JP2009115759A - Defect inspection method and method of manufacturing optical film using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a defect inspection method of an optical film constituted such that adhesion of an adhesive on a mold releasing film or roughening of the surface of a mold releasing agent is inhibited during defect inspection of a part of the mold releasing film by peeling while remaining a part of the mold releasing film in the defect inspection of the optical film. <P>SOLUTION: The defect inspection the steps are as follows: a leader member bonding step of providing a leader member which is bonded at the end of the mold releasing film; a leader member folding step of folding the leader member to the end of the mold releasing film; a mold releasing film peeling step of peeling the mold releasing film from the adhesive agent layer continuously to a prescribed position after the end of the mold releasing film started to peel from the adhesive agent layer while relatively moving the optical film and adhesive agent layer to the folded leader member so as to peel the releasing film from the adhesive agent layer; and a defect inspection step of defect inspecting the peeled prescribed region. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a defect inspection method for inspecting defects of a single-sheet product having at least an optical film that is a member of an optical display device, and a method for producing an optical film using the defect inspection method.

  2. Description of the Related Art Conventionally, an optical film manufacturer manufactures a belt-like sheet product having an optical film member continuously on a roll or on a separate production line for each step so as to be wound around a roll. Then, this strip-shaped sheet-like product is cut into sheet-like sheet-like products in accordance with the size of, for example, a liquid crystal display device to be finally incorporated. Examples of the sheet-like product include a polarizing plate incorporated in a liquid crystal display device, a retardation plate, a laminated film of a polarizing plate and a retardation plate.

  Since the sheet-like product is bonded to the optical display unit, an adhesive layer is formed on the sheet-like product in advance, and a release film (sometimes referred to as a separator) is formed to protect the adhesive layer. Has been.

  A conventional example of the manufacturing process of the sheet-like product having the laminated structure polarizing plate of FIG. 7 will be described below. First, as a previous step, (A) a step of obtaining a polarizer. Here, a polarizer is obtained by drying a polyvinyl alcohol (PVA) film subjected to dyeing / crosslinking and stretching treatment. (B) The process of manufacturing a polarizing plate. Here, a polarizing plate is manufactured by laminating a triacetyl cellulose (TAC) film on both surfaces of a polarizer via an adhesive, laminating a polarizer protective layer, and drying. Here, in the drawing, the anti-glare treatment is applied in advance to the TAC film laminated thereon. (C) The process of bonding a separator and a protective film together. A separator is bonded to one surface (lower side in the drawing) of the polarizing plate via a strong adhesive, and a protective film is bonded to the other surface (upper side in the drawing) via a weak adhesive. Here, a strong adhesive is applied to the separator in advance, and a weak adhesive is applied to the protective film. The strong adhesive applied to the separator is transferred to the TAC film after peeling the separator. Moreover, the weak adhesive applied to the protective film remains formed on the protective film even when the protective film is peeled off, and is not substantially transferred to the TAC film. In the above pre-process, a strip-shaped sheet product is manufactured and wound into a roll. (D) Manufacturing process of single wafer products. A strip-shaped sheet-shaped product wound in a roll is fed out and cut into a predetermined size to produce a sheet-shaped sheet product. There is also a method of cutting into a predetermined size without winding up into a roll. Examples of the cutting method include fixed length cutting and continuous punching.

  A predetermined quality inspection is performed on the sheet-like product manufactured as described above. For example, there is a defect inspection of a polarizing plate that is a constituent member of a sheet-like product. The defect inspection of the polarizing plate is important from the viewpoint of the quality of the optical properties, but the separator is stuck on the polarizing plate. When the defect inspection of the polarizing plate is performed through the separator, the position of the separator itself is determined. There is a problem that the optical characteristics or the defect inspection of the polarizing plate cannot be accurately and accurately performed due to the phase difference (a phase difference that is partially different and not constant).

  Therefore, conventionally, all the separators are peeled off from the sheet-like product before the defect inspection of the polarizing plate, and the separators are again bonded again after the defect inspection. At the time of this re-bonding, instead of reusing the peeled separator, a new separator having a size larger than the size of the sheet-like product was attached to the polarizing plate through the adhesive layer. The reason why the size of the separator for re-bonding is made larger than the size of the sheet-like product is that it is difficult to accurately align the end faces, and when the separator is incorporated into an optical display unit. Therefore, it is not necessary to match the end faces with high accuracy, and the bonding work cost is increased to match the end faces, and there are few merits.

  Examples of the method of peeling the separator include the following Patent Documents 1 to 3. Patent Document 1 has a configuration in which an adhesive roller is pressure-bonded and bonded to a separator of a polarizing plate fixed to a stage, and the separator is peeled off while being wound up by the adhesive roller by relative movement between the adhesive roller and the stage. However, in this configuration, since the separator acts in the normal direction (perpendicular direction) to the adhesive roller in the peeling action, a large peeling force (peeling) is required to peel the separator (particularly its end face) from the adhesive. Force) (details will be described later). However, if the peeling force is large, the pressure-sensitive adhesive may adhere to the separator or the surface of the pressure-sensitive adhesive may become rough (for example, the flatness may be impaired, unevenness, The state etc.) is not preferable in terms of the quality of the optical characteristics. In addition, in this configuration, the apparatus is complicated, and there is a problem of peeling errors due to variations in the adhesive force of the adhesive roller. And patent document 1 is a structure which does not need to bond a separator to a polarizing plate again after peeling a separator completely, and affixes the polarizing plate after separator peeling to a liquid crystal panel.

  Patent document 2 is an improvement of the above-mentioned patent document 1, and has a configuration in which the separator is peeled off from the adhesive using a peeling blade when the separator and the polarizing plate are peeled off. In the case of this configuration, it is necessary to position the peeling sword accurately and with high accuracy. If the positioning accuracy is poor, the adhesive adheres to the separator or roughens the surface of the adhesive. In this configuration, the apparatus is complicated, which is not preferable from the viewpoint of cost. In addition, as in Patent Document 1, it is not necessary to attach the separator to the polarizing plate again after the separator is completely peeled off, and the polarizing plate after the separator is peeled off is attached to the liquid crystal panel.

  Further, Patent Document 3 discloses a protection provided on the other surface of the polarizing plate by removing the release sheet provided on one surface of the polarizing plate while leaving only a part of the non-inspecting region when inspecting the polarizing plate. The sheet is pinched by the pinching portion at the tip of the lifting jig, and is lifted by the lifting jig, the polarizing plate is irradiated with light, and the transmitted light is imaged for defect inspection. . And it is described that after the inspection, the protective sheet that has been rolled up by the roll-up jig is attached to the polarizing plate again. However, there is no specific description as to how the end portion of the protective sheet is clamped by the sandwiching portion of the lifting jig, and there is no specific description of lifting the protective sheet with the lifting jig, and the drawing. Then, only the last state raised is described. When the end portion of the protective sheet attached to the adhesive is directly sandwiched between the sandwiching portions, it is predicted that the adhesive will adhere to the protective sheet. Then, when the adhesive is rolled up with the adhesive adhered, there arises a problem that the surface of the adhesive becomes rough (for example, a state in which flatness is impaired, a concavo-convex state, or a streak mark is generated on the adhesive surface). Moreover, although a protective sheet is again affixed on a polarizing plate after a test | inspection, it is described that the release sheet is still removed and it adheres to a liquid crystal panel in the next process.

In addition, due to the recent demand for high quality and high image quality of display devices, it is necessary to improve the deterioration of optical characteristics due to the influence of the surface state of the pressure-sensitive adhesive layer.

JP-A-5-273508 JP-A-10-115828 JP 2005-134573 A

  The present invention has been made in view of the above circumstances, and its purpose is to release a part of the release film in the defect inspection of the optical film, and to perform the defect inspection by peeling off the part of the release film. It is an object of the present invention to provide a defect inspection method for an optical film configured so that the pressure-sensitive adhesive does not adhere to the release film and the surface of the pressure-sensitive adhesive is not roughened when the film is peeled off.

  As a result of intensive research to solve the above-mentioned problems, the inventors have found a release film peeling method that does not cause adhesion of adhesive or rough surface of the adhesive from the optical film, and have completed the present invention. It is.

The defect inspection method of the present invention is a defect inspection method for inspecting defects of an optical film having a release film attached at least via an adhesive layer,
A leader member affixing the first part of the leader member to the end part of the release film and providing the leader member to the release film so that the other part of the leader member extends outward from the end part. Arrival processing,
A leader member folding process for folding the other part of the leader member extending outward from the end part of the release film in the direction of the end part of the release film;
In order to peel the release film from the adhesive layer, the folded leader member and the optical film and the adhesive layer are relatively moved,
After the start of peeling of the release film from the pressure-sensitive adhesive layer, continuously to a predetermined position, a release film peeling treatment for peeling the release film from the pressure-sensitive adhesive layer;
A defect inspection process for inspecting the peeled predetermined area for defects.

  The effect by this structure is as follows. The optical film of the present invention is a sheet-like product having a predetermined size. A release film (sometimes referred to as a separator) is attached to one side of the optical film via an adhesive, and a protective film is attached to the other side of the optical film via an adhesive. The leader member is affixed to the release film and functions as a lead for peeling the release film. The leader member may be preliminarily coated with an adhesive, and may be configured so that the adhesive is applied to the adhered portion of the leader member before being adhered to the release film.

  One part of this leader member (at least including the part where the adhesive is formed) is attached to the end part of the release film, and the other part of the leader member is extended outward from the end part. The leader member is provided on the release film as described above. In this case, the optical film is fixed by, for example, fixing means on the side opposite to the surface on the release film side.

  Next, the other part of the leader member extended outward from the end part of the release film is folded back toward the end part of the release film. For example, it can be constituted by a folding means for holding the leader member by the holding means and turning back so as to reverse the direction of the holding means by 180 degrees. Since the leader member is sandwiched by the sandwiching means, the release film is not directly sandwiched by the sandwiching means, so there is no fear of deformation of the release film and adhesion of the adhesive. Moreover, it is important not to apply an excessive force to the release film during the folding, and as a result, the adhesive does not adhere to the release film.

  Next, the folded leader member, the optical film, and the pressure-sensitive adhesive layer are relatively moved so that the release film is peeled from the pressure-sensitive adhesive layer. The folded leader member can be fixed by the clamping means and the optical film can be moved, and conversely the optical film can be fixed and the folded means can be moved to move the folded leader member. Or both can move in opposite directions to each other.

  Next, after the end face portion of the release film starts peeling from the pressure-sensitive adhesive layer, the release film is peeled from the pressure-sensitive adhesive layer continuously to a predetermined position. The “predetermined position” is a position within the non-defect inspection area, a position where the image is finally cut, a position not incorporated in the display device unit, and / or a position that does not affect the display function. This is because the adhesive film does not adhere to the release film and does not stop in the middle of movement because the end face part of the release film is continuously moved to the specified position after peeling starts from the adhesive layer. Or adhesion of the adhesive by re-transfer does not occur, and further, the surface of the adhesive layer does not become rough.

  Subsequently, the predetermined area (area required for defect inspection) that has been peeled off is inspected for defects. Since the surface of the adhesive layer is not roughened, defect inspection can be performed with high accuracy. If it is determined that the product is non-defective in the defect inspection, the release film that has been peeled off is re-applied to form a sheet-like product, and then end face protection processing is performed to protect the end faces of the four sides. Pack in.

  Further, the defect inspection method of the present invention is characterized by further comprising an adhesion treatment for adhering the peeled release film to the optical film through the adhesive layer under tension control after the defect inspection. .

  According to this configuration, after the defect inspection, the peeled release film can be attached to the optical film through the adhesive layer under tension control. No overhangs occur. In addition, since tension control is performed on the release film, the sheet-like product after bonding does not bend (sometimes referred to as curl), and changes in optical characteristics (for example, phase difference value) due to this bend. Can be suppressed. The tension control can be configured by a known means. Moreover, when sticking a release film, the structure which uses a roller as a holding | suppressing of a release film for the press-contact and tension control of a release film and an optical film can be illustrated.

  In the defect inspection method of the present invention, the leader member is characterized in that the warpage is larger than that of the release film.

  According to this configuration, since the leader member is more warped than the release film, when the leader member is folded back, no extra pressure is applied to the release film (particularly the end portion), and the leader member is rotated 180 degrees. The folding direction can be reversed as much as possible, and the curvature of the folding can be made as small as possible. The peeling direction of the end portion of the release film is wider than 90 degrees (perpendicular direction) to the optical film surface, for example, 180 degrees. The folding direction can be set in the direction approaching the degree, and the peeling direction can be set in the 180 degree direction.

  In the defect inspection method of the present invention, when the end surface portion of the release film is peeled from the adhesive layer, the folded leader member and the optical film are relatively moved in parallel or substantially in parallel.

  According to this configuration, the peeling direction at the time of disclosing the release of the release film edge and the peeling direction thereafter can be set to 180 degrees or substantially 180 degrees with respect to the optical film surface. Roughness does not occur.

  In the defect inspection method of the present invention, the moving speed is relatively constant.

  In the defect inspection method of the present invention, the defect inspection is performed by measuring reflected light or transmitted light of light irradiated on the inspection region.

  In the defect inspection method of the present invention, the optical film has a polarizing plate in which a transparent protective film is laminated on one side or both sides of a polarizer.

  In the present invention, the “defect” refers to, for example, surface or internal dirt, scratches, a special defect such as a dent formed by biting a foreign object (sometimes referred to as a knick), a bubble, a foreign object, etc. Means.

Hereinafter, preferred embodiments of the present invention will be described.

<Sheet product>
In the present invention, a polarizing plate will be described as an example of the optical film. A polarizing plate can be obtained by bonding, for example, a triacetyl cellulose film (transparent polarizer protective film (polarizer protective layer)) to both front and back surfaces of a polyvinyl alcohol film (polarizer) manufactured in advance. . It is necessary to detect defects (scratches, foreign matter, nicks, dirt, etc.) present on the surface or inside of the polarizing plate having the multilayer structure. This is detected by detection means described later.

  The single-wafer polarizing plate has been described in the prior art, but (A) a step of obtaining a polarizer, (B) a step of manufacturing a polarizing plate, (C) a step of bonding a separator and a surface protective film, (D) predetermined Manufactured by a manufacturing method including a step of cutting into single-sized sheets.

  Each treatment of dyeing, crosslinking and stretching of the polyvinyl alcohol film need not be performed separately and may be performed simultaneously, and the order of the treatments may be arbitrary. In addition, you may use the polyvinyl alcohol-type film which gave the swelling process as a polyvinyl-alcohol-type film. Generally, a polyvinyl alcohol film is immersed in a solution containing iodine or a dichroic dye, dyed by adsorbing iodine or a dichroic dye, washed, and stretched in a solution containing boric acid or borax. After uniaxial stretching at a magnification of 3 to 7 times, it is dried. After stretching in a solution containing iodine or dichroic dye, further stretching (two-stage stretching) in a solution containing boric acid or borax, etc., and then drying, the orientation of iodine increases, and the degree of polarization This is particularly preferable because the characteristics are improved.

  Examples of the polyvinyl alcohol polymer include those obtained by polymerizing vinyl acetate and then saponifying vinyl acetate and a small amount of a copolymerizable monomer such as unsaturated carboxylic acid, unsaturated sulfonic acid, and cationic monomer. Polymerized products and the like can be mentioned. The average degree of polymerization of the polyvinyl alcohol polymer is not particularly limited, and any one can be used, but 1000 or more is preferable, and 2000-5000 is more preferable. Moreover, 85 mol% or more is preferable and, as for the saponification degree of a polyvinyl alcohol-type polymer, More preferably, it is 98-100 mol%.

  The thickness of the manufactured polarizer is generally 5 to 80 μm, but is not limited thereto, and the method for adjusting the thickness of the polarizer is not particularly limited. Ordinary methods such as roll stretching and rolling can be used.

  The adhesive treatment between the polarizer and the transparent polarizer protective film that is the protective layer is not particularly limited, but for example, an adhesive made of a vinyl alcohol polymer, boric acid, borax, or glutaraldehyde Or an adhesive comprising at least a water-soluble crosslinking agent of a vinyl alcohol polymer such as melamine or oxalic acid. Such an adhesive layer is formed as a coating / drying layer or the like of an aqueous solution. When preparing the aqueous solution, other additives and a catalyst such as an acid can be blended as necessary.

  An appropriate transparent film can be used for the polarizer protective film provided on one side or both sides of the polarizer. Among them, a film made of a polymer excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferably used. Examples of the polymer include acetate resins such as triacetyl cellulose, polycarbonate resins, polyarylate, polyester resins such as polyethylene terephthalate, polyimide resins, polysulfone resins, polyethersulfone resins, polystyrene resins, polyethylene, polypropylene. And other polyolefin resins, polyvinyl alcohol resins, polyvinyl chloride resins, polynorbornene resins, polymethyl methacrylate resins, liquid crystal polymers, and the like. The film may be produced by any of the casting method, calendar method, and extrusion method.

  Moreover, the polymer film described in JP-A-2001-343529 (WO01 / 37007), for example, (A) a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain, and (B) a substitution in the side chain And / or a resin composition containing an unsubstituted phenyl and a thermoplastic resin having a nitrile group. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Moreover, it is preferable that a polarizer protective film has as little color as possible. Therefore, Rth = [(nx + ny) / 2−nz] · d (where nx and ny are the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, and d is the film thickness). A protective film having a retardation value in the film thickness direction of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  From the viewpoints of polarization characteristics and durability, an acetate resin such as triacetyl cellulose is preferable, and a triacetyl cellulose film whose surface is saponified with an alkali or the like is particularly preferable.

  The thickness of the polarizer protective film is arbitrary, but is generally 500 μm or less, preferably 1 to 300 μm, particularly preferably 5 to 200 μm for the purpose of thinning the polarizing plate. In addition, when providing the polarizer protective film of a transparent film in the both sides of a polarizing film, it can also be set as the transparent film which consists of a polymer etc. which are different in the front and back.

  As long as the object of the present invention is not impaired, the polarizer protective film may be subjected to a treatment for the purpose of hard coat treatment, antireflection treatment, prevention of sticking, diffusion or antiglare, and the like. The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate. For example, a hard coating with an appropriate UV curable resin such as a silicone type is applied to the surface of the transparent protective film. It can be formed by a method to be added to.

  On the other hand, the antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the prior art. Anti-sticking is used for the purpose of preventing adhesion to the adjacent layer, and anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, it can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a roughening method by a sandblasting method or an embossing method, or a blending method of transparent fine particles.

  Examples of the transparent fine particles include silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide having an average particle diameter of 0.5 to 20 μm. Alternatively, organic fine particles composed of crosslinked or uncrosslinked polymer particles and the like can be used. The amount of the transparent fine particles used is generally 2 to 70 parts by mass, particularly 5 to 50 parts by mass per 100 parts by mass of the transparent resin.

  Furthermore, the antiglare layer containing transparent fine particles can be provided as the transparent protective layer itself or as a coating layer on the surface of the transparent protective layer. The antiglare layer may also serve as a diffusion layer (viewing angle compensation function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle. The antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer, and the like described above can be provided separately from the transparent protective layer as an optical layer composed of a sheet provided with these layers.

  The optical film according to the present invention can also be exemplified by an optical film having a multilayer laminated structure in which various optical layers are laminated in practical use. The optical layer is not particularly limited, for example, on the surface of the transparent protective film that does not adhere the polarizer (the surface on which the adhesive coating layer is not provided), hard coat treatment or antireflection treatment, Examples thereof include a method of applying a surface treatment for the purpose of preventing sticking, diffusion or antiglare, and laminating an alignment liquid crystal layer for the purpose of viewing angle compensation or the like. Further, an optical film used for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a phase difference plate (including a wave plate (λ plate) such as 1/2 or 1/4), a viewing angle compensation film, etc. A layer or a laminate of two or more layers is also included. Particularly in the case of a polarizing plate, a reflective polarizing plate or semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is laminated, an elliptical polarizing plate or circular polarizing plate in which a retardation plate is laminated, a viewing angle compensation layer or a viewing angle. It is preferably applied as a wide viewing angle polarizing plate in which a compensation film is laminated or a polarizing plate in which a brightness enhancement film is laminated.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. Moreover, the transparent protective film contains fine particles so as to have a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. The transparent protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it, and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by transparent the metal by an appropriate method such as a vapor deposition method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of attaching directly to the surface of the protective layer.

  Instead of the method of directly applying the reflecting plate to the transparent film (polarizer protective layer) of the polarizing plate, it can also be used as a reflecting sheet having a reflecting layer provided on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent film, a polarizing plate or the like is used to prevent a decrease in reflectance due to oxidation, and in terms of long-term maintenance of the initial reflectance. More preferable is the point of avoiding the additional attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function.

  Another example is a retardation plate. Examples of the retardation plate include a refracting film formed by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The stretching treatment can be performed by, for example, a roll stretching method, a long gap stretching method, a tenter stretching method, a tubular stretching method, or the like. In the case of uniaxial stretching, the stretching ratio is generally about 1.1 to 3 times. The thickness of the retardation plate is not particularly limited, but is generally 10 to 200 μm, preferably 20 to 100 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, and polyethersulfone. , Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulosic polymers, or binary, ternary various copolymers, graft copolymers, Examples include blends. These polymer materials become oriented products (stretched films) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of the main chain type liquid crystalline polymer include, for example, a nematic alignment polyester liquid crystalline polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded to a spacer portion that imparts flexibility. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystalline polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment-treated surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of the liquid crystal layer, viewing angle, and the like. What laminated | stacked the phase difference plate and controlled optical characteristics, such as phase difference, etc. may be used.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. As such a viewing angle compensation phase difference plate, for example, a retardation film, an alignment film such as a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate is used. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetylcellulose film. A plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things such as a thing can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer. However, in order to suppress absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

  A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region exhibits, for example, a retardation layer that functions as a quarter-wave plate for light-color light having a wavelength of 550 nm and other retardation characteristics. It can be obtained by a method of superposing a retardation layer, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one or more retardation layers.

  In addition, a cholesteric liquid crystal layer having a structure in which two layers or three or more layers are superposed with a combination of those having different reflection wavelengths can obtain a layer that reflects circularly polarized light in a wide wavelength range such as a visible light region. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Moreover, the optical film (for example, polarizing plate) of this invention may consist of what laminated | stacked the polarizing plate and the optical layer of 2 layers or 3 layers or more like said polarization-separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as a pressure-sensitive adhesive layer can be used. When adhering the polarizing plate and the other optical layer, their optical axes can be set at an appropriate arrangement angle in accordance with a target phase difference characteristic.

  The polarizing plate according to the present invention and the laminated optical member are provided with an adhesive layer for bonding with other members such as a liquid crystal cell. The pressure-sensitive adhesive layer is not particularly limited, but can be formed with a suitable pressure-sensitive adhesive according to the conventional type such as acrylic. Low moisture absorption and heat resistance due to prevention of foaming and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference, prevention of liquid crystal cell warpage, and formation of a high-quality and durable image display device. It is preferable that it is an adhesive layer excellent in property. Moreover, it can be set as the adhesion layer etc. which contain microparticles | fine-particles and show light diffusivity. The adhesive layer may be provided on a necessary surface as necessary. For example, when referring to a polarizing plate comprising a polarizer and a polarizer protective layer, the adhesive layer is adhered to one or both surfaces of the polarizer protective layer as necessary. A layer may be provided.

  The exposed surface of the adhesive layer is temporarily covered with a separator (sometimes referred to as a release film) for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  A protective film is formed on the polarizing plate opposite to the surface provided with the separator via a weak adhesive. Its main purpose is to prevent scratches and pollution. Examples of protective films include plastic films, rubber sheets, paper, cloth, non-woven fabrics, nets, foam sheets and metal foils, and appropriate thin leaves such as laminates thereof. An appropriate one according to the prior art, such as a system or one coated with an appropriate release agent such as molybdenum sulfide, can be used.

  In the present invention, the polarizer, the polarizer protective layer, the optical film, and the like that form the polarizing plate described above, and the adhesive layer and the like are each composed of, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, or a cyano compound. Those having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as an acrylate compound or a nickel complex salt compound may be used.

  The optical film according to the present invention can be preferably used for forming an image display device (corresponding to an optical display device) such as a liquid crystal display device, an organic EL display device, and a PDP.

  The optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, in general, a liquid crystal display device includes a liquid crystal cell (corresponding to an optical display unit), an optical film (for example, a polarizing plate), and components such as an illumination system as necessary, and a drive circuit is assembled. However, in the present invention, there is no particular limitation except that the optical film according to the present invention is used. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an optical film (for example, a polarizing plate) is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When providing an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  The optical film (for example, polarizing plate) according to the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device has an appropriate structure according to the conventional transmissive type, reflective type, or transmissive / reflective type in which the optical film (for example, polarizing plate) according to the present invention is disposed on one side or both sides of the liquid crystal cell. Can be formed as Accordingly, the liquid crystal cell forming the liquid crystal display device is arbitrary, and for example, a liquid crystal cell of an appropriate type such as a simple matrix driving type typified by a thin film transistor type may be used.

  Moreover, when providing a polarizing plate and an optical member in the both sides of a liquid crystal cell, they may be the same thing and may differ. Furthermore, when forming the liquid crystal display device, for example, appropriate components such as a prism array sheet, a lens array sheet, a light diffusing plate, and a backlight can be arranged in one or more layers at appropriate positions.

<Leader member>
The leader member needs to have a larger warp than the release film. In other words, the leader member needs to be softer than the release film. Thus, since the leader member is more warped than the release film, when the leader member is folded back, the leader member is rotated 180 degrees without applying extra pressure to the release film (particularly its end portion). Can be folded back, the curvature of the folding can be made as small as possible, and the peeling direction of the end of the release film is set to a wider angle than 90 degrees (perpendicular direction) to the optical film surface, for example, 180 degrees The folding direction can be set in the approaching direction, and the peeling direction can be set to 180 degrees or approximately 180 degrees. When a strong member is used as the leader member, it is not preferable because it cannot be folded back to a wider angle than 90 degrees (vertical direction) with respect to the optical film surface, for example, a direction approaching 180 degrees.

  From the above viewpoint, the material and thickness of the leader member are designed. Examples of the base material of the leader member include a polyester film. In the case of a polyester film, a film having a thickness in the range of 15 to 50 μm is preferably used from the viewpoint of mechanical strength. When the thickness is less than 15 μm, it is easy to cut and is not preferable in terms of strength. On the other hand, if the thickness exceeds 50 μm, the rigidity becomes high and difficult to handle, and the waist is not softer than the release film. Further, the upper limit of the thickness is set in relation to the release film.

<Configuration of defect inspection method>
(Embodiment 1)
The configuration of the defect inspection method of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart of the defect inspection method. 2 and 3 are conceptual diagrams for explaining each process corresponding to the flowchart of FIG.

  (1) Fixing process. First, as shown in step S <b> 1 of FIGS. 1 and 2, the sheet-like product is fixed by the fixing means 10. The sheet-like product is composed of a polarizing plate 2, a protective film 5 provided on one surface of the pressure-sensitive adhesive layer 4, and a release film 1 provided on the other surface of the pressure-sensitive adhesive layer 3. It is configured. As shown to Fig.2 (a), it is fixed with the fixing means 10 with respect to the protective film 5 side. The fixing means 10 can be constituted by, for example, a suction means of a vacuuming mechanism.

  (2) Leader member sticking process. In step S <b> 2, the leader member 20 is attached to the release film 1. As shown in FIG. 2B, one part of the leader member 20 is attached to the end part of the release film 1, and the other part of the leader member 20 is extended from the end part to the outside. A leader member 20 is provided on the release film 1. The sticking range between the leader member 20 and the release film 1 is not particularly limited, but is designed so that the leader member 20 is not peeled off from the release film 1 in the peeling step, and preferably one side of the release film 1 In all of the cases, the distance is about 10 mm to 30 mm from the end of one side toward the inner direction. Moreover, as a position to stick, it is not limited to the above-mentioned one side, One corner may be sufficient. In this case, the peeling direction is a direction from the pasted corner to the corner facing the corner. As the pressure-sensitive adhesive, a known pressure-sensitive adhesive can be applied, but the leader member 20 is not peeled off from the release film 1 in the peeling step, and can be peeled off when it is desired to peel off the leader member 20 from the release film 1. It is necessary that the adhesive does not remain after peeling.

  (3) Leader member folding process. In step S3, the leader member 20 is folded back. As shown in FIG. 2C, the other portion of the leader member 20 extending outward from the end portion of the release film 1 is folded back toward the end portion of the release film 1. When folding back, it is preferable to fold the folded part with slackness because unnecessary pressure is not applied to the pressure-sensitive adhesive layer 3. Then, the end portion of the leader member 20 is oriented in the 180 degree direction (or substantially 180 degree direction). The leader member 20 can be constituted by a folding means (not shown) that holds the leader member 20 by clamping means (not shown) and folds back so that the direction of the clamping means is reversed 180 degrees. Since the leader member 20 is sandwiched by the sandwiching means, the release film 1 is not directly sandwiched by the sandwiching means, so there is no fear of deformation of the release film 1 or adhesion of the adhesive 3. In addition to the configuration in which the end portion of the leader member 20 is clamped by the clamping means, the leader member 20 may be fixed to a rotating roller (not shown), and the rotating roller may be reversed 180 degrees. Alternatively, the rotating roller can be configured to rotate at a constant speed in accordance with the peeling direction.

  (4) Release film peeling treatment. In step S4, the leader member 20 is pulled to a predetermined position continuously in the peeling direction. As shown in FIGS. 2D and 3D, the folded leader member 20 is moved so that the release film 1 is peeled from the adhesive layer 3. In this case, the polarizing plate 2, the pressure-sensitive adhesive layer 3, etc. are fixed by the fixing means 10. When the end surface portion of the release film 1 is peeled off from the pressure-sensitive adhesive layer 3, it is preferable to relatively move the folded leader member 20 and the fixed polarizing plate and pressure-sensitive adhesive layer 3 in parallel or substantially in parallel. According to this, since the peeling direction at the start of peeling of the end portion of the release film 1 and the peeling direction thereafter can be set to 180 degrees or substantially 180 degrees with respect to the surface of the polarizing plate 2, adhesion of the pressure-sensitive adhesive or pressure-sensitive adhesive layer This is because the surface does not become rough. Then, after the end surface portion of the release film 1 starts peeling from the pressure-sensitive adhesive layer 3, the release film 1 is peeled from the pressure-sensitive adhesive layer 3 continuously to a predetermined position. When the end face of the release film 1 is peeled off, a peeling force is applied to the end face of the release film 1 in the direction of about 180 degrees. Similarly, after the peeling of the end face of the release film 1, a peeling force is applied in the direction of about 180 degrees to the part where the release film 1 is peeled off. In the peeling step, peeling is continuously performed from the start of peeling to a predetermined position which is a non-peeling position. This is because it is not preferable that the surface of the pressure-sensitive adhesive layer 3 is roughened when it is stopped in the middle of peeling without being continuously peeled and then peeled again. The moving speed of the folded leader member 20 is preferably a constant speed, and the surface of the pressure-sensitive adhesive layer 3 can be more effectively prevented from being rough.

  Moreover, it is preferable to set the peeling direction of the release film 1 to a wider angle than 90 degrees (perpendicular direction) with respect to the optical film surface, for example, in a range of 140 degrees to 180 degrees, and more preferably 150 degrees to 180 degrees. It is the range of degrees, More preferably, it is the range of 170 degree | times to 180 degree | times, Most preferably, it is 180 degree | times or about 180 degree | times.

  (5) Defect inspection processing. In step S5, a defect inspection is performed on the peeled predetermined area. A known defect inspection method can be applied to the defect inspection. Examples of the defect inspection method include a single-wafer automatic inspection apparatus and a visual inspection by an inspector. The single-wafer type automatic inspection apparatus is an apparatus that automatically inspects defects (also referred to as defects) of single-sheet sheet-like products. The single-wafer type automatic inspection apparatus emits light and reflects the reflected light image or transmitted light image with a line sensor or 2 A defect is detected based on the acquired image data acquired through an imaging unit such as a three-dimensional TV camera. Further, the image data is acquired in a state where the inspection polarizing filter is interposed in the optical path between the light source and the imaging unit. Usually, the polarization axis (for example, the polarization absorption axis) of the polarizing filter for inspection is arranged to be in a state (crossed Nicols) orthogonal to the polarization axis (for example, the polarization absorption axis) of the polarizing plate to be inspected. . By arranging in crossed Nicols, a black image is input from the imaging unit if there is no defect, but if there is a defect, that part will not be black (recognized as a bright spot). Therefore, a defect can be detected by setting an appropriate threshold value. In such bright spot detection, defects such as surface deposits and internal foreign matter are detected as bright spots. In addition to this bright spot detection, there is also a method of detecting a foreign object by CCD imaging a transmitted light image on an object and analyzing the image. There is also a method for detecting a surface-attached foreign substance by subjecting an object to a reflected light image by CCD imaging and analyzing the image.

  (6) Sticking process. In step S6, the peeled release film 1 is bonded. As shown in FIG. 3 (e), after the defect inspection in step S5, the peeled release film 1 is attached to the polarizing plate 2 via the pressure-sensitive adhesive layer 3 under tension control. The tension control can be configured by a known means. Further, when sticking the release film 1, the roller 30 is used as a presser for the release film 1 for pressure contact and tension control between the release film 1, the polarizing plate 2 and the pressure-sensitive adhesive layer 3. When the bonding is completed, the leader member 20 is peeled off from the release film 1, and the roller 30 is also moved to a predetermined position. Since tension control is applied to the release film 1, the sheet-like product after bonding is not curved (sometimes referred to as curl), and changes in optical characteristics (for example, phase difference value) due to this curvature are suppressed. it can. Moreover, when peeling the leader member 20 from the release film 1, it can comprise so that the one end part of the leader member 20 may be installed in a winding apparatus (not shown), and the leader member 20 may be wound up with this winding apparatus. . In addition, when one end of the leader member 20 is installed in the winding device, re-bonding tension control can be executed by controlling the winding device, and depending on the arrangement of the winding device. The peeling direction of the release film 1, that is, the pulling angle of the leader member 20 can be adjusted.

  (7) Next, the fixing by the fixing means 10 is released, end face protection processing is performed to protect the four end faces of the sheet-like product, the unit is packed into a predetermined number of sheets, and shipped to the process of assembling into the liquid crystal panel.

Example 1
Below, the peeling force verification test of a release film end surface is demonstrated. The test conditions are as follows.
(1) Testing machine: Tensilon (universal tensile testing machine)
(2) Test conditions: Adhesive strength is N / 25 mm, pulling speed is 300 mm / min. (3) As shown in FIG. 4, the polarizing plate side is fixed and the leader member is perpendicular to the polarizing plate surface or in the direction of 180 degrees. The peel force when the end face of the release film was peeled when was pulled was measured. The peel force was measured by measuring the peel force from the initial peel to 100 mm at 10 points every 10 mm and calculating the average value. This was done 20 times each. The results are shown in Table 1 and FIG.

表１、図５に示す結果から、１８０度方向にリーダー部材を引っ張った場合の剥離力は、垂直方向にリーダー部材を引っ張った場合のそれより約３分の１であった。この結果により、１８０度方向に引っ張った方が剥離力が小さく、つまり粘着剤層の付着が生じにくいと考えられる。また、９０度方向での引っ張りでは、粘着剤が離型フィルムに付着したり、粘着剤表面の荒れが確認された。

From the results shown in Table 1 and FIG. 5, the peel force when the leader member was pulled in the 180 degree direction was about one third of that when the leader member was pulled in the vertical direction. From this result, it is considered that the direction of pulling in the direction of 180 degrees has a smaller peeling force, that is, the adhesive layer is less likely to adhere. In addition, in the pulling in the 90 ° direction, the pressure-sensitive adhesive adhered to the release film or the surface of the pressure-sensitive adhesive was confirmed to be rough.

(Example 2)
Next, the release behavior of the release film (from the initial stage to 100 mm) was verified.
(1) Testing machine: Tensilon (universal tensile testing machine)
(2) Test conditions: Adhesive strength is N / 25 mm, pulling speed is 300 mm / min. (3) As shown in FIG. 4, the polarizing plate side is fixed and the leader member is perpendicular to the polarizing plate surface or in the direction of 180 degrees. The peel force from the initial peel to 100 mm was measured every 10 mm. The results are shown in Table 2 and FIG.

表２、図６に示す結果から、９０度方向にリーダー部材を引っ張った場合、剥離開始から１００ｍｍまでの剥離力のなかで剥離開始初期に極端な力が必要であることが分かった。この結果から、剥離開始であるきっかけを作るリーダー部材としては、腰の強いものは好ましくないことが分かった。腰の強いものは、反り返り性が小さく、傾向として９０度方向に近い剥離方向を生じさせる結果になるからである。また、１８０度方向にリーダー部材を引っ張った場合、粘着剤の付着や、粘着剤層の荒れは生じなかったが、９０度方向での引っ張りでは、粘着剤が離型フィルムに付着したり、粘着剤表面の荒れが確認された。

From the results shown in Table 2 and FIG. 6, it was found that when the leader member was pulled in the 90-degree direction, an extreme force was required at the beginning of peeling, among peeling forces from the start of peeling to 100 mm. From this result, it was found that a strong leader is not preferable as a leader member for triggering peeling. This is because those having a strong waist are less warped and tend to produce a peeling direction close to 90 degrees. In addition, when the leader member was pulled in the 180 degree direction, no adhesion of the adhesive or roughening of the adhesive layer occurred. However, when the leader member was pulled in the 90 degree direction, the adhesive adhered to the release film, Roughness of the agent surface was confirmed.

(Example 3)
Next, the release film peeled off by pulling in the 180 ° direction was bonded under tension control according to the method shown in FIG. As a result of pulling in the direction of 180 degrees, the end face of the polarizing plate and the end face of the release film could be neatly bonded, and the curled state was within the quality standard. There was no sticking out of the adhesive. After the pasting, when the phase difference was measured with a phase difference measuring machine, the dispersion of the phase difference value was within the quality standard.

Example 4
Also, the defect rate due to the pulling angle was verified. (1) 90 degree direction, (2) 120 degree direction, (3) 140 degree direction, (4) 150 degree direction, (5) 170 degree direction, (6) 180 degree direction, 1000 times each A visual appearance inspection was performed for adhesion of the pressure-sensitive adhesive to the release film when the member was pulled and for roughness of the pressure-sensitive adhesive layer. When adhesion of adhesive or roughening of adhesive occurred, it was judged as “bad”. As a result, the defect rate in the 180 degree direction is 0%, the defect rate in the 170 degree direction is 0.1%, the defect rate in the 150 degree direction is 0.2%, the defect rate in the 140 degree direction is 0.3%, The defect rate in the 120 degree direction was 2%, and the defect rate in the 90 degree direction was 5%. In addition, about the defect which is not observed by visual confirmation, quality judgment is carried out by the curl state and phase difference measurement like the said Example, and it is based on a curl state and phase difference measurement, so that a pull angle is a wide angle (approaching 180 degree direction). The quality judgment was also good.

<Another embodiment>
Although this invention demonstrated the polarizing plate, this invention is not restrict | limited to this, It can apply also only to the laminated body of a polarizing plate and a phase difference plate, a phase difference plate, and a polarizer (PVA).

  Also, in the folding process, as an alternative to the clamping means, the function can be realized by the hand of the operator, and in the peeling process, the peeling can be performed manually, continuously, and at a substantially constant speed. Further, only in the case of the peeling process, the leader member can be held by the holding means and continuously peeled at a constant speed. In the re-bonding process, a squeegee means that moves in parallel while maintaining a constant thickness can be used as an alternative to the roller.

Flow chart of defect inspection method Schematic diagram for explaining each process corresponding to the flowchart of the defect inspection method Schematic diagram for explaining each process corresponding to the flowchart of the defect inspection method The figure which shows the peeling force verification test method of the release film end face The figure which shows the experimental result of the peeling force of a release film end face Figure showing experimental results of peeling behavior Diagram showing the structure of the polarizing plate

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Release film 2 Polarizing plate 3, 4 Adhesive (layer)
5 Protective film 10 Fixing means 20 Leader member 30 Roller

Claims (8)

A defect inspection method for inspecting a defect of an optical film having a release film attached at least via an adhesive layer,
A leader member affixing the first part of the leader member to the end part of the release film and providing the leader member to the release film so that the other part of the leader member extends outward from the end part. Arrival processing,
A leader member folding process for folding the other part of the leader member extending outward from the end part of the release film in the direction of the end part of the release film;
In order to peel the release film from the adhesive layer, the folded leader member and the optical film and the adhesive layer are relatively moved,
After the start of peeling of the release film from the pressure-sensitive adhesive layer, continuously to a predetermined position, a release film peeling treatment for peeling the release film from the pressure-sensitive adhesive layer;
A defect inspection method including defect inspection processing for inspecting the peeled predetermined area for defects.   2. The defect inspection method according to claim 1, further comprising a bonding process for bonding the peeled release film to an optical film through a pressure-sensitive adhesive layer under tension control after the defect inspection.   The defect inspection method according to claim 1, wherein the leader member has a larger curvature than the release film.   4. The method according to claim 1, wherein when the end surface portion of the release film is peeled from the adhesive layer, the folded leader member and the optical film are relatively moved in parallel or substantially in parallel. The defect inspection method according to claim 1.   The defect inspection method according to claim 1, wherein the relatively moving speed is constant.   The defect inspection method according to claim 1, wherein the defect inspection is performed by measuring reflected light or transmitted light of light irradiated on the inspection region.   The defect inspection method according to claim 1, wherein the optical film includes a polarizing plate in which a transparent protective film is laminated on one side or both sides of a polarizer. A method for producing an optical film using the defect inspection method according to any one of claims 1 to 7,
Cutting an optical film having at least a release film through a pressure-sensitive adhesive layer into a predetermined size to obtain a sheet-like product of a single sheet;
Performing the defect inspection method according to any one of claims 1 to 7, and performing a defect inspection;
The manufacturing method of the optical film which has this.

Images