with the sheet material of this invention by which laser cutting was carried out. FIG. 4 is a diagram showing an example of depolarization width achieved by using a laminate with sheet material according to an embodiment of the present invention; FIG. 4 shows an example of depolarization width achieved by using a conventional end mill. A cross-sectional SEM image in the vicinity of the polarizing film of the laminate with sheet material according to one embodiment of the present invention that has been laser-cut. An EDX (energy dispersive X-ray analysis) image of the same location as in FIG. 8 is a cross-sectional SEM image showing an enlarged view of the cut edge of the polarizer in the image shown in FIG. 7; EDX image of the same location as in FIG. FIG. 2 is a schematic view of a laser shape processing apparatus that laser-cuts a long belt-like polarizing optical function film laminate by a roll-to-roll method. FIG. 10 is a diagram showing an example of a cutting layout when manufacturing a smartphone-shaped product cut out from a large-sized polarizing film, and is a plan view showing the whole. FIG. 10 is a diagram showing an example of a cutting layout in the case of manufacturing a smartphone-shaped product cut out from a large-size polarizing film, and is a partially enlarged plan view. FIG. 10 is a diagram showing an example of a cutting layout when manufacturing a product cut out from a large polarizing film into a shape of an automobile meter panel, and is a plan view showing the whole. FIG. 10 is a diagram showing an example of a cutting layout for manufacturing a product cut out from a large-size polarizing film into an automobile meter panel shape, and is a partially enlarged plan view. A photograph showing an example of polarizing films cut out in the shape of a smartphone, arranged side by side. SEM image of the cut end surface of Example 1 observed from the direction of molecular orientation. The SEM image which observed the cut end surface from the molecular orientation direction about Example 2. FIG. The SEM image which observed the cut end surface from the molecular orientation direction about the comparative example 1. FIG. The SEM image which observed the cut end surface from the molecular orientation direction about the comparative example 2. FIG. 4 is an image showing analysis results by TOF-SIMS in Example 1. FIG. An optical microscope image showing laser-cut grooves formed in a sheet material peeled off after laser cutting. 4 is a diagram showing the results of elemental analysis of the coating layer formed on the cut end face in Example 1. FIG. The image which showed the analysis result by TOF-SIMS in Example 6. An image showing analysis results by TOF-SIMS in Example 7. FIG. 4 is an image showing analysis results by TOF-SIMS in Comparative Example 4. FIG. 11 is an image showing analysis results by TOF-SIMS in Comparative Example 5. FIG. 4 is an image showing analysis results by TOF-SIMS in Reference Example 1. FIG. 4 is an image showing analysis results by TOF-SIMS in Reference Example 2. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail based on embodiments, but the present invention is not limited to these embodiments.

(Polarizing optical functional film laminate)
FIG. 1 shows a schematic cross-sectional view of an example of a polarizing optical functional film laminate that can be used in the laser cutting method according to one embodiment of the present invention. The polarizing optically functional film laminate 1 includes at least the polarizing film 12, and optionally includes, but is not limited to, a surface treatment layer 13, a surface protection film 14, and an anti-contamination film 23. can contain.
A release liner 16 may be further attached to the polarizing optical functional film laminate 1 with an adhesive layer 15 interposed therebetween. Hereinafter, the polarizing optical function film laminate 1 provided with the pressure-sensitive adhesive layer 15 and the release liner 16 is denoted by reference numeral "1A", and the polarizing optical function film laminate 1A will be described as an example.

Usually, the polarizing film 12 is mainly composed of a polarizer 10 and a protective film 11 laminated on one or both main surfaces of the polarizer 10, as shown in FIG. Other optical functional films exhibiting optical functions such as brightness enhancement films and viewing angle compensation films may be further laminated. In such a case, a laminate containing these optical functional films constitutes the polarizing film 12 . Although FIG. 1 shows an example in which the protective films 11a and 11b are laminated on both main surfaces of the polarizer 10, the protective film 11 may be laminated only on one of the main surfaces.

The polarizer 10 is composed of a resin film. Any appropriate resin can be used as the resin film, but a polyvinyl alcohol-based resin (hereinafter referred to as a PVA-based resin) is usually used. Examples of PVA-based resins include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. An ethylene-vinyl alcohol copolymer is obtained by saponifying an ethylene-vinyl acetate copolymer. The saponification degree of the PVA-based resin is usually 85 mol% to 100 mol%, preferably 95.0 mol% or more, more preferably 99.0 mol% or more, and particularly preferably 99.93 mol% or more. . The degree of saponification can be determined according to JIS K 6726-1994. By using the PVA-based resin having such a degree of saponification, the polarizer 10 having excellent durability can be obtained.

The PVA-based resin that constitutes the polarizer 10 is subjected to various treatments such as swelling treatment, stretching treatment, dyeing treatment with a dichroic substance, typically iodine, cross-linking treatment, washing treatment, and drying treatment, by a commonly used method. applied and ready for use as a polarizer. The number of times, order, time, etc. of each process can be set as appropriate. The PVA-based resin may be a thin film formed as a coating film layer on another base material, and may be formed by subjecting this thin film to the above-described treatments. The stretching direction in the stretching process corresponds to the absorption axis direction of the resulting polarizer. From the viewpoint of obtaining excellent polarizing properties, the PVA-based resin is usually uniaxially stretched 3 to 7 times.

As the PVA-based resin film, a film formed by an arbitrary method such as a casting method, a casting method, an extrusion method, or the like can be used as appropriate.

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 6,000, more preferably 2,000 to 5,000. The average degree of polymerization can be determined according to JIS K 6726-1994.

The resin film forming the polarizer 10 is typically impregnated with a dichroic substance. Dichroic substances include, for example, iodine and organic dyes. These can be used alone or in combination of two or more. Iodine is preferably used as the dichroic substance.

Examples of organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, and Black. H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Supra Blue G, Supra Blue GL, Supra Orange GL, Direct Sky Blue, Direct Fast Orange S, Fast Black, etc. can be used. These dichroic substances may be used alone or in combination of two or more.

The thickness of polarizer 10 can be set to any suitable value. The thickness of the polarizer in practical use is 5 μm to 30 μm.

The polarizer 10 preferably has a property of exhibiting absorption dichroism in the wavelength range of 380 nm to 780 nm. The single transmittance (Ts) of the polarizer 10 is generally 43% 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 2 degree field of view (C light source) based on JIS Z8701 and corrected for visibility. can be measured using The polarization degree of the polarizer 10 is generally 99.9% or more.

Examples of materials for forming the protective films 11a and 11b include cellulosic resins such as diacetyl cellulose and triacetyl cellulose (TAC), (meth)acrylic resins, cycloolefin resins, olefin resins such as polypropylene, and polyethylene terephthalate. Examples include ester-based resins such as system-based resins, polyamide-based resins, polycarbonate-based resins, and copolymer resins thereof. The expression "(meth)acrylic resin" means acrylic resin and/or methacrylic resin.
The thickness of the protective films 11a and 11b is usually selected as an arbitrary value within the range of 10 μm to 200 μm.
The material, thickness, etc. of the protective film 11a and the protective film 11b may be the same or may be different.

Each of protective films 11a and 11b is typically laminated on each of the main surfaces of polarizer 10 via an adhesive layer (not shown). Any appropriate adhesive can be used as the adhesive constituting the adhesive layer. For example, water-based adhesives, solvent-based adhesives, active energy ray-curable adhesives, and the like are used. As the water-based adhesive, it is preferable to use an adhesive containing a PVA-based resin.
Protective films 11a and 11b may contain one or more of any appropriate additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

A surface treatment layer 13 may be formed on the surface of each of the protective films 11a and 11b opposite to the polarizer 10 by performing a hard coat treatment, an antireflection treatment, or a treatment for the purpose of diffusion and antiglare. good. In the embodiment shown in FIG. 1, an example in which the surface treatment layer 13 is formed only on the protective film 11a laminated on one main surface of the polarizer 10 is shown.

The surface protective film 14 is laminated on the protective film 11 via the surface-treated layer 13 when the surface-treated layer 13 is formed, or on the protective film 11 when the surface-treated layer 13 is not formed. The surface protective film 14 is a member that is detachably adhered to the protective film 11a for the purpose of protecting the protective film 11a from scratches due to contact or adhesion of foreign substances, and is composed of an adhesive layer 14a and a resin film 14b.
The adhesive that constitutes the adhesive layer 14a is a material whose main component is any one of acrylic, rubber, urethane, silicone, and polyester polymer materials, and has a thickness in the range of 1 to 100 μm. It can be selected as appropriate.
Examples of the resin film 14b include acrylic resins, olefin resins such as polyethylene and polypropylene, and ester resins such as polyethylene terephthalate resins.

The surface protective film 14 is peeled off when the polarizing film is mounted on an optical display device or the like. For this reason, the adhesive constituting the adhesive layer 14a preferably has a light adhesive strength, and a preferred peel strength is 5 N/20 mm or less.

The release liner 16 is laminated on the surface of the polarizing film 12 opposite to the surface protective film 14, that is, on the surface of the protective film 11b opposite to the polarizer 10, with the pressure-sensitive adhesive layer 15 interposed therebetween. The main surface of the release liner 16 that is in contact with the adhesive layer 15 is subjected to a release treatment in order to obtain good releasability. A release liner 16 covers the adhesive layer 15 until the polarizing film 12 is laminated to the optical display panel. The release liner 16 is peeled off from the protective film 11 b leaving the adhesive layer 15 on the polarizing film 12 side when the polarizing film 12 is attached to the optical display panel. It is attached to the optical display panel via the optical display panel. Considering workability, the release force of the release liner 16 to the pressure-sensitive adhesive layer 15 is preferably 5 N/20 mm or less.

The release liner 16 is preferably composed of a resin film. For example, olefin resins such as polyethylene and polypropylene or ester resins such as polyethylene terephthalate resin can be used, but the release liner 16 is not limited to these. The thickness of the release liner 16 can be appropriately selected within the range of 1 μm to 100 μm. In addition, the release liner 16 is desirably made of a material with low moisture permeability. m ² ·24 h or less, and more preferably 150 g/m ² ·24 h or less.

As the adhesive that constitutes the adhesive layer 15, it is possible to use one whose main component is any polymer material selected from the group of acrylic, rubber, urethane, silicone, olefin, and polyester. can. From the viewpoint of suppressing costs, an acrylic or rubber-based pressure-sensitive adhesive is preferable. The thickness of the adhesive layer 15 can be appropriately set within the range of 1 μm to 50 μm.

An anti-contamination film 23 may be provided on the surface protection film 14 . The antifouling film 23 includes at least a resin film substrate 23a made of a resin material, and further includes an adhesive layer 23b arranged on one surface of the resin film substrate 23a. The resin film substrate 23a is laminated on the surface protective film 14 via the adhesive layer 23b.

As the resin film 23a, a general resin film can be used. For example, an acrylic resin, an olefin resin such as polyethylene and polypropylene, or an ester resin such as polyethylene terephthalate resin can be used. The resin film 23a preferably has a thickness in the range of 20 μm to 100 μm.

On the other hand, as the adhesive that constitutes the adhesive layer 23b, a material containing any one of acrylic, rubber, urethane, silicone, and polyester polymer materials as a main component can be used. The thickness of the layer 23b can be appropriately selected within the range of 1 to 100 μm.

The anti-contamination film 23 is peeled off after the laser cutting process. For this reason, the adhesive constituting the adhesive layer 23b preferably has a light adhesive force to the surface protective film 14, and the adhesive force is equal to or smaller than the adhesive force of the surface protective film 14 to be used. is preferred. If the adhesive strength of the adhesive is greater than the adhesive strength of the surface protective film 14, the surface protective film 14 may be peeled off when the anti-contamination film 23 is peeled off, which is not preferable.

In the present invention, the polarizing optical functional film laminate 1A is cut into a desired shape by laser cutting before bonding the polarizing film 12 to the optical display panel via the pressure-sensitive adhesive layer 15. There is a possibility that melted matter or fine particles generated during this laser cutting process will scatter in the form of droplets, and the scattered components will contaminate the surface layer of the main surface of the polarizing film on the laser incident surface side. By providing the anti-contamination film 23, this contamination can be prevented or suppressed.

Furthermore, providing such an anti-fouling film can also suppress burrs that may occur on the cut end face. Among the layers or films constituting the polarizing optical function film laminate 1A, the layer or film located on the frontmost side as viewed in the laser irradiation direction, in the example of FIG. In the polarizing optical function film laminate 1A, burrs "A" (see FIG. 5) may be generated in a state of protruding outside the polarizing optical function film laminate 1A. It is possible to suppress it to 0 to 20 μm in the lamination direction of the optical function film laminate 1A. As a result, when stacking multiple laminates that have been cut into the same predetermined shape after cutting, it is possible to suppress the increase in stacking height due to burrs and improve transportation efficiency. Become. By setting the burr to 10 μm or less, the transportation efficiency is further enhanced, and by setting the burr to 5 μm or less, the transportation efficiency is particularly enhanced.

(laser cutting)
FIG. 2 shows an example of the state when the polarizing optical function film laminate 1A of FIG. 1 is cut into a desired shape by laser irradiation, in the same manner as in FIG. By using a laser, not only can the polarizing optical functional film laminate 1A be easily cut into a predetermined shape, but also the polarized light contained in the polarizing optical functional film laminate 1A can be easily cut along with this cutting process. A coating layer can be formed on the cut end face of the child 10 . In the cutting process, the main surface of the polarizing film 12 on the side opposite to the laser incident surface, for example, the surface located outside the release liner 16 of the polarizing optical function film laminate 1A in the present embodiment. A sheet material 17 is arranged so as to face 16a. Hereinafter, the polarizing optical function film laminate 1A on which the sheet material 17 is arranged is referred to as a "laminate with sheet material", and the whole is denoted by reference numeral "2".

The sheet material 17 includes at least a resin film substrate 17a made of a resin material, and further includes an adhesive layer 17b arranged on one surface of the resin film substrate 17a. The resin film substrate 17a is releasably attached to the release liner 16 via the adhesive layer 17b, and is released from the release liner 16 after cutting.
A general resin film can be used as the resin film constituting the resin film substrate 17a. For example, an acrylic resin, an olefin resin such as polyethylene and polypropylene, or an ester resin such as polyethylene terephthalate resin can be used. can do. The resin film substrate 17a preferably has a thickness in the range of 5 μm to 200 μm. Moreover, the resin film substrate 17a is desirably made of a material having a low moisture permeability. and is 200 g/m ² ·24h or less, more preferably 150 g/m ² ·24h or less.

On the other hand, the pressure-sensitive adhesive layer 17b is preferably made of a polymeric material containing any one of acrylic, urethane, silicone, rubber, and polyester as a main component. Further, the adhesive layer 17b is preferably made of an adhesive having a light peeling adhesive force, and the peeling force of the adhesive layer 17b is equal to the peeling force of the release liner 16 of the polarizing optical function film laminate 1A. is preferably equal to or less than If the release force of the adhesive layer 17b of the sheet material 17 is greater than the release force of the release liner 16, the release liner 16 is also peeled off when the sheet material 17 is peeled off after the laser cutting process. This is because there is a possibility that The adhesive layer 17b is usually removed together with the resin film substrate 17a when the sheet material 17 is peeled off after the laser cutting process.

With respect to the laminated body 2 with sheet material, the laser is applied from the other side of the polarizing optical function film laminated body 1A located on the opposite side to the sheet material 17, in the illustrated embodiment, the surface on the anti-contamination film 23 side. , the light is irradiated in the thickness direction of the polarizing optical function film laminate 1A. This "thickness direction" is sufficient as long as it penetrates the layers constituting the polarizing optical function film laminate 1A, and for example, does not necessarily have to be a direction perpendicular to these layers. This laser cutting process may be performed in a state where the polarizing optical function film laminate 1A is separated into single plates. It is preferable to carry out in the state of a belt-shaped film. Therefore, it is preferable to form the laminated body 2 with sheet material in the form of a long belt-like film wound in a roll.

FIG. 3 shows the state of the laminated body 2 with the sheet material during the cutting process by laser irradiation as a schematic cross-sectional view of the laminated body. By laser irradiation, a cut groove 2a is formed over the entire thickness including the release liner 16 in the polarizing optical function film laminate 1A of the laminate 2 with sheet material. Therefore, the polarizing optical function film laminate 1A can be cut into a desired shape by moving the laser irradiation position along the predetermined shape in the plane of the polarizing optical function film laminate 1A. For cutting, the polarizing optical function film laminate 1A constituting the laminate 2 with sheet material is completely cut in the thickness direction, and further cut to such a depth that a part of the sheet material is left. In order to sufficiently form a coating layer (particularly, a coating layer 18b) described later, to enable the sheet material to be reused as a carrier film, and in consideration of handling properties in the post-process, the positional deviation is This is to prevent In order to prevent misalignment and the like, it is preferable that this laser cutting process be performed while the laminated body 2 with the sheet material is placed on a suction type fixed stage 19 and held by a suction force, as shown in FIG.

In the shape processing of the polarizing optical function film laminate 1A, by using the laminate 2 with sheet material, the coating layer 18a can be formed on the cut end surface of the polarizing film 12, especially the cut end surface of the polarizer 10, at the same time as the laser cutting processing. , 18b. By forming these coating layers 18a and 18b, it is possible to reduce the "depolarization width" described below, in other words, to improve reliability in a high-temperature, high-humidity environment.

(depolarization width)
When the polarizer 10, which is the main component of the polarizing film 12, is left in a high-temperature and high-humidity environment for a long time, moisture enters and exits from the cut end surface of the polarizing film that is subjected to a heat load. A decolorization phenomenon occurs in which the polyiodine ion complex contained in the polarizer 10 changes in quality, becomes fluid, and escapes from the polarizer 10 . As a result, there is a quality-related problem that the polarizing function disappears at the ends of the polarizer 10 . Loss of this polarization function is called depolarization, and the width of the depolarized region from the cut end face is called the depolarization width. FIGS. 4A and 4B show optical microscope images showing the depolarization width when the cut end face in the direction perpendicular to the light absorption axis of the polarizer is planarly viewed under crossed Nicols transmitted illumination. FIG. 4A shows an example of a polarizing film that has not caused depolarization due to color loss, while FIG. 4B shows an example of a polarizing film that has undergone depolarization as a result of a reliability test performed in a high-temperature, high-humidity environment. . In FIG. 4B, the cut edge of the polarizing film 12 is indicated by reference numeral 12a, and color loss occurs in a region of width 12b from the cut edge 12a. The width 12b of this region is the depolarization width.

(Coating layer 18a)
The protective films 11a and 11b constituting the polarizing film 12 and other adhesives (not shown) that adhere the polarizer 10 and the protective films 11a and 11b are generally exposed to infrared laser energy above the threshold. It is composed of a resin material that exhibits the property of softening or melting at Therefore, at least the protective films 11a, 11b, etc. adjacent to the cutting groove 2a can be melted by the thermal energy of the laser during the laser cutting process to form a melt. For convenience, FIG. 3 shows only the melt formed by the protective film 11a and the associated adhesive. This melt is thought to contain many components of the protective films 11a and 11b, and flows along the laser-cut end face of the polarizer 10 exposed by the cutting process, covering part or all of the cut end face. Form layer 18a. Therefore, according to the present embodiment, in the shape processing of the polarizing optical function film laminate 1A, the coating layer 18a is formed on the cut end surface of the polarizing film 12, especially the cut end surface of the polarizer 10, at the same time as the laser cutting processing. It is possible to improve the reliability in a high-temperature and high-humidity environment.

The area formed by the thermal energy of the laser is preferably 200 μm or less, more preferably 100 μm or less, and particularly preferably 50 μm or less along the surface of the protective film 11 from the cut edge. This is because if the thickness exceeds 200 μm, the melted region protrudes from the frame portion of the display panel when the polarizing film 12 is attached to the display panel, which may impair the appearance quality.

(Coating layer 18b)
When the laser penetrates the polarizing optical functional film laminate 1A in the thickness direction and reaches the sheet material 17, the thermal energy of the laser causes the thickness of the polarizing optical functional film laminates 1 and 1A to be removed. At least the components of the sheet material 17 that are present in a part of the direction are not included in the polarizing optical function film laminate 1, but the pressure-sensitive adhesive layer 15 and the release liner 16 that may be present in a part of the thickness direction. Further, other components that can be contained in the polarizing optical function film laminate 1 are scattered as droplets, and at least part of the droplets are deposited on the laser-cut end surface formed on the polarizer 10. do. As a result, a coating layer 18b containing at least the components of the sheet material 17, optionally the components of the pressure-sensitive adhesive layer 15 and the release liner 16, and other components is formed. Desired effects can be expected depending on the properties (hydrophobicity or moisture permeability). In addition, regardless of the components or properties of the coating layer to be formed, more specifically, depending on the moisture barrier properties (hydrophobicity or moisture permeability) of the coating layer to be formed, even if the thickness is the same, a high temperature and high humidity environment Although the degree of influence on the reliability of the cut end portion of the polarizing film 12 below varies, the formation of such a coating layer 18b on the cut end face at least physically removes moisture. A predetermined effect of blocking infiltration can be expected. Therefore, according to the present embodiment, in the shape processing of the polarizing optical function film laminate 1A, at the same time as the laser cutting processing, the cut end surface of the polarizing film 12, particularly the cut end surface of the polarizer 10, is added to the coating layer 18a. Thus, the coating layer 18b can be formed, and the reliability can be improved in a high-temperature and high-humidity environment.

In order to facilitate the formation of the coating layer 18b, the width of the cut grooves 2a formed on the sheet material 17 is preferably set appropriately within the range of 5 μm to 300 μm, and the depth of the cut grooves 2a is set to 5 μm to 200 μm. is preferably determined appropriately within the range of

The thickness of the coating layer 18b formed on the cut end surface of the polarizing film 12, more specifically, the length in the direction orthogonal to the cut end surface of the polarizing film 12 is preferably 10 μm or less. If the thickness of the coating layer 18b exceeds 10 μm, the dimensional accuracy of the product may be affected, and problems may occur when mounting the product on the intended display panel. This is because there is concern about the influence on the releasability of the surface protection film, which is not preferable.

Further, considering that the component of the adhesive layer 17b of the sheet material 17 constitutes part or all of the component of the coating layer 18b formed on the cut end surface of the polarizing film 12, the adhesive layer 17b The thickness is preferably in the range of 1 μm to 100 μm, more preferably in the range of 5 μm to 50 μm. When the thickness of the adhesive layer 17b is less than 1 μm, sufficient adhesive strength cannot be obtained, and there is a risk that the adhesive layer 17b may be peeled off during transportation. This is because the total thickness of the laminated body 2 with lumber becomes too thick, and the handleability deteriorates. Furthermore, for the purpose of effectively blocking moisture from entering the polarizer from the outside in a high-temperature and high-humidity environment, the pressure-sensitive adhesive layer 17b is mainly composed of hydrophobic silicone or rubber. In particular, those having an alkyl group such as a methyl group or an ethyl group, or a hydrophobic group such as a phenyl group are preferred. Furthermore, the pressure-sensitive adhesive layer 17b is preferably made of a material with low moisture permeability. , 200 g/m ² ·24 h or less, more preferably 150 g/m ² ·24 h or less. However, as described above, the coating layer 18b formed on the cut end surface can be expected to have a certain effect of physically blocking the infiltration of moisture. It is not limited.
Furthermore, when the laser penetrates the adhesive layer 17b of the sheet material 17 and reaches the resin film substrate 17a, the components of the resin film substrate 17a as well as the components of the adhesive layer 17b are cut into the polarizing film 12. Since it constitutes a part of the component of the coating layer 18b formed on the end surface, from this point of view and from the point of view of preventing breakage during handling, etc., the thickness of the resin film base material 17a is 10 μm to 150 μm. is preferred.

(Relationship between covering layer 18a and covering layer 18b)
As is clear from the above description, it is considered that the coating layer 18a contains a large amount of molten material of the protective films 11a and 11b.
On the other hand, in the coating layer 18b, at least the component of the sheet material 17, which is a component other than the polarizing optical function film laminates 1 and 1A, and an adhesive which is a component other than the polarizing optical function film laminate 1 It is believed that many of the components of layer 15 and release liner 16 are included.
Thus, although the coating layer 18a and the coating layer 18b can be theoretically distinguished relatively clearly as shown in the schematic diagram of FIG. 3, in practice it is difficult to clearly distinguish them. is. This is because the state of the coating layer can easily change due to, for example, thermal properties such as reactivity of the adhesive to the laser used and fluidity during heating. As is clear from the description of Examples and the like to be described later, in fact, both the coating layer 18a and the coating layer 18b contain at least the components of the protective films 11a and 11b and the components melted and scattered from the sheet material 17, Furthermore, it contains components melted and scattered from the release liner 16, the pressure-sensitive adhesive layer 15, and the like. In other words, the components of the coating layer 18a and the components of the coating layer 18b are in a mixed or blended state, and therefore the components of the coating layer 18a and the coating layer 18b cannot be clearly distinguished, and there is no need to do so. do not have. This is because both the coating layer 18a and the coating layer 18b are formed on the cut end surface of the polarizing film at the same time as laser cutting in the shape processing of the polarizing optical function film laminate, etc., improving reliability in a high-temperature and high-humidity environment. because it can contribute to Accordingly, FIG. 3 is merely a conceptual diagram for ease of explanation. As will be apparent from the description below, in the examples and the like, the components contained in the coating layers 18a and 18b were analyzed by TOF-SIMS (time-of-flight secondary ion mass spectrometry) or energy dispersive X-ray spectrometry. are analyzed by

FIG. 5 shows an SEM image of a cut cross section of the laminated body 2 with sheet material as an example that has been laser-cut. Further, in Figures 6A and 6B, the effect obtained by the laminate with sheet material 2 is shown by "depolarization width" in comparison with the effect obtained by the end mill according to the prior art. FIG. 6A shows an example of the depolarization width achieved by Example 4, which will be described later, and FIG. 6B shows an example of the depolarization width achieved by Comparative Example 3, which will be described later.
Although it is not necessarily clear from the image shown in FIG. 5, in consideration of the analysis results by TOF-SIMS shown in Examples, etc., the coating layer (18a) has melted and scattered from the release liner 16 and the sheet material 17. components are considered to be included. Therefore, as is clear from the comparison results of FIGS. 6A and 6B, the coating layer (18a) contributes to improving the quality reliability of the cut end face of the polarizer 10 in a high-temperature and high-humidity environment.
Although an example in which the adhesive layer 15 is provided has been shown, the adhesive layer 15 is not necessarily required. Depending on thermal properties, such as reactivity and fluidity when heated, the coating layer (18a) may not contain the melt component from this adhesive layer 15. FIG. However, the components of the coating layer 18a and the components of the coating layer 18b are in a state of being mixed or blended. Therefore, even in such a case, the quality reliability of the cut end surface of the polarizer 10 can be improved. .

FIG. 7 shows a cross-sectional SEM image in the vicinity of the polarizing film of the laminate with a sheet material according to an example (equivalent to Example 1 described later) of the present invention that has been laser-cut, more specifically, the molecular orientation of the polarizer. A cross-sectional SEM image of the cut end face perpendicular to the (light absorption axis) is shown in FIG. 8, an EDX (energy dispersive X-ray analysis) image of the same location as in FIG. 10 shows an enlarged cross-sectional SEM image of the cut end of the polarizer, and FIG. 10 shows an EDX image of the same portion as in FIG.

(Swelling of polarizer)
When the polarizer 10 made of PVA-based resin containing iodine is laser-cut, the thickness of the polarizer 10 at the cut end face perpendicular to the light absorption axis direction of the polarizer 10 is as shown in FIG. As shown in FIG. 10, a bulge (10a) is generated compared to the thickness other than the vicinity of the cut end face, and the thickness increases 1.1 to 2.5 times. This is because the PVA-based resin containing iodine is subjected to thermal stress by laser energy, and shrinks in the light absorption axis direction, which is the stretching direction of the PVA-based resin. As a result, the PVA-based resin is compressed in the light absorption axis direction. This is thought to be due to expansion in the thickness direction. Accompanying this phenomenon, the softened or melted protective film 11 and adhesive flow into the space created by the compression, facilitating the formation of the coating layer (18a). Such a phenomenon is not seen on the cut end face parallel to the light absorption axis direction of the polarizer 10 .

(laser)
As the laser light source, for example, it is preferable to use an infrared laser including a CO ₂ laser light source whose laser light has an oscillation wavelength of 9 to 11 μm in the infrared region from the viewpoint of high productivity. The infrared laser can easily obtain a power of several tens of watts, and by efficiently heating the film and adhesive layer that constitute the polarizing optical function film laminate 1A by molecular vibration accompanying infrared absorption, It is possible to cause etching associated with the phase transition of the substance.

However, the present invention is not limited to the infrared laser, and it is also possible to use a CO ₂ laser light source having a laser light oscillation wavelength of 5 μm.

As the laser light source, a near-infrared (NIR) light source, a visible light (Vis) light source, and an ultraviolet (UV) light source can be used as long as they are pulsed laser light sources. Examples of pulsed laser light sources with NIR, Vis, and UV wavelengths include solid-state laser light sources with laser light oscillation wavelengths of 1064 nm, 532 nm, 355 nm, 349 nm, or 266 nm (Nd:YAG, Nd:YLF, or YVO4). an excimer laser light source with a laser light oscillation wavelength of 351 nm, 248 nm, 222 nm, 193 nm or 157 nm, and an F2 laser light source with a laser light oscillation wavelength of 157 nm.

As the oscillation mode of the laser light source, a pulse wave is preferable to a continuous wave (CW) from the viewpoint of suppressing thermal damage to the polarizing film. The pulse width in this case can be appropriately set within the range of 10 femtoseconds (10 ^-14 seconds) to 1 millisecond (10 ^-3 seconds). It is also possible to set two or more pulse widths for processing. Also, the repetition frequency, which is the temporal interval of pulses, is preferably 1 to 1,000 kHz, more preferably 10 to 500 kHz.

There are no particular restrictions on the polarization state of laser light, and linearly polarized light, circularly polarized light, and random polarized light are applicable.

There are no particular restrictions on the spatial intensity distribution of the laser beam, but a Gaussian beam is preferred because it exhibits good convergence, enables a small spot, and can be expected to improve productivity. It may be shaped into a flat top beam using a diffractive optical element, an aspherical lens, or the like.

In order to cut into the desired shape, the laser beam may be irradiated along the target shape once, or may be irradiated multiple times to achieve the desired cutting depth. Moreover, it is possible to appropriately adjust the processing conditions for the first time and the second and subsequent times within the above-described condition range.

By using a general scanning device such as a stage drive system such as an XY precision stage, an optical scanning system such as a galvano scanner and a polygon scanner, or a combination of them (multi-axis synchronous control), a polarized optical function that becomes a work While changing the relative position between the film laminate 1A and the laser beam at a predetermined speed, the laser irradiation is controlled on and off using a mechanical shutter mechanism or an AOM (acousto-optical device) to obtain a desired shape. can be processed into

The scanning speed of the laser irradiation achieves a desired etching depth that can completely cut the polarizing optical function film laminate 1A in the thickness direction and form cut grooves to a sufficient depth in the sheet material 17. can be set as appropriate.

It is preferable to condense the laser light with an objective lens such as an Fθ lens and irradiate the polarizing optical function film laminate 1A to be processed, from the viewpoint of improving processing efficiency and suppressing thermal damage. The laser beam preferably has a focused spot diameter that allows processing with a cutting width of 500 μm or less, and more preferably has a focused spot diameter that allows processing with a cutting width of 300 μm or less. When the spot diameter is defined as the point at which the intensity is attenuated to 1/e ² of the peak intensity value, the focused spot diameter is preferably 200 μm or less, more preferably 100 μm or less. When using a galvanometer scanner, it is preferable to use a telecentric Fθ lens in order to irradiate the work with laser light perpendicularly.

In order to obtain a desired condensed spot diameter and cutting width, a beam expanding unit for adjusting the beam diameter may be arranged in the middle of the optical path from the output end of the laser oscillator to the objective lens.

The laser power may be appropriately set according to the thickness and properties of the polarizing optical function film laminate _1A to be processed. and more preferably in the range of 20 to 200W.

It is also possible to irradiate two or more kinds of lasers simultaneously, and it is also possible to sequentially irradiate two or more kinds of lasers.

(processing equipment)
The laser cutting process for the polarizing functional optical film laminate 1A may be performed while continuously unwinding the polarizing optical functional film laminate 1A wound in a roll, or may be cut to a predetermined length in advance. It may be performed on the polarizing functional optical film laminate 1A that has been separated into individual pieces by the above.

In the case of cutting the long belt-shaped film wound in a roll, the polarizing optical functional film laminate 1A is continuously or intermittently supplied by a so-called roll-to-roll method, during which a desired In order to process the laminate into the shape of , it is preferable to cut the laminate while two-dimensionally scanning the laminate with the laser beam and the polarizing optical function film laminate. In this case, for example, by placing and fixing an optical element such as a laser light source and a lens or a mirror on an XY biaxial movable stage and driving the XY biaxial movable stage, the XY2 of the laser beam irradiated to the polarizing film is Change the position on the dimensional plane. It is also possible to employ both laser light source scanning using an XY-operating biaxial stage and laser light scanning using a galvanomirror or the like (so-called cooperative control). During the laser treatment, the long belt-shaped film laminate may be stopped from being conveyed, or it is possible to carry out synchronous processing according to the feeding speed and position while continuously conveying.

A suction fixing stage for holding the laminated body 2 with sheet material during processing may or may not be present.
It is preferable to provide a dust collection mechanism in the vicinity of the laser irradiation part for the purpose of suppressing the adhesion of the scattered matter generated during processing that does not contribute to the formation of the coating layer to the product.
According to the present invention, by appropriately setting the thickness of the sheet material, the amount of the sheet material-derived material that is scattered from the sheet material by the laser energy received during laser cutting and adheres to the cut end surface of the polarizing film can be reduced to a desired amount. can be a value. Therefore, simultaneously with the laser cutting process, a coating layer that contributes to improved reliability in a high-temperature, high-humidity environment can be formed on the cut end surface of the polarizing film, thereby obtaining an effect of preventing depolarization.

FIG. 11 is a schematic diagram showing an example of a laser cutting apparatus 30 that can be used in a continuous roll-to-roll laser cutting process. In this device 30, a laminate 31 having the same structure as the polarizing optical function film laminate 1A shown in FIG. used as is. The long belt-like laminate 31 is wound to form a roll 31a, and the roll 31a is rotatably supported by a roll supporter (not shown). Similarly, a sheet material 37 having a structure similar to that of the sheet material 17 is used in a state of being formed into a long strip shape. A long band-shaped sheet material 37 is wound to form a roll 37a, and the roll 37a is rotatably supported by a roll supporter (not shown).
The laminate 31 and the sheet material 37 fed out from the rolls 31a and 37a are sent to the nip of the pair of superposing rollers 40 in a state of being superimposed on each other. The layered body 31 and the sheet material 37 are layered by the superposition roller 40 to form a layered body 41 with the sheet material, which is fed into the nip of the second superposition roller 42 at the next stage. An anti-contamination film 43 is sent to the second superimposing roller 42 on the side of the laminated body 41 with sheet material that overlaps the surface protection film 34 . The anti-contamination film 43 is supplied in the form of a roll and is rotatably supported by a roll supporter (not shown). The second superposition roller 42 laminates the anti-contamination film 43 on the surface protection film 34 of the laminated body 41 with the sheet material, and transfers the laminated body 41 with the sheet material to which the anti-contamination film 43 is laminated to the next stage. It acts to feed under the guide roller 44 of the.
Between the second overlapping roller 42 and the guide roller 44, a laser irradiation device 45 capable of moving on two XY axes is arranged. The laser irradiation device 45 irradiates the layered body 41 with the sheet material from the upper side of the anti-contamination film 43 with a laser beam, and during that time, moves along the XY axes to irradiate the anti-contamination film 43 and the layered body 41 with the sheet material. A cut groove 46 is formed as shown in the lower cross-sectional view of FIG. A laser cutting process of a desired pattern is performed by this cutting groove 46 . As shown in the lower cross-sectional view of FIG. 11, the cutting groove 46 cuts the anti-contamination film 43 and the laminate with sheet material 41 in the thickness direction, and reaches a certain depth in the thickness direction of the sheet material 37. . Due to the cut groove 46 , a cut portion 47 having a predetermined pattern is formed in the anti-contamination film 43 and the laminated body 41 with sheet material.
When the sheet-attached laminate 41 to which the anti-contamination film 43 is attached passes through the pair of anti-contamination film recovery rollers 48, the anti-contamination film recovery tape 49 made of an adhesive tape stretches its adhesive surface. It is pressed against the anti-contamination film 43 and the anti-contamination film 43 is collected from the upper surface of the laminate 41 . After that, the laminated body 41 with the sheet material that has passed through the guide roller 44 is wound and collected by leaving the product portion defined by the cutting groove 46 on the sheet material 37 and the other unnecessary portion (unnecessary material). After that, the laminated body 41 with the sheet material in which the product portion remains is sent to the sheet material peeling section 51 via a pair of guide rollers 50 . The sheet material peeling unit 51 is provided with a wedge-shaped peeling plate 51a. The peeling plate 51a peels off the used sheet material after laser cutting from the laminate 31, which is the product portion. The remaining laminate 31 is sent to the product collection section 52 and collected as a product. The laminate 31 that has reached the product collection section 52 may be wound into a roll here to form a product roll. FIG. 11 shows a configuration in which the unnecessary material and the anti-contamination film are collected separately, but the present invention is not limited to this, and it is possible to collect them at the same time.

(processing shape)
The polarizing film 12 contained in the polarizing optical function film laminate of the present invention can be used for automobile meter display, smart watches, goggles, smartphones, laptop computers, liquid crystal displays including note pads, and organic EL displays. Since it is used in many devices such as optical display devices such as devices or optical display panels such as plasma display panels (PDP), as illustrated in FIGS. It is cut into various shapes, such as shapes with edges and holes. Here, FIGS. 12A and 12B are diagrams showing an example of a cutting layout when manufacturing a product cut into a smartphone shape from a large-sized polarizing film, FIG. 12A is a plan view showing the whole, and FIG. FIG. 13A and FIG. 13B are plan views showing an enlarged part thereof, and FIG. 13A and FIG. 13B are diagrams showing an example of a cutting layout in the case of manufacturing a product cut out in the shape of an automobile meter panel from a large-sized polarizing film, and FIG. 13A. is a plan view showing the whole, FIG. 13B is a plan view showing an enlarged part thereof, and FIG. Therefore, the present invention is applicable to cutting of all these shapes. By using a laser for cutting, processing having a curved portion with a small radius of curvature (R) is possible, and cutting with a radius of curvature R of 2 mm or less is also possible.

For example, the polarizing film used for the meter panel of an automobile may adopt a structure in which a through hole is formed to fix the meter needle. However, it is possible to meet such demands by using laser cutting technology.

The laser cutting process of the polarizing film 12 of the present invention is not limited to the shapes described above, and can be applied to various shapes.

Furthermore, the method of the present invention can also be applied to a step of slit-cutting a long strip-shaped film laminate containing a polarizing film in the longitudinal direction with a laser. A coating layer according to the present invention can be formed on the cut end face of the film laminate. This coating layer makes it possible to suppress deterioration of the cut end face of the long strip film laminate due to the ingress of moisture from the cut end face of the long strip film laminate during storage and transportation of the laminate. .

Further, in the method of the present invention, the long belt-shaped film laminate containing the polarizing film is conveyed by a roll-to-roll method while being conveyed at a predetermined feed amount and then stopped, with respect to the conveying direction. Application to a fixed-length cutting process for cutting a long belt-shaped film laminate in a vertical direction is also possible.

[Examples, etc.]
Hereinafter, the present invention will be specifically described with reference to examples and the like. However, the examples described below are presented only to aid in understanding the invention and to demonstrate that the invention can be practiced, and the invention is not limited to these examples. isn't it.

[Table 1]

[Example 1]
(Polarizing optical functional film laminate)
A polymer film with a thickness of 30 μm containing PVA-based resin as a main component is sequentially immersed in the following five baths [1] to [5] while applying a tension that allows stretching in the longitudinal direction of the film, and the stretching ratio is 6 times ( polymer film manufactured by Kuraray Co., Ltd.). This stretched film was dried to obtain a polarizer 10 having a thickness of 12 μm.
<Condition>
[1] Swelling bath: 30°C pure water [2] Dyeing bath: 30°C aqueous solution containing iodine and potassium iodide [3] First cross-linking bath: 40 containing potassium iodide and boric acid [4] Second cross-linking bath: 60°C aqueous solution containing potassium iodide and boric acid [5] Cleaning bath: 25°C aqueous solution containing potassium iodide

A PVA-based adhesive was applied to one side of the polarizer so that the thickness after drying was 100 nm, and a long TAC film having a thickness of 25 μm was laminated so that the longitudinal directions of each other were aligned to form a protective film 11a. and

Subsequently, a PVA-based adhesive was applied to the other side of the polarizer so that the thickness after drying was 100 nm, and long TAC films having a thickness of 25 μm were attached so that their longitudinal directions were aligned with each other. A protective film 11b was used.
The polarizing film 12 was produced by the above.

Next, on the main surface of one TAC film 11a opposite to the polarizer, a hard coat layer is formed so as to have a thickness of 7 μm after drying to form a surface treatment layer 13, and further a surface treatment layer 13 is formed thereon. A protective film 14 was formed. The surface protective film 14 is made of a polyethylene terephthalate base material (thickness: 38 μm) and an acrylic adhesive (thickness: 23 μm).

On the main surface of the other TAC film 11b opposite to the polarizer, an acrylic adhesive with a thickness of 12 μm is applied to form an adhesive layer 15, and a release liner made of polyethylene terephthalate is further applied thereon. 16 was pasted together.

The surface protective film E-MASK manufactured by Nitto Denko Co., Ltd., which is composed of an acrylic adhesive layer (thickness 20 μm) and a polyethylene terephthalate base (thickness 38 μm), is used as the acrylic adhesive anti-contamination film 23 (43). It was attached to the main surface of the surface protective film 14 of the functional film laminate 1A.

By this procedure, anti-contamination film 23 / surface protection film 14 / hard coat 13 / TAC film 11a / PVA adhesive / polarizer 10 / PVA adhesive / TAC film 11b / pressure-sensitive acrylic adhesive layer 15 / peeling A polarizing optical function film laminate 1A having a structure of the liner 16 and having a total thickness of about 180 μm was obtained.

(laser)
The laser oscillator uses a CO ₂ laser (Coherent J-3, wavelength 9.4 μm, Gaussian beam, pulse oscillation), and the theoretical spot diameter is defined by the intensity of 1/e ² of the peak value by the objective lens. ) is about 90 μm, and an XY stage and a galvano scanner are used together, and the desired processing shape is scanned once with a laser power of 65 W, a repetition frequency of 30 kHz, and a scan speed of 500 mm / s. It was cut into a rectangular shape with dimensions of 80 mm×50 mm.

(sheet material)
A sheet material 17 composed of a silicone adhesive layer 17b (thickness 75 μm) and a polyethylene terephthalate base material 17a (Mitsubishi Chemical Co., Ltd., T100-75S, thickness 75 μm) is placed through the silicone adhesive layer 17b. It was attached to the main surface 16a of the release liner 16 of the polarizing optical function film laminate 1A described above.

(laser cutting)
The polarizing optical function film laminate 1A to which the sheet material 17 and the anti-contamination film 43 were adhered was laser-cut into a desired shape under the laser conditions described in the section "Laser" above. By this laser cutting process, the polarizing optical function film laminate 1A is fully cut over the entire thickness together with the silicone pressure-sensitive adhesive layer 17b of the sheet material 17, while the polyethylene terephthalate base material 17a is not completely cut. , It was confirmed that the cutting process was performed in a half-cut state.

After the laser cutting process, the anti-contamination film 43 was peeled off, and the height of the burr formed on the cut end face of the surface protection film 14 was measured.

In addition, the thickness of the polarizer at the cut end face in the direction perpendicular to the stretching direction of the polarizer 10, that is, the direction perpendicular to the orientation direction of the PVA-based molecules is 1.0 .8 times.

(evaluation)
The sheet material 17 and anti-contamination film 43 are peeled off from a polarizing film sample cut into a rectangular shape by laser, the cut surface is embedded in epoxy resin, and the state of the cut cross section is examined by FE-SEM (scanning electron microscope, Japan). Electron Co., Ltd., JSM-7001F) was observed, and SEM images were obtained (FIGS. 7 and 9).
Further, the state of the cut end surface of the polarizer 10, in other words, the state of the coating layer was observed from the direction of molecular orientation using the same FE-SEM to obtain an SEM image (FIG. 15A). This FIG. 15A is an SEM image in Example 1 and corresponds to the SEM image viewed from the direction of arrow “C” in FIG. For ease of comparison, FIG. 15B shows a similar SEM image for Example 2, and FIGS. 15C and 15D show similar SEM images for Comparative Examples 1 and 2, respectively.
As can be seen from these images, the cut end faces of the polarizer 10 are reliably covered with the coating layers 18a, 18b.

In order to obtain information on the substances contained in the coating layers 18a and 18b, elemental analysis by EDX (energy dispersive X-ray spectroscopy, manufactured by Oxford Instruments, Energy 250) was performed on the same locations as in FIG. 9 (FIG. 8). and FIG. 10). FIGS. 8 and 10 are EDX images that have been software processed so that if silicon is included in the coating layers 18a, 18b, the silicon will appear bright and shiny. 10, it can be seen that the coating layer 18b formed on the cut end surface of the polarizing film contains silicon (Si element) derived from the silicone adhesive layer 17b constituting the sheet material 17. . Furthermore, the thickness of the coating layer 18b was approximately 2 to 5 μm.

In order to obtain further information about the substances contained in the coating layers 18a and 18b, a TOF- (time-of-flight) secondary ion mass spectrometer manufactured by ULVAC-PHI, Inc. was used for the same locations as those shown in FIG. Analysis by SIMS was performed. More specifically, focusing on the analytically obtained ion intensity of PET-derived C ₈ H ₅ O ₄ ⁻ (m/z 165) (m/z represents the mass-to-charge ratio), mapping the data bottom. FIG. 16 shows an image showing the analysis results. From this image, it was confirmed that a polyethylene terephthalate (PET) film was formed not only on the coating layer 18b but also on the coating layer 18a.

Furthermore, when the laser-irradiated portion of the peeled sheet material was confirmed, a cut groove 17-1a having a width of about 40 μm and a depth of about 100 μm, which was formed by cutting with laser energy, was confirmed. This indicates that at least the components of the sheet material 17 scattered from the cut groove 17-1a adhere to the cut end surfaces of the polarizing film 12 and form the coating layers 18a and 18b (FIG. 17). .

FIG. 18 is a graph showing the results of component analysis of materials contained in the coating layers 18a and 18b in Example 1. FIG. More specifically, it is a graph showing the EDX elemental analysis results of the portion indicated by the arrow "B" in FIG. 10, where the horizontal axis indicates X-ray energy (keV) and the vertical axis indicates the X-ray count. As shown in this figure, in this example, in addition to silicon (Si), carbon (C) and oxygen (O) were detected from the coating layers 18a and 18b. As can be seen from this, the coating layers 18a and 18b formed on the cut end face of the polarizer 10 are composed of at least the polarizing film 12, the adhesive layer 15, the release liner 16, the organic component derived from the sheet material, and the It can be seen that the layer is formed by mixing silicon (Si) derived from the adhesive layer 17b.

(Reliability test in high temperature and high humidity environment)
The surface protective film 14 and the release liner 16 were peeled off from the prepared sample of the rectangular polarizing optical function film laminate 1A, and the adhesive layer 15 was bonded to the glass plate so that the surface thereof was in contact with the glass plate. In this state, the sample was placed in an oven set at a temperature of 65° C. and a humidity of 90% to conduct a reliability test. The conditions of the reliability test were to hold the sample for 240 hours (10 days) in the oven in the above environment, and to observe the depolarization due to the color loss of the polarizing film 12 on the processed end face in the high temperature and high humidity environment.

(Confirmation of evaluation results for processing edge reliability)
Samples that have undergone the reliability test described above are observed using an optical microscope (crossed Nicols, transmitted illumination) and are subject to the following definitions from the laser-cut cut ends, based on the definitions described above in connection with FIGS. 4A and 4B: Depolarization width was measured.

As a result of the measurement, the depolarization width of the cut end surface (alignment parallel surface) parallel to the light absorption axis of the polarizer was 135 μm, and the depolarization width of the cut end surface (alignment parallel surface) perpendicular to the light absorption axis was 183 μm. rice field. It can be seen that the depolarization width could be suppressed as compared with Comparative Examples described later.

[Example 2]
In the sheet material 17, an acrylic adhesive layer (23 μm thick) was used as the adhesive layer 17b, and a polyethylene terephthalate substrate (38 μm thick) was used as the resin film substrate 17a, and the laser power was changed to 55 W. Evaluation of depolarization due to laser cutting and color loss of the polarizer 10 was performed under the same conditions as in Example 1 except that the laser cutting process was performed.

As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer 10 was 153 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 216 μm. The depolarization width could be suppressed as compared with Comparative Examples described later.

[Example 3]
In the sheet material 17, a rubber adhesive layer (10 μm thick) was used as the adhesive layer 17b, and a polyethylene terephthalate substrate (38 μm thick) was used as the resin film substrate 17a, and the laser power was changed to 55 W. Evaluation of depolarization due to laser cutting and color loss of the polarizer 10 was performed under the same conditions as in Example 1 except that the laser cutting process was performed.

As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 120 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 191 μm. The depolarization width could be suppressed as compared with Comparative Examples described later.

[Example 4]
The conditions were the same as in Example 2, except that the thickness of the polarizer 10 was set to 5 μm, the protective film 11b was removed, and a base material having a silicone pressure-sensitive adhesive layer with a thickness of 20 μm was used, and the laser power was changed to 35 W. , evaluation of depolarization due to laser cutting processing and color omission of the polarizer 10 was performed. Note that FIG. 5 corresponds to an SEM image of the configuration of Example 4 with the anti-contamination film removed.

As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 113 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 103 μm. As compared with Comparative Example 3, which will be described later, the depolarization width could be suppressed.

[Comparative Example 1]
Except that the polarizing optical function film laminate 1A described in Example 1, which does not use the sheet material and the antifouling film 23, was cut into a predetermined shape, that is, a rectangular shape with dimensions of 80 mm × 50 mm using an end mill. , was evaluated under the same conditions as in Example 1.

As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 182 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 251 μm. Compared with Examples 1 and 2, the depolarization width was increased.

[Comparative Example 2]
Depolarization due to laser cutting and color loss of the polarizer 10 was evaluated under the same conditions as in Example 1, except that the sheet material was not used and the laser power was changed to 55 W. In this case, it was confirmed that the polarizing optical function film laminate 1A was fully cut, while the release liner 16 was not completely cut, but cut into a half-cut state.

As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 170 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 231 μm. The use of the infrared laser produced the effect of covering the edges of the polarizer with the melt of the protective film, and although there was a slight improvement compared to Comparative Example 1, Examples 1 and 2 described above Compared to , the effect of suppressing depolarization was weakened.

[Comparative Example 3]
The polarizing optical function film laminate 1A described in Example 4, which does not use the sheet material and the anti-fouling film 23, was subjected to end mill processing under the same conditions as in Comparative Example 1, and the shape-processed sample obtained was evaluated.

As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer 10 was 129 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 177 μm. Compared with Example 4, the depolarization width was increased.

[Example 5]
Under the same conditions as in Example 1, except that the anti-pollution film 23 was not used, the laser power was changed to 43 W, and the repetition frequency was 15 kHz. A depolarization evaluation was performed.
As a result, the depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 122 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 195 μm. The depolarization width could be suppressed as compared with Comparative Examples described later.

[Example 6]
Analysis by TOF-SIMS was performed under the same conditions as in Example 2 except that the anti-contamination film 23 was not used, the laser power was changed to 39 W, and the repetition frequency was changed to 15 kHz. And evaluation of depolarization caused by color loss of the polarizer 10 was carried out.
FIG. 19 is an image showing analysis results by TOF-SIMS. From this figure, it was confirmed that a polyethylene terephthalate (PET) film was formed not only on the coating layer 18b but also on the coating layer 18a.
The depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 132 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 214 μm. The depolarization width could be suppressed as compared with Comparative Examples described later.

[Example 7]
Analysis by TOF-SIMS was performed under the same conditions as in Example 2 except that the anti-contamination film 23 was not used, the laser power was changed to 20 W, the repetition frequency was 15 kHz, and the number of scans was 2. Also, evaluation of depolarization due to laser cutting processing and color loss of the polarizer 10 was performed.
FIG. 20 is an image showing analysis results by TOF-SIMS. From this figure, it was confirmed that a polyethylene terephthalate (PET) film was formed not only on the coating layer 18b but also on the coating layer 18a.
The depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 133 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 233 μm. The depolarization width could be suppressed as compared with Comparative Examples described later.
It was also found that by increasing the number of scans while weakening the laser power, results comparable to those obtained when the laser power is strong and the number of scans is small are obtained.

[Comparative Example 4]
Analysis by TOF-SIMS was performed under the same conditions as in Example 5, except that the sheet material was not used and the laser power was changed to 20 W. An evaluation of depolarization was performed. In this case, it was confirmed that the release liner 16 of the polarizing optical functional film laminate 1A was not completely cut, but cut into a half-cut state.
FIG. 21 is an image showing analysis results by TOF-SIMS. From this figure, it was confirmed that a film of polyethylene terephthalate (PET) was not formed on the coating layers 18a and 18b.
The depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 158 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 235 μm. Compared with Example 5, the depolarization width was increased.

[Comparative Example 5]
Analysis by TOF-SIMS was performed under the same conditions as in Example 6, except that the sheet material was not used and the laser power was changed to 27 W. An evaluation of depolarization was performed.
In this laser cutting process, the polarizing optical function film laminate 1A was completely cut, and it was confirmed that the cutting process was performed in a fully cut state. Here, since no sheet material was provided, the laser beam was completely emitted in the irradiation direction.
FIG. 22 is an image showing analysis results by TOF-SIMS. From this figure, it was confirmed that a film of polyethylene terephthalate (PET) was not formed on the coating layers 18a and 18b.
The depolarization width of the cut end surface parallel to the light absorption axis of the polarizer was 163 μm, and the depolarization width of the cut end surface perpendicular to the light absorption axis was 268 μm. Compared with Example 6, the depolarization width was increased.

[Reference Example 1]
Analysis by TOF-SIMS was performed under the same conditions as in Example 1, except that the antifouling film 23 and the surface protection film 14 were not used.
FIG. 23 is an image showing analysis results by TOF-SIMS. From this figure, it was confirmed that a polyethylene terephthalate (PET) film was formed not only on the coating layer 18b but also on the coating layer 18a.
As a result, it was found that a film of polyethylene terephthalate (PET) was formed on the coating layers 18a and 18b even when the antifouling film 23 and the like were not present.

[Reference example 2]
Analysis by TOF-SIMS was performed under the same conditions as in Example 1 except that the release liner 16 and sheet material 17 were not used. The polarizing optical function film laminate 1 and the pressure-sensitive adhesive layer 15 were fully cut by laser cutting.
FIG. 24 is an image showing analysis results by TOF-SIMS. From this figure, it was confirmed that a polyethylene terephthalate (PET) film was not formed not only on the coating layer 18b but also on the coating layer 18a.
As a result, it was found that polyethylene terephthalate (PET) films were not formed on the coating layers 18a and 18b when the release liner and sheet material were not used, even if the anti-contamination film 23 and the like were present.

[Discussion]
The coating layers 18a and 18b contain at least the components of the sheet material 17, that is, the components of the adhesive layer 17b and/or the PET components of the resin film substrate 17a. Therefore, by properly selecting the components of the adhesive layer 17b, it is possible to effectively prevent moisture from entering the polarizer 10 from the outside through the cut end face, depending on the components of these sheet materials. Prevention of color omission, in other words, reduction of depolarization width can be expected.
Further, when the polarizing optical functional film laminate 1 constitutes the polarizing optical functional film laminate 1A including the adhesive layer 15 and the release liner 16, depending on the components of the adhesive layer 15, , the PET component derived from the release liner 16 can make the coating layers 18a, 18b thicker to more effectively prevent the penetration of moisture.

Claims (10)

A cutting method for laser cutting a polarizing optical function film laminate having at least a polarizing film in which a protective film is laminated on at least one side of a polarizer,
A sheet material that is separate from the polarizing optical function film laminate is placed on one surface of the polarizing optical function film laminate, and the sheet material of the polarizing optical function film laminate is Laser cutting is performed by irradiating a laser in the thickness direction of the polarizing optical functional film laminate from the other surface located on the opposite side, and moving the laser irradiation position along a predetermined shape within the plane of the laminate. By cutting the polarizing optical function film laminate into the predetermined shape,
When the sheet material is irradiated with a laser, the sheet material components present in a part in the thickness direction are scattered as droplets by the laser energy, and at least a part of the droplets of the sheet material components has the polarizing property. forming a coating layer containing at least the sheet material component so as to be deposited on the laser-cut end face formed on the polarizer of the optical functional film laminate so as to cover the laser-cut end face of the polarizer; A laser cutting method, characterized by: 2. The laser cutting method according to claim 1, wherein the coating layer formed so as to cover the laser-cut end surface of the polarizer is a layer of the polarizing optical functional film laminate other than the polarizing film. A laser cutting method, comprising: 3. The laser cutting method according to claim 1, wherein a release liner is releasably attached to the surface of the polarizing film located on the side opposite to the laser irradiation side via an adhesive layer. and irradiating the polarizing optical function film laminate with a laser. 4. The laser cutting method according to any one of claims 1 to 3, wherein the polarizing optical functional film is laminated while a surface protective film is laminated on the surface of the polarizing film positioned on the laser irradiation side. A laser cutting method comprising irradiating a body with a laser. 5. The laser cutting method according to any one of claims 1 to 4, wherein the sheet material is composed of an adhesive and a resin film substrate, and the resin film substrate is attached by the adhesive. A laser cutting method characterized by: 6. The laser cutting method according to claim 5, wherein the main component of the adhesive in the sheet material is any polymeric material selected from the group of acrylic, rubber, urethane, silicone, or polyester. A laser cutting method characterized by: 7. The laser cutting method according to claim 5, wherein the sheet material has a moisture permeability of 200 g/m ² ·24 h or less in an atmosphere of 40° C. and 90% RH. as at least part of the constituent material. 8. The laser cutting method according to any one of claims 1 to 7, wherein the length of the coating layer in the direction perpendicular to the laser-cut end surface is 10 μm or less. Method. 9. A method according to any one of claims 1 to 8, wherein said sheet material is not completely cut by said laser irradiation. 10. A method according to any one of claims 1 to 9, characterized in that said laser is a _CO2 laser.

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