TW201900424A - Optical film manufacturing method - Google Patents

Abstract

Disclosed is a method for fabricating an optical film. The optical film is of a laminate structure in which at least a first film and a second film are laminated, the method for fabricating the optical film includes a coating step, that is, a coating liquid is coated on a lamination surface of the first film and the second film by using a gravure roll coating manner of a gravure roll. Meanwhile, in the coating step, widths of the coating liquids deposited between the first film and the second film and the gravure roll in a film traveling direction, that is, liquid bead widths, are set to 4 to 20 mm.

Description

Manufacturing method of optical film

FIELD OF THE INVENTION The present invention relates to a method for manufacturing an optical film. The optical film includes a laminated structure, and the laminated structure is at least adhered through an adhesive layer or an adhesive layer composed of a cured material layer of an adhesive composition or an adhesive composition. The first film and the second film are combined.

BACKGROUND OF THE INVENTION Liquid crystal display devices have rapidly expanded their markets in clocks, mobile phones, PDAs, notebook computers, personal computer monitors, DVD players, TVs, and the like. A liquid crystal display device is a device for visualizing a state of polarization caused by liquid crystal conversion, and a polarizer is used in accordance with a display principle thereof. Especially in applications such as TV, high brightness, high contrast, and wide viewing angle are increasingly required, and high transmittance, high polarization, and high color reproducibility are increasingly required in polarizing films.

As a polarizer, an iodine-based polarized light having a structure in which iodine is adsorbed on polyvinyl alcohol (hereinafter also simply referred to as "PVA") is stretched from the aspects of high transmittance and high polarization. Pieces. Generally, conventionally, a polarizing film is a polarizing film formed by laminating transparent protective films on both sides of a polarizer by a so-called water-based adhesive in which a polyvinyl alcohol-based material is dissolved in water. However, in recent years, active energy ray-curable resin compositions using non-water-containing, organic solvents have gradually become mainstream from the point that they can omit the drying step and have small dimensional changes.

When a plurality of films are bonded by using an active energy ray-curable resin composition to manufacture an optical film, generally, for example, an adhesive composition is coated only on the bonding surface of a transparent protective film, and the bonding surface is from the bonding surface side. An optical film including a laminated structure is manufactured by bonding a polarizer or the like. However, in the conventional manufacturing method, foreign matter such as dirt and dust is adhered to the surface of the polarizer, transparent protective film, etc. before the adhesive composition is applied, or when the adhesive composition contains minute foreign matter, Foreign matter remains in the agent layer, and as a result, appearance defects may occur.

The following Patent Document 1 describes a method for manufacturing an optical film, which includes applying a thin layer on a transparent support or an undercoat layer formed on the transparent support with a wet coating amount of 10 mL / m ² or less. The step of the optical functional layer includes a step of removing foreign matter having a height of 10 μm or more from the transparent support or the undercoat layer before the optical functional layer is applied. Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2008-180905

SUMMARY OF THE INVENTION Problems to be Solved by the Invention However, as a result of research conducted by the present inventors, in the technique described in the aforementioned Patent Document 1, an attempt was made to crush by a rolling process or the like in a state where a foreign substance is already present on a transparent support or the like. The foreign matter is removed, so the removal accuracy of the foreign matter is not high, and minute foreign matter remains after the removal step. Therefore, the actual situation is that the technique described in the above Patent Document 1 is difficult to apply to a thin optical film manufacturing method that is particularly thin and can cause problems with appearance defects even in the presence of minute foreign matter.

The present invention has been made in consideration of the above-mentioned actual situation, and an object thereof is to provide a method for manufacturing an optical film that prevents appearance defects caused by foreign matter even if the optical film is thin.

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and have found that when manufacturing an optical film including a laminated structure in which at least two films are bonded, a specific coating method is used, The coating liquid is applied to the bonding surfaces of both of the two films to be bonded, so that the removal of the foreign matter and the application of the adhesive composition or the adhesive composition can be performed at one time. The present invention has been made as a result of intensive studies and has the following configuration.

That is, the present invention relates to a method for manufacturing an optical film, which includes a laminated structure in which at least a first film and a second film are bonded. The method for manufacturing the optical film is characterized in that the manufacturing method has a coating step, A gravure roll coating method using a gravure roll is used to apply a coating liquid to the bonding surface of both the first film and the second film; and in the coating step, the first film and the film are formed. The width of the film in the film traveling direction, that is, the width of the liquid beads, between the second film and the gravure roll is set to 4 to 20 mm.

In the above manufacturing method, it is preferable that the coating liquid is at least one coating liquid selected from the group consisting of an adhesive composition, an adhesive composition, and a liquid substance having a viscosity of 0.5 to 10,000 cP, and The optical film includes a laminated structure in which at least a first film and a second film are bonded through an adhesive layer or an adhesive layer composed of the adhesive composition or the cured material layer of the adhesive composition. .

In the above manufacturing method, it is preferable that the coating step includes the following steps: a first coating step of applying the adhesive composition or the adhesive composition to a bonding surface of the first film; and a second coating step Applying the adhesive composition or the adhesive composition, or a liquid substance having a viscosity of 0.5 to 10,000 cP to the bonding surface of the second film.

In the above manufacturing method, it is preferable that the rotation direction of the gravure roll is opposite to the traveling direction of the first film and the second film.

In the above manufacturing method, it is preferable that the diameter of the gravure roll is 80φ to 140φ.

In the manufacturing method described above, it is preferable that the pattern formed on the surface of the gravure roll is a honeycomb pattern.

In the manufacturing method, it is preferable that a ratio of a rotation speed of the gravure roll to a traveling speed of the first film and the second film is 100 to 300%.

In the above manufacturing method, it is preferable that the gravure roll coating method is a method in which the coating liquid is cyclically applied, and further includes a method for mixing the first film and / or the second film into the coating liquid by coating. Foreign matter removal function for removing foreign matter from the coating liquid.

In the above manufacturing method, the first film may be a transparent protective film and the second film is a polarizer, or the second film may be a transparent protective film and the first film may be a polarizer.

In the above manufacturing method, it is preferable that the thickness of the polarizer is 10 μm or less.

ADVANTAGE OF THE INVENTION When manufacturing the optical film which laminated | stacked two films, and has a laminated structure, it is common to apply an adhesive agent composition or an adhesive agent composition to one of the two films, and to bond another on it One sheet of film is produced (hereinafter also referred to as "single-side coating method"). However, in the present invention, the coating liquid is applied to both the bonding surface of the first film and the bonding surface of the second film, and a gravure roll coating method using a gravure roll is used, and this is performed while removing foreign matter. Coated. Specifically, a gravure roll coating method is used to scrape off foreign matters such as dirt and dust existing on the bonding surfaces of the two films to be bonded, and also from the bonding of the two films The gelatinous substance or agglomerate derived from the adhesive agent composition or the adhesive agent composition was scraped off from the surface, and the above-mentioned coating solution was applied to the bonding surfaces of the two films. As a result, in the manufacturing method of the optical film of this invention, the possibility of the presence of the foreign material on the bonding surface of both the two films becomes extremely low. As a result, in the method for producing an optical film of the present invention, it is possible to produce an optical film that prevents appearance defects caused by foreign matter.

On the other hand, in the single-sided coating method, it is not possible to remove the foreign matter existing on the bonding surface of the film on which the adhesive composition or the adhesive composition is not applied. Therefore, the adhesive layer (or adhesion) formed after lamination is formed. Agent layer) is more likely to remain.

In addition, in the present invention, the "gravure roll coating method" means that the gravure roll takes up the coating liquid from the container into which the coating liquid is added, forms a liquid accumulation of the coating liquid between the gravure roll and the film to be coated, and uses the A method for applying a coating liquid to a predetermined thickness. The width of the liquid accumulating portion of the coating liquid in the film traveling direction is referred to as a liquid bead width. At the inner portion of the liquid bead width, a friction force is generated between the film and the liquid accumulating portion, so the above-mentioned film bonding surface is generated. The effect of removing foreign matter. In the present invention, in particular, by setting the liquid bead width to 4 to 20 mm, the effect of removing foreign matter at the film bonding surface can be further improved, and stable production can be performed.

In the method for producing an optical film of the present invention, it is possible to efficiently remove foreign matter existing on the bonding surfaces of the two films to be bonded, and to exist in the adhesive composition or the adhesive composition. Therefore, it is possible to manufacture an optical film that prevents appearance defects caused by the foreign matter. Therefore, the manufacturing method of the optical film of the present invention is particularly effective as a manufacturing method of an optical film having a thin adhesive layer having an appearance defect caused by a foreign substance, which is particularly a problem, and an optical film having a small total thickness, particularly a thin polarizing film.

Embodiments for Carrying Out the Invention Hereinafter, a method for manufacturing an optical film of the present invention will be described with reference to the drawings.

The manufacturing method of the optical film of the present invention has a coating step. The coating step uses a gravure roll coating method, and the bonding surface of both the first film and the second film is coated with a material selected from the group consisting of an adhesive composition and an adhesive. At least one coating liquid in the group consisting of a composition and a liquid substance having a viscosity of 0.5 to 10,000 cP.

As the liquid substance of the coating liquid, a liquid substance having a viscosity of 0.5 to 10,000 cP was used. In particular, as the liquid substance, it is preferable to use a liquid substance containing water as a main component, specifically containing at least 50% by weight of water, more preferably a liquid substance containing 60% by weight or more of water, and still more preferably using 70% by weight or more of water. In addition, in order to improve the wettability (leveling property) of the liquid substance itself on the film and the evaporation rate of the liquid substance, it is preferable that the liquid substance further contains an alcohol, and the liquid substance more preferably contains 50 to 100% by weight. Water and 0 to 50% by weight of alcohol, particularly preferably 50 to 70% by weight of water and 30 to 50% by weight of alcohol. The adhesive composition and the adhesive composition as the coating liquid will be described later.

FIG. 1 shows an example of a schematic diagram of a method for manufacturing an optical film of the present invention. In this embodiment, an example is shown in which a gravure roll coating method using a gravure roll is used and applied to the first film and the second film. The adhesive liquid was used as the coating liquid of both the bonding surfaces. In FIG. 1, when the adhesive composition 3 is applied using the gravure roll coating method 10, the first film 1 is conveyed to the right in FIG. 1. On the other hand, the gravure roll provided in the gravure roller coating method 10 is clockwise. Ground rotation. That is, the rotation direction of the gravure roll is opposite to the traveling direction of the first film. Similarly, in the relationship between the second film 2 and the gravure roll, the rotation direction of the gravure roll and the traveling direction of the second film 2 are also opposite directions. At this time, the effect of scraping off foreign matters such as dirt and dust existing on the bonding surface of the first film 1 and the bonding surface of the second film 2 and the effect of gelling or agglomerating from the adhesive composition is effectively removed. The improvement makes it possible to more effectively prevent appearance defects of the finally obtained optical film.

In this embodiment, an example is shown in which the application step includes a first application step of applying the adhesive composition to the bonding surface of the first film, and a bonding method of applying the adhesive composition to the second film in the same manner. The second coating step of the surface, but the present invention is not limited to this embodiment. As a coating liquid to be applied to the bonding surface of both the first film and the second film, it can be selected from the group consisting of an adhesive composition, At least one coating liquid in the group consisting of an adhesive composition and a liquid substance having a viscosity of 0.5 to 10,000 cP can be arbitrarily selected. For example, the following aspects can be exemplified.

In one aspect, the application step includes a first application step of applying an adhesive composition to the bonding surface of the first film, and a second application of applying a liquid substance having a viscosity of 0.5 to 10,000 cP to the bonding surface of the second film. step. In this aspect, if necessary, a third coating step of applying the adhesive composition to the bonding surface of the second film may be further provided after the second coating step.

In one aspect, the coating step includes a first coating step of applying a liquid substance having a viscosity of 0.5 to 10,000 cP to the bonding surface of the first film, and a liquid substance having a viscosity of 0.5 to 10000 cP to similarly applies the second film. The second coating step of the bonding surface. In addition, after the first coating step and / or the second coating step, the pattern is further provided with a third coating step and / or a step of applying an adhesive composition to the bonding surface of the first film and / or the second film. Fourth coating step.

In order to more effectively prevent the appearance defect of the finally obtained optical film, the rotation speed of the gravure roll is preferably 100 to 300%, and more preferably 150 to 250% with respect to the traveling speed of the first film 1 and the second film 2.

FIG. 2 shows an example of a schematic diagram of a gravure roll coating method used in the present invention, and particularly shows a case where the adhesive composition 3 is coated on the first film 1 using the gravure coating method 10. As shown in FIG. 2, if foreign matter is removed while pressing the first film 1 against the gravure roll 4, foreign matter such as dirt, dust, and the like from the bonding surface of the first film 1 can be removed more effectively. Gels or agglomerates of matter.

As shown in FIG. 2, the gravure roll coating method 10 includes at least a gravure roll 4. An uneven pattern such as a honeycomb mesh pattern, a trapezoidal pattern, a lattice pattern, a pyramid pattern, or a diagonal pattern is formed on the surface of the gravure roll. In order to improve the surface accuracy of the coated surface after applying the adhesive composition or the adhesive composition, it is preferable to form a honeycomb mesh pattern, and the cell volume is preferably 1 to 5 cm ³ / m ² , and more preferably 2 to 3 cm ³ / m ² . Similarly, in order to improve the surface accuracy of the coated surface after the adhesive composition or the adhesive composition is applied, the number of mesh lines per 1 inch roll is preferably 200 to 2000 lines / inch. The concave-convex pattern of the gravure roll 4 has a function of applying the adhesive composition 3 on the bonding surface of the first film while lifting up the adhesive composition (coating solution) 3.

In the coating step of the present invention, the width of the film in the direction of travel of the coating liquid scum formed between the first film and the gravure roll, that is, the bead width, and the coating liquid scum formed between the second film and the gravure roll The width of the film in the direction of travel, that is, the width of the liquid beads, is set to 4 to 20 mm. This makes it possible to further improve the effect of removing foreign matter at the film bonding surface, and to implement stable production. FIG. 3 is a schematic view showing a liquid accumulation of a coating liquid (adhesive composition) 3 formed between the first film 1 and the gravure roll 4. In FIG. 3, d indicates the width of the film in the direction of travel of the coating liquid scum formed between the first film 1 and the gravure roll 4, that is, the width of the bead. In the present invention, when the width of the liquid beads in the coating step is 5 mm or more, the effect of removing foreign matter at the film bonding surface is further improved, which is preferable. In addition, even if the width of the bead is enlarged to exceed 20 mm, the effect of removing foreign matter at the film bonding surface is hardly changed. On the other hand, as the bead width is enlarged, the applicability of the coating liquid is significantly reduced and the uniformity is not uniform. When the coating liquid is applied, the coating surface of the film is roughened, resulting in poor appearance. In the present invention, as a method of adjusting the width of the liquid beads, the position of the gravure roll with respect to the film can be appropriately adjusted. Specifically, for example, when the gravure roll is moved in the direction of pressing the film, the liquid bead width can be enlarged. Conversely, when the film and the gravure roll are separated, the liquid bead width can be narrowed.

In the coating step, in order to set the film traveling direction width, that is, the bead width, of the coating liquid effusion formed between the first film and the second film and the gravure roller to 4 to 20 mm, the diameter of the gravure roller is preferably 80 φ. ~ 140φ.

In the present invention, in order to prevent foreign matter from being mixed into the adhesive composition 3, a closed system in which the adhesive coating liquid is not exposed to outside air is preferred. In the example shown in FIG. 2, foreign matter existing on the bonding surface of the first film 1 and gel or aggregate from the adhesive composition 3 may be scraped off by the gravure roll 4 during coating. , They are transferred to the container 5 in which the adhesive composition 3 is placed, and are again coated on the bonding surface of the first film by the gravure roll 4. Therefore, especially in the case where the gravure roll coating method is a method in which the adhesive composition or the adhesive composition is cyclically coated, it is worrying that as the time for the coating step of the adhesive composition 3 becomes longer, the The accumulation amount of the foreign matter scraped off by the gravure roll 4 increases. However, the gravure coating method 10 has a foreign matter removal function for removing foreign matter mixed into the adhesive agent composition or the adhesive agent composition from the first film and / or the second film due to the application from the adhesive agent composition or the adhesive agent composition. In the case of ZnO, the amount of foreign matter and the like present in the applied adhesive composition 3 is kept extremely small or even zero for a long period of time. Therefore, finally, the amount of foreign matter and the like generated on the bonding surface of the first film 1 can be extremely reduced. In the present invention, examples of the foreign matter removing function include a filter, a distillation apparatus, and centrifugation. When a filter is used as the foreign matter removal function, as shown in FIG. 2, for example, the filter 7 may be disposed on the downstream side of the pump function 8. In addition, the number of filters 7 can be arranged on the upstream side of the pump function 8. The mesh size of the filter 7 can be appropriately changed depending on the materials of the first film 1 and the second film, the blending design of the adhesive composition 3, and the like, but it is preferably 10 μm or less, and more preferably 5 μm or less. The adhesive composition 3 may be circulated using a tank 6 or the like as shown in FIG. 2, or the adhesive composition 3 coated with the gravure roll 4 may be discarded.

The gravure roll coating method shown in FIG. 1 is used to apply the adhesive composition 3 to both the bonding surface of the first film 1 and the bonding surface of the second film 2, and then, for example, to pass through the bonding using a nip roller 9. The agent composition (adhesive layer) adheres the first film 1 and the second film 2.

In the case of manufacturing optical films in a continuous production line, the production line speed of the first film and / or the second film depends on the curing time of the adhesive composition (or adhesive composition), but is preferably 1 to 500 m / min, more It is preferably 5 to 300 m / min, and more preferably 10 to 100 m / min. When the line speed is too small, productivity is insufficient, or damage to the first film and / or the second film is excessive, and an optical film capable of withstanding durability tests and the like cannot be produced. When the line speed is too high, curing of the adhesive composition becomes insufficient, and the target adhesiveness may not be obtained in some cases.

Next, the optical film manufactured by the manufacturing method of this invention is demonstrated as follows. This optical film includes a laminated structure in which at least a first film and a second film are pasted through an adhesive layer or an adhesive layer composed of a cured material layer of an adhesive composition or an adhesive composition.

<Adhesive Layer or Adhesive Layer> The above-mentioned adhesive layer or adhesive layer is not particularly limited as long as it is optically transparent, and various types of adhesives using water-based, solvent-based, hot-melt, and radical curing types are used. Layer or adhesive layer. When manufacturing a transparent conductive laminated body or a polarizing film as an optical film, a transparent curing type adhesive layer can be used suitably.

<Transparent curing type adhesive layer> When forming a transparent curing type adhesive layer, for example, a radical curing type adhesive is suitably used as an adhesive composition. Examples of the radical-curable adhesive include active-energy-ray-curable adhesives such as electron-ray-curable and ultraviolet-curable. In particular, an active energy ray-curable type that can be cured in a short time is preferable, and an ultraviolet-curable adhesive that can be cured with low energy is more preferable.

The ultraviolet-curable adhesive is roughly classified into a radical polymerization-curable adhesive and a cationic polymerization-type adhesive. In addition, the radical polymerization-curable adhesive can be used as a heat-curable adhesive.

Examples of the curable component of the radical polymerization-curable adhesive include a compound having a (meth) acrylfluorenyl group and a compound having a vinyl group. As these curable components, any of monofunctional or difunctional or higher components can be used. These curable components may be used alone or in combination of two or more. As these curable components, for example, a compound having a (meth) acrylfluorenyl group is suitable.

Specific examples of the compound having a (meth) acrylfluorenyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and iso (meth) acrylate. Propyl ester, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, secondary butyl (meth) acrylate, (formyl) Base) tert-butyl acrylate, n-amyl (meth) acrylate, tert-amyl (meth) acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate Ester, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl (meth) acrylate (Meth) acrylic acid (carbon number 1-20) alkyl esters such as propyl pentyl ester and n-octadecyl (meth) acrylate.

Examples of the compound having a (meth) acrylfluorenyl group include cycloalkyl (meth) acrylate (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), and (meth) ) Aryl acrylate (e.g. benzyl (meth) acrylate, etc.), polycyclic (meth) acrylate (e.g. 2-isoamyl (meth) acrylate, 2-norbornyl (meth) acrylate) Esters, 5-norbornene-2-yl-methyl (meth) acrylate, 3-methyl-2-norbornylmethyl (meth) acrylate, etc.), (meth) acrylates containing hydroxyl groups (E.g. hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethylbutyl (meth) methacrylate, etc.), alkoxy-containing or Phenoxy (meth) acrylates (2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxy (meth) acrylate Ethyl ester, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), epoxy-containing (methyl ) Acrylates (e.g., propylene oxide (meth) acrylate, etc.), containing (Meth) acrylates (e.g. 2,2,2-trifluoroethyl (meth) acrylate, 2,2,2-trifluoroethyl ethyl (meth) acrylate, (meth) acrylic acid Tetrafluoropropyl ester, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) acrylate ( For example, dimethylaminoethyl (meth) acrylate, etc.).

Examples of the compound having a (meth) acrylfluorenyl group other than the above include hydroxyethylacrylamide, N-methylolacrylamide, N-methoxymethacrylamine, and N-ethyl Ammonium group-containing monomers such as oxymethacrylamide and (meth) acrylamide. In addition, nitrogen-containing monomers such as acrylamidomorpholine and the like can also be mentioned.

Examples of the curable component of the radical polymerization-curable adhesive include compounds having a plurality of polymerizable double bonds such as a (meth) acrylfluorenyl group and a vinyl group. The compound may be mixed as a cross-linking component. Adhesive ingredients. Examples of the curable component serving as the crosslinking component include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, and cyclic trimethylolpropane formal. Acrylate, Di Alkanediol diacrylate, EO modified diglycerol tetraacrylate, ARONIX M-220 (manufactured by Toa Synthetic Corporation), LIGHT ACRYLATE 1, 9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), LIGHT ACRYLATE DGE-4A (total (Produced by Sakae Chemical Co., Ltd.), LIGHT ACRYLATE DCP-A (produced by Kyoeisha Chemical Co., Ltd.), SR-531 (produced by Sartomer), CD-536 (produced by Sartomer), etc. In addition, various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate-based monomers, etc. can be listed as necessary.

The radical polymerization-curable adhesive contains the above-mentioned curable component, but in addition to the above-mentioned component, a radical polymerization initiator may be added depending on the type of curing. When the above-mentioned adhesive is used in an electron beam curing type, it is not necessary to specifically include a radical polymerization initiator in the above-mentioned adhesive. However, when the above-mentioned adhesive is used in an ultraviolet curing type and a heat curing type, it is used. Free radical polymerization initiator. The amount of the radical polymerization initiator used is usually about 0.1 to 10 parts by weight, and preferably 0.5 to 3 parts by weight per 100 parts by weight of the curable component. In addition, to the radical polymerization curing type adhesive, a photosensitizer, such as a carbonyl compound or the like, may be added as necessary to increase the curing speed and sensitivity by electron beams. The use amount of the photosensitizer is usually about 0.001 to 10 parts by weight, and preferably 0.01 to 3 parts by weight per 100 parts by weight of the curable component.

Examples of the curable component of the cation polymerization curing type adhesive include compounds having an epoxy group and an oxetanyl group. The compound having an epoxy group is not particularly limited as long as it is a compound having at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used. Preferred epoxy compounds include compounds having at least two epoxy groups and at least one aromatic ring in the molecule, at least two epoxy groups in the molecule, and at least one epoxy group formed in the constituent lipid. As examples, a compound or the like between two adjacent carbon atoms of a cyclic ring.

In addition, when forming a transparent curing type adhesive layer, examples of the water-based curing type adhesive include vinyl polymer, gelatin, vinyl latex, polyurethane, isocyanate, and polyester. , Epoxy system, etc. The adhesive layer composed of such an aqueous adhesive may be formed as a coating and drying layer of an aqueous solution. In the preparation of the aqueous solution, a catalyst such as a crosslinking agent, other additives, or an acid may be blended as necessary.

As the water-based adhesive, a vinyl polymer-containing adhesive or the like is preferably used, and as the vinyl polymer, a polyvinyl alcohol-based resin is preferable. Moreover, as a polyvinyl alcohol-type resin, the adhesive agent containing the polyvinyl alcohol-type resin which has an acetamidine group is more preferable from the point of improving durability. Moreover, as a crosslinking agent which can be mix | blended with a polyvinyl-alcohol-type resin, the compound which has at least two functional groups reactive with a polyvinyl-alcohol-type resin can be used preferably. Examples include: boric acid, borax, carboxylic acid compounds, alkyldiamines; isocyanates; epoxys; monoaldehydes; dialdehydes; amino-formaldehyde resins; and salts of divalent or trivalent metals and Its oxide.

If necessary, the adhesive forming the above-mentioned curing type adhesive layer may also be an adhesive containing additives appropriately. Examples of the additive include a coupling agent such as a silane coupling agent and a titanium coupling agent; an adhesion promoter typified by ethylene oxide; an additive that enhances wettability with a transparent film; a propylene hydroxide compound or a hydrocarbon Series (natural, synthetic resins) and other additives that increase mechanical strength and processability; UV absorbers; anti-aging agents; dyes; processing aids; ion trapping agents; antioxidants; tackifiers; fillers (except Other than metal compound fillers); plasticizers; leveling agents; foaming inhibitors; antistatic agents; heat stabilizers, hydrolysis stabilizers and other stabilizers.

The thickness of the transparent curing-type adhesive layer is preferably 0.01 to 10 μm. It is more preferably 0.1 to 5 μm, and still more preferably 0.3 to 4 μm. In addition, since the height between each film layer of the appearance defect from a foreign body is generally several micrometers (about 2-5 micrometers), if the thickness of an adhesive layer is 2 micrometers or less, the problem of an appearance defect becomes large. However, the method for producing an optical film of the present invention is particularly useful as a method for producing an optical film having an adhesive layer thickness of 2 μm or less because it can prevent appearance defects.

The adhesive layer is formed of an adhesive. As the adhesive, various adhesives can be used, and examples thereof include rubber-based adhesives, acrylic-based adhesives, polysiloxane-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, and polyvinyl-based adhesives. Pyrrolidone-based adhesives, polypropylene amidamine-based adhesives, cellulose-based adhesives, and the like. The adhesive base polymer is selected according to the type of the adhesive. Among the above-mentioned adhesives, an acrylic adhesive is preferably used from the viewpoints of excellent optical transparency, exhibiting adhesive properties of suitable wettability, cohesiveness, and adhesiveness, and excellent weather resistance, heat resistance, and the like.

The radical polymerization curing type adhesive can be used in the form of an electron beam curing type or an ultraviolet curing type.

In the electron beam curing type, any appropriate conditions can be adopted as long as the conditions for irradiating the electron beam are conditions under which the radical polymerization curing type adhesive composition can be cured. For example, the acceleration voltage for electron beam irradiation is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. When the acceleration voltage is less than 5kV, there is a risk that the electron beam does not reach the adhesive and the curing is insufficient. If the acceleration voltage exceeds 300kV, the penetration force through the sample is too strong, which may cause damage to the transparent protective film and polarizer. Risk of damage. The irradiation dose is 5 to 100 kGy, and more preferably 10 to 75 kGy. When the radiation dose is less than 5 kGy, the curing of the adhesive is insufficient. If the radiation dose exceeds 100 kGy, the transparent protective film and polarizer are damaged, mechanical strength is reduced, yellowing occurs, and predetermined optical characteristics cannot be obtained.

Electron beam irradiation is usually performed in an inert gas, and if necessary, it can be performed in the atmosphere or with a small amount of oxygen introduced. Although it depends on the material of the transparent protective film, by properly introducing oxygen, the surface of the transparent protective film to which the original electron rays first reach will be blocked by oxygen, which can prevent damage to the transparent protective film and can effectively irradiate only the adhesive. Electron rays.

On the other hand, in the case of the ultraviolet curing type, when a transparent protective film provided with an ultraviolet absorbing ability is used, light having a shorter wavelength than about 380 nm is absorbed, so light having a shorter wavelength than 380 nm does not reach the active energy ray curing type. Agent composition, and therefore does not participate in the polymerization reaction. In addition, light having a shorter wavelength than 380 nm absorbed by the transparent protective film is converted into heat, and the transparent protective film itself generates heat, which causes defects such as curling and wrinkling of the polarizing film. Therefore, when an ultraviolet curing type is used in the present invention, it is preferable to use a device that does not emit light having a shorter wavelength than 380 nm as the ultraviolet generating device. More specifically, the cumulative illuminance in the wavelength range of 380 to 440 nm and the wavelength range of 250 are used. The ratio of the cumulative illuminance of ˜370 nm is preferably 100: 0 to 100: 50, and more preferably 100: 0 to 100: 40. As the ultraviolet rays satisfying such a relationship of accumulated illuminance, a metal halide lamp enclosed with gallium and an LED light source emitting light in a wavelength range of 380 to 440 nm are preferred. Alternatively, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, incandescent lamps, xenon lamps, halogen lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, gallium lamps, An excimer laser or sunlight is used as a light source, and a band-pass filter is used to block light having a shorter wavelength than 380 nm.

The first film and / or the second film can be used without particular limitation as long as they are transparent optical films. As described above, the thicker the thickness of the adhesive layer (or the adhesive layer) and the thicker the total thickness of the optical film, the more difficult it is to visually recognize foreign objects, and it tends to be difficult to make appearance defects problematic. On the other hand, the thinner the thickness of the adhesive layer (or the adhesive layer) and the thinner the total thickness of the optical film, the easier it is to visually recognize the foreign matter. As a result, appearance defects often cause problems. However, in the method for producing an optical film of the present invention, an optical film having a very low foreign matter occurrence rate in an adhesive layer (or an adhesive layer) can be produced. Therefore, even in an optical film, a thinning requirement is particularly large. The manufacturing method of the polarizing film is specifically when the first film is a transparent protective film and the second film is a polarizer, or when the second film is a transparent protective film and the first film is a polarizer In this case, the production method of the present invention is particularly useful. With the manufacturing method of the present invention, as in the case where the thickness of the polarizer is 10 μm or less, particularly in the case of manufacturing a thin polarizing film, it is possible to manufacture a protective layer (or an adhesive layer) from occurring in the adhesive layer. A thin polarizing film having an appearance defect caused by a foreign substance is preferable.

The first film and / or the second film may be surface-modified before being coated with the active energy ray-curable adhesive composition. Specific examples of the treatment include a corona treatment, a plasma treatment, and a treatment using a saponification treatment.

In addition, in the method for manufacturing an optical film of the present invention, the first film and the second film may be bonded together through an adhesive layer formed by using the cured product layer of the radical polymerization-curable adhesive composition, and the first film and the second film may be bonded together. An easy-adhesive layer is provided between one film and the second film. For the easy-adhesion layer, for example, various types including a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a polysiloxane, a polyamide skeleton, a polyimide skeleton, and a polyvinyl alcohol skeleton can be used. Resin to form. These polymer resins can be used individually by 1 type or in combination of 2 or more types. In addition, other additives may be added when forming the easy-adhesion layer. Specifically, stabilizers such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat-resistant stabilizer can be further used.

The formation of the easy-adhesion layer is performed by applying a known material to the film and drying the material. In general, the thickness of the dried layer, the smoothness of the coating, and the like are considered, and the material for forming the easy-adhesive layer is adjusted to a solution diluted to an appropriate concentration. The thickness of the easily adhered layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and still more preferably 0.05 to 1 μm. In addition, the easy-adhesion layer may be provided in a plurality of layers. However, in this case, it is also preferable that the total thickness of the easy-adhesion layer is within the above range.

Hereinafter, as an optical film, a polarizing film is mentioned as an example and demonstrated. A polarizing film including a laminated structure in which at least a first film and a second film are laminated can be manufactured, for example, as follows: In FIG. 1, a first film 1 which is a transparent protective film, and a transparent protective film or a PET substrate If necessary, the laminated second film 2 having the polarizer laminated thereon with the adhesive layer interposed therebetween is bonded through the adhesive layer composed of the cured product layer of the adhesive composition. This embodiment shows an example in which the polarizer surface on which the second film 2 is laminated is used as a bonding surface, and an adhesive composition is applied to the bonding surface.

In the manufacturing method of the present invention, an optical film which can effectively prevent the generation of a foreign substance in the adhesive layer can be manufactured. Therefore, it is suitable for manufacturing an optical film, especially a thin optical film, which causes a large problem in appearance defects caused by the foreign substance. Therefore, the thickness of the first film and the second film (in this embodiment, the first film is a protective film, and the second film is a laminated film of a PET substrate + a polarizer) are preferably 60 μm or less, and more preferably 40 μm or less. In addition, when the total thickness of the polarizing film is 100 μm or less, since the thickness is thin, appearance defects caused by foreign matter or the like of the adhesive layer often become a problem. However, in the manufacturing method of the present invention, since an optical film capable of effectively preventing the generation of foreign matter in the adhesive layer can be manufactured, it is suitable for manufacturing a thin polarizing film having a total thickness of 100 μm or less, especially for manufacturing a total thickness. In the case of a thin polarizing film of 50 μm or less. In the present invention, even in the case of manufacturing a thin polarizing film, particularly in the case of manufacturing a thin polarizing film including a thin polarizer having a thickness of 10 μm or less, appearance defects can be effectively prevented.

The polarizer is not particularly limited, and various polarizers can be used. Examples of the polarizer include a dichroic material such as iodine or a dichroic dye, which is adsorbed on a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene-vinyl acetate copolymer-based partially saponified film. A polarizer made of a hydrophilic polymer film and uniaxially stretched; a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride. Among them, a polarizer made of a polyvinyl alcohol-based film and a dichroic material such as iodine is more suitable. The thickness of these polarizers is not particularly limited, but is generally about 80 μm or less.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching it can be produced, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine, dyeing it, and stretching it to 3 to 7 times its original length. It can also be immersed in an aqueous solution, such as a boric acid and potassium iodide, as needed. If necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. In addition to washing the polyvinyl alcohol-based film with water to clean dirt or an anti-blocking agent on the surface of the polyvinyl alcohol-based film, it also has the effect of preventing uneven dyeing and the like by swelling the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, or may be stretched while dyeing, or may be dyed with iodine after stretching. Stretching can be performed even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

As the polarizer, a thin polarizer having a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer is preferred in terms of small thickness unevenness, excellent visibility, excellent durability due to small dimensional change, and reduction in thickness as a polarizing film.

Examples of thin polarizers include Japanese Patent Application Laid-Open No. 51-069644, Japanese Patent Application Laid-Open No. 2000-338329, WO2010 / 100917 pamphlet, PCT / JP2010 / 001460 specification, or Japanese Patent Application No. 2010- Thin polarizers described in 269002 and 2010-263692. These thin polarizers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a stretching resin substrate in a laminated state, and performing Steps of dyeing. According to this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched by being supported by the stretch resin substrate, and there are no defects such as breakage due to stretch.

As the above-mentioned thin polarizer, even in a manufacturing method including a step of stretching in a laminated state and a step of dyeing, it can be stretched at a high magnification to improve polarizing performance, and is preferably used. WO2010 / 100917 booklet, PCT / JP2010 / 001460, or Japanese Patent Application No. 2010-269002 or Japanese Patent Application No. 2010-263692, which are obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution. The polarizer is particularly preferably produced by a method including the step of auxiliaryly performing aerial stretching before performing stretching in a boric acid aqueous solution described in Japanese Patent Application No. 2010-269002 or Japanese Patent Application No. 2010-263692. The obtained polarizer.

The thin high-function polarizer described in the above-mentioned PCT / JP2010 / 001460 specification is a thin high-function thin film having a thickness of 7 μm or less, which is formed integrally with a resin substrate and made of a PVA-based resin in which a dichroic material is oriented. A polarizer has optical characteristics of a single transmittance of 42.0% or more and a polarization degree of 99.95% or more.

The above-mentioned thin high-function polarizer can be manufactured by forming a PVA-based resin layer by coating and drying a PVA-based resin on a resin substrate having a thickness of at least 20 μm, and dipping the generated PVA-based resin layer in two layers. In a dyeing solution for a chromic substance, a dichroic substance is adsorbed on the PVA-based resin layer, and a PVA-based resin layer on which the dichroic substance is adsorbed is added to a boric acid aqueous solution at a total stretching ratio of 5 times or more the original length. Stretched integrally with the resin substrate.

In addition, the above-mentioned thin high-function polarizer can be manufactured by a method of manufacturing a laminated film including a thin high-function polarizer in which a dichroic substance is oriented, and the method includes the following steps: generating a laminated film The laminate film includes a resin substrate having a thickness of at least 20 μm, and a PVA-based resin layer formed by coating and drying an aqueous solution containing a PVA-based resin on one side of the resin substrate; and an adsorption step, The resin substrate and the above-mentioned laminate film of the PVA-based resin layer formed on one side of the resin substrate are immersed in a dyeing solution containing a dichroic substance, so that the dichroic substance is adsorbed on the PVA-based resin contained in the laminate film. A layer step; an extending step of stretching the above-mentioned laminate film including the PVA-based resin layer having adsorbed dichroic substances in a boric acid aqueous solution so that the total stretching ratio becomes 5 times or more the original length; and manufacturing In the step of a laminate film, a PVA-based resin layer to which a dichroic substance is adsorbed is integrally stretched with a resin substrate to produce a film formed on one side of the resin substrate. PVA-based resin layer of a substance composed of oriented dichroic thickness of 7μm or less, a monomer having transmittance of 42.0% and a polarization degree of highly functional thin film laminate polarizer optical characteristics of 99.95% or more.

The thin polarizers described in Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 described above are continuous thin-film polarizers composed of a PVA-based resin in which a dichroic material is oriented, and will be included in the amorphous The laminated body of the PVA-based resin layer obtained by forming a film on an ester-based thermoplastic resin substrate is stretched by a two-stage stretching step consisting of air-assisted stretching and boric acid water stretching so as to have a thickness of 10 μm or less. The thin polarizer is preferably set in the monomer transmittance T, satisfying the degree of polarization P is set to ^{P> - (10 0.929T -42.4 -1} ) × 100 ( where, T <42.3) and P≥99.9 ( Among them, a thin polarizer having optical characteristics under the condition of T ≧ 42.3).

Specifically, the above-mentioned thin polarizer can be manufactured by a thin polarizer manufacturing method including the following steps: high temperature in the air for a PVA-based resin layer formed on a continuous sheet-like amorphous ester-based thermoplastic resin substrate A step of stretching to generate a stretched intermediate product composed of an oriented PVA-based resin layer; using adsorption of a dichroic substance to the stretched intermediate product to generate a dichroic substance (preferably iodine, or A mixture of iodine and an organic dye) orienting the PVA-based resin layer to form a colored intermediate product step; by stretching the colored intermediate product in boric acid water, a PVA-based resin layer is formed by orienting a dichroic substance A step of forming a polarizer having a thickness of 10 μm or less.

In this manufacturing method, it is desirable that the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate using high-temperature air stretching and boric acid water stretching to be 5 times or more. The liquid temperature of the boric acid aqueous solution used for drawing in boric acid water may be 60 ° C or higher. It is desirable to insolubilize the colored intermediate product before stretching the colored intermediate product in an aqueous boric acid solution. In this case, it is desirable to immerse the colored intermediate product in a boric acid aqueous solution whose liquid temperature does not exceed 40 ° C. The amorphous ester-based thermoplastic resin substrate may be a copolymerized polyethylene terephthalate copolymerized with isophthalic acid, a copolymerized polyethylene terephthalate copolymerized with cyclohexanedimethanol, or The amorphous polyethylene terephthalate containing other copolymerized polyethylene terephthalate is preferably a substrate made of a transparent resin, and the thickness may be the thickness of the PVA-based resin layer of the film to be formed More than 7 times. In addition, the stretching ratio in the high-temperature air stretching is preferably 3.5 times or less, and the stretching temperature in the high-temperature air stretching is preferably equal to or higher than the glass transition temperature of the PVA-based resin, and specifically in the range of 95 ° C to 150 ° C. In the case of performing high-temperature aerial stretching by free-end uniaxial stretching, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate is preferably 5 times or more and 7.5 times or less . In addition, in the case of high-temperature aerial stretching by uniaxial stretching at a fixed end, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin substrate is preferably 5 times or more and 8.5 Times below. More specifically, a thin polarizer can be manufactured by the method shown below.

A continuous sheet-like base material in which isophthalic acid copolymerized with polyethylene terephthalate (amorphous PET) was copolymerized with 6 mol% of isophthalic acid. The glass transition temperature of the amorphous PET was 75 ° C. A laminated body composed of a continuous sheet-like amorphous PET substrate and a polyvinyl alcohol (PVA) layer was produced as follows. Incidentally, the glass transition temperature of PVA is 80 ° C.

An amorphous PET substrate having a thickness of 200 μm and a 4 to 5% concentration PVA aqueous solution in which PVA powder having a degree of polymerization of 1,000 or more and a degree of saponification of 99% or more was prepared were dissolved in water. Next, a 200 μm-thick amorphous PET substrate was coated with an aqueous PVA solution, and dried at a temperature of 50 to 60 ° C. to obtain a laminate having a 7 μm-thick PVA layer formed on the amorphous PET substrate.

A laminated body including a PVA layer having a thickness of 7 μm was subjected to the following steps including a two-stage stretching step including air-assisted stretching and boric acid water stretching to produce a thin, high-function polarizer with a thickness of 3 μm. In the first stage of the air-assisted stretching step, the laminated body including the PVA layer having a thickness of 7 μm and the amorphous PET substrate are integrally stretched to generate a stretched laminated body including the PVA layer having a thickness of 5 μm. Specifically, in this stretched laminate, a laminate including a PVA layer having a thickness of 7 μm is set in a stretching device arranged in an oven set at a stretching temperature environment of 130 ° C. so that the stretching ratio becomes 1.8 times. The stretched laminate obtained by uniaxially stretching the free end in the manner described above. By this stretching treatment, the PVA layer included in the stretched laminate was changed to a PVA layer having a thickness of 5 μm in which PVA molecules were oriented.

Next, a dyeing step was performed to generate a colored laminate having a PVA layer having a thickness of 5 μm after iodine was adsorbed onto the PVA molecules. Specifically, the colored laminated body is obtained by immersing the stretched laminated body in a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ° C. for an arbitrary time, so that the monomers constituting the PVA layer of the finally produced high-function polarizer The transmittance reaches 40 to 44%, thereby causing iodine to be adsorbed on the PVA layer included in the stretched laminate. In this step, the dyeing liquid uses water as a solvent, sets the iodine concentration in the range of 0.12 to 0.30% by weight, and sets the potassium iodide concentration in the range of 0.7 to 2.1% by weight. The ratio of the concentration of iodine to potassium iodide was 1 to 7. Incidentally, potassium iodide is required to dissolve iodine in water. More specifically, the stretched laminate was immersed in a dyeing solution having an iodine concentration of 0.30% by weight and a potassium iodide concentration of 2.1% by weight for 60 seconds, thereby generating a coloration of a PVA layer having a thickness of 5 μm after the iodine was adsorbed on the PVA molecules. Laminated body.

Further, in the second step of boric acid water stretching step, the colored laminate and the amorphous PET substrate were further integrally stretched to produce an optical film laminate including a PVA layer constituting a high-function polarizer with a thickness of 3 μm. Specifically, the optical film laminate is obtained by setting a colored laminate in a stretching device arranged in a processing device set to a boric acid aqueous solution containing boric acid and potassium iodide and having a liquid temperature range of 60 to 85 ° C. Uniaxial stretching at the free end in a way that the stretch ratio reaches 3.3 times. More specifically, the liquid temperature of the boric acid aqueous solution was 65 ° C. The boric acid content was 4 parts by weight with respect to 100 parts by weight of water, and the potassium iodide content was 5 parts by weight with respect to 100 parts by weight of water. In this step, first, the colored laminated body whose iodine adsorption amount is adjusted is immersed in an aqueous boric acid solution for 5 to 10 seconds. Then, the colored laminate was directly passed through a stretching device arranged in a processing device, that is, between a plurality of sets of rollers having different peripheral speeds, and uniaxially pulled at the free end so that the stretching ratio reached 3.3 times in 30 to 90 seconds. Stretch. By this stretching treatment, the PVA layer contained in the colored laminate was changed to a PVA layer having a thickness of 3 μm in which the adsorbed iodine was highly oriented in one direction as a polyiodide ion complex. This PVA layer constitutes a highly functional polarizer of an optical film laminate.

Although it is not an essential step in the manufacture of the optical film laminate, it is preferable that the optical film laminate be taken out of the boric acid aqueous solution by a cleaning step, and the thickness of the 3 μm film formed on the amorphous PET substrate be reduced. The boric acid attached to the surface of the PVA layer was washed with an aqueous potassium iodide solution. Then, the washed optical film laminate was dried in a drying step under a warm air at 60 ° C. The cleaning step is a step for eliminating appearance defects such as boric acid precipitation.

Similarly, it is not an essential step in the manufacture of an optical film laminate, but it is also possible to apply an adhesive on the surface of a 3 μm-thick PVA layer formed on an amorphous PET substrate using a lamination and / or transfer step, and apply the adhesive A 80 μm-thick triethylammonium cellulose film was combined, and then the amorphous PET substrate was peeled off, and a 3 μm-thick PVA layer was transferred to an 80 μm-thick triethylammonium cellulose film.

[Other Steps] The manufacturing method of the above-mentioned thin polarizer may include other steps in addition to the above steps. Examples of the other steps include an insolubilization step, a cross-linking step, and a drying (adjusting the moisture content) step. The other steps can be performed at any appropriate time. The said insolubilization process is typically performed by immersing a PVA-type resin layer in a boric-acid aqueous solution. By carrying out the insolubilization treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight based on 100 parts by weight of water. The liquid temperature of the insolubilization bath (aqueous boric acid solution) is preferably 20 ° C to 50 ° C. The insolubilization step is preferably performed after the laminate is produced and before the dyeing step or the water stretching step. The above-mentioned crosslinking step is typically performed by immersing a PVA-based resin layer in an aqueous boric acid solution. By performing a crosslinking treatment, water resistance can be imparted to the PVA-based resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight based on 100 parts by weight of water. When the crosslinking step is performed after the dyeing step, it is preferable to further blend iodide. By blending iodide, elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The blending amount of the iodide is preferably 1 to 5 parts by weight based on 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably 20 ° C to 50 ° C. The crosslinking step is preferably performed before the second boric acid water stretching step. In a preferred embodiment, the dyeing step, the cross-linking step, and the second boric acid water stretching step are sequentially performed.

As a material for forming a transparent protective film provided on one or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Examples thereof include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diethyl cellulose and triethyl cellulose, and polymethyl Acrylic polymers such as methyl acrylate, styrene polymers such as polystyrene, acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, nylon, or aromatic polyfluorene Amidine-based polymers such as amines, amidine-based polymers, amidine-based polymers, polyether amidine-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, Vinyl chloride-based polymer, vinyl butyral-based polymer, aryl ester-based polymer, polyoxymethylene-based polymer, epoxy-based polymer, or a blend of the above-mentioned polymers, etc., as polymerization for forming the transparent protective film Examples of things. The transparent protective film may contain one or more arbitrary appropriate additives. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, release agents, anti-colorants, flame retardants, nucleating agents, antistatic agents, pigments, and colorants. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50% by weight or less, there is a risk that the high transparency and the like originally possessed by the thermoplastic resin may not be sufficiently exhibited.

Moreover, as a transparent protective film, the polymer film described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, the polymer film which contains (A) which has a substituted and / or unsubstituted fluorenimine group in a side chain is mentioned. A thermoplastic resin and (B) a resin composition of a thermoplastic resin having a substituted and / or unsubstituted phenyl group and a nitrile group in a side chain. Specific examples include a film of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide, and an acrylonitrile-styrene copolymer. As the film, a film composed of a mixed extrusion of a resin composition or the like can be used. These films have a small phase difference and a small photoelastic coefficient, so that it is possible to eliminate the unevenness caused by the distortion of the polarizing film, and because of its low moisture permeability, it has excellent humidification durability.

The thickness of the transparent protective film can be appropriately determined, but is generally about 1 to 500 μm in terms of workability such as strength and workability, and thinness. It is particularly preferably 20 to 80 μm, and more preferably 30 to 60 μm.

In addition, when a transparent protective film is provided on both sides of the polarizer, a transparent protective film made of the same polymer material may be used on the front and back surfaces, or a transparent protective film made of different polymer materials or the like may be used.

A functional layer such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, or an anti-glare layer may be provided on the surface of the transparent protective film to which the polarizer is not attached. In addition, the functional layers such as the hard coating layer, the anti-reflection layer, the anti-adhesion layer, the diffusion layer, and the anti-glare layer may be provided in addition to the transparent protective film itself, or may be separately provided as a functional layer separate from the transparent protective film. .

The polarizing film of the present invention can be used as an optical film laminated with another optical layer when practical. The optical layer is not particularly limited. For example, one or two or more reflective plates, transflective plates, retardation plates (including wavelength plates such as 1/2 or 1/4), and viewing angle compensation films can be used. An optical layer such as a liquid crystal display device is formed. In particular, a reflective polarizing film or a transflective polarizing film in which a reflecting plate or a transflective reflecting plate is further laminated on the polarizing film of the present invention, an elliptical polarizing film or a circle in which a retardation plate is further laminated on the polarizing film is preferred A polarizing film, a wide-angle polarizing film in which a viewing angle compensation film is further laminated on a polarizing film, or a polarizing film in which a brightness enhancing film is further laminated on a polarizing film.

An optical film in which the above-mentioned optical layer is laminated on a polarizing film can be formed by sequentially and sequentially laminating in the manufacturing process of a liquid crystal display device, etc., but an optical film made in advance is excellent in quality stability, assembly work, etc. , And has the advantage of improving the manufacturing steps of the liquid crystal display device and the like. An appropriate bonding means such as an adhesive layer can be used for the lamination. When the above-mentioned polarizing film or other optical film is adhered, their optical axes can be set to an appropriate arrangement angle in accordance with the target retardation characteristics and the like.

An adhesive layer may be provided on the above-mentioned polarizing film or an optical film on which at least one layer of polarizing film is laminated to be adhered to other members such as a liquid crystal cell. The adhesive for forming the adhesive layer is not particularly limited. For example, acrylic polymers, polysiloxane polymers, polyesters, polyurethanes, polyamides, polyethers, fluorine-based polymers, and rubbers can be appropriately selected and used. Polymers such as polymers are used as adhesives for base polymers. In particular, an adhesive such as an acrylic adhesive that is excellent in optical transparency and exhibits moderate wettability, cohesiveness, and adhesiveness, and is excellent in weather resistance and heat resistance can be preferably used.

The adhesive layer may be provided on one or both sides of a polarizing film or an optical film in the form of an overlapping layer of adhesive layers of different compositions or types. In addition, when provided on both sides, an adhesive layer having a different composition, type, and thickness may be formed on the surface and the back surface of the polarizing film or optical film. The thickness of the adhesive layer can be appropriately determined depending on the purpose of use, adhesive force, etc., and is generally 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

The exposed surface of the adhesive layer is temporarily covered with a separator for the purpose of preventing contamination, etc., until it is put to practical use. This can prevent contact with the adhesive layer in a normal operation state. As the separator, in addition to the above-mentioned thickness conditions, for example, a suitable sheet such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, mesh, foamed sheet, metal foil, or a laminate thereof may be used as needed. Suitable separators based on conventional methods, such as materials obtained by applying a suitable release agent such as polysiloxane-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

The polarizing film or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device and the like. The liquid crystal display device can be formed based on a conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell, a polarizing film or an optical film, and a component such as a lighting system as required and incorporating a driving circuit. The film is not particularly limited in this respect, and can be based on a conventional method. As the liquid crystal cell, any type of liquid crystal cell such as a TN type, an STN type, or a π type can be used.

Suitable liquid crystal display devices such as a liquid crystal display device in which a polarizing film or an optical film is arranged on one or both sides of a liquid crystal cell, and a liquid crystal display device using a backlight or a reflection plate in an illumination system can be formed. At this time, the polarizing film or optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. When a polarizing film or an optical film is provided on both sides, they may be the same or different. In the formation of a liquid crystal display device, for example, one or two or more diffusion plates, anti-glare layers, anti-reflection films, protective plates, chirped arrays, lens array sheets, light diffusion plates, Suitable parts such as backlight.

Examples Hereinafter, examples of the present invention will be described. However, the embodiments of the present invention are not limited to these examples. In addition, "weight part" in a composition means the part when the total amount of a composition is 100 weight part.

(1) Preparation of adhesive composition <Preparation of active energy ray-curable adhesive composition> HEAA (Hydroxyethylpropenamide) [manufactured by Hingren Co., Ltd.] 38.5 parts by weight, ARONIX M-220 (tripropylene glycol di Acrylic acid ester] [manufactured by Toa Synthesis Co., Ltd.] 20.0 parts by weight, ACMO (acrylic fluorenylmorpholine) [manufactured by Keihin Corporation] 38.5 parts by weight, KAYACURE DETX-S (diethylthioxanthone) [manufactured by Nippon Kayaku Co., Ltd.] 1.5 parts by weight, IRGACURE 907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one) [manufactured by BASF] 1.5 parts by weight are mixed and stirred at 50 ° C For 1 hour, an active energy ray-curable adhesive composition (only described as "adhesive composition" in Table 1) was obtained.

(2) Production of thin polarizers In order to produce thin polarizers, first, a laminated body having a 24 μm-thick PVA layer formed on an amorphous PET substrate was stretched by air-assisted stretching at a stretching temperature of 130 ° C. The laminated body is then dyed to produce a colored laminated body, and the colored laminated body is further stretched by boric acid water at a stretching temperature of 65 ° C to produce a total stretching ratio of 5.94 times. A 10 μm-thick optical film laminate including a PVA layer obtained by integrally stretching a crystalline PET substrate. With this two-stage stretching, an optical film laminate (second film (total thickness: 40 μm)) including a PVA layer having a thickness of 5 μm constituting a thin polarizer can be produced. The polarizer includes an amorphous PET substrate. The PVA molecules of the PVA layer formed on the upper film are highly oriented, and the iodine adsorbed by dyeing is highly oriented in one direction as a polyiodide ion complex.

As the first film, a transparent protective film (thickness: 40 μm) made of a (meth) acrylic resin having a lactone ring structure was used.

Example 1 In the production line shown in FIGS. 1 and 2, a gravure roll coating method 10 (MCD coater (manufactured by Fuji Machinery Co., Ltd.)) having a gravure roll 4 was used (mesh shape: honeycomb pattern, and number of mesh lines of the gravure roll). : 1000 pieces / inch, rotation speed ratio is 140%), the adhesive composition 3 is applied to both the bonding surface of the first film 1 and the bonding surface of the second film 2, and the bead width is adjusted to the table The width of the bead is 1 and the polarizing film is manufactured while removing the foreign matter. In Table 1, the bead width of the first film and the gravure roll is set to L1 (mm), and the bead width of the second film and the gravure roll is set to L2 ( mm). Next, the adhesive composition 3 is applied to the second film 2 composed of the PET substrate and the thin polarizer so that the thin polarizer surface becomes a bonding surface. The adhesive composition 3 is dried. The subsequent adhesive layer was applied to the first film and the second film so that the thickness of the adhesive layer became 1 μm. As a gravure roll coating method 10, a gravure having a foreign matter removal function (a foreign matter removal method using a filter) shown in FIG. 2 was used. Roll coating method.

<Active energy ray> After passing through the production line shown in FIG. 1, as an active energy ray, an ultraviolet (gallium-encapsulated metal halide lamp) irradiation device was used: Fusion UV Systems, Inc. Light HAMMER10 lamp: V lamp peak illumination: The adhesive composition 3 was cured at 1600 mW / cm ² and a cumulative irradiation amount of 1000 / mJ / cm ² (wavelength 380 to 440 nm) to produce an optical film. The illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell.

Examples 2 to 12 and Comparative Examples 1 to 18 were used and implemented except that the type and bead width of the coating liquid to which the first film and the second film were bonded were changed to the type and bead width of the coating liquid described in Table 1. An optical film was produced in the same manner as in Example 1. In Table 1, the water used as a liquid was 100 weight% of water and 1 cP of viscosity.

＜ Counting method of the number of foreign matters in the adhesive layer ＞ Visual inspection and reflection inspection using an automatic inspection device are used to detect the number of appearance defects in the adhesive layer of the polarizing film (the number of appearance defects from foreign matters (a / m ² )). Count. The results are shown in Table 1.

<Appearance Evaluation at the Coating Surface of the Coating Liquid> When visually confirmed, the case where the appearance failure of the coating surface after the application of the coating liquid became rough was set to "yes", and the case where no appearance failure occurred was set to "yes" "no". The results are shown in Table 1.

[Table 1]

1‧‧‧ the first film

2‧‧‧Second film

3‧‧‧ coating liquid (adhesive composition)

4‧‧‧ Gravure roller

5‧‧‧ container

6‧‧‧ cans

7‧‧‧ Filter

8‧‧‧ pump function

9‧‧‧ pinch roller

10‧‧‧ Gravure roller coating method

d‧‧‧The width of the film in the direction of travel of the coating liquid scum formed between the first film 1 and the gravure roll 4 is the width of the liquid beads.

FIG. 1 is an example of a schematic diagram of a method for manufacturing an optical film of the present invention. FIG. 2 is an example of a schematic diagram of a gravure roll coating method which is a post-metering coating method used in the present invention. FIG. 3 is an example of a schematic view of a coating liquid accumulation liquid formed between a first film and a gravure roll.

Claims (11)

An optical film manufacturing method, which includes a laminated structure in which at least a first film and a second film are bonded. The method for manufacturing the optical film is characterized in that the manufacturing method has a coating step and uses a gravure A gravure roll coating method of a roller, in which a coating liquid is coated on a bonding surface of both the first film and the second film; and in the coating step, the first film and the second film are formed on the bonding surface The width of the film traveling direction, that is, the width of the liquid bead, of the coating liquid accumulation between the gravure rolls was set to 4 mm to 20 mm. According to the method for manufacturing an optical film according to claim 1, the coating liquid is at least one coating liquid selected from the group consisting of an adhesive composition, an adhesive composition, and a liquid substance having a viscosity of 0.5 cP to 10000 cP. In addition, the optical film includes a laminated structure, and the laminated structure includes at least a first film and a first film through an adhesive layer or an adhesive layer composed of the adhesive composition or a cured product layer of the adhesive composition. Two film people. The method for manufacturing an optical film according to claim 2, wherein the coating step includes the following steps: a first coating step of coating the adhesive composition or the adhesive composition on the bonding surface of the first film; and In the two coating steps, the adhesive composition or the adhesive composition, or a liquid substance having a viscosity of 0.5 cP to 10,000 cP is applied to the bonding surface of the second film. The method for manufacturing an optical film according to claim 1 or 2, wherein the rotation direction of the gravure roll is opposite to the traveling direction of the first film and the second film. The method for manufacturing an optical film according to any one of claims 1 to 4, wherein the diameter of the aforementioned gravure roll is 80φ to 140φ. The method for producing an optical film according to any one of claims 1 to 5, wherein the pattern formed on the surface of the aforementioned gravure roll is a honeycomb pattern. The method for manufacturing an optical film according to any one of claims 1 to 6, wherein a ratio of a rotation speed of the gravure roll to a traveling speed of the first film and the second film is 100% to 300%. The method for manufacturing an optical film according to any one of claims 1 to 7, wherein the gravure roll coating method is a method in which the coating liquid is cyclically coated, and the coating method includes applying the coating film from the first film and / or the first A foreign matter removing function in which the two films are mixed into the coating liquid and the foreign matter is removed from the coating liquid. The method for manufacturing an optical film according to any one of claims 1 to 8, wherein the first film is a transparent protective film, and the second film is a polarizer. The method for manufacturing an optical film according to any one of claims 1 to 8, wherein the second film is a transparent protective film, and the first film is a polarizer. The method for manufacturing an optical film according to claim 9 or 10, wherein the thickness of the aforementioned polarizer is 10 μm or less.