Method for manufacturing light-transmitting laminate

Abstract

To provide a light permeable laminate capable of detecting significantly minute foreign matter compared to conventional arts.SOLUTION: A light permeable laminate according to embodiments of the present invention has a first main surface and a second main surface, and includes at least one reflective protective film releasably and temporarily attached to the first main surface. The reflective protective film has a function of reflecting irradiation light when an optical system with a predetermined magnification is focused on the surface of the first main surface, and transmitting inspection light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a light-transmitting laminate. [Background technology]

[0002] Light-transmitting laminates (e.g., optical components, optical laminates, optical films, and light-transmitting pressure-sensitive adhesive sheets) used in image display devices require the removal of foreign matter from within the laminate to prevent image display defects and the like. Therefore, such light-transmitting laminates are typically subjected to foreign matter inspection. Foreign matter inspection is typically a transmission inspection performed while a long web of the light-transmitting laminate is being transported, and in this transmission inspection, foreign matter and / or defects can be recognized as dark spots. In recent years, the display performance required of image display devices has become significantly higher, resulting in a significantly higher demand for precision in foreign matter inspection of light-transmitting laminates. Specifically, while it was previously acceptable to detect foreign matter and / or defects of about 50 μm, it has become necessary to detect foreign matter and / or defects of about 10 μm. However, it is extremely difficult to detect such small foreign matter and / or defects in the above-mentioned foreign matter inspection performed while a long web is being transported. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-062165 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made to solve the above-mentioned problems, and its main object is to provide a light-transmitting laminate that can detect much smaller foreign matter and / or defects than conventional methods. [Means for solving the problem]

[0005] A light-transmitting laminate according to an embodiment of the present invention has a first main surface and a second main surface; and includes at least one reflective protective film releasably and temporarily attached to the first main surface; the reflective protective film has the function of reflecting irradiated light when an optical system with a predetermined magnification is focused on the surface of the first main surface, and transmitting inspection light. In one embodiment, the reflective protective film satisfies the following relationship: y≧0.0181x-11.142 Here, x is the absolute value of the detection wavelength in the wavelength range of 650 nm to 800 nm, and y is the absolute value of the reflectance. In one embodiment, the light-transmitting laminate further includes a surface protection film temporarily and releasably attached to the surface of the reflective protection film. In one embodiment, the light-transmitting laminate further includes a hard coat layer formed on the surface of the reflective protective film. In one embodiment, the optically transparent laminate is used for transmission inspection to detect defects of 8 μm to 50 μm in size while being fixed in a hollow state as a sheet. In one embodiment, the optically transparent laminate is provided with a recognition means capable of recognizing an inspected area after the transmission inspection. In one embodiment, the recognition means is a straight or dashed line, a cross mark, or regularly spaced dots surrounding the inspected area. [Effects of the Invention]

[0006] According to the light-transmitting laminate according to the embodiment of the present invention, it is possible to detect foreign matter and / or defects that are much smaller (for example, about 8 μm in size) than conventionally possible. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic side view illustrating an example of transmission inspection in an embodiment of the present invention. [Figure 2]10(a) to 10(d) are schematic side views illustrating an example of a procedure for fixing a light-transmitting laminate to a support member in detecting defects in a transmission inspection. [Figure 3] FIG. 10 is a schematic diagram illustrating focusing of an image sensor in detecting defects in transmission inspection. [Figure 4] 10 is a schematic perspective view illustrating scanning of the XY plane of the optically transparent laminate by an imaging element in detecting defects in a transmission inspection. FIG. [Figure 5] FIG. 10 is a conceptual diagram illustrating an example of an XY coordinate map of defects in the detection of defects by transmission inspection. [Figure 6] FIG. 10 is a conceptual diagram illustrating an example of integrating XY coordinate maps of a predetermined number of defects in the detection of defects by transmission inspection. [Figure 7] 1(a) to 1(c) are schematic plan views illustrating a recognition means that can be provided on a light-transmitting laminate. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. Furthermore, all drawings are schematic and do not accurately depict actual conditions.

[0009] A. Overview of inspection method for light-transmitting laminates In an inspection method for a light-transmitting laminate according to an embodiment of the present invention, a light-transmitting laminate sheet is fixed in a hollow state and subjected to a transmission inspection. FIG. 1 is a schematic side view illustrating an example of the transmission inspection. The transmission inspection involves, for example, using an optical system to obtain an image of the light-transmitting laminate 10 suspended between a pair of support members 20. The optical system includes, for example, an imaging element 30 disposed on one side (the upper side in the illustrated example) of the light-transmitting laminate 10 and configured to obtain an image of the light-transmitting laminate; and a light source 40 disposed on the other side (the lower side in the illustrated example) of the light-transmitting laminate 10 and configured to emit light that illuminates the light-transmitting laminate 10. Note that the imaging element 30 may be disposed below the light-transmitting laminate 10, and the light source 40 may be disposed above the light-transmitting laminate 10. The imaging element 30 captures a transmitted light (inspection light) image, and foreign matter and / or defects (hereinafter, sometimes simply referred to as foreign matter or defects depending on the context) can be recognized as dark spots in the captured image. More specific embodiments of the transmission inspection will be described later. By performing a transmission inspection while a sheet of the light-transmitting laminate is fixed in the air, defects of 8 μm to 50 μm in size, preferably 8 μm to 30 μm in size, more preferably 8 μm to 20 μm in size, even more preferably 8 μm to 15 μm in size, and particularly preferably approximately 10 μm in size, can be detected in the light-transmitting laminate. Conventionally, foreign substance inspection of light-transmitting laminates such as optical films has been performed while a long web is being transported. This type of foreign substance inspection makes it virtually impossible to detect small foreign substances (typically, those of 50 μm or less in size). Conventionally, detection of foreign substances of approximately 50 μm in size was acceptable, and there were no particular problems with foreign substance inspection while the web was being transported. However, with the increasing precision of image display devices, a new need has arisen for detecting foreign substances of approximately 10 μm in size. After extensive research into this problem, the inventors have discovered that this may be due to the flapping of the web during transport and / or vibration of the transport device, which prevents accurate images from being obtained by the imaging element.After much trial and error, it was found that by cutting the light-transmitting laminate into sheets and performing a transmission inspection while the sheet-like light-transmitting laminate was fixed in the air (i.e., not placed on a surface), it was possible to eliminate the adverse effects of flapping of the web during transport and / or vibrations of the transport device, as well as the adverse effects of foreign matter on the loading surface. As a result, extremely high-precision foreign matter inspection was achieved, making it possible to detect foreign matter and / or defects of approximately 10 μm in size. In this way, the present invention solves new problems that had not been encountered before.

[0010] B.Light transparent laminate The light-transmitting laminate may be any suitable light-transmitting laminate that requires foreign matter inspection. Specific examples include optical films, pressure-sensitive adhesive sheets, and combinations thereof (e.g., optical films with a pressure-sensitive adhesive layer). Examples of optical films include polarizing plates, retardation plates, conductive films for touch panels, surface-treated films, and laminates obtained by appropriately stacking these films according to the purpose (e.g., anti-reflection circular polarizing plates, polarizing plates with a conductive layer for touch panels). The pressure-sensitive adhesive sheet typically includes a pressure-sensitive adhesive and a release film temporarily attached to at least one side of the pressure-sensitive adhesive. The light-transmitting laminate may typically be an optical film with a pressure-sensitive adhesive layer. The thickness of the light-transmitting laminate is preferably 300 μm or less, more preferably 280 μm or less, and even more preferably 250 μm or less. According to an embodiment of the present invention, even in such a thin light-transmitting laminate, minute foreign matter can be effectively detected. The lower limit of the thickness of the light-transmitting laminate may be, for example, 30 μm.

[0011] The light-transmitting laminate can be produced, for example, by laminating the layers constituting the light-transmitting laminate by a so-called roll-to-roll process. The light-transmitting laminate has a first main surface and a second main surface. The first main surface is typically the surface opposite the image display cell to which the light-transmitting laminate is attached; the second main surface is typically the surface on the image display cell side, and more specifically, may be the surface of the pressure-sensitive adhesive layer. The produced long light-transmitting laminate is cut to a predetermined size and subjected to foreign matter inspection. Typically, this size may be a size that allows multiple sheets of the final product to be obtained. After inspection, the light-transmitting laminate can be typically cut to the final product size and shipped.

[0012] In one embodiment, when the light-transmitting laminate is subjected to foreign substance inspection, a reflective protective film may be temporarily and removably attached to the first main surface. Depending on the type and configuration of the light-transmitting laminate (for example, when the light-transmitting laminate includes a low-reflection layer (AR layer)), autofocus of the imaging element may not function on the first main surface of the light-transmitting laminate. However, by temporarily attaching the reflective protective film, even in such cases, autofocus of the imaging element can function well on the first main surface of the light-transmitting laminate. The reflective protective film typically has the function of reflecting irradiated light when the focus of an optical system with a predetermined magnification is adjusted on the surface of the first main surface of the light-transmitting laminate, and transmitting inspection light. In one embodiment, the reflective protective film satisfies the following relationship: y≧0.0181x-11.142 Here, x is the absolute value of the detection wavelength in the wavelength range of 650 nm to 800 nm, and y is the absolute value of the reflectance. This configuration allows the autofocus of the imaging element to function more effectively. Any appropriate configuration can be adopted as the reflective protective film as long as it has the above-mentioned function. Specifically, the reflective protective film can be made of a cyclic olefin-based resin, for example, as described in paragraph

[0031] of JP 2019-099751 A. Examples of cyclic olefin-based resins include polynorbornene. Commercially available cyclic olefin-based resins may also be used. Specific examples of commercially available products include Zeonor and Zeonex manufactured by Zeon Corporation, Arton manufactured by JSR Corporation, Apel manufactured by Mitsui Chemicals, and Topas manufactured by TOPAS ADVANCED POLYMERS. The cyclic olefin-based resin film preferably contains 50% or more by weight of the cyclic olefin-based resin. In one embodiment, a hard coat layer may be formed on the surface of the reflective protective film. By forming a hard coat layer, it is possible to prevent scratches on the reflective protective film and adhesion of foreign matter to the reflective protective film, thereby enabling more accurate foreign matter inspection and accurate detection of minute foreign matter and / or defects.

[0013] Multiple reflective protective films may be temporarily attached depending on the number of inspections planned. For example, if two foreign substance inspections are planned, by attaching two reflective protective films together and peeling off one outer reflective protective film before the second foreign substance inspection, it is possible to prevent scratches on the inner reflective protective film and the adhesion of foreign substances to the inner reflective protective film, thereby enabling multiple foreign substance inspections to be carried out with higher accuracy. Note that even if multiple inspections are planned, only one reflective protective film may be temporarily attached.

[0014] In one embodiment, a surface protective film may be temporarily attached in a releasable manner to the surface of the reflective protective film (or to the surface of the outermost reflective protective film when multiple reflective protective films are present). Temporarily attaching the surface protective film can prevent scratches on the reflective protective film and adhesion of foreign matter to the reflective protective film, thereby enabling more accurate foreign matter inspection. The surface protective film is typically peeled off and removed during inspection. After the inspection is completed, the surface protective film peeled off during inspection may be temporarily attached again to the surface of the light-transmitting laminate, or another surface protective film may be temporarily attached in a releasable manner.

[0015] The reflective protective film and the surface protective film may be temporarily attached to the light-transmitting laminate by a roll-to-roll method (that is, before cutting), or may be temporarily attached after cutting.

[0016] C. Specific embodiments of the method for inspecting a light-transmitting laminate C-1. Fixing in the air The detection of defects during transmission inspection will be described in more detail below. In defect detection, as described above, a sheet of the light-transmitting laminate is fixed in the air. The light-transmitting laminate can be fixed in the air by being spanned across a pair of support members, as shown in FIG. 1 . Opposing ends of the light-transmitting laminate, which are non-product regions, can be fixed to the support members. Typically, the light-transmitting laminate includes a pressure-sensitive adhesive layer, and the light-transmitting laminate can be fixed to the support member via the pressure-sensitive adhesive layer. FIGS. 2(a) to 2(d) are schematic side views illustrating an example of a procedure for fixing the light-transmitting laminate to a support member. In this procedure, preferably, the light-transmitting laminate has a reflective protective film 50 and a surface protective film 60 releasably temporarily attached to the first main surface 10a. First, as shown in FIG. 2(a), the separator at one end 10c, which is the non-product region of the light-transmitting laminate, is peeled off and removed to expose the pressure-sensitive adhesive layer. The end 10c is then bonded to the support member 20 via the pressure-sensitive adhesive layer. Next, as shown in FIG. 2(b), the separator at end 10d opposite end 10c, which is the non-product area, is peeled and removed to expose the adhesive layer, and end 10d is bonded to a support member 20 via the adhesive layer. Bonding (the end of) the light-transmitting laminate to a support member using the adhesive layer allows for simple fixation without the need for a separate fixture. Once end 10c and end 10d are bonded, the separator is completely removed as shown in FIG. 2(c). The reflective protective film 50 and surface protective film 60 not only prevent scratches on the light-transmitting laminate and / or adhesion of foreign matter to the light-transmitting laminate, but also function as reinforcing materials when removing the separator and bonding the end. In this way, the light-transmitting laminate is laid horizontally on the support member. Next, as shown in FIG. 2(d), the surface protective film 60 is peeled off, and the light-transmitting laminate 10 with the reflective protective film 50 temporarily attached is subjected to foreign matter inspection. By peeling off the surface protective film after fixing the light-transmitting laminate to a support member (i.e., by fixing the light-transmitting laminate to a support member with the surface protective film temporarily attached), it becomes possible to maintain the rigidity (stiffness) of the light-transmitting laminate even after peeling off the separator, making it easier to handle.As a result, wrinkles and the like are prevented, allowing for highly accurate foreign substance inspection and accurate detection of minute foreign substances and / or defects. Furthermore, by performing foreign substance inspection with the single-sheet light-transmitting laminate horizontally suspended, the effects of flapping due to transport and / or vibration of the transport device can be eliminated. This allows for highly accurate foreign substance inspection and accurate detection of minute foreign substances and / or defects even after the surface protective film has been peeled off. Additionally, peeling off the surface protective film eliminates the need to detect foreign substances in the surface protective film, resulting in a synergistic effect with the above-mentioned effects, allowing for more accurate foreign substance inspection. In one embodiment, as described in Section B above, multiple reflective protective films may be temporarily attached. In this case, the surface protective film is peeled off and removed during the first foreign substance inspection, and the reflective protective films can be peeled off one by one for each subsequent foreign substance inspection.

[0017] The pair of support members 20, 20 are typically configured to be able to move relatively close to or apart from one another. In one embodiment, the support members are configured to be slidable and are biased in a direction away from each other. Specifically, as shown in FIGS. 2(b) to 2(d), one of the support members (on the right side of the drawing in the illustrated example) is fixed, and the other (on the left side of the drawing in the illustrated example) is configured to be slidable, and the other is biased in a direction away from the other by an elastic member (e.g., a spring). With this configuration, an appropriate tension is applied to the light-transmitting laminate, and the light-transmitting laminate is in a stretched state. As a result, wrinkles and distortions in the light-transmitting laminate are significantly suppressed, allowing for more accurate foreign substance inspection and accurate detection of minute foreign substances and / or defects. The tension can be controlled by adjusting the strength of the spring itself and the tightness of the spring fixing screws. Note that both support members may be configured to be slidable, and both may be biased in a direction away from each other by an elastic member.

[0018] C-2. Detecting defects As described above, defect detection is typically performed using an optical system (including an image sensor 30 and a light source 40) as shown in FIG. 1 . A more detailed description follows. First, as shown on the left side of FIG. 3 , an optical system (effectively, an image sensor 30) with a predetermined magnification (hereinafter sometimes referred to as low magnification) is focused on the first main surface 10 a of the light-transmitting laminate 10. In this state, the image sensor 30 scans the entire plane (XY plane) of the light-transmitting laminate 10 as shown in FIG. 4 to create an XY coordinate map of defects (first XY coordinate map). As described in Section A above, defects are recognized as dark spots. Therefore, in the first XY coordinate map, defects near the first main surface 10 a of the light-transmitting laminate 10 (up to a predetermined distance inward in the thickness direction from the first main surface) are recognized as dark spots on the image, as shown in FIG. 5 . Note that the first XY coordinate map alone may not be able to detect minute defects deep in the thickness direction (close to the second main surface). In contrast, according to an embodiment of the present invention, as described below, defects are detected by shifting a predetermined distance P inward in the thickness direction from the surface of the first main surface, thereby making it possible to accurately detect minute defects throughout the entire thickness direction of the light-transmitting laminate.

[0019] Next, as shown in the center of FIG. 3 , the focal point of the imaging element 30 is shifted a predetermined distance P inward in the thickness direction (Z direction) from the surface of the first main surface 10a of the light-transmitting laminate 10, and the focal point is adjusted to a predetermined position inside the thickness direction of the light-transmitting laminate 10. In this state, the imaging element 30 scans the entire XY plane of the light-transmitting laminate 10 as shown in FIG. 4 , similarly to the above, to create an XY coordinate map of defects (a second XY coordinate map). In the second XY coordinate map, defects near a predetermined position inside the thickness direction of the light-transmitting laminate 10 (up to a predetermined distance from the predetermined position) are recognized as dark spots on the image at positions substantially different from those shown in FIG. 5 . Note that, in this specification, the predetermined distance P may be referred to as the imaging pitch. Focusing of the imaging element can be achieved using any appropriate means. For example, the imaging element itself may be moved in the Z direction, the focal length of the imaging element may be changed using a lens or the like, or a combination of these may be used. The illustrated example shows a configuration in which the focal length of the imaging element is changed using a lens or the like.

[0020] If necessary, as shown on the right side of FIG. 3 , the focus of the imaging element 30 is further shifted a predetermined distance P in the thickness direction (Z direction) to focus on the next predetermined position inside the thickness direction of the light-transmitting laminate 10. In this state, the imaging element 30 is used to scan the entire XY plane of the light-transmitting laminate 10 as shown in FIG. 4 , as described above, to create an XY coordinate map of defects (third XY coordinate map). This operation is repeated a predetermined number of times as necessary to create a predetermined number of XY coordinate maps of defects. The imaging pitch and the number of defect XY coordinate maps to be created can be appropriately set depending on the total thickness of the light-transmitting laminate, the number of layers constituting the light-transmitting laminate, the thickness of each layer, etc. The imaging pitch P is, for example, 10 μm to 100 μm, preferably 20 μm to 80 μm, and more preferably 40 μm to 60 μm. This configuration makes it possible to detect substantially all defects present in the thickness direction (and therefore substantially all defects in the light-transmitting laminate) and their approximate positions without scanning the entire thickness direction with the imaging element. Although Figure 3 shows a form in which three defect XY coordinate maps are created, the number of defect XY coordinate maps created is not limited to this, and is preferably 2 to 10, more preferably 3 to 8, and even more preferably 4 to 6.

[0021] Next, the XY coordinate maps of a predetermined number of defects created as described above are integrated. For example, FIG. 6 shows an example in which the XY coordinate maps of five defects are integrated to create an XY coordinate map of defects (integrated XY coordinate map). By integrating each image data as shown in FIG. 6, defects present in each XY coordinate map can be represented on a common XY coordinate. In this way, an integrated XY coordinate map can be created. In the integrated XY coordinate map, substantially all defects in the light-transmitting laminate are represented by XY coordinates (two-dimensional coordinates).

[0022] The predetermined magnification (low magnification) of the imaging element in creating the integrated XY coordinate map described above is preferably less than 10, and more preferably 5 or less. The lower limit of the magnification may be, for example, 1.5. If the magnification is within this range, a wide range of the optically transparent laminate can be efficiently imaged, and as a result, the integrated XY coordinate map can be efficiently created.

[0023] Next, the depth of the defect (its position in the thickness direction of the light-transmitting laminate) is measured. It is difficult to detect defects over the entire plane and thickness of the light-transmitting laminate, and even if it were possible, it would be impractical in terms of cost, time, and efficiency. Therefore, in this embodiment, the thickness direction position of the defect is measured only at the defect occurrence coordinates in the integrated XY coordinate map. As described above, in the integrated XY coordinate map, substantially all defects in the light-transmitting laminate are represented in two-dimensional coordinates. Therefore, by measuring the thickness direction position of the defect only at the defect occurrence coordinates, it is possible to detect the thickness direction position of substantially all defects in the light-transmitting laminate.

[0024] Measuring the depth of the defect involves focusing the imaging element on the surface of the first principal surface of the light-transmitting laminate and moving the focus inward in the thickness direction of the light-transmitting laminate to measure the distance from the surface of the first principal surface to the defect. Specifically, the focus of the imaging element is moved in the thickness direction, a position with high contrast is recognized as the in-focus position, and the distance from the surface of the first principal surface to the in-focus position can be determined as the position of the defect in the thickness direction. Detecting the accurate position of the defect in the thickness direction can significantly improve the efficiency of product inspection and shipping.

[0025] The magnification (high magnification) of the imaging element in measuring the depth of the defect as described above is preferably 10 times or more, and more preferably 20 times or more. The upper limit of the magnification can be, for example, 50 times. If the magnification is within this range, the position of the minute defect in the thickness direction can be reliably detected.

[0026] Defect depth measurement is described in, for example, Japanese Patent Application Laid-Open Nos. 2001-124660, 2004-077261, and 2009-250893, the disclosures of which are incorporated herein by reference.

[0027] In one embodiment, the defect detection can be performed in a region where the amount of variation in the thickness direction (Z direction) of the first main surface of the light-transmitting laminate per 1000 μm of scanning distance by the imaging element in the defect XY coordinate map is preferably within ±10 μm, more preferably within ±8 μm. In another embodiment, the defect detection can be performed in a region where the deflection angle of the light-transmitting laminate with respect to the horizontal direction is preferably within ±0.57°, more preferably within ±0.50°. That is, in both embodiments, defect detection can be performed in a region where the deflection of the light-transmitting laminate is very small. With this configuration, focusing of the imaging element on the first main surface of the light-transmitting laminate (and consequently focusing on a predetermined position inward in the thickness direction) can be performed very accurately. As a result, the position of the minute defect in the thickness direction can be accurately detected. Such a region where the deflection of the light-transmitting laminate is very small can be achieved by the method for fixing a light-transmitting laminate described in Section C-1 above. If the amount of variation and / or the bending angle is outside the above range, accurate transmission inspection may not be possible, resulting in the occurrence of areas in the light-transmitting laminate that cannot be subjected to transmission inspection. In such cases, by providing the light-transmitting laminate with a means for recognizing inspected areas, as will be described later, it is possible to prevent the non-inspected areas from being shipped as products.

[0028] In this manner, a transmission inspection (detection of defects) can be performed. After the inspection, the light-transmitting laminate can be typically cut to the final product size and shipped, as described above. Also as described above, after the inspection, the peeled surface protective film may be temporarily re-attached to the light-transmitting laminate in a releasable manner, if necessary.

[0029] In one embodiment, the inspected light-transmitting laminate (substantially, the surface protective film or reflective protective film remaining on the first main surface of the light-transmitting laminate) is provided with a recognition means capable of recognizing the inspected area. For example, if the bending angle of the light-transmitting laminate is very large relative to the horizontal direction, an area of ​​the light-transmitting laminate that cannot be inspected through transmission may be generated. Alternatively, depending on the state in which the light-transmitting laminate is fixed by the support member, the inspection area may deviate from the setting. By providing a means for recognizing the inspected area, it is possible to prevent a situation in which an uninspected area is shipped as a product, even in such a case. The recognition means can be formed, for example, by marking the light-transmitting laminate with, for example, a plotter that moves in conjunction with the imaging element. Specific forms of the recognition means include, for example, a straight or dashed line surrounding the inspected area, a cross mark, or dots at regular intervals.

[0030] The recognition means will be described in detail with reference to Figures 7(a) to 7(c). For example, if the fixation of the optically transparent laminate 10 by the support member 20 is misaligned as shown in Figure 7(a), the imaging element scans in the X and Y directions (the long and short side directions when the optically transparent laminate 10 is properly fixed), and as shown in Figure 7(b), the inspected area 70a will be misaligned with the product area 80. If the recognition means were not marked, there is a possibility that the non-inspection area indicated by an "x" in Figure 7(c) would be shipped as a product. However, by marking the recognition means 70b, the non-inspection area can be identified, and as a result, it is possible to prevent the non-inspection area from being shipped as a product. [Industrial Applicability]

[0031] The method for inspecting a light-transmitting laminate according to an embodiment of the present invention can be suitably used to detect foreign matter in an optical film, an adhesive sheet, or the like in the manufacturing process of an image display device. [Explanation of symbols]

[0032] 10 Light-transparent laminate 20 Support member 30 Image sensor 40 light source 50 Reflective protective film 60 Surface protection film

Claims

1. A method for producing a light-transmitting laminate including a pressure-sensitive adhesive layer and an optical film, The method includes a step of inspecting a laminate having a pressure-sensitive adhesive layer, an optical film, and at least one reflective protective film in this order for foreign matter, The step of inspecting for foreign matter includes performing a transmission inspection while the laminate of sheets is fixed in a hollow space, detecting defects in the laminate that are between 8 μm and 50 μm in size; The detection of the defect focusing an optical system having a predetermined magnification on the first major surface of the laminate, and scanning the laminate with the optical system to create an XY coordinate map of defects; shifting the focus of the optical system inward in the thickness direction from the surface of the first main surface of the laminate by a predetermined distance, and scanning the laminate with the optical system to create an XY coordinate map of another defect; and integrating the generated defect XY coordinate map; Including, A method for producing a light-transmitting laminate.

2. 2. The method for producing a light-transmitting laminate according to claim 1, further comprising: prior to the step of inspecting for foreign matter, laminating the pressure-sensitive adhesive layer and the optical film by a roll-to-roll method to form a long laminate; and then cutting the long laminate into sheets.

3. The method for producing a light-transmitting laminate according to claim 1 or 2, further comprising cutting the laminate into a final product size after the step of inspecting for foreign matter.

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