WO2015072205A1 - Method for producing optical film, optical film and image display device - Google Patents

Abstract

A method for producing an optical film which comprises a multilayer structure wherein at least a first film and a second film are bonded with each other with an adhesive layer or bonding agent layer being interposed therebetween, said adhesive layer or bonding agent layer being composed of a layer of a cured product of an adhesive composition or bonding agent composition. This method for producing an optical film comprises a coating step wherein foreign materials and/or air bubbles are removed by applying the adhesive composition or bonding agent composition to both the bonding surface of the first film and the bonding surface of the second film using a post-measurement coating method.

Description

Optical film manufacturing method, optical film, and image display device

The present invention provides an optical film including a laminated structure in which at least a first film and a second film are bonded via an adhesive layer or a pressure-sensitive adhesive layer composed of a cured product layer of an adhesive composition or a pressure-sensitive adhesive composition, and It relates to the manufacturing method. Furthermore, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, and a PDP using the optical film.

Liquid crystal display devices are rapidly expanding in the market for watches, mobile phones, PDAs, notebook computers, personal computer monitors, DVD players, TVs, etc. The liquid crystal display device visualizes the polarization state by switching of the liquid crystal, and a polarizer is used from the display principle. In particular, in applications such as TV, higher brightness, higher contrast, and wider viewing angle are required, and polarizing films are also required to have higher transmittance, higher degree of polarization, and higher color reproducibility.

As the polarizer, since it has a high transmittance and a high degree of polarization, for example, an iodine-based polarizer having a stretched structure by adsorbing iodine to polyvinyl alcohol (hereinafter also simply referred to as “PVA”) is most widely used. in use. In general, a polarizing film in which a transparent protective film is bonded to both surfaces of a polarizer by a so-called aqueous adhesive in which a polyvinyl alcohol-based material is dissolved in water has been used. However, in recent years, the use of an active energy ray-curable resin composition that does not contain water or an organic solvent is becoming mainstream because it has advantages such that the drying step can be omitted and the dimensional change is small. is there.

When using an active energy ray-curable resin composition to produce an optical film by laminating a plurality of films, for example, the adhesive composition is applied only to the laminating surface of the transparent protective film, and the laminating surface. In general, an optical film including a laminated structure is manufactured by laminating a polarizer or the like from the side. However, in the conventional manufacturing method, foreign matter such as dust or dust adheres to the surface of the polarizer / transparent protective film before application of the adhesive composition or the like, or the adhesive composition contains minute foreign matter. In this case, foreign matters remain in the adhesive layer, and as a result, appearance defects may occur.

In the following Patent Document 1, an optical film including a step of thinly coating an optical functional layer having a wet coating amount of 10 mL / m ² or less on a transparent support or an undercoat layer formed on the transparent support. In the manufacturing method, an optical film manufacturing method including a step of removing foreign matters having a height of 10 μm or more from the transparent support or the undercoat layer before applying the optical functional layer is described.

JP 2008-180905 A

However, as a result of investigation by the present inventors, the technique described in Patent Document 1 attempts to crush and remove foreign matters by calendaring or the like in a state where foreign matters already exist on the transparent support or the like. Therefore, the foreign matter removal accuracy is not high, and minute foreign matter remains after the removal step. For this reason, the technique described in Patent Document 1 is difficult to apply to a method for manufacturing a thin optical film in which the appearance defect is a problem even when the thickness is particularly thin and minute foreign matter is present. Was the actual situation.

The present invention has been completed as a result of taking the above circumstances into consideration, and its purpose is to produce an optical film in which appearance defects due to foreign matters and / or bubbles are prevented even when the optical film is thin. It is to provide a method.

As a result of intensive studies to solve the above problems, the present inventor adopts a specific coating method when manufacturing an optical film including a laminated structure in which at least two films are bonded together, It has been found that by applying the adhesive composition or the pressure-sensitive adhesive composition to both bonding surfaces of the film, it is possible to remove foreign substances and / or bubbles and apply the adhesive composition or the pressure-sensitive adhesive composition at a time. It was. The present invention has been obtained as a result of such diligence, and has the following configuration.

That is, the present invention provides an optical film including a laminated structure in which at least a first film and a second film are bonded via an adhesive layer or a pressure-sensitive adhesive layer comprising a cured product layer of the adhesive composition or the pressure-sensitive adhesive composition. It is a manufacturing method of this, Comprising: Apply | coating the said adhesive composition or the said adhesive composition to both the bonding surface of a said 1st film and the bonding surface of a said 2nd film using a back metering application system. The present invention relates to a method for producing an optical film characterized by having a coating step of removing foreign substances and / or bubbles.

When an optical film having a laminated structure is manufactured by laminating two films, an adhesive composition or an adhesive composition is applied to one of the two films, and the other film is applied thereto. Is generally manufactured by bonding (hereinafter, also referred to as “one-side coating method”). However, in the present invention, the adhesive composition or the pressure-sensitive adhesive composition is applied to both the bonding surface of the first film and the bonding surface of the second film, and this application is performed by a coating method of a post-metering application method. Is carried out while removing foreign substances and / or bubbles. Specifically, using a post-measuring coating method, while scraping off foreign matters such as dust and dust present on both bonding surfaces of the two films to be bonded together, and derived from the adhesive composition or pressure-sensitive adhesive composition The adhesive composition or the pressure-sensitive adhesive composition is applied to both the bonding surfaces of the two films while scraping the gel-like materials and aggregates of both from the bonding surfaces of the two films. As a result, in the method for producing an optical film according to the present invention, the possibility that foreign matter exists on both bonding surfaces of the two films is extremely low. As a result, the optical film manufacturing method according to the present invention can manufacture an optical film in which appearance defects due to foreign matters are prevented.

On the other hand, in the single-sided coating method, foreign matter present on the bonding surface of the film to which the adhesive composition or the pressure-sensitive adhesive composition is not applied cannot be removed, so that the foreign matter is formed in the adhesive layer (or pressure-sensitive adhesive layer) formed after lamination. Is likely to remain. In addition, in the single-side coating method, the adhesive (or pressure-sensitive adhesive) coating surface of one film is directly on the bonding surface of the other film (the adhesive composition (or pressure-sensitive adhesive composition) is not present). Laminated while in contact. In this case, since the adhesive composition (or the pressure-sensitive adhesive composition) having viscosity is in direct contact with the bonding surface of the other film, air bubbles are easily caught during bonding. On the other hand, in the method according to the present invention, in order to apply the adhesive composition (or the pressure-sensitive adhesive composition) to both the bonding surface of the first film and the bonding surface of the second film, the adhesive ( Or an adhesive) application surface is bonded together in contact with the adhesive (or adhesive) application surface of the second film. That is, since adhesive compositions (or pressure-sensitive adhesive compositions) having viscosity are bonded together while being overlapped, bubbles are difficult to bite at the time of bonding, and bubbles are easily removed. Therefore, the method according to the present invention is superior in terms of the effect of removing bubbles as compared with the single-side coating method, and thus an optical film in which appearance defects due to bubbles are prevented can be produced.

In the present invention, the “post-measuring coating method” means a method for obtaining a predetermined coating film thickness by applying an external force to the liquid film to remove excess liquid. In the method for producing an optical film according to the present invention, when an external force is applied to a liquid film made of an adhesive composition or a pressure-sensitive adhesive composition, foreign matters such as dust and dust existing on the bonding surface are scraped off. . Specific examples of the post-metering coating method include a gravure roll coating method, a forward roll coating method, an air knife coating method, a rod / bar coating method, etc., but from the viewpoints of foreign matter removal accuracy and coating film thickness uniformity In the present invention, the coating method is preferably a gravure roll coating method using a gravure roll. In the present invention, “removing foreign matters and / or bubbles” means removing at least one or both of foreign matters and bubbles.

In the above manufacturing method, the post-metering application method is a method of applying the adhesive composition or the pressure-sensitive adhesive composition by circulation, and the adhesive composition or the second film is applied from the first film and / or the second film by application. It is preferable to have a foreign matter removing function for removing foreign matters mixed in the pressure-sensitive adhesive composition from the adhesive composition or the pressure-sensitive adhesive composition. In the post-measuring coating method, a coating liquid composed of an adhesive composition or a pressure-sensitive adhesive composition is applied to the bonding surfaces of the first film and the second film, and the coating liquid is applied to the first film and / or the first film by coating. When the foreign material removed from the bonding surface of 2 films is included, possibility that a foreign material will exist in the bonding surface of the 1st film after application | coating and the 2nd film will increase. However, the coating method used has a foreign matter removing function that removes foreign matter mixed in the adhesive composition or pressure-sensitive adhesive composition from the first film and / or second film by coating from the adhesive composition or pressure-sensitive adhesive composition. If it is provided, the amount of foreign matter in the coating solution can be significantly reduced. Thereby, possibility that a foreign material exists in the bonding surface of the 1st film and 2nd film after application | coating can be reduced significantly.

In the above manufacturing method, it is preferable that the rotation direction of the gravure roll and the traveling direction of the first film and the second film are opposite to each other. In this case, foreign matter such as dust and dust existing on the bonding surface of the first film and the bonding surface of the second film, and further, a gel-like material and an aggregate derived from the adhesive composition or the pressure-sensitive adhesive composition are scraped off. The effect is effectively enhanced, and the appearance defect of the optical film finally obtained can be more effectively prevented.

Various patterns can be formed on the surface of the gravure roll. For example, a honeycomb mesh pattern, a trapezoid pattern, a lattice pattern, a pyramid pattern, or a diagonal line pattern can be formed. In order to effectively prevent the appearance defect of the optical film finally obtained, the pattern formed on the surface of the gravure roll is preferably a honeycomb mesh pattern. In the case of a honeycomb mesh pattern, the cell volume is preferably 1 to 5 cm ³ / m ² in order to increase the surface accuracy of the coated surface after application of the adhesive composition or pressure-sensitive adhesive composition, and 2 to 3 cm ³ / m. ² is preferable. Similarly, the number of cell lines per roll is preferably 200 to 3000 lines / inch in order to increase the surface accuracy of the coated surface after application of the adhesive composition or pressure-sensitive adhesive composition. In addition, the rotation speed ratio of the gravure roll with respect to the traveling speed of the first film and the second film is preferably 100 to 300%.

By the way, as the thickness of the adhesive layer (or the pressure-sensitive adhesive layer) and further the total thickness of the optical film are larger, the foreign matter is less likely to be visually recognized, and the appearance defect tends to be less problematic. On the other hand, the thinner the adhesive layer (or pressure-sensitive adhesive layer), and the thinner the total thickness of the optical film, the easier it is to visually recognize foreign matter, and as a result, appearance defects become a problem. There are many cases. However, in the method for producing an optical film according to the present invention, an optical film having a very low incidence of foreign matters in the adhesive layer (or pressure-sensitive adhesive layer) can be produced. The manufacturing method according to the present invention is particularly useful when the manufacturing method of a particularly large polarizing film, specifically, when the first film is a transparent protective film and the second film is a polarizer. In the production method according to the present invention, even in the case of producing a thin polarizing film, particularly when the polarizer has a thickness of 10 μm or less, in the adhesive layer (or the pressure-sensitive adhesive layer), foreign matter or This is preferable because a thin polarizing film in which the occurrence of appearance defects due to bubbles can be prevented can be produced.

The present invention also relates to an optical film produced by any one of the production methods described above, and further to an image display device using the optical film described above.

In the method for producing an optical film according to the present invention, foreign matters existing on both bonding surfaces of two films to be bonded, and foreign matters existing in the adhesive composition or the pressure-sensitive adhesive composition are efficiently removed. In addition, since it is possible to prevent air bubbles from being mixed into the adhesive layer or the pressure-sensitive adhesive layer, it is possible to produce an optical film in which appearance defects due to foreign matters and / or air bubbles are prevented. . Therefore, the optical film manufacturing method according to the present invention is particularly problematic in appearance defects due to foreign matters, an optical film having a thin adhesive layer, an optical film having a thin total thickness, particularly a thin polarizing film. This is particularly effective as a manufacturing method.

It is an example of the schematic of the manufacturing method of the optical film which concerns on this invention. It is an example of the schematic diagram of the gravure roll coating system which is a post-metering coating system used for this invention.

Hereinafter, a method for producing an optical film according to the present invention will be described with reference to the drawings.

The manufacturing method of the optical film which concerns on this invention is applying an adhesive composition or an adhesive composition to both the bonding surface of a 1st film and the bonding surface of a 2nd film using a back metering application system. And a coating process for removing foreign matter.

FIG. 1 shows an example of a schematic diagram of a method for producing an optical film according to the present invention. In this embodiment, a gravure roll coating method using a gravure roll is used as a post-measuring coating method, and an adhesive composition is used. An example in which is applied. In FIG. 1, the first film 1 is conveyed rightward in FIG. 1 when the adhesive composition 3 is applied using the gravure roll coating method 10, while the gravure coating method 10 is The gravure roll provided is rotating clockwise. That is, the rotation direction of the gravure roll and the traveling direction of the first film are opposite to each other. Similarly, also 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 opposite to each other. In this case, the effect of scraping off foreign matters such as dust and dust existing on the bonding surface of the first film 1 and the bonding surface of the second film 2, and further the gel-like material and aggregate derived from the adhesive composition is effective. The appearance defect of the optical film finally obtained can be prevented more effectively.

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

FIG. 2 shows an example of a schematic diagram of a gravure roll coating method, which is a post-metering coating method used in the present invention. In particular, the adhesive composition 3 is applied to the first film 1 using the gravure coating method 10. It represents the situation. As shown in FIG. 2, when the foreign matter is removed while pressing the gravure roll 4 against the first film 1, the foreign matter such as dust and dust existing on the bonding surface of the first film 1, and further, the adhesive composition is derived. It is possible to more effectively remove the gel-like and aggregates.

As shown in FIG. 2, the gravure coating method 10 includes at least a gravure roll 4. On the surface of the gravure roll, an uneven pattern such as a honeycomb mesh pattern, trapezoid pattern, lattice pattern, pyramid pattern or oblique line pattern is formed. In order to increase the surface accuracy of the coated surface after application of the adhesive composition or pressure-sensitive adhesive composition, a honeycomb mesh pattern is preferably formed, and the cell volume is preferably 1 to 5 cm ³ / m ^2. It is preferably 2 to 3 cm ³ / m ² . Similarly, the number of cell lines per roll is preferably 200 to 3000 lines / inch in order to increase the surface accuracy of the coated surface after application of the adhesive composition or pressure-sensitive adhesive composition. The concavo-convex pattern of the gravure roll 4 has a function of applying the adhesive composition 3 to the bonding surface of the first film while scraping the adhesive composition (coating liquid) 3. In the present invention, in order to prevent foreign matters from being mixed into the adhesive composition 3, it is preferably a closed system in which the adhesive coating liquid is not exposed to the outside air.

In the example shown in FIG. 2, the foreign matter existing on the bonding surface of the first film 1, and further the gel-like substance and aggregate derived from the adhesive composition 3 are scraped off by the gravure roll 4 during the application, and the adhesive It moves in the container 5 containing the composition 3 and may be applied again to the bonding surface of the first film by the gravure roll 4. Therefore, particularly when the post-measuring application method is a method in which the adhesive composition or the pressure-sensitive adhesive composition is circulated and applied, the gravure roll 4 is scraped as the application process of the adhesive composition 3 becomes longer. There is a concern that the amount of accumulated foreign matter and the like taken will increase. However, the gravure coating method 10 has a foreign matter removing function for removing foreign matters mixed in the adhesive composition or the pressure-sensitive adhesive composition from the first film and / or the second film by coating from the adhesive composition or the pressure-sensitive adhesive composition. In the case where it is provided, the amount of foreign matter or the like present in the applied adhesive composition 3 is always kept from a very small amount to zero. Therefore, finally, the generation amount of foreign matters and the like on the bonding surface of the first film 1 can be extremely reduced. In the present invention, the foreign matter removing function includes a filter, a distillation apparatus, and centrifugal separation. When a filter is used as the foreign matter removing function, for example, the filter 7 can be arranged on the downstream side of the pump function 8 as shown in FIG. Moreover, the filter 7 can also be arrange | positioned in the upstream of the pump function 8, and the number does not ask | require. The mesh size of the filter 7 can be appropriately changed depending on the material of the first film 1 and the second film, the blending design of the adhesive composition 3, and the like, 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 after being applied by the gravure roll 4 may be discarded.

After 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 by the application method of the post-metering application method shown in FIG. 1, for example, using a nip roll 9. The 1st film 1 and the 2nd film 2 are bonded through an adhesive composition (adhesive layer).

When the optical film is produced in a continuous line, the line speed of the first film and / or the second film depends on the curing time of the adhesive composition (or the pressure-sensitive adhesive composition), but is preferably 1 to 500 m / min. Preferably, it is 5 to 300 m / min, and more preferably 10 to 100 m / min. If the line speed is too low, the productivity is poor, or the damage to the first film / and / or the second film is too great to produce an optical film that can withstand a durability test. If the line speed is too high, the adhesive composition may not be sufficiently cured, and the target adhesiveness may not be obtained.

Next, the optical film manufactured by the manufacturing method according to the present invention will be described below. Such an optical film includes a laminated structure in which at least a first film and a second film are bonded via an adhesive layer or an adhesive layer composed of a cured product layer of an adhesive composition or an adhesive composition.

<Adhesive layer or pressure-sensitive adhesive layer>
The adhesive layer or the pressure-sensitive adhesive layer is not particularly limited as long as it is optically transparent, and water-based, solvent-based, hot-melt, and radical-curing types are used. When producing a transparent conductive laminate or a polarizing film as the optical film, a transparent curable adhesive layer is suitable.

<Transparent curable adhesive layer>
For forming the transparent curable adhesive layer, for example, a radical curable adhesive is suitably used as the adhesive composition. Examples of the radical curable adhesive include active energy ray curable adhesives such as an electron beam curable adhesive and an ultraviolet curable adhesive. In particular, an active energy ray curable adhesive 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.

UV curing adhesives can be broadly classified into radical polymerization curing adhesives and cationic polymerization adhesives. In addition, the radical polymerization curable adhesive can be used as a thermosetting adhesive.

Examples of the curable component of the radical polymerization curable adhesive include a compound having a (meth) acryloyl group and a compound having a vinyl group. These curable components may be monofunctional or bifunctional or higher. Moreover, these curable components can be used individually by 1 type or in combination of 2 or more types. As these curable components, for example, compounds having a (meth) acryloyl group are suitable.

Specific examples of the compound having a (meth) acryloyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and 2-methyl-2-nitro. Propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, t-pentyl (meth) Acrylate, 3-pentyl (meth) acrylate, 2,2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate 4-methyl-2 Propyl pentyl (meth) acrylate, n- octadecyl (meth) (meth) acrylic acid (1-20 carbon atoms) such as acrylates alkyl esters.

Examples of the compound having a (meth) acryloyl group include cycloalkyl (meth) acrylate (for example, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), aralkyl (meth) acrylate (for example, benzyl (meth)). Acrylates), polycyclic (meth) acrylates (eg 2-isobornyl (meth) acrylate, 2-norbornylmethyl (meth) acrylate, 5-norbornen-2-yl-methyl (meth) acrylate, 3-methyl -2-norbornylmethyl (meth) acrylate, etc.), hydroxyl group-containing (meth) acrylic acid esters (eg, hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl) -Butyl (meth) methacrylate), alkoxy group or phenoxy group-containing (meth) acrylic acid esters (2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate) , 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), epoxy group-containing (meth) acrylic acid esters (eg glycidyl (meth) acrylate, etc.), halogen-containing (Meth) acrylic acid esters (for example, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,2-trifluoroethylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl) Pill (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.) and the like.

Examples of compounds having a (meth) acryloyl group other than the above include amide group-containing monomers such as hydroxyethyl acrylamide, N-methylol acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, and (meth) acrylamide. It is done. Moreover, nitrogen-containing monomers, such as acryloyl morpholine, etc. are 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) acryloyl group and a vinyl group, and the compound can be used as a crosslinking component. It can also be mixed with the adhesive component. Examples of the curable component that becomes such a crosslinking component include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, and EO. Modified diglycerin tetraacrylate, Aronix M-220 (manufactured by Toagosei Co., Ltd.), light acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DCP-A (kyoeisha) Chemical), SR-531 (Sartomer), CD-536 (Sartomer) and the like. Moreover, various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate monomers, and the like are included as necessary.

The radical polymerization curable adhesive contains the curable component, and in addition to the component, a radical polymerization initiator is added according to the type of curing. When the adhesive is used as an electron beam curable type, it is not particularly necessary that the adhesive contains a radical polymerization initiator, but when it is used as an ultraviolet curable type or a thermosetting type, radical polymerization is started. An agent is used. The amount of the radical polymerization initiator used is usually about 0.1 to 10 parts by weight, preferably 0.5 to 3 parts by weight per 100 parts by weight of the curable component. Moreover, the radical polymerization curable adhesive may be added with a photosensitizer that increases the curing speed and sensitivity of the electron beam typified by a carbonyl compound, if necessary. The amount of the photosensitizer used is usually about 0.001 to 10 parts by weight, preferably 0.01 to 3 parts by weight per 100 parts by weight of the curable component.

Examples of the curable component of the cationic polymerization curable adhesive include compounds having an epoxy group or an oxetanyl group. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various generally known curable epoxy compounds can be used. As a preferable epoxy compound, a compound having at least two epoxy groups and at least one aromatic ring in the molecule, or at least two epoxy groups in the molecule, at least one of which has an alicyclic ring. Examples thereof include a compound formed between two adjacent carbon atoms constituting it.

For forming the transparent curable adhesive layer, examples of the water-based curable adhesive include vinyl polymer, gelatin, vinyl latex, polyurethane, isocyanate, polyester, and epoxy. . Such an adhesive layer composed of an aqueous adhesive can be formed as an aqueous solution coating / drying layer, etc., but when preparing the aqueous solution, a catalyst such as a crosslinking agent, other additives, and an acid can be used as necessary. Can be blended.

The water-based adhesive is preferably an adhesive containing a vinyl polymer, and the vinyl polymer is preferably a polyvinyl alcohol resin. Moreover, as a polyvinyl alcohol-type resin, the adhesive agent containing the polyvinyl alcohol-type resin which has an acetoacetyl group is more preferable from the point which improves 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. For example, boric acid and borax, carboxylic acid compounds, alkyl diamines; isocyanates; epoxies; monoaldehydes; dialdehydes; amino-formaldehyde resins; and divalent or trivalent metal salts and oxides thereof Is mentioned.

The adhesive that forms the curable adhesive layer may contain an additive as necessary. Examples of additives include coupling agents such as silane coupling agents and titanium coupling agents, adhesion promoters typified by ethylene oxide, additives that improve wettability with transparent films, acryloxy group compounds and hydrocarbons (Natural and synthetic resins) and other additives that improve mechanical strength and processability, UV absorbers, anti-aging agents, dyes, processing aids, ion trapping agents, antioxidants, tackifiers, Stabilizers such as fillers (other than metal compound fillers), plasticizers, leveling agents, foaming inhibitors, antistatic cracks, heat stabilizers, hydrolysis stabilizers, and the like.

The thickness of the transparent curable adhesive layer is preferably 0.01 to 10 μm. More preferably, it is 0.1 to 5 μm, and still more preferably 0.3 to 4 μm. Since the height between each film layer of appearance defects due to foreign matters or bubbles is generally several μm (about 2 to 5 μm), if the thickness of the adhesive layer is 2 μm or less, the problem of appearance defects is significant. Become. However, since the optical film manufacturing method according to the present invention can prevent appearance defects, it is particularly useful as a method for manufacturing an optical film having an adhesive layer thickness of 2 μm or less.

The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive. Various pressure-sensitive adhesives can be used as the pressure-sensitive adhesive, such as rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, polyvinylpyrrolidone-based pressure-sensitive adhesives, Examples include acrylamide-based adhesives and cellulose-based adhesives. An adhesive base polymer is selected according to the type of the adhesive. Among the pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they are excellent in optical transparency, exhibit appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and are excellent in weather resistance and heat resistance. The

The radical polymerization curable adhesive can be used in an electron beam curable type or an ultraviolet curable type.

In the electron beam curable type, any appropriate condition can be adopted as the electron beam irradiation condition as long as the radical polymerization curable adhesive composition can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and may be insufficiently cured. If the acceleration voltage exceeds 300 kV, the penetration force through the sample is too strong and damages the transparent protective film and the polarizer. There is a risk of giving. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficiently cured, and when it exceeds 100 kGy, the transparent protective film and the polarizer are damaged, resulting in a decrease in mechanical strength and yellowing, thereby obtaining predetermined optical characteristics. I can't.

The electron beam irradiation is usually performed in an inert gas, but if necessary, it may be performed in the atmosphere or under a condition where a little oxygen is introduced. Depending on the material of the transparent protective film, by appropriately introducing oxygen, the transparent protective film surface where the electron beam first hits can be obstructed to prevent oxygen damage and prevent damage to the transparent protective film. An electron beam can be irradiated efficiently.

On the other hand, in the case of using a transparent protective film imparted with ultraviolet absorbing ability in the ultraviolet curable type, light having a wavelength shorter than about 380 nm is absorbed. Therefore, light having a wavelength shorter than 380 nm is applied to the active energy ray curable adhesive composition. Since it does not reach, it does not contribute to the polymerization reaction. Furthermore, light having a wavelength shorter 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 the ultraviolet curable type is adopted in the present invention, it is preferable to use a device that does not emit light having a wavelength shorter than 380 nm as the ultraviolet ray generating device, and more specifically, the integrated illuminance and wavelength in the wavelength range of 380 to 440 nm. The ratio with the integrated illuminance in the range of 250 to 370 nm is preferably 100: 0 to 100: 50, and more preferably 100: 0 to 100: 40. As the ultraviolet ray satisfying such a relationship of integrated illuminance, a gallium-filled metal halide lamp and an LED light source that emits light in the wavelength range of 380 to 440 nm are preferable. Alternatively, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, incandescent lamp, xenon lamp, halogen lamp, carbon arc lamp, metal halide lamp, fluorescent lamp, tungsten lamp, gallium lamp, excimer laser or sunlight as the light source, It is also possible to use a light having a wavelength shorter than 380 nm by using a band pass filter.

The first film and / or the second film can be used without particular limitation as long as it is a transparent optical film. As described above, the greater the thickness of the adhesive layer (or the pressure-sensitive adhesive layer) and the greater the total thickness of the optical film, the more difficult it is to visually recognize foreign matter, and the appearance defects tend to be less problematic. On the other hand, the thinner the adhesive layer (or pressure-sensitive adhesive layer), and the thinner the total thickness of the optical film, the easier it is to visually recognize foreign matter, and as a result, appearance defects become a problem. There are many cases. However, in the method for producing an optical film according to the present invention, an optical film having a very low incidence of foreign matters in the adhesive layer (or pressure-sensitive adhesive layer) can be produced. The manufacturing method according to the present invention is particularly useful when the manufacturing method of a particularly large polarizing film, specifically, when the first film is a transparent protective film and the second film is a polarizer. In the production method according to the present invention, even in the case of producing a thin polarizing film, particularly when the polarizer has a thickness of 10 μm or less, in the adhesive layer (or the pressure-sensitive adhesive layer), foreign matter or This is preferable because a thin polarizing film in which the occurrence of appearance defects due to bubbles can be prevented can be produced.

The first film and / or the second film may be subjected to a surface modification treatment before applying the active energy ray-curable adhesive composition. Specific examples of the treatment include corona treatment, plasma treatment, and saponification treatment.

In the method for producing an optical film according to the present invention, the first film and the second film are preferably bonded via an adhesive layer formed by a cured product layer of the radical polymerization curable adhesive composition. However, an easy-adhesion layer can be provided between the first film and the second film. The easy adhesion layer can be formed of, for example, various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins can be used alone or in combination of two or more. Moreover, you may add another additive for formation of an easily bonding layer. Specifically, a stabilizer such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat resistance stabilizer may be used.

The easy-adhesion layer is formed by applying and drying a material for forming the easy-adhesion layer on a film by a known technique. The material for forming the easy-adhesion layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of thickness after drying, smoothness of application, and the like. The thickness of the easy-adhesion 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. Note that a plurality of easy-adhesion layers can be provided, but also in this case, the total thickness of the easy-adhesion layers is preferably in the above range.

Hereinafter, a polarizing film will be described as an example of the optical film. For example, in FIG. 1, a polarizing film including a laminated structure in which at least a first film and a second film are bonded is necessary on the first film 1 that is a transparent protective film and the transparent protective film or the PET base material. Accordingly, the laminated second film 2 in which a polarizer is laminated via an adhesive layer can be produced by bonding them together via an adhesive layer made of a cured product layer of the adhesive composition. In this embodiment, the polarizer surface of the laminated second film 2 is used as a bonding surface, and an example in which the adhesive composition is applied to the bonding surface is shown.

In the production method according to the present invention, an optical film in which the generation of foreign matters in the adhesive layer can be effectively prevented can be produced, so that the appearance defect due to the foreign matters can be a big problem. Suitable for manufacturing. 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 base material and a polarizer) is preferably 60 μm or less, and 40 μm or less. It is more preferable that In addition, when the total thickness of the polarizing film is 100 μm or less, since the thickness is thin, appearance defects due to foreign matters in the adhesive layer often become a problem. However, in the manufacturing method according to the present invention, an optical film in which the generation of foreign matters in the adhesive layer can be effectively prevented can be manufactured. Therefore, when manufacturing a thin polarizing film having a total thickness of 100 μm or less, particularly Is suitable for producing a thin polarizing film having a total thickness of 50 μm or less. When producing a thin polarizing film in the present invention, it is possible to effectively prevent appearance defects even when producing a thin polarizing film including a thin polarizer having a thickness of 10 μm or less.

The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymer films such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. And polyene-based oriented films such as those obtained by adsorbing a functional material and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. 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 film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous iodine solution and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of boric acid or potassium iodide. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched in an aqueous solution of 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 preferable in that the thickness unevenness is small, the visibility is excellent, the dimensional change is small, the durability is excellent, and the thickness of the polarizing film can be reduced.

As the thin polarizer, typically, JP-A-51-069644, JP-A-2000-338329, WO2010 / 100917, PCT / JP2010 / 001460, or Japanese Patent Application No. 2010- And a thin polarizer described in Japanese Patent Application No. 269002 and Japanese Patent Application No. 2010-263692. These thin polarizers can be obtained by a production method including a step of stretching and dyeing a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a stretching resin base material in a laminated state. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

Among the thin polarizers, among the production methods including the step of stretching in the state of a laminate and the step of dyeing, WO2010 / 100917 pamphlet, PCT / PCT / PCT / JP 2010/001460 specification, or Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692, the one obtained by a production method including a step of stretching in a boric acid aqueous solution is preferable. What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric acid aqueous solution as described in Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 is preferable.

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

The thin high-performance polarizer generates a PVA-based resin layer by applying and drying a PVA-based resin on a resin substrate having a thickness of at least 20 μm, and the generated PVA-based resin layer is used as a dichroic dyeing solution. So that the dichroic substance is adsorbed on the PVA resin layer, and the PVA resin layer on which the dichroic substance is adsorbed is integrated with the resin base material in the boric acid aqueous solution so that the total draw ratio is the original length. It can manufacture by extending | stretching so that it may become 5 times or more.

Moreover, it is a method for producing a laminate film including a thin high-functional polarizer in which a dichroic material is oriented, and includes a resin substrate having a thickness of at least 20 μm and a PVA resin on one side of the resin substrate. The said laminated body containing the process of producing | generating the laminated body film containing the PVA-type resin layer formed by apply | coating and drying aqueous solution, and the PVA-type resin layer formed in the single side | surface of the resin base material A step of adsorbing the dichroic substance to the PVA resin layer contained in the laminate film by immersing the film in a dye solution containing the dichroic substance, and a PVA resin adsorbing the dichroic substance A step of stretching the laminate film including a layer in a boric acid aqueous solution so that the total stretching ratio is 5 times or more of the original length, and a PVA resin layer on which a dichroic substance is adsorbed Integrated with As a result, a thickness of 7 μm or less, a single transmittance of 42.0% or more, and a degree of polarization of 99.95% or more consisting of a PVA-based resin layer in which a dichroic material is oriented on one surface of a resin base material. The thin high-performance polarizer can be produced by including a step of producing a laminate film in which a thin high-performance polarizer having the above optical properties is formed.

The above-mentioned Japanese Patent Application Nos. 2010-269002 and 2010-263692 are thin polarizers, which are continuous web polarizers made of a PVA-based resin in which a dichroic material is oriented, and are amorphous esters. A laminate including a PVA-based resin layer formed on a thermoplastic resin base material is stretched in a two-stage stretching process consisting of air-assisted stretching and boric acid-water stretching to a thickness of 10 μm or less. It is. Such a thin polarizer has P> − (100.929T−42.4-1) × 100 (where T <42.3) and P ≧ 99, where T is the single transmittance and P is the polarization degree. .9 (where T ≧ 42.3) is preferable.

Specifically, the thin polarizer is a stretch intermediate composed of an oriented PVA resin layer by high-temperature stretching in the air with respect to a PVA resin layer formed on an amorphous ester thermoplastic resin substrate of a continuous web. A colored intermediate product comprising a PVA-based resin layer in which a dichroic material (preferably iodine or a mixture of iodine and an organic dye) is oriented by adsorption of the dichroic material to the stretched intermediate product and a step of generating the product. A thin polarizer comprising a step of generating a product, and a step of generating a polarizer having a thickness of 10 μm or less comprising a PVA-based resin layer in which a dichroic material is oriented by stretching in a boric acid solution with respect to a colored intermediate product It can be manufactured by a manufacturing method.

In this production method, the total draw ratio of the PVA resin layer formed on the amorphous ester thermoplastic resin base material by high-temperature drawing in air and drawing in boric acid solution should be 5 times or more. desirable. The liquid temperature of the boric acid aqueous solution for boric-acid water extending | stretching can be 60 degreeC or more. Before stretching the colored intermediate product in the aqueous boric acid solution, it is desirable to insolubilize the colored intermediate product. In this case, the colored intermediate product is added to the aqueous boric acid solution whose liquid temperature does not exceed 40 ° C. It is desirable to do so by dipping. The amorphous ester-based thermoplastic resin base material is amorphous polyethylene containing copolymerized polyethylene terephthalate copolymerized with isophthalic acid, copolymerized polyethylene terephthalate copolymerized with cyclohexanedimethanol, or other copolymerized polyethylene terephthalate. It can be terephthalate and is preferably made of a transparent resin, and the thickness thereof can be 7 times or more the thickness of the PVA resin layer to be formed. In addition, the draw ratio of high-temperature drawing in the air is preferably 3.5 times or less, and the drawing temperature of high-temperature drawing in the air is preferably not less than the glass transition temperature of the PVA resin, specifically in the range of 95 ° C to 150 ° C. When performing high temperature stretching in the air by free end uniaxial stretching, the total stretching ratio of the PVA resin layer formed on the amorphous ester thermoplastic resin base material is preferably 5 to 7.5 times . In addition, when performing high-temperature stretching in the air by uniaxial stretching at the fixed end, the total stretching ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material is 5 times or more and 8.5 times or less. Is preferred.
More specifically, a thin polarizer can be produced by the following method.

A base material for a continuous web of isophthalic acid copolymerized polyethylene terephthalate (amorphous PET) in which 6 mol% of isophthalic acid is copolymerized is prepared. The glass transition temperature of amorphous PET is 75 ° C. A laminate comprising a continuous web of amorphous PET substrate and a polyvinyl alcohol (PVA) layer is prepared as follows. Incidentally, the glass transition temperature of PVA is 80 ° C.

A 200 μm-thick amorphous PET base material and a 4-5% PVA aqueous solution in which PVA powder having a polymerization degree of 1000 or more and a saponification degree of 99% or more are dissolved in water are prepared. Next, an aqueous PVA solution is applied to a 200 μm thick amorphous PET substrate and dried at a temperature of 50 to 60 ° C. to obtain a laminate in which a 7 μm thick PVA layer is formed on the amorphous PET substrate. .

A thin high-functional polarizer having a thickness of 3 μm is manufactured from the laminate including the PVA layer having a thickness of 7 μm through the following steps including a two-step stretching process of air-assisted stretching and boric acid water stretching. In the first-stage aerial auxiliary stretching step, the laminate including the 7 μm-thick PVA layer is integrally stretched with the amorphous PET substrate to produce a stretched laminate including the 5 μm-thick PVA layer. Specifically, in this stretched laminate, a laminate including a 7 μm-thick PVA layer is subjected to a stretching apparatus disposed in an oven set to a stretching temperature environment of 130 ° C. so that the stretching ratio is 1.8 times. Are stretched uniaxially at the free end. By this stretching treatment, the PVA layer contained in the stretched laminate is changed to a 5 μm thick PVA layer in which PVA molecules are oriented.

Next, a colored laminate in which iodine is adsorbed on a 5 μm-thick PVA layer in which PVA molecules are oriented is generated by a dyeing process. Specifically, this colored laminate has a single transmittance of the PVA layer constituting the high-performance polarizer finally produced by using the stretched laminate in a dye solution containing iodine and potassium iodide at a liquid temperature of 30 ° C. Iodine is adsorbed to the PVA layer contained in the stretched laminate by dipping for an arbitrary period of time so as to be 40 to 44%. In this step, the staining solution uses water as a solvent, and an iodine concentration within the range of 0.12 to 0.30% by weight and a potassium iodide concentration within the range of 0.7 to 2.1% by weight. The concentration ratio of iodine and potassium iodide is 1 to 7. Incidentally, potassium iodide is required to dissolve iodine in water. More specifically, the stretched laminate is immersed for 60 seconds in a dyeing solution having an iodine concentration of 0.30% by weight and a potassium iodide concentration of 2.1% by weight. A colored laminate is adsorbed on the substrate.

Further, the colored laminate is further stretched integrally with the amorphous PET base material by the second stage boric acid water stretching step to produce an optical film laminate including a PVA layer constituting a highly functional polarizer having a thickness of 3 μm. To do. Specifically, the optical film laminate is subjected to stretching by applying the colored laminate to a stretching apparatus provided in a treatment apparatus set to a boric acid aqueous solution having a liquid temperature range of 60 to 85 ° C. containing boric acid and potassium iodide. It is stretched uniaxially at the free end so that the magnification is 3.3 times. More specifically, the liquid temperature of the boric acid aqueous solution is 65 ° C. It also has a boric acid content of 4 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 5 parts by weight with respect to 100 parts by weight of water. In this step, the colored laminate having an adjusted iodine adsorption amount is first immersed in an aqueous boric acid solution for 5 to 10 seconds. After that, the colored laminate is passed as it is between a plurality of sets of rolls with different peripheral speeds, which is a stretching apparatus installed in the processing apparatus, and the stretching ratio can be freely increased to 3.3 times over 30 to 90 seconds. Stretch uniaxially. By this stretching treatment, the PVA layer contained in the colored laminate is changed into a PVA layer having a thickness of 3 μm in which the adsorbed iodine is oriented higher in one direction as a polyiodine ion complex. This PVA layer constitutes a high-functional polarizer of the optical film laminate.

Although not an indispensable step for the production of an optical film laminate, the optical film laminate was removed from the boric acid aqueous solution and adhered to the surface of the 3 μm-thick PVA layer formed on the amorphous PET substrate by the washing step. It is preferable to wash boric acid with an aqueous potassium iodide solution. Thereafter, the washed optical film laminate is dried by a drying process using hot air at 60 ° C. The cleaning process is a process for eliminating appearance defects such as boric acid precipitation.

Similarly, it is not an indispensable process for producing an optical film laminate, but an adhesive is applied to the surface of a 3 μm-thick PVA layer formed on an amorphous PET substrate by a bonding and / or transfer process. However, after bonding the 80 μm thick triacetyl cellulose film, the amorphous PET substrate can be peeled off, and the 3 μm thick PVA layer can be transferred to the 80 μm thick triacetyl cellulose film.

[Other processes]
The manufacturing method of said thin polarizer may contain another process other than the said process. Examples of other steps include an insolubilization step, a crosslinking step, and a drying (adjustment of moisture content) step. The other steps can be performed at any appropriate timing. The insolubilization step is typically performed by immersing the PVA resin layer in a boric acid aqueous solution. By performing the insolubilization treatment, water resistance can be imparted to the PVA resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilizing bath (boric acid aqueous solution) is preferably 20 ° C. to 50 ° C. Preferably, the insolubilization step is performed after the laminate is manufactured and before the dyeing step and the underwater stretching step. The crosslinking step is typically performed by immersing the PVA resin layer in an aqueous boric acid solution. By performing the crosslinking treatment, water resistance can be imparted to the PVA resin layer. The concentration of the boric acid aqueous solution is preferably 1 to 4 parts by weight with respect to 100 parts by weight of water. Moreover, when performing a bridge | crosslinking process after the said dyeing | staining process, it is preferable to mix | blend iodide further. By blending iodide, elution of iodine adsorbed on the PVA resin layer can be suppressed. The blending amount of iodide is preferably 1 to 5 parts by weight with respect to 100 parts by weight of water. Specific examples of the iodide are as described above. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably 20 ° C. to 50 ° C. Preferably, the crosslinking step is performed before the second boric acid aqueous drawing step. In a preferred embodiment, the dyeing step, the crosslinking step, and the second boric acid aqueous drawing step are performed in this order.

The material for forming the transparent protective film provided on one or both sides of the polarizer is preferably a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of the polymer that forms the transparent protective film include polymer blends. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. 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 content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

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

The thickness of the transparent protective film can be determined as appropriate, but is generally about 1 to 500 μm from the viewpoints of workability such as strength and handleability and thin layer properties. In particular, 20 to 80 μm is preferable, and 30 to 60 μm is more preferable.

In addition, when providing a transparent protective film on both surfaces of a polarizer, the transparent protective film which consists of the same polymer material may be used by the front and back, and the transparent protective film which consists of a different polymer material etc. may be used.

Functional surfaces such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the transparent protective film to which the polarizer is not adhered. The functional layers such as the hard coat layer, antireflection layer, antisticking layer, diffusion layer and antiglare layer can be provided on the transparent protective film itself, and separately provided separately from the transparent protective film. You can also

The polarizing film of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing film or semi-transmissive polarizing film in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing film of the present invention, an elliptical polarizing film or circularly polarizing film in which a retardation film is further laminated on a polarizing film. A wide viewing angle polarizing film obtained by further laminating a viewing angle compensation film on a film or a polarizing film, or a polarizing film obtained by further laminating a brightness enhancement film on the polarizing film is preferred.

An optical film obtained by laminating the above optical layer on a polarizing film can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. It is excellent in stability and assembly work, and has the advantage of improving the manufacturing process of a liquid crystal display device and the like. For the lamination, an appropriate adhesive means such as a pressure-sensitive adhesive layer can be used. When adhering the above polarizing film and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

A pressure-sensitive adhesive layer for adhering to other members such as a liquid crystal cell can be provided on the polarizing film described above or an optical film in which at least one polarizing film is laminated. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or rubber-based polymer is appropriately used as a base polymer. It can be selected and used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing film or an optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of a polarizing film or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, 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 until it is put to practical use. Thereby, it can prevent contacting an adhesive layer in the usual handling state. As the separator, except for the above thickness conditions, for example, an appropriate thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foamed sheet, metal foil, or a laminate thereof, or a silicone-based or long sheet as necessary. Appropriate ones according to the prior art, such as those coated with an appropriate release agent such as a chain alkyl type, fluorine type or molybdenum sulfide, can be used.

The polarizing film or optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing film or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing film or optical film by invention, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, an STN type, or a π type can be used.

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

Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto. “Parts by weight” in the composition means the number of parts when the total amount of the composition is 100 parts by weight.

(1) Adjustment of adhesive composition <Adjustment of active energy ray-curable adhesive composition>
HEAA (hydroxyethyl acrylamide) [manufactured by Kojin Co., Ltd.] 38.5 parts by weight, Aronix M-220 (tripropylene glycol diacrylate) [manufactured by Toagosei Co., Ltd.] 20.0 parts by weight, ACMO (acryloylmorpholine) [Kojinsha 38.5 parts by weight, KAYACURE DETX-S (diethylthioxanthone) [manufactured by Nippon Kayaku Co., Ltd.], 1.5 parts by weight, IRGACURE907 (2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane- 1-On) 1.5 parts by weight [manufactured by BASF] was mixed and stirred at 50 ° C. for 1 hour to obtain an active energy ray-curable adhesive.

<Preparation of polyvinyl alcohol-based adhesive composition>
Polyvinyl alcohol-based resin containing acetoacetyl group (average polymerization degree: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) to 100 parts, Under temperature conditions, an aqueous solution dissolved in pure water and adjusted to a solid content concentration of 3.7% was prepared. An aqueous adhesive solution was prepared by adding 18 parts of an aqueous colloidal alumina solution (average particle size 15 nm, solid content concentration 10%, positive charge) to 100 parts of the aqueous solution.

<Organic solvent-based adhesive composition>
Cemedine 198L (Cemedine) was used.

(2) Production of Thin Polarizer In order to produce a thin polarizer, first, a laminate in which a PVA layer having a thickness of 24 μm is formed on an amorphous PET substrate is stretched by air-assisted stretching at a stretching temperature of 130 ° C. Next, a colored laminate is produced by dyeing the stretched laminate, and further, the colored laminate is amorphous so that the total draw ratio becomes 5.94 times by stretching in boric acid water at a stretching temperature of 65 degrees. An optical film laminate comprising a 10 μm thick PVA layer stretched together with a PET substrate was produced. The PVA molecules in the PVA layer formed on the amorphous PET substrate by such two-stage stretching are oriented in the higher order, and the iodine adsorbed by the dyeing is oriented in the one direction as the polyiodine ion complex. It was possible to produce an optical film laminate (second film (total thickness 40 μm)) including a PVA layer having a thickness of 5 μm, constituting a thin polarizer.

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
1 and 2, a gravure roll coating method 10 (MCD coater (manufactured by Fuji Machine Co., Ltd.)) (cell shape: honeycomb mesh pattern, number of gravure roll cell lines: 1000 / inch, rotation speed) Ratio 140%), and applying the adhesive composition 3 to both the bonding surface of the first film 1 and the bonding surface of the second film 2, the polarizing film is removed while removing foreign substances and bubbles. The second film 2 made of the PET base material and the thin polarizer was coated with the adhesive composition 3 so that the thin polarizer surface became the bonding surface, and the adhesive composition 3 was dried. It applied to the 1st film and the 2nd film so that the thickness of a back adhesive layer might be set to 1 micrometer. Was used with a use foreign matter removal method).

<Active energy rays>
After passing through the line shown in FIG. 1, as an active energy ray, an ultraviolet ray (gallium filled metal halide lamp) irradiation device: Fusion UV Systems, Inc. Light HAMMER10 bulb: V bulb Peak illuminance: 1600 mW / cm ² , integrated dose The adhesive composition 3 was cured using 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 9, Comparative Examples 1 to 6
Type of adhesive composition for bonding first film and second film, presence / absence of application of adhesive composition to first film and / or second film, type of post-measuring application method, formation pattern of gravure roll surface The optical film was manufactured by the same method as Example 1 except having changed into the thing of Table 1. In the bar coater coating method and the air knife coating method, commercially available coating devices were used.

<Counting method of the number of foreign matters in the adhesive layer> The number of appearance defects (foreign matter-derived and (lamination) bubble-derived appearance defects in the adhesive layer of the polarizing film by visual inspection and reflection inspection using an automatic inspection device. The number (pieces / m ² ) was counted. The results are shown in Table 1.

Claims (10)

1. It is a method for producing an optical film including a laminated structure in which at least a first film and a second film are bonded via an adhesive layer or an adhesive layer composed of a cured product layer of an adhesive composition or an adhesive composition. And
   By applying the adhesive composition or the pressure-sensitive adhesive composition to both the bonding surface of the first film and the bonding surface of the second film using a post-metering application method, foreign matter and / or bubbles The manufacturing method of the optical film characterized by having the application | coating process which removes.
2. The post-measuring application method is a method in which the adhesive composition or the pressure-sensitive adhesive composition is circulated and applied to the adhesive composition or the pressure-sensitive adhesive composition from the first film and / or the second film by application. The manufacturing method of the optical film of Claim 1 provided with the foreign material removal function which removes the mixed foreign material from the said adhesive composition or an adhesive composition.
3. The method for producing an optical film according to claim 1 or 2, wherein the coating method is a gravure roll coating method using a gravure roll.
4. The method for producing an optical film according to claim 3, wherein the rotation direction of the gravure roll is opposite to the traveling direction of the first film and the second film.
5. The method for producing an optical film according to claim 3 or 4, wherein the pattern formed on the surface of the gravure roll is a honeycomb mesh pattern.
6. The method for producing an optical film according to any one of claims 3 to 5, wherein a rotation speed ratio of the gravure roll with respect to a traveling speed of the first film and the second film is 100 to 300%.
7. The method for producing an optical film according to any one of claims 1 to 6, wherein the first film is a transparent protective film, and the second film is a polarizer.
8. The method for producing an optical film according to claim 7, wherein the polarizer has a thickness of 10 μm or less.
9. An optical film produced by the production method according to any one of claims 1 to 8.
10. An image display device using the optical film according to claim 9.

Images