Optical laminated film with adhesive layer, method for polishing optical laminated film with adhesive layer

Abstract

The present invention provides an optical laminated film with an adhesive layer that prevents the inclusion of air bubbles near the edges when bonding to the surface of the substrate. [Solution] The adhesive-layered optical laminated film 1A comprises, in this order, a surface protective film 7, an optical laminated film 4A containing a polarizer 2 on which a dichroic dye is adsorbed and oriented, an adhesive layer 5, and a separator 6 that is peelably in contact with the adhesive layer 5. On at least a portion of the side surface of the adhesive-layered optical laminated film 1A, the adhesive layer 5 and the separator 6 protrude outward by 1 μm to less than 10 μm beyond the outermost position of the optical laminated film 4A, and the protruding portion of the adhesive layer 5 is curved upward by 1 μm or more towards the optical laminated film 4A. When the separator 6 is peeled off and the optical laminated film 4A is bonded to the surface of the adherend, the outermost edge of the adhesive layer 5 does not come into contact with the surface of the adherend first, and therefore air bubbles are less likely to be introduced.

Description

Technical Field

[0001] The present invention relates to an optical laminated film with an adhesive layer and a polishing method thereof.

Background Art

[0002] An optical laminated film such as a polarizing plate is bonded to the surface of a liquid crystal cell, an organic EL display device, etc. In recent years, in the development of optical laminated films, various developments have been made, such as making the shape have recesses in the outer edge part or through holes in the plane, or giving bend resistance that can follow the bending of a flexible image display device. In such developments, cracks often occur in the optical laminated film, and in order to solve this problem, the form of the adhesive used for bonding the optical laminated film has been studied (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, when laminating optical laminated films to the surface of liquid crystal cells, organic EL display devices, etc. (hereinafter, these may be referred to as "adherends"), air bubbles may be introduced. The lamination to the adherend is performed by drawing the surface protective film side of the optical laminated film into a lamination device, peeling off the separator, pressing a lamination roll against the end of the surface protective film side, and laminating it towards the other end with the lamination roll. At this time, if the adhesive layer of the optical laminated film is curled upward towards the separator side, the outermost edge of the adhesive layer may come into contact with the surface of the adherend first, causing air bubbles to be introduced and their escape route to be blocked. Air bubbles introduced in this way near the edges may not be removed even when processed with a pressure degassing device.

[0005] Therefore, the present invention aims to provide an optical laminated film with an adhesive layer that can avoid the inclusion of air bubbles near the edges when bonding to the surface of an object. Furthermore, it aims to provide a polishing method for an optical laminated film with an adhesive layer that can be de-aerationd to a level that does not pose a practical problem even if bonding bubbles occur. [Means for solving the problem]

[0006] The present invention provides an optical laminated film with an adhesive layer, comprising, in this order: a surface protective film; an optical laminated film containing a polarizer on which a dichroic dye is adsorbed and oriented; an adhesive layer; and a separator in peelable contact with the adhesive layer, wherein at least a portion of the side surface of the optical laminated film with an adhesive layer has the adhesive layer and the separator protruding 1 μm or more and less than 10 μm outward from the outermost position of the optical laminated film, and the protruding portion of the adhesive layer is curved upward by 1 μm or more toward the optical laminated film.

[0007] According to the inventors' research, when bonding an optical laminated film to the surface of an object, the cause of air bubbles being introduced is thought to be that if the bonding is carried out by first contacting the beginning of the optical laminated film and then proceeding toward the end, the outermost edge of the adhesive layer comes into contact with the surface of the object near the end of the optical laminated film just before the bonding is completed, causing air bubbles to be introduced and blocking their escape route. In the optical laminated film with adhesive layer of the present invention, the adhesive layer protrudes outward from the outermost position of the optical laminated film and is curved upward toward the optical laminated film, so the outermost edge of the adhesive layer does not come into contact with the surface of the object first, and therefore air bubbles are less likely to be introduced.

[0008] In the present invention, the adhesive layer may have a storage modulus of 0.01 MPa or more and 0.5 MPa or less at 23°C.

[0009] The optical laminated film may further include a phase difference layer.

[0010] The present invention provides a method for polishing an optical laminated film with an adhesive layer, comprising, in this order, a surface protective film, an optical laminated film containing a polarizer on which a dichroic dye is adsorbed and oriented, an adhesive layer, and a separator that is peelably in contact with the adhesive layer. The method involves repeatedly applying a first cutting blade, a second cutting blade, and a third cutting blade in this order from the separator side toward the surface protective film side, and the total number of times the first cutting blade, second cutting blade, and third cutting blade are applied to the side is 8,000 to 25,000 times per minute.

[0011] In this polishing method, the sides are continuously cut and polished in the circumferential direction of the adhesive-coated optical laminated film, and the circumferential feed speed of the first cutting blade, the second cutting blade, and the third cutting blade may be 300 mm / min to 600 mm / min. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an optical laminated film with an adhesive layer that can avoid the inclusion of air bubbles near the edges when bonding to the surface of an object. Furthermore, according to the present invention, it is possible to provide a method for polishing such an optical laminated film with an adhesive layer. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view of an optical laminated film with an adhesive layer according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of an optical laminated film with an adhesive layer according to another embodiment of the present invention. [Figure 3] This is a side view of a cutting tool. [Figure 4] This is a front view of the cutting tool. [Modes for carrying out the invention]

[0014] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In each drawing, the same parts or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0015] As shown in Figure 1, the adhesive-layered optical laminated film 1A of this embodiment is a film having an optical laminated film 4A formed by laminating protective films 3, 3 on both sides of a thin-film polarizing film (polarizer) 2. Here, the optical laminated film 4A is a polarizing plate. A separator 6 is laminated to one of the protective films 3 of the optical laminated film 4A via an adhesive layer 5. A surface protective film 7 is laminated to the other protective film 3. The adhesive-layered optical laminated film 1A is a rectangular sheet in plan view.

[0016] As the material of the polarizing film 2, known materials conventionally used in the production of polarizing plates can be used. For example, polyvinyl alcohol-based resins, polyvinyl acetate resins, ethylene / vinyl acetate (EVA) resins, polyamide resins, polyester-based resins, etc. can be mentioned. Among them, polyvinyl alcohol-based resins are preferred. When these materials are formed into a film shape, the uniaxially stretched film is dyed with iodine or a dichroic dye, and then boric acid treatment is performed to adsorb and orient the dichroic dye.

[0017] The thickness of the polarizing film 2 is preferably 2 to 50 μm, more preferably 3 to 40 μm, and even more preferably 4 to 30 μm.

[0018] The protective film 3 is a film that prevents cracks and damage to the main surface and ends of the polarizing film 2. Here, the "protective film" refers to the film that is physically laminated at the position closest to the polarizing film 2 for the purpose of protecting the polarizing film 2 among the films that can be variously laminated on the polarizing film 2.

[0019] The protective film 3 can be composed of various transparent resin films known in the field of polarizing plates. For example, cellulose-based resins typified by triacetyl cellulose, polyolefin-based resins typified by polypropylene-based resins, cyclic olefin-based resins typified by norbornene-based resins, acrylic-based resins typified by polymethyl methacrylate-based resins, polyester-based resins typified by polyethylene terephthalate-based resins, etc. can be mentioned. Among them, cellulose-based resins are representative. Here, "transparent" means that the visible light transmittance is 80% or more.

[0020] The thickness of the protective film 3 is preferably 5 to 90 μm, more preferably 10 to 80 μm, and even more preferably 20 to 50 μm.

[0021] The lamination of the polarizing film 2 and the protective film 3 may be formed by bonding the film-shaped polarizing film 2 and the protective film 3 via an adhesive, or the protective film 3 may be formed by a coating layer. A solution of a material constituting the coating layer (for example, the adhesive described later) may be applied onto the polarizing film 2 and dried, or it may be formed by irradiating active energy rays. Note that the adhesive layer is not illustrated in FIG. 1.

[0022] When an adhesive is used in the lamination of the polarizing film 2 and the protective film 3, various adhesives conventionally used in the production of polarizing plates can be used. For example, from the viewpoints of weather resistance, refractive index, cationic polymerizability, etc., an epoxy resin not containing an aromatic ring in the molecule is preferable. A composition containing an acrylic resin such as acrylamide, acrylate, urethane acrylate, epoxy acrylate, etc., or an aqueous adhesive containing a polyvinyl alcohol-based resin can also be used.

[0023] The adhesive layer 5 can be composed of an acrylic resin, a silicone resin, polyester, polyurethane, polyether, or the like.

[0024] The thickness of the adhesive layer 5 is preferably 2 to 500 μm, more preferably 10 to 200 μm, and even more preferably 20 to 50 μm.

[0025] As a method for laminating the adhesive layer 5 on the optical laminated film 4A, for example, a method of applying a solution containing the above resin and an arbitrary additive component onto the optical laminated film 4A may be used, or a method of forming the adhesive layer 5 with the solution on a separately prepared base film and then transferring this onto the optical laminated film 4A may also be used.

[0026] The adhesive layer 5 protrudes outward from the outermost position of the optical laminated film 4A on the side surface of the optical laminated film 1A with the adhesive layer. The amount of this protrusion, that is, the distance (indicated by the symbol d in Figure 1) perpendicular to the thickness direction of the optical laminated film 1A with the adhesive layer between the outermost position of the optical laminated film 4A and the outermost position of the adhesive layer 5, is 1 μm or more and less than 10 μm. This amount of protrusion d may be 2 μm or more and 8 μm or less, or 3 μm or more and 7 μm or less.

[0027] Furthermore, the protruding portion of the adhesive layer 5 is curved upward toward the optical laminated film 4A. The amount of this upward curve, i.e., the distance in the thickness direction of the optical laminated film 1A with the adhesive layer (symbol h in Figure 1) between the interface between the adhesive layer 5 and the optical laminated film 4A and the outermost position of the adhesive layer 5, is 1 μm or more. This amount of upward curve h may be 1 μm or more and 10 μm or less, 2 μm or more and 8 μm or less, or 3 μm or more and 7 μm or less.

[0028] If both the protrusion amount d and the upward angle h of the adhesive layer 5 are within these ranges, when peeling the separator 6 from the adhesive-coated optical laminated film 1A and bonding it to the surface of the substrate, air bubbles are less likely to be introduced near the edges. For example, first, one edge of the adhesive layer 5 is applied to the surface of the substrate. Next, bonding is carried out using a roller, moving from that edge to the other edge. If the edge shape of the adhesive layer 5 is not as described above, when the bonding roll makes contact, the outermost edge of the adhesive layer 5 may come into contact with the surface of the substrate first, causing air bubbles to be introduced and blocking their escape route. In contrast, if the edge shape of the adhesive layer 5 is as described above, the outermost edge of the adhesive layer 5 does not come into contact with the surface of the substrate first, and therefore air bubbles are less likely to be introduced.

[0029] Of the four sides of the adhesive-coated optical laminated film 1A, which forms a rectangle in plan view, the side whose outermost edge of the adhesive layer 5 has the above-mentioned protrusion and upward curve may be one side, two sides, three sides, or all four sides (i.e., the entire circumference).

[0030] To avoid the inclusion of air bubbles in the bonding surface, it is preferable that the flexibility of the adhesive layer 5 is moderate. From this viewpoint, the storage modulus of the adhesive layer 5 at 23°C may be 0.01 MPa or more and 0.5 MPa or less, 0.03 MPa or more and 0.3 MPa or less, or 0.05 MPa or more and 0.2 MPa or less.

[0031] The separator 6 is generally a peelable film attached for purposes such as protecting the adhesive layer 5 and preventing the adhesion of foreign matter. When the optical laminated film 1A with the adhesive layer is used, the separator 6 is peeled off, exposing the adhesive layer 5. The separator 6 can be made of, for example, a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate. Among these, a stretched polyethylene terephthalate film is preferred.

[0032] The thickness of the separator 6 is preferably 2 to 500 μm, more preferably 10 to 200 μm, and even more preferably 20 to 100 μm.

[0033] The separator 6 protrudes outward from the outermost position of the optical laminated film 4A on at least a portion of the side surface of the optical laminated film 1A with the adhesive layer. The amount of this protrusion, i.e., the distance between the outermost position of the optical laminated film 4A and the outermost position of the separator 6 (indicated as d' in Figure 1), is 1 μm or more and less than 10 μm. This amount of protrusion d' may also be 2 μm or more and 8 μm or less, or 3 μm or more and 7 μm or less. When the amount of protrusion d' is within this range, the edge of the adhesive layer 5 is protected. In other words, the protrusion of the edge of the separator 6 prevents the edge of the adhesive layer 5 from inadvertently coming into contact with an object during storage of the optical laminated film 1A with the adhesive layer, thus preventing adhesive chipping. Furthermore, the protrusion of the edge of the separator 6 prevents the peeling member from coming into contact with the adhesive layer 5 and causing adhesive chipping when peeling off the separator 6.

[0034] The surface protection film 7 consists of a base film and an adhesive layer having weak adhesive strength. The surface protection film 7 is peeled off together with the adhesive layer after, for example, the optical laminated film 1A with an adhesive layer is laminated to a liquid crystal cell.

[0035] The thickness of the surface protective film 7 is, for example, 15 μm or more and 100 μm or less, preferably 20 μm or more and 80 μm or less, and more preferably 30 μm or more and 60 μm or less.

[0036] The resin forming the base film can be, for example, a thermoplastic resin such as a chain-like polyolefin resin like polyethylene or polypropylene; a cyclic polyolefin resin like norbornene resin; a polyester resin like polyethylene terephthalate or polyethylene naphthalate; a polycarbonate resin; or a mixture of one or more of these.

[0037] The adhesive layer laminated to the base film can be composed of an adhesive composition mainly consisting of resins such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether. Among these, an adhesive composition using a (meth)acrylic resin as the base polymer, which has excellent transparency, weather resistance, and heat resistance, is preferred. The adhesive composition may be of the active energy ray curing type or thermosetting type.

[0038] As shown in Figure 2, the optical laminated film 4B may include a phase difference layer 8. The phase difference layer 8 may be a stretched resin film, or a liquid crystal cured layer made of a polymerizable liquid crystal compound. Examples of the phase difference layer 8 include positive A plates such as λ / 4 plates and λ / 2 plates, and positive C plates. The phase difference layer 8 may consist of one or more of these layers.

[0039] In Figure 2, the adhesive-layered optical laminated film 1B is configured such that the protrusion amount d of the adhesive layer 5 and the protrusion amount d' of the separator 6 are different from each other. When d' > d, the risk of failure to peel off when the optical laminated film 4B is sucked from the surface protective film 7 side during lamination and the separator 6 is picked up and peeled off can be reduced. However, if the difference between the two (d'-d) is too large, the separator 6 will float and become difficult to handle, so it is preferable that the difference between the two is 10 μm or less, 8 μm or less, or 5 μm or less.

[0040] <Method for polishing the edges of optical laminated films with adhesive layer> The end shape of the adhesive-coated optical laminated film 1A described above can be formed, for example, by cutting (polishing) the end surface of the adhesive-coated optical laminated film 1A as follows.

[0041] First, prepare approximately 100 to 200 sheets of adhesive-coated optical laminated film by laminating a surface protective film, protective film, polarizing film, protective film, adhesive layer, and separator in that order and cutting them to the same shape. These sheets are then stacked so that the same surfaces face the same direction to form an adhesive-coated optical laminated film laminate. Next, cut the edges of this adhesive-coated optical laminated film laminate using the cutting tool described below.

[0042] As shown in Figures 3 and 4, the cutting tool 10 is a rotating body fixed to a support base 10a and rotatable in the direction of the arrow in Figure 4, with respect to the rotation axis A. Although the cutting tool 10 is depicted as a disc shape in Figures 3 and 4, it is not limited to this shape. The rotation axis A extends in a direction perpendicular to the end face of the adhesive-coated optical laminated film laminate that is to be cut.

[0043] The cutting tool 10 has a mounting surface S perpendicular to the rotation axis A (and therefore parallel to the end face of the adhesive-coated optical laminated film laminate to be cut). On the mounting surface S are provided a first group of cutting parts consisting of cutting parts 11a, 11b, and 11c (a first cutting blade, a second cutting blade, and a third cutting blade, respectively), and a second group of cutting parts consisting of cutting parts 11d, 11e, and 11f (a first cutting blade, a second cutting blade, and a third cutting blade, respectively), and each cutting part has a cutting blade B for removing the end face. Each cutting part is arranged around the rotation axis A. Each cutting part protrudes from the mounting surface S toward the end face of the adhesive-coated optical laminated film laminate to be cut, and the cutting blade B is positioned on the top surface of the protruding cutting part. The cutting blade B of each cutting part is usually positioned to extend parallel to the mounting surface S (and therefore to the end face of the polarizing plate laminate to be cut).

[0044] As shown in Figure 4, the cutting sections 11a, 11b, and 11c that constitute the first cutting section group contact the end face of the adhesive-coated optical laminated film laminate in this order when the cutting tool 10 is rotated in its rotational direction (direction of the arrow shown in Figure 4), and cut the end face. The cutting sections 11a, 11b, and 11c are arranged such that the distance from the mounting surface S to the cutting blade B (the protrusion height of the cutting blade B) is larger for cutting sections located further downstream in the rotational direction of the cutting tool 10. That is, the protrusion height of the cutting blade B of cutting section 11b is greater than that of cutting section 11a, and the protrusion height of the cutting blade B of cutting section 11c is greater than that of cutting section 11b.

[0045] The same applies to the second group of cutting parts. When the cutting tool 10 is rotated in its rotational direction, the cutting parts 11d, 11e, and 11f constituting the second group of cutting parts contact the end face of the polarizing plate laminate in this order and cut the end face. The cutting parts 11d, 11e, and 11f are arranged such that the protrusion height of the cutting blade B increases as the cutting part is located further downstream in the rotational direction of the cutting tool 10. That is, the protrusion height of the cutting blade B of cutting part 11e is greater than the protrusion height of the cutting blade B of cutting part 11d, and the protrusion height of the cutting blade B of cutting part 11f is greater than the protrusion height of the cutting blade B of cutting part 11e.

[0046] Furthermore, as shown in Figure 4, the cutting sections 11a, 11b, and 11c that constitute the first cutting section group are arranged such that the distance from the rotation axis A to the cutting blade B becomes shorter the further downstream the cutting section is located in the rotational direction of the cutting tool 10. That is, the distance from the rotation axis A to the cutting blade B in cutting section 11b is shorter than that in cutting section 11a, and the distance from the rotation axis A to the cutting blade B in cutting section 11c is shorter than that in cutting section 11b. The same applies to the second cutting section group, where the cutting sections 11d, 11e, and 11f that constitute the second cutting section group are arranged such that the distance from the rotation axis A to the cutting blade B becomes shorter the further downstream the cutting section is located in the rotational direction of the cutting tool 10. That is, the distance from the rotation axis A to the cutting blade B in cutting section 11e is shorter than that in cutting section 11d, and the distance from the rotation axis A to the cutting blade B in cutting section 11f is shorter than that in cutting section 11e.

[0047] It is preferable that each cutting section, positioned on the mounting surface S, be arranged at equal intervals from one another around the rotation axis A.

[0048] In the cutting tool 10, the cutting sections 11a, 11b, 11d, and 11e in each cutting section group, excluding the last cutting section (the cutting section furthest downstream in the rotational direction), are for rough cutting, and their cutting blades B are made of metal, for example, tungsten carbide blades. The last cutting sections 11c and 11f in each cutting section group are for finishing, and their cutting blades B can be made of single-crystal diamond or polycrystalline diamond.

[0049] In this embodiment, the number of times the cutting blade B strikes the end face of the adhesive-coated optical laminated film laminate (referred to as "cutting count") is set to 8,000 to 25,000 times / minute as the total for all cutting blades B. This count may also be 10,000 to 20,000 times / minute, or 12,000 to 18,000 times / minute. This makes it possible to set the protrusion amounts d, d' and the upward curve amount h of the adhesive-coated optical laminated film 1A shown in Figure 1 to values ​​within the above predetermined numerical range.

[0050] The rotational speed of the cutting tool 10 should be adjusted to match the number of cutting operations mentioned above. For example, set it to 2000 rpm to 3000 rpm.

[0051] In this embodiment, it is also possible to use only some of the six cutting sections instead of all of them. For example, cutting blades B may be attached to only three locations: cutting sections 11a, 11c, and 11e. In this case, the protrusion height of the cutting blade B and the distance from the rotation axis A to the cutting blade B should be adjusted as appropriate to match the above-described stepwise specifications. Furthermore, when cutting blades B are attached to only three locations, the rotational speed of the cutting tool 10 should be adjusted to 4000 rpm to 6000 rpm.

[0052] The size of the cutting tool 10 is not particularly limited, as long as the diameter of the circle traced by the cutting part as the cutting tool 10 rotates (the shortest diameter) is the same as or longer than the height of the optical laminated film stack with adhesive layer, so that the end faces of all the stacked polarizing plates can be cut at once.

[0053] When cutting the edges of an optical laminate with an adhesive layer, the cutting tool 10 is rotated in the direction of the arrow in Figure 4, and the two are moved relative to each other so that the direction perpendicular to the lamination direction of the optical laminate with an adhesive layer is the approaching direction, bringing them into contact. At this time, the orientation of the polarizing plate laminate is such that the cutting blade B enters from the separator side. The cutting tool 10 is designed so that when rotated in the direction of the arrow in Figure 4, it can cut from the top to the bottom of the illustration, but cannot cut from the bottom to the top of the illustration. As a result, the edges of the optical laminate with an adhesive layer are always cut from the separator side toward the surface protective film side.

[0054] The cutting of the edges is performed continuously in the circumferential direction of the rectangle of the adhesive-coated optical laminated film by moving the cutting tool 10 and the adhesive-coated optical laminated film laminate relative to each other. The feed rate may be 300 mm / min to 600 mm / min, or 320 mm / min to 550 mm / min.

[0055] As described above, the edges of the adhesive-coated optical laminated film laminate can be cut to produce the adhesive-coated optical laminated film 1A shown in Figure 1.

[0056] Although preferred embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments. For example, in the above embodiments, a configuration in which protective films 3, 3 are laminated on both sides of the polarizing film 2 is shown, but the protective film 3 may be laminated on only one side of the polarizing film. [Examples]

[0057] The present invention will be explained in more detail below with reference to test examples. However, the present invention is not limited to the following test examples.

[0058] <Fabrication of optical stacks> (Preparing the protective film) I prepared the following protective film. • Protective film F1: Saponified triacetylcellulose (TAC) film with a hard coat layer (manufactured by Toppan Printing Co., Ltd.; product name "40FJCHCN-TC", triacetylcellulose film thickness: 40 μm, hard coat layer thickness: 7 μm). • Protective film F2: TAC film (manufactured by Konica Minolta, Inc.; product name "KC2CT1W"), 20μm thick.

[0059] (Fabrication of polarizers) A 30 μm thick polyvinyl alcohol-based resin film was immersed in pure water at 21.5°C for 79 seconds. Next, the film was immersed for 151 seconds in a 23°C aqueous solution with a potassium iodide / boric acid / water mass ratio of 2 / 2 / 100 and containing 1.0 mM iodine. Following this, it was immersed for 76 seconds in a 62.0°C aqueous solution with a potassium iodide / boric acid / water mass ratio of 2.5 / 4 / 100. Subsequently, the film was immersed for 11 seconds in a 45°C aqueous solution with a potassium iodide / boric acid / water mass ratio of 3 / 5.5 / 100. Finally, it was dried at 38°C to obtain a 12 μm thick polarizer with iodine adsorbed and oriented on the polyvinyl alcohol. Stretching was performed during each of the above steps, resulting in a total stretching ratio of 5.85 times. The thickness of the obtained polarizer was measured using a Nikon MH-15M digital micrometer.

[0060] (Preparation of adhesive composition) 50 g of a modified polyvinyl alcohol resin containing acetoacetyl groups (manufactured by Mitsubishi Chemical Corporation; Gosenex Z-410) was dissolved in 950 g of pure water, heated at 90°C for 2 hours, and then cooled to room temperature to obtain an acetoacetyl-modified polyvinyl alcohol resin.

[0061] The obtained acetoacetyl-modified polyvinyl alcohol resin solution was mixed with maleic acid, a 40% by mass solution of glyoxal, and pure water so that the content of each component in the prepared adhesive composition was as shown below, and an adhesive composition was prepared. Glyoxal (per 100 parts by mass of polyvinyl alcohol-based resin solids)...10 parts by mass Maleic acid (per 100 parts by mass of polyvinyl alcohol-based resin solids)...0.33 parts by mass • Acetoacetyl-modified polyvinyl alcohol resin (per 100 parts by mass of adhesive composition)...3.0 parts by mass

[0062] (Preparation of the adhesive layer) The following adhesive layers were prepared. • Adhesive layer: A commercially available sheet-type acrylic adhesive layer with a thickness of 38 μm and a release agent attached to both sides of a PET film. The thickness of the adhesive layer is 25 μm, and the storage modulus at 23°C is 0.10 MPa.

[0063] (Preparation of release film with low tack) As a surface protective film, a release film with a slight adhesive (manufactured by Fujimori Kogyo Co., Ltd.: product name "AY638") with a thickness of 53 μm was prepared.

[0064] (Fabrication of polarizing plates) On one side of the polarizer fabricated above, the side of protective film F1 without the hard coat layer was laminated via the adhesive composition prepared above. On the other side of the polarizer, protective film F2 was laminated via the same adhesive composition and bonded using a roll laminating machine. The polarizer was then dried at 75°C for 8 minutes to obtain a polarizing plate. The adhesive layers, each composed of the adhesive composition, had a thickness of 80 nm after drying.

[0065] (Fabrication of optical stacks) An optical laminate (optical laminated film with adhesive layer) having a laminated structure of "low-tack release film / polarizing plate / adhesive layer / separator film" was fabricated by laminating the previously prepared release film with a low-tack release film onto the surface of the polarizing plate protective film F1, and then laminating the previously prepared adhesive layer onto the surface of the second protective film after peeling off one of the PET films.

[0066] The resulting optical laminate was placed on a 121.5 mm x 206.5 mm rectangular die using a Thomson blade and punched out from the side with the release film containing a slight adhesive. The punching process was repeated to produce 180 punched optical laminates required for the next polishing step. Sets of 180 were prepared according to the number of test examples described below.

[0067] <Cutting and polishing> (Test Example 1) 180 punched optical laminates were placed in a polishing machine (manufactured by Megalotechnica) with a configuration similar to the polishing apparatus shown in Figures 3 and 4, with the separator side facing upwards. The polishing machine has six polishing blades, but three of them, the 1st, 3rd, and 5th blades, were used. Carbide blades were used for the 1st and 3rd blades, and a diamond blade was used for the 5th blade. The sides of the optical laminate were polished by applying the blades from the separator side, so that the amount of material removed by the 1st, 3rd, and 5th blades was 0.3 mm, 0.4 mm, and 0.05 mm on each side of the laminate, respectively. Polishing was performed on two parallel sides of the rectangular optical laminate simultaneously, so all four sides were polished. The size of the optical laminate after polishing was 120 mm x 205 mm. The polishing conditions were as follows: Feed speed: 550 mm / min Rotation speed: 5500 rpm Clamping pressure: 0.35 MPa

[0068] (Test Example 2) The sides of 180 punched optical laminates were polished in the same manner as in Test Example 1, except that the feed rate was changed to 320 mm / min.

[0069] (Test Example 3) The sides of 180 punched optical laminates were polished in the same manner as in Test Example 1, except that all six polishing blades of the polishing machine were used. Specifically, the first, second, fourth, and fifth polishing blades were carbide blades, and the third and sixth blades were diamond blades. As a result, the number of times the blades contacted the sides of the optical laminates per unit time was doubled compared to Test Example 1.

[0070] (Test Example 4) The sides of 180 punched optical laminates were polished in the same manner as in Test Example 1, except that all three polishing blades were carbide blades, the amount of material removed by the first, third, and fifth blades was set to 0.35 mm, 0.3 mm, and 0.1 mm on each side of the laminate, respectively, and the feed rate was changed to 220 mm / min.

[0071] (Test Example 5) The sides of 180 punched optical laminates were polished in the same manner as in Test Example 4, except that the direction in which the polishing blade was applied was from the side of the release film with a slight adhesive.

[0072] <Measurement of protrusion and upward curve> After polishing Test Examples 1-5, one optical laminate was removed, and its cross-section was observed using a microscope (KEYENCE VHX-8000). The protrusion amount d and the curvature amount h of the adhesive layer and separator film were measured. The curvature amount is expressed as a positive value for curvature toward the surface protective film side and a negative value for curvature toward the separator side.

[0073] <Evaluation of laminated foam> The separators of the polished optical laminates in Test Examples 1-5 were peeled off, and alkali-free glass (Corning's "EAGLE XG") was bonded to the exposed 25 μm thick adhesive layer. The bonded optical laminates were observed with a microscope to check for the presence or absence of bonding bubbles. Subsequently, each of the three evaluation samples was subjected to a temperature of 50°C and a pressure of 5 kgf / cm². 2 The samples were autoclaved for 15 minutes under the condition of (490.3 kPa), and then left to stand for 1 hour in an environment of 23°C and 50% relative humidity. After that, they were observed with a microscope in the same manner to check for the presence or absence of bonding bubbles. Criteria for determining laminated foam: AA: No foam during lamination A: Only tiny bonding bubbles (no actual harm) occur. B: Lamination bubbles occur, but they disappear after autoclave treatment. C: Lamination bubbles form and remain even after autoclaving.

[0074] Table 1 summarizes the cutting and polishing conditions, shapes, and evaluations for Test Examples 1-5.

[0075] [Table 1]

[0076] In Test Examples 1 and 2, both the protrusion amount and the curl-up amount were within the desired values ​​(protrusion amount: 1 μm or more and less than 10 μm; curl-up amount: 1 μm or more towards the optical laminated film side). On the other hand, when the number of times the blade made contact per unit time was too high (Test Example 3) or when the finishing cut was not made with a diamond blade (Test Examples 4 and 5), neither the protrusion amount nor the curl-up amount reached the desired values. In all examples, the outermost position of the adhesive layer after polishing coincided with the outermost position of the separator.

[0077] In test examples 3 and 4, bonding bubbles occurred, but these disappeared after autoclave treatment (evaluation "B"). It can be said that performing cutting and polishing from the separator side limited the amount of bonding bubbles to a level that could be removed. [Industrial applicability]

[0078] This invention can be used to bond optical laminated films to an substrate. [Explanation of symbols]

[0079] 1A, 1B... Optical laminated film with adhesive layer, 2... Polarizing film (polarizer), 3... Protective film, 4A, 4B... Optical laminated film, 5... Adhesive layer, 6... Separator, 7... Surface protective film, 8... Phase difference layer, 10... Cutting tool, 10a... Support base, 11a~11d... Cutting section, A... Rotating shaft, B... Cutting blade, d, d'... Protrusion amount, h... Curve upward amount, S... Installation surface.

Claims

1. An optical laminated film with an adhesive layer comprising, in this order: a surface protective film; an optical laminated film containing a polarizer on which a dichroic dye is adsorbed and oriented; an adhesive layer; and a separator that is peelably in contact with the adhesive layer, At least a portion of the side surface of the optical laminated film with the adhesive layer is such that the adhesive layer and the separator protrude outward by 1 μm or more but less than 10 μm beyond the outermost position of the optical laminated film. The adhesive layer is applied to an optical laminated film, wherein the protruding portion of the adhesive layer is curved upward by 1 μm or more towards the optical laminated film side.

2. The adhesive layer has a storage modulus of 0.01 MPa or more and 0.5 MPa or less at 23°C, as described in claim 1.

3. The optical laminated film with an adhesive layer according to claim 1, wherein the optical laminated film further comprises a phase difference layer.

4. The optical laminated film with an adhesive layer comprises, in this order, a surface protective film, an optical laminated film containing a polarizer on which a dichroic dye is adsorbed and oriented, an adhesive layer, and a separator that is peelably in contact with the adhesive layer. The side surface of the optical laminated film with an adhesive layer is cut and polished by repeatedly applying a first cutting blade, a second cutting blade, and a third cutting blade in this order from the separator side toward the surface protective film side. A method for polishing an optical laminated film with an adhesive layer, wherein the number of times the first cutting blade, the second cutting blade, and the third cutting blade are applied to the side surface is 8,000 times / minute to 25,000 times / minute in total.

5. The aforementioned side surface is continuously cut and polished in the circumferential direction of the adhesive-coated optical laminated film. The method for polishing an optical laminated film with an adhesive layer according to claim 4, wherein the circumferential feed speed of the first cutting blade, the second cutting blade, and the third cutting blade is 300 mm / min to 600 mm / min.

Images