KR20160033193A - Optical film production method, optical film, and image display device - Google Patents

Abstract

A step of applying a liquid material having a viscosity of 1 to 10000 cP to the concave surface of the first film and the concave surface of the second film using a post-metering coating method to remove foreign matter Way. In the case where the liquid material is applied only to the concave surface of one film, when the liquid material is applied to the concave surface of the film not coated with the liquid material, or when the liquid material is applied to the concave surface of both films, , And a second coating step of applying the adhesive composition or the pressure-sensitive adhesive composition using a post-metering coating method.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing an optical film, an optical film, and an image display device using the optical film,

The present invention relates to an optical film comprising a laminate structure in which at least a first film and a second film are laminated via an adhesive layer or a pressure-sensitive adhesive layer comprising a cured layer of an adhesive composition or a pressure- . Further, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device, or a PDP using the optical film.

Liquid crystal display devices are rapidly developing on the market in watches, mobile phones, PDAs, notebook PCs, PC monitors, DVD players, TVs, and the like. The liquid crystal display device is made by visualizing the polarization state due to the switching of liquid crystal, and from the principle of display, a polarizer is used. Particularly in applications such as TVs, higher brightness, higher contrast, and a wider viewing angle are required, and polarizing films are increasingly required to have high transmittance, high polarization degree, and high color reproducibility.

As a polarizer, an iodine-based polarizer having a structure in which iodine is adsorbed to, for example, polyvinyl alcohol (hereinafter simply referred to as " PVA ") in view of high transmittance and high polarization degree is most widely used . In general, a polarizing film has been used in which a transparent protective film is adhered to both surfaces 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, it has become mainstream to use an active energy ray-curable resin composition containing no water or an organic solvent, in view of advantages such as omission of the drying step and less dimensional change.

In the case of producing an optical film by bonding a plurality of films using an active energy ray-curable resin composition, for example, an adhesive composition is applied only to the concave surface of a transparent protective film, It is general to produce an optical film containing a laminated structure. However, in the conventional manufacturing method, when foreign substances such as dust or dust adhere to the surface of the polarizer or transparent protective film before applying the adhesive composition or the like, or when the adhesive composition contains minute foreign matters, Foreign matters remain, and as a result, appearance defects may occur.

The following Patent Document 1 discloses a method for producing an optical film comprising a step of applying a thin layer of an optical function layer having a wet coating amount of 10 ml / m 2 or less on a transparent support or a primer layer formed on the transparent support, There is disclosed a process for producing an optical film comprising a step of removing foreign matter having a height of 10 占 퐉 or more from the surface of the transparent support or the undercoat layer before applying the functional layer.

Japanese Patent Application Laid-Open No. 2008-180905

However, as a result of the investigation by the present inventor, it has been found that the technique described in Patent Document 1 attempts to crumble and remove foreign matter by calendering or the like in a state in which foreign matter already exists on a transparent support or the like. Precision is not high, and minute foreign matters remain after the removal process. For this reason, the technique described in Patent Document 1 is difficult to apply to a method of manufacturing a thin optical film in which appearance defects become a problem, particularly when the thickness is thin and minute foreign matters are present.

SUMMARY OF THE INVENTION The present invention has been accomplished in view of the above problems, and an object of the present invention is to provide a method of manufacturing an optical film in which occurrence of appearance defects caused by foreign matter and / or bubbles is prevented even if the optical film is thin.

Means for Solving the Problem As a result of diligent studies for solving the above problems, the present inventors have found that, when an optical film comprising a laminated structure in which at least two films are laminated is produced, a specific coating system is employed, It has been found that foreign substances such as dust and dust present on the coplanar surface of the film can be removed by applying the liquid material. Further, more effectively, by applying the adhesive composition or the pressure-sensitive adhesive composition to the cohesive surface of at least one film in the subsequent step of applying the adhesive composition (or pressure-sensitive adhesive composition), removal of foreign matter and / Layer or the pressure-sensitive adhesive composition layer can be carried out at one time. The present invention is obtained as a result of the study of this example, and has the following constitution.

That is, the present invention is a method for producing an optical film comprising a laminate 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 layer of an adhesive composition or a pressure- And a first coating step of applying a liquid material having a viscosity of 1 to 10000 cP to the concave surface of the first film and the concave surface of the second film by using a coating method to remove foreign matter And a method for producing an optical film.

In the case of producing an optical film having a laminated structure by bonding two films to each other, it is general to manufacture an optical film by applying an adhesive composition or a pressure-sensitive adhesive composition to one of the two films and bonding the other film to the adhesive composition or the pressure- (Hereinafter, also referred to as " single-side coating method "). However, since the single-sided coating method can not remove the foreign substances present on the cohesive surface of the film that is not coated with the adhesive composition or the pressure-sensitive adhesive composition, there is a high possibility that foreign matter remains in the adhesive layer (or pressure-sensitive adhesive layer) formed after lamination. On the other hand, in the present invention, a liquid material having a viscosity of 1 to 10000 cP is applied to both the concave surface of the first film and the concave surface of the second film (first coating step). Then, the application of the liquid material is carried out while removing the foreign matter by using a coating method of a post-metering coating method. As a result, foreign matter such as dust or dust existing on the concave surface of the film coated with the liquid material is scraped off. As a result, in the method for producing an optical film according to the present invention having the first coating step, it is possible to produce an optical film in which occurrence of appearance defects due to foreign substances is prevented even if the optical film is thin.

In the above manufacturing method, it is preferable that the second coating step of removing foreign matter and / or air bubbles by applying the adhesive composition or the pressure-sensitive adhesive composition to the concave surface of at least one of the films using the post-metering coating method desirable. According to this constitution, the liquid material and / or the adhesive composition (or the pressure-sensitive adhesive composition) is applied at least once to the concave surfaces of both the first film and the second film by using a post-metering coating method. This makes it possible to more surely scrape off foreign matter such as dust and dust present on both of the two adjoining faces of the cohesive two films, and also to prevent the gel composition or agglomerates derived from the adhesive composition or the adhesive composition from adhering to both of the two coats of the two films . As a result, in the method for producing an optical film, it is possible to produce an optical film in which generation of appearance defects due to foreign substances is more reliably prevented.

Further, in the single-sided coating method, the adhesive (or pressure-sensitive adhesive) application side of one film is directly bonded to the other side of the film (the adhesive composition (or the pressure-sensitive adhesive composition) does not exist). In this case, since the adhesive composition (or the pressure-sensitive adhesive composition) having a viscosity is in direct contact with the concave surface of the other film, bubbles are likely to come into contact with each other at the time of applying. In the method according to the present invention, on the other hand, when the adhesive composition (or the pressure-sensitive adhesive composition) is applied to both the concave surface of the first film and the concave surface of the second film, , And is adhered while being in contact with the application surface of the adhesive (or pressure-sensitive adhesive) of the second film. That is, since the adhesive composition (or the pressure-sensitive adhesive composition) having viscosity is superimposed on each other and bonded together, it is difficult for the bubbles to come into contact with each other at the time of coalescence, and the bubbles are easily released. Therefore, in the method according to the present invention, particularly when applying the adhesive composition (or the pressure-sensitive adhesive composition) to both the cohesive face of the first film and the cohesive face of the second film, It is possible to produce an optical film in which occurrence of appearance defects caused by bubbles is prevented.

In the present invention, the " post-metering coating system " means a system in which an external force is applied to a liquid film to remove excess liquid to obtain a predetermined coating film thickness. In the method for producing an optical film according to the present invention, when an external force applied to a liquid film composed of an adhesive composition or a pressure-sensitive adhesive composition is applied, foreign matter such as dust or dust existing on the coaptation surface is 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, and a rod / bar coating method. However, in view of accuracy of removal of foreign matter and uniformity of coating film thickness , In the present invention, it is preferable that the coating method is a gravure roll coating method using a gravure roll. In the present invention, "removal of foreign matter and / or bubbles" means removal of at least one or both of foreign matter and bubbles.

In the above production method, it is preferable that the liquid material contains at least 50% by weight of water. If the liquid material to be applied to remove foreign matter remains in the second coating step of applying the adhesive composition (or the pressure-sensitive adhesive composition), there is a possibility of causing a poor adhesion (or poor adhesion). Therefore, after the first coating step, the liquid material needs to be removed promptly in the drying step and the like. And, if the liquid material contains at least 50% by weight of water, the drying step after application of the liquid material can be simplified, which is preferable.

In the above production method, it is preferable that the liquid material further contains an alcohol. According to such a constitution, the wettability (leveling property) of the liquid material itself on the film can be improved and the evaporation rate of the liquid material can be increased. Therefore, the drying and removing efficiency of the liquid material can be further improved, and productivity is improved, which is preferable.

In the above manufacturing method, the post-metering coating method is a method of applying the adhesive composition or the pressure-sensitive adhesive composition in a circulating manner, and a method of coating a foreign matter mixed in the adhesive composition or the pressure- Is removed from the adhesive composition or the pressure-sensitive adhesive composition. As a post-metering coating method, a coating liquid composed of an adhesive composition or a pressure-sensitive adhesive composition is applied to the laminated surface of the first film and / or the second film, and the coating liquid is applied to the first film and / The possibility that foreign matter exists on the surface of the first film and the second film after the application of the foreign matter is high. However, when the coating method to be used is provided with 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 the application, from the adhesive composition or the pressure- It is possible to remarkably reduce the amount of foreign substances in the liquid. As a result, the possibility that foreign matter is present on the concave surface of the first film and the second film after coating can be remarkably reduced.

In the above manufacturing method, it is preferable that the rotational direction of the gravure roll and the advancing direction of the first film and the second film are opposite to each other. In this case, the effect of scraping foreign substances such as dust and dust existing on the coalescence surface of the first film and the coalescence surface of the second film, and further the gel or aggregate derived from the adhesive composition or the pressure-sensitive adhesive composition is effectively increased, The appearance defects of the optical film can be prevented more effectively.

Various patterns can be formed on the surface of the gravure roll. For example, a honeycomb pattern, a trapezoidal pattern, a lattice pattern, a pyramid pattern, or a diagonal pattern can be formed. It is preferable that the pattern formed on the surface of the gravure roll is a honeycomb pattern in order to effectively prevent appearance defects of the finally obtained optical film. In the honeycomb pattern, the cell volume is preferably 1 to 5 cm 3 / m 2, more preferably 2 to 3 cm 3 / m 2 in order to increase the surface accuracy of the coated surface after applying the adhesive composition or the pressure-sensitive adhesive composition. Similarly, in order to increase the surface accuracy of the coated surface after application of the adhesive composition or the pressure-sensitive adhesive composition, it is preferable that the number of cell lines per 1 inch of the roll is 200 to 3000 lines / inch. It is preferable that the rotational speed ratio of the gravure roll to the advancing speed of the first film and the second film is 100 to 300%.

However, the thicker the thickness of the adhesive layer (or the pressure-sensitive adhesive layer) and hence the greater the total thickness of the optical film, the more difficult it is for the foreign substances to be visually observed, and the appearance defects tend to be unlikely to be problematic. On the other hand, the thinner the thickness of the adhesive layer (or the pressure-sensitive adhesive layer) becomes, the thinner the total thickness of the optical film becomes, and the more likely the foreign substance becomes visible, as a result, the more the appearance defect becomes a problem in 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 matter in the adhesive layer (or the pressure-sensitive adhesive layer) can be produced. Therefore, among the optical films, Specifically, the manufacturing method related to the present invention is particularly useful when the first film is a transparent protective film and the second film is a polarizer. The manufacturing method according to the present invention is capable of producing appearance defects due to foreign matter or bubbles in the adhesive layer (or pressure-sensitive adhesive layer) even when a thin polarizing film is produced, as in the case where the thickness of the polarizer is 10 m or less It is preferable since the thin polarizing film can be produced.

The present invention also relates to an image display device characterized in that an optical film produced by any of the above-described manufacturing methods, and further, the optical film described above is used.

In the method for producing an optical film according to the present invention, it is possible to efficiently remove foreign matters present on both of the two adjoining faces of the two films to be laminated, and foreign matters existing in the adhesive composition or in the pressure-sensitive adhesive composition, An optical film in which the occurrence of defects is prevented can be produced. Therefore, the method for producing an optical film according to the present invention is a method for producing an optical film having a thin adhesive layer, particularly an optical film having a thin total thickness, particularly a thin polarizing film Method.

Fig. 1 is an example of a schematic view of a method for producing an optical film according to the present invention.
Fig. 2 is an example of a schematic view of a gravure roll coating system, which is a post-metering coating system used in the present invention.

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

The method for producing an optical film according to the present invention is a method for removing an impurity by applying a liquid material having a viscosity of 1 to 10000 cP to the concave surface of the first film and the concave surface of the second film using a post- The first coating step.

Fig. 1 shows an example of a schematic view 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- And an adhesive surface of the second film are coated on both sides of the second film. From the viewpoint of removing foreign matter, it is preferable to apply the liquid material to both the cohesive face of the first film and the cohesive face of the second film.

In the first coating step, the liquid material applied to the first film and the second film using the gravure roll coating system (10A) is subjected to a coating treatment to remove foreign substances present on the concave surface of the two films to be laminated, And a viscosity of 1 to 10,000 cP is used. Particularly, as the liquid material, it is preferable to use water containing as a main component and concretely containing at least 50% by weight of water, more preferably 60% by weight or more of water, more preferably 70% Is more preferably used.

Further, in order to improve the wettability (leveling property) of the liquid material itself on the film and the evaporation rate of the liquid material, it is preferable that the liquid material further contains alcohol, and the liquid material contains 50 to 100% More preferably, it contains an alcohol in an amount of 50 to 70% by weight and an alcohol in an amount of 30 to 50% by weight.

After the first coating step and before the second coating step is reached, a drying step for drying and removing the liquid material may be formed if necessary. In the drying step, a drying method known to a person skilled in the art can be used.

1, the first film 1 is transported toward the right side in FIG. 1 at the time when the adhesive composition 3 is applied using the gravure roll coating system 10B, and on the other hand, The gravure roll provided in the image forming apparatus 10B rotates clockwise. That is, the rotational direction of the gravure roll and the advancing direction of the first film are opposite to each other. Likewise, in the relationship between the second film 2 and the gravure roll, the direction of rotation of the gravure roll and the direction of advance of the second film 2 are opposite to each other. In this case, the effect of scraping foreign matters such as dust and dust existing on the coplanar surface of the first film 1 and the coplanar surface of the second film 2, as well as the gel or aggregate derived from the adhesive composition, It is possible to more effectively prevent appearance defects of the finally obtained optical film.

The rotation speed of the gravure roll relative to the advancing speed of the first film 1 and the second film 2 is preferably 100 to 300% and more preferably 150 to 300% in order to more effectively prevent appearance defects of the finally obtained optical film. To 250%.

2 shows an example of a schematic view of a gravure roll coating system used in the present invention, in which a first film 1 is coated with an adhesive composition 3 by using a gravure coating system 10B in particular, . As shown in Fig. 2, when foreign matter is removed while pressing the gravure roll 4 against the first film 1, foreign matter such as dust and dust existing on the concave surface of the first film 1, It is possible to more effectively remove the gel or aggregate derived from the adhesive composition.

As shown in Fig. 2, the gravure coating system 10B includes at least a gravure roll 4. Fig. A concavo-convex pattern such as a honeycomb pattern, a trapezoidal pattern, a lattice pattern, a pyramid pattern, or an oblique line pattern is formed on the surface of the gravure roll. In order to improve the surface accuracy of the coated surface after application of the adhesive composition or the pressure-sensitive adhesive composition, it is preferable that a honeycomb pattern is formed, and the cell volume is preferably 1 to 5 cm 3 / m 2, more preferably 2 to 3 cm 3 / Do. Similarly, in order to increase the surface accuracy of the coated surface after application of the adhesive composition or the pressure-sensitive adhesive composition, it is preferable that the number of cell lines per 1 inch of the roll is 200 to 3000 lines / inch. The concavo-convex pattern of the gravure roll 4 has a function of applying the adhesive composition 3 to the concave surface of the first film while scraping off the adhesive composition (coating liquid) 3. In the present invention, in order to prevent foreign matter from being mixed into the adhesive composition (3), it is preferable that the adhesive application liquid is a closed system which is not exposed to the outside air.

In the example shown in Fig. 2, the foreign substance present on the coplanar surface of the first film 1, and further the gel product or aggregate derived from the adhesive composition 3 are scraped off by the gravure roll 4, It is sometimes transferred into the container 5 containing the adhesive composition 3 and again applied to the concave surface of the first film by the gravure roll 4. [ Therefore, particularly in the case of a system in which the post-metering application method is applied by circulating the adhesive composition or the pressure-sensitive adhesive composition, as the coating process of the adhesive composition 3 becomes prolonged, the accumulation amount of foreign substances scraped off by the gravure roll 4 Is increased. However, in the case where the gravure coating system 10B has a foreign matter removing function for removing foreign matters mixed in the adhesive composition or the adhesive composition from the first film and / or the second film by application, from the adhesive composition or the adhesive composition , The amount of the foreign substances or the like present in the adhesive composition 3 to be applied is always kept at a trace amount to zero. Therefore, finally, the amount of foreign matter or the like generated on the concave surface of the first film 1 can be significantly reduced. In the present invention, the foreign matters removing function includes a filter, a distillation apparatus, and a centrifugal separator. When the filter is used as the foreign matter removing function, as shown in Fig. 2, for example, the filter 7 can be disposed on the downstream side of the pump function 8. The filter 7 may be disposed upstream of the pump function 8, and the number of the filters 7 is not limited. The mesh size of the filter 7 can be suitably changed according to the material of the first film 1 and the second film or the blend design of the adhesive composition 3 and is preferably 10 m or smaller and more preferably 5 m or smaller Do. The adhesive composition 3 may be circulated by using a tank 6 or the like as shown in Fig. 2, and the adhesive composition 3 after being applied by the gravure roll 4 may be discarded.

In the present invention, the gravure coating method (10A) used in the first coating step of applying the liquid material can employ the same method as the gravure coating method (10B).

The adhesive composition 3 is applied to the application surface of the first film 1 and / or the application surface of the second film 2 in the second application step by the application method of the metering application system shown in Fig. The first film 1 and the second film 2 are bonded to each other via an adhesive composition (adhesive layer) using, for example, a nip roll 9.

In the case of producing the optical film as a continuous line, the line speed of the first film and / or the second film varies depending on the curing time of the adhesive composition (or the pressure-sensitive adhesive composition), but is preferably 1 to 500 m / min, Min, preferably 5 to 300 m / min, more preferably 10 to 100 m / min. When the line speed is too small, it is impossible to produce an optical film which is insufficient in productivity or excessively damages to the first film and / or the second film, and can endure a durability test and the like. If the line speed is excessively large, the curing of the adhesive composition becomes insufficient, and the intended adhesive property may not be obtained.

Next, the optical film produced 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 a pressure-sensitive adhesive layer comprising a cured layer of an adhesive composition or a pressure-sensitive adhesive composition.

≪ Adhesive layer or pressure-sensitive adhesive layer >

When the adhesive layer or the pressure-sensitive adhesive layer is optically transparent, it is not particularly limited, and various types of water-based, solvent-based, hot-melt-based, and radical-curing types are used. In the case of producing a transparent conductive laminate or a polarizing film as an optical film, a transparent curing type adhesive layer is preferable.

≪ Transparent curable adhesive layer >

As the adhesive composition, for example, a radical-curable adhesive is preferably used for forming the transparent curable adhesive layer. As the radical curing type adhesive, an active energy ray curing type adhesive such as an electron beam curable type or an ultraviolet ray curable type can be exemplified. In particular, an active energy ray curable type which is curable in a short time is preferable, and further, an ultraviolet curable type adhesive which can be cured with a low energy is preferable.

As ultraviolet curable adhesives, radical curing curable adhesives and cationic curable adhesives can be categorized. In addition, the radical polymerization curing type 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 more. These curable components may be used singly or in combination of two or more. As the curable component, for example, a compound having a (meth) acryloyl group is preferable.

Specific examples of the compound having a (meth) acryloyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) (Meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s- (Meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-hexyl Acrylates such as n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl- ) Acrylic acid (C 1-20) alkyl esters.

Examples of the compound having a (meth) acryloyl group include a cycloalkyl (meth) acrylate (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) (Meth) acrylate (for example, benzyl (meth) acrylate and the like), polycyclic (meth) acrylates (for example, 2-isobornyl (meth) acrylate and 2-norbornylmethyl (Meth) acrylate), hydroxyl group-containing (meth) acrylate esters (for example, methacrylic acid esters) (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) methacrylate and the like), an alkoxy group or a phenoxy group- (Meth) acrylate esters (2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) (Meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol Methacrylic acid esters such as glycidyl (meth) acrylate, halogen-containing (meth) acrylic esters (such as 2,2,2-trifluoroethyl (meth) acrylate, (Meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluoro (meth) acrylate, (Meth) acrylate), and alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate).

Examples of the compound having a (meth) acryloyl group other than the above include hydroxyethyl acrylamide, N-methylol acrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, And amide group-containing monomers such as amide. And nitrogen-containing monomers such as acryloylmorpholine.

Examples of the curable component of the radical polymerization curable adhesive include compounds having a plurality of polymerizable double bonds such as (meth) acryloyl groups and vinyl groups, and the compounds may be mixed with an adhesive component as a crosslinking component You may. Examples of the curable component which becomes a crosslinking component include, for example, tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, (Manufactured by Toa Chemical Industry Co., Ltd.), light acrylate 1,9ND-A (manufactured by Kyowa Chemical Industry Co., Ltd.), light acrylate DGE-4A (available from Kyowa Chemical Industry Co., Ltd.), ethylene glycol diacrylate, EO-modified diglycerin tetraacrylate, Aronix M- SR-531 (manufactured by Sartomer Company), CD-536 (manufactured by Sartomer Company), and the like. If necessary, various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, and various (meth) acrylate monomers may be cited.

The radical polymerization curing type adhesive contains the above-mentioned curable component, but in addition to the above components, a radical polymerization initiator is added according to the curing type. When the adhesive is used in an electron beam hardening type, it is not particularly necessary to include a radical polymerization initiator in the adhesive, but when used in an ultraviolet hardening type or thermosetting type, a radical polymerization initiator is used. The amount of the radical polymerization initiator to be 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. Further, to the radical polymerization curing type adhesive, a photosensitizer which improves the curing speed and sensitivity by electron beam represented by a carbonyl compound or the like may be added, if necessary. The amount of the photosensitizer is generally 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 and 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 a compound having at least two epoxy groups in the molecule, at least one of which has two adjacent carbon atoms constituting an alicyclic ring And the like, and the like.

For the formation of the transparent curing type adhesive layer, for example, a vinyl polymer type, a gelatin type, a vinyl type latex type, a polyurethane type, an isocyanate type, a polyester type, an epoxy type and the like can be cited as an aqueous curing type adhesive . The adhesive layer made of such an aqueous adhesive can be formed as a coating and drying layer of an aqueous solution. However, when preparing the aqueous solution, a catalyst such as a crosslinking agent, other additives, and an acid may be added as needed.

As the water-based adhesive, it is preferable to use an adhesive containing a vinyl polymer, and as the vinyl polymer, a polyvinyl alcohol-based resin is preferable. As the polyvinyl alcohol-based resin, an adhesive containing a polyvinyl alcohol-based resin having an acetoacetyl group is more preferable in terms of improving durability. As the crosslinking agent that can be blended in the polyvinyl alcohol-based resin, a compound having at least two functional groups having reactivity with the polyvinyl alcohol-based resin can be preferably used. For example, it is possible to use boric acid or borax, carboxylic acid compounds, alkyldiamines, isocyanates, epoxies, monoaldehydes, dialdehydes, amino-formaldehyde resins, Oxides.

The adhesive forming the curable adhesive layer may contain an additive agent as appropriate. Examples of the additive include a coupling agent such as a silane coupling agent and a titanium coupling agent, an adhesion promoter represented by ethylene oxide, an additive for improving wettability with a transparent film, an acryloxy group compound or a hydrocarbon type (natural or synthetic resin) An antioxidant, a dye, a processing aid, an ion trap agent, an antioxidant, a tackifier, a filler (other than a metal compound filler), a plasticizer, a leveling agent, a foam inhibitor , Stabilizers such as antistatic agents, heat stabilizers, and moisture stabilizers.

The thickness of the transparent curing adhesive layer is preferably 0.01 to 10 mu m. More preferably 0.1 to 5 占 퐉, and still more preferably 0.3 to 4 占 퐉. Further, since the height of the appearance defects originating from foreign matter or air bubbles between the respective film layers is generally several micrometers (about 2 to 5 占 퐉), if the thickness of the adhesive layer is 2 占 퐉 or less, the problem of appearance defects becomes large. However, the production method of the optical film according to the present invention is particularly useful as a method for producing an optical film in which the thickness of the adhesive layer is not more than 2 占 퐉 because occurrence of appearance defects can be prevented.

The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used. Examples of the pressure-sensitive adhesive include rubber pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, vinyl alkyl ether pressure-sensitive adhesives, polyvinylpyrrolidone pressure-sensitive adhesives, polyacrylamide pressure- . Depending on the type of the pressure-sensitive adhesive, a tacky base polymer is selected. Of the above pressure-sensitive adhesives, an acrylic pressure-sensitive adhesive is preferably used because it has excellent optical transparency, exhibits appropriate wettability, cohesiveness and adhesive property, and is excellent in weather resistance and heat resistance.

The radical polymerization curing type adhesive can be used as an electron beam hardening type or an ultraviolet ray hardening type.

In the electron beam hardening type, the irradiation condition of the electron beam may be any appropriate condition as long as the condition is such that the radical polymerization hardening 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 accelerating voltage is less than 5 kV, the electron beam may not reach the adhesive, which may cause insufficient curing. If the accelerating voltage exceeds 300 kV, the penetration force through the sample is too strong to damage the transparent protective film or polarizer. There is a concern. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. If the irradiation dose is less than 5 kGy, the adhesive becomes insufficient in curing. If the irradiation dose exceeds 100 kGy, the transparent protective film or the polarizer is damaged, resulting in a decrease in mechanical strength or yellowing, and desired optical characteristics can not be obtained.

The electron beam irradiation is usually carried out in an inert gas atmosphere, but it may be carried out under a condition in which air or oxygen is slightly introduced, if necessary. By properly introducing oxygen, it is possible to forcibly oxygen inhibit the surface of the transparent protective film, which is first contacted with the electron beam, to prevent damage to the transparent protective film, and it is possible to efficiently irradiate only the adhesive with the electron beam .

On the other hand, when a transparent protective film imparting ultraviolet ray absorbing ability is used in the ultraviolet ray curing type, light having a wavelength shorter than 380 nm is absorbed by light having a wavelength shorter than approximately 380 nm, and thus light having a shorter wavelength than 380 nm does not reach the active energy ray curable adhesive composition. It does not contribute to the polymerization reaction. In addition, the 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 curing type is adopted in the present invention, it is preferable to use an apparatus which does not emit light having a shorter wavelength than 380 nm as the ultraviolet ray generating apparatus, and more specifically, And the integrated illuminance of the wavelength range of 250 to 370 nm is preferably 100: 0 to 100: 50, more preferably 100: 0 to 100: 40. As the ultraviolet rays satisfying the relationship of the integrated illuminance, gallium-encapsulated metal halide lamps and LED light sources emitting light in the wavelength range of 380 to 440 nm are preferable. Alternatively, the light source may be a metal halide lamp, a fluorescent lamp, a tungsten lamp, a gallium lamp, an excimer laser or a solar light as a light source, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, an incandescent lamp, a xenon lamp, a halogen lamp, Pass filter may be used to shield light of shorter wavelength than 380 nm.

The first film and / or the second film may be used as a transparent optical film without particular limitation. As described above, the thicker the thickness of the adhesive layer (or the pressure-sensitive adhesive layer), or the total thickness of the optical film, becomes, the more likely it is that the foreign matter becomes hard to be visually observed and the appearance defect tends to become unlikely to be a problem. On the other hand, the thinner the thickness of the adhesive layer (or the pressure-sensitive adhesive layer) becomes, the thinner the total thickness of the optical film becomes, and the more likely the foreign substance becomes visible, as a result, the more the appearance defect becomes a problem in 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 matter in the adhesive layer (or the pressure-sensitive adhesive layer) can be produced. Therefore, among the optical films, Specifically, the manufacturing method related to the present invention is particularly useful when the first film is a transparent protective film and the second film is a polarizer. The manufacturing method according to the present invention is capable of producing appearance defects due to foreign matter or bubbles in the adhesive layer (or pressure-sensitive adhesive layer) even when a thin polarizing film is produced, as in the case where the thickness of the polarizer is 10 m or less It is preferable since the thin polarizing film can be produced.

The first film and / or the second film may be subjected to 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 the cured layer of the radical polymerization curable adhesive composition, Between the two films, an easy adhesion layer can be formed. The adhesion facilitating layer can be formed by various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone type, a polyamide skeleton, a polyimide skeleton, and a polyvinyl alcohol skeleton, for example . These polymer resins may be used singly or in combination of two or more. Further, other additives may be added to form the adhesion-facilitating layer. Specifically, stabilizers such as a tackifier, ultraviolet absorber, antioxidant, heat stabilizer and the like may be used.

The easy-to-adhere layer is formed by applying the forming material of the easy-to-adhere layer onto a film by a known technique and drying it. The forming material of the easy-to-adhere layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying, the original activity of coating, and the like. The thickness of the facilitating layer after drying is preferably 0.01 to 5 占 퐉, more preferably 0.02 to 2 占 퐉, and still more preferably 0.05 to 1 占 퐉. Also, a plurality of layers can be formed as the easy-to-adhere layer. In this case as well, the total thickness of the easy-to-adhere layer is preferably in the above range.

Hereinafter, a polarizing film will be described as an example of the optical film. A polarizing film including a laminated structure in which at least a first film and a second film are bonded is formed on the first film 1 as a transparent protective film and a transparent protective film or PET substrate, (2) in which a polarizer is laminated via an adhesive layer according to the above-described method, via an adhesive layer comprising a cured layer of an adhesive composition. In the present embodiment, the polarizing surface of the second laminated film 2 is set as a coherent surface, and an example of applying the adhesive composition to such a coherent surface is shown.

In the manufacturing method according to the present invention, it is possible to manufacture an optical film in which foreign matter is effectively prevented from being generated in the adhesive layer, and thus an optical film having a particularly thin thickness, . Therefore, the thickness of the first film and the second film (in this embodiment, the first film is the protective film and the second film is the laminated film of the PET substrate and the polarizer) is preferably 60 m or less, more preferably 40 m or less desirable. Further, when the total thickness of the polarizing film is 100 m or less, the thickness of the polarizing film is thin, so that appearance defects due to foreign substances in the adhesive layer often become a problem. However, in the manufacturing method according to the present invention, it is possible to produce an optical film in which foreign substances are effectively prevented from being generated in the adhesive layer. Therefore, when a thin polarizing film having a total thickness of 100 m or less is produced, It is preferable in the case of producing a thin polarizing film having a thickness of 탆 or less. In the case of producing a thin polarizing film in the present invention, occurrence of appearance defects can be effectively prevented even when a thin polarizing film including a thin polarizer having a thickness of 10 m or less is produced.

The polarizer is not particularly limited and various kinds of polarizers can be used. Examples of the polarizer include dichroic materials such as iodine and dichroic dyes, for example, on a hydrophilic polymer film such as a polyvinyl alcohol film, a partially porous polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer system partially saponified film A polyvinyl alcohol-based dehydrated product, a polyvinyl chloride dehydrochloric acid-treated product, and the like. Among them, a polarizer comprising a polyvinyl alcohol film and a dichromatic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 80 占 퐉 or less.

A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching can be produced by, for example, dying polyvinyl alcohol in an aqueous solution of iodine, and stretching it to 3 to 7 times the original length. If necessary, it may be immersed in an aqueous solution of boric acid, potassium iodide or the like. If necessary, the polyvinyl alcohol film may be dipped in water and washed with water before dyeing. The polyvinyl alcohol film is washed with water to thereby clean the surface of the polyvinyl alcohol film and to prevent unevenness such as deviation in dyeing by swelling the polyvinyl alcohol film. The stretching may be carried out after dyeing with iodine, stretching while dyeing, and dyeing with iodine after stretching. It can be stretched 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 탆 or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 mu m. Such a thin polarizer preferably has a small thickness deviation, an excellent visibility, and a small dimensional change, so that it is preferable that the polarizer is excellent in durability, and further, the thickness and thickness of the polarizing film can be reduced.

Typical examples of the thin polarizer include those described in Japanese Laid-Open Patent Publication Nos. 51-069644 and 2000-338329, WO2010 / 100917, PCT / JP2010 / 001460, and Japanese Patent Application No. 2010-269002 And a thin polarizer described in Specification and Japanese Patent Application No. 2010-263692. These thin polarizers can be obtained by a manufacturing method including a step of stretching a layer of a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) and a lead resin base material in a laminate state and a step of dyeing. With this method, even if the PVA resin layer is thin, it can be stretched without any problem such as breakage due to stretching because it is supported on the resin base material for drawing.

The thin polarizers described in WO2010 / 100917 pamphlet, PCT / JP201010, JP02010 / 100917, JP02010 / 100917 and JP2010 / 100917 can be used as the thin polarizers in that they can be stretched at a high magnification and can be improved in polarizing performance, In a boric acid aqueous solution as described in Japanese Patent Application No. 2010-269002 or Japanese Patent Application No. 2010-263692, in particular, Japanese Patent Application No. 2010 In the aqueous boric acid solution described in the specification of Japanese Patent Application Laid-Open No. H06-269002 or in Japanese Patent Application No. 2010-263692, it is preferred that it is obtained by a process including a step of auxiliary drawing publicly before stretching.

The thin, high-performance polarizer disclosed in the specification of PCT / JP2010 / 001460 is a thin, high-performance polarizer made of a PVA-based resin in which a dichromatic material is aligned and formed integrally on a resin substrate, A transmittance of 42.0% or more, and a polarization degree of 99.95% or more.

The thin, high-performance polarizer is produced by applying a PVA resin to a resin substrate having a thickness of at least 20 탆 and drying the PVA resin layer, and immersing the resulting PVA resin layer in a dyeing solution of a dichroic substance , A PVA resin layer in which a dichroic substance is adsorbed to a PVA resin layer and a dichroic substance is adsorbed is stretched in an aqueous solution of boric acid together with a resin base so that the total draw ratio is 5 times or more the original length can do.

Further, a method for producing a laminated film including a thin, highly functional polarizer in which a dichroic substance is aligned, comprising the steps of: applying and drying an aqueous solution containing a PVA resin on one side of a resin substrate and a resin substrate having a thickness of at least 20 mu m A step of producing a laminate film comprising a PVA resin layer formed on the surface of the resin base material; and a step of immersing the laminate film comprising a resin base material and a PVA resin layer formed on one side of the resin base material in a dyeing solution containing a dichroic material , A step of adsorbing the dichroic material to the PVA resin layer contained in the laminate film, and a step of forming the laminated film including the PVA resin layer on which the dichroic substance is adsorbed, in the aqueous solution of boric acid, And a step of stretching the PVA resin layer on which the dichroic substance is adsorbed in unison with the resin base material, A laminated film having a thickness of 7 占 퐉 or less, a single-layer transmittance of 42.0% or more, and a polarization degree of 99.95% or more and having a thin film type high-performance polarizer formed on the PVA resin layer with a dichroic substance oriented on one side thereof is produced By including the step, the thin, highly functional polarizer can be produced.

The above-mentioned Japanese Patent Application No. 2010-269002 specification or Japanese Patent Application No. 2010-263692 specification

A thin polarizer is a polarizer of a continuous web made of a PVA-based resin in which a dichroic material is oriented, and is a polarizer comprising a PVA resin layer formed on an amorphous ester-based thermoplastic resin base material, But is stretched by a stretching process to have a thickness of 10 mu m or less. Such a thin polarizer is characterized in that P> - (100.929T-42.4-1) x 100 (where T <42.3) and P≥99.9 (however, T ≥ 42.3) are satisfied when the simple transmittance is T and the polarization degree is P It is preferable to have optical characteristics satisfying the conditions.

Specifically, the thin polarizer comprises a step of producing a drawn intermediate product comprising a PVA-based resin layer oriented by air high-temperature stretching to a PVA-based resin layer formed on an amorphous ester-based thermoplastic resin base material of a continuous web , A step of producing a colored intermediate product comprising a PVA-based resin layer in which a dichroic substance (preferably a mixture of iodine or iodine and an organic dye) is oriented by adsorption of a dichroic substance to the drawn intermediate product, And a step of producing a polarizer having a thickness of 10 占 퐉 or less and made of a PVA resin layer in which a dichroic substance is oriented by stretching in boric acid in water for the product.

In this production method, it is preferable that the total draw ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material by public hot drawing and boric acid in water drawing is 5 times or more. Boric acid The liquid temperature of the boric acid aqueous solution for in-water elongation can be 60 占 폚 or higher. It is preferable to carry out the insolubilization treatment with respect to the colored intermediate product before stretching the colored intermediate product in the aqueous solution of boric acid. In this case, the coloring intermediate product is immersed in an aqueous boric acid solution having a liquid temperature not exceeding 40 캜 desirable. The amorphous ester thermoplastic resin base material may be a copolymerized polyethylene terephthalate copolymerized with isophthalic acid, a copolymerized polyethylene terephthalate copolymerized with cyclohexane dimethanol, or an amorphous polyethylene terephthalate containing other copolymerized polyethylene terephthalate, The thickness of the PVA resin layer is preferably 7 times or more the thickness of the PVA resin layer to be formed. The stretching magnification of the air high-temperature stretching is preferably 3.5 times or less, and the stretching temperature of the public high-temperature stretching is preferably not lower than the glass transition temperature of the PVA-based resin, specifically 95 ° C to 150 ° C. It is preferable that the total draw ratio of the PVA resin layer formed on the amorphous ester thermoplastic resin base material is not less than 5 times and not more than 7.5 times when the public high temperature stretching is performed by free uniaxial stretching. When the public high-temperature stretching is carried out by a fixed single uniaxial stretching, the total stretch ratio of the PVA-based resin layer formed on the amorphous ester-based thermoplastic resin base material is preferably 5 times or more and 8.5 times or less.

More specifically, a thin polarizer can be produced by the following method.

A substrate of 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 the amorphous PET is 75 캜. A laminate composed of an amorphous PET substrate and a polyvinyl alcohol (PVA) layer of a continuous web is prepared as follows. In addition, the glass transition temperature of PVA is 80 ° C.

An amorphous PET substrate having a thickness of 200 탆 and a PVA aqueous solution having a PVA concentration of 4 to 5% in which PVA powder having a degree of polymerization of 1000 or more and a saponification degree of 99% or more are dissolved in water is prepared. Next, a PVA aqueous solution is applied to an amorphous PET substrate having a thickness of 200 mu m and dried at a temperature of 50 to 60 DEG C to obtain a laminate having a PVA layer having a thickness of 7 mu m formed on an amorphous PET substrate.

A laminate including a PVA layer having a thickness of 7 占 퐉 is subjected to the following steps including a two-step stretching process of air-assisted stretching and boric acid in-water stretching to produce a thin, highly functional polarizer having a thickness of 3 占 퐉. The laminate including the PVA layer having a thickness of 7 占 퐉 is integrally stretched with the amorphous PET substrate by the air assisted stretching process of the first stage to produce a stretched laminate including the PVA layer having a thickness of 5 占 퐉. Specifically, this oriented laminate was obtained by laminating a laminate including a PVA layer having a thickness of 7 占 퐉 to a stretching apparatus arranged in an oven set at a stretching temperature environment of 130 占 폚 and stretching it in a single free- It is. By this stretching treatment, the PVA layer contained in the stretched laminate is changed to a PVA layer having a thickness of 5 탆 in which the PVA molecules are oriented.

Next, a colored layered product in which iodine is adsorbed to a PVA layer having a thickness of 5 占 퐉 in which PVA molecules are oriented is produced by a dyeing step. Specifically, this colored layered product is obtained by laminating the drawn laminate to a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 占 폚, so that the ultimate transmittance of the PVA layer constituting the highly functional polarizer finally produced is 40 to 44% The PVA layer contained in the stretched laminate is adsorbed to iodine by dipping for an arbitrary time. In the present step, the dyeing solution is prepared so that the concentration of iodine is within a range of 0.12 to 0.30% by weight, and the concentration of potassium iodide is within a range of 0.7 to 2.1% by weight with water as a solvent. The ratio of iodine to potassium iodide is 1 to 7. In addition, potassium iodide is required to dissolve iodine in water. More specifically, the drawn laminate was immersed in a dyeing solution having an iodine concentration of 0.30 wt% and a potassium iodide concentration of 2.1 wt% for 60 seconds to obtain a colored laminate in which iodine was adsorbed on a PVA layer having a thickness of 5 mu m .

In addition, the colored laminate is further stretched integrally with the amorphous PET substrate by a boric acid in-water elongation step of the second stage to produce an optical film laminate comprising a PVA layer constituting a highly functional polarizer with a thickness of 3 탆 . Specifically, this optical film laminate is obtained by applying the colored laminate to a drawing apparatus which is arranged in a processing apparatus set in a boric acid aqueous solution having a liquid temperature range of 60 to 85 DEG C containing boric acid and potassium iodide, It is stretched in one axis. More specifically, the liquid temperature of the aqueous solution of boric acid is 65 캜. It is also made such that the content of boric acid is 4 parts by weight with respect to 100 parts by weight of water, and the content of potassium iodide is 5 parts by weight with respect to 100 parts by weight of water. In the present step, the colored laminate having the iodine adsorption amount adjusted is first immersed in an aqueous solution of boric acid for 5 to 10 seconds. After that, the colored laminate is directly passed through a plurality of sets of rolls whose principal axes are different from that of the oriented apparatus extended to the processing apparatus, and the uncoloured single axes are stretched so that the draw ratio is 3.3 times over 30 to 90 seconds. By this stretching treatment, the PVA layer contained in the colored laminate is changed to a PVA layer having a thickness of 3 占 퐉 in which iodine adsorbed is highly oriented in one direction as a polyiodide ion complex. This PVA layer constitutes a highly functional polarizer of the optical film laminate.

The optical film laminate is taken out from the aqueous solution of boric acid by a washing step and the boric acid attached to the surface of the 3 mu m thick PVA layer formed on the amorphous PET substrate is subjected to iodination Potassium aqueous solution. After that, the washed optical film laminate is dried by a drying process by hot air at 60 캜. The cleaning process is a process for eliminating appearance defects such as boric acid precipitation.

Likewise, the adhesive is applied to the surface of the 3 占 퐉 -thick PVA layer formed on the amorphous PET substrate by the bonding and / or transferring process, which is not essential for the production of the optical film laminate, After the acetylcellulose film is laminated, the amorphous PET substrate is peeled off, and the PVA layer having a thickness of 3 탆 can be transferred to a triacetylcellulose film having a thickness of 80 탆.

[Other processes]

The manufacturing method of the above-described thin polarizer may include other processes in addition to the above processes. Examples of the other steps include an insolubilization step, a crosslinking step, and a drying step (controlling the water content). Other processes can be carried out at any appropriate timing. The above-mentioned insolubilization step is typically performed by immersing a PVA-based resin layer in an aqueous solution of boric acid. By carrying out the insolubilization treatment, it is possible to impart water resistance 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 insoluble body (aqueous solution of boric acid) is preferably 20 ° C to 50 ° C. Preferably, the insolubilization step is carried out after the production of the laminate, before the dyeing step or the underwater stretching step. Typically, the crosslinking step is carried out by immersing the PVA resin layer in an aqueous solution of boric acid. By carrying out the crosslinking treatment, it is possible to impart water resistance 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. Further, in the case of carrying out the crosslinking step after the dyeing step, it is also preferable to add iodide. By combining iodide, the elution of iodine adsorbed to the PVA-based resin layer can be suppressed. The blending amount of iodide is preferably 1 part by weight 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 (boric acid aqueous solution) is preferably 20 ° C to 50 ° C. Preferably, the crosslinking step is carried out in the second boric acid aqueous solution before the stretching step. In a preferred embodiment, the dyeing step, the crosslinking step and the second boric acid in water step are carried out in this order.

As a material for forming the transparent protective film formed on one side or both sides of the polarizer, it is preferable that the material is excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like. For example, a polyester polymer such as polyethylene terephthalate or polyethylene naphthalate, a cellulose polymer such as diacetylcellulose or triacetylcellulose, an acrylic polymer such as polymethyl methacrylate, a polystyrene or an acrylonitrile styrene copolymer (AS resin), and polycarbonate-based polymers. Examples of the polymer include polyolefin-based polymers such as polyethylene, polypropylene, cyclo- or norbornene-based polyolefins, ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamides, imide- Based polymers, polyether sulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate- An epoxy-based polymer, or a blend of the above polymer may be mentioned as an example of the polymer forming the transparent protective film. The transparent protective film may contain one or more optional additives. Examples of the additive include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, coloring inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants and the like. 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, 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 possibility that the high transparency and the like inherently possessed by the thermoplastic resin can not be sufficiently exhibited.

Examples of the transparent protective film include a polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01 / 37007), for example, a thermoplastic resin having a substituted and / or unsubstituted imide group in the side chain (A) And a thermoplastic resin having substituted and / or unsubstituted phenyl and nitrile groups in the side chain (B) side chain. Specific examples include films of a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile styrene copolymer. The film may be a film composed of a mixture of resin compositions and the like. Since these films have a small retardation and a small photoelastic coefficient, problems such as deviation due to deformation of the polarizing film can be solved, and the moisture permeability is small, so that the durability against humidification is excellent.

The thickness of the transparent protective film can be appropriately determined. Generally, the thickness of the transparent protective film is about 1 to 500 占 퐉 in terms of workability such as strength and handleability, and thin layer properties. Particularly preferably 20 to 80 mu m, and more preferably 30 to 60 mu m.

When a transparent protective film is formed on both sides of the polarizer, a transparent protective film made of the same polymer material may be used for the front and back sides, or a transparent protective film made of a different polymer material or the like may be used.

On the surface of the transparent protective film on which the polarizer is not adhered, a functional layer such as a hard coat layer, an antireflection layer, a sticking prevention layer, a diffusion layer, or an antiglare layer can be formed. The functional layer such as the hard coat layer, the antireflection layer, the anti-sticking layer, the diffusion layer, and the antiglare layer may be formed on the transparent protective film itself or may be formed separately from the transparent protective film have.

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, a liquid crystal display device such as a reflection plate, a semitransmissive plate, a retardation plate (including a wave plate of 1/2 or 1/4) One or more optical layers that may be used may be used. In particular, a reflection type polarizing film or a semi-transmission type polarizing film in which a reflection plate or a transflective reflection plate is further laminated on the polarizing film of the present invention, an elliptically polarizing film or a circularly polarizing film laminated with a retardation film in addition to the polarizing film, A polarizing film in which a time compensating film is further laminated, or a polarizing film in which a luminance improving film is laminated in addition to a polarizing film.

The optical film obtained by laminating the above optical layers on a polarizing film can be formed by sequentially laminating them separately in the course of production of a liquid crystal display device or the like. Is advantageous in that the manufacturing process of a liquid crystal display device and the like can be improved. Appropriate adhesion means such as a pressure-sensitive adhesive layer can be used for the lamination. When the above polarizing film or other optical film is adhered, the optical axis thereof can be set at an appropriate arrangement angle in accordance with the objective retardation property and the like.

A pressure-sensitive adhesive layer for bonding to other members such as a liquid crystal cell can be formed on the above-mentioned polarizing film or an optical film in which at least one polarizing film is laminated. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited. For example, a polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, have. In particular, an acrylic pressure-sensitive adhesive which is excellent in optical transparency, exhibits appropriate wettability, cohesiveness and adhesive property, and is excellent in weather resistance and heat resistance can be preferably used.

The pressure-sensitive adhesive layer may be formed on one side or both sides of a polarizing film or an optical film as a superposition layer of a different composition or kind. Further, in the case of forming on both surfaces, a pressure-sensitive adhesive layer such as a composition, kind, or thickness may be formed on the front and back of the polarizing film or the optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the intended use and the adhesive force, and is generally 1 to 500 占 퐉, preferably 1 to 200 占 퐉, particularly preferably 1 to 100 占 퐉.

The exposed surface of the pressure-sensitive adhesive layer is temporarily covered with a separator for the purpose of prevention of contamination or the like until it is provided for practical use. This makes it possible to prevent contact with the pressure-sensitive adhesive layer in a conventional handling state. As the separator, a suitable thin film such as a plastic film, a rubber sheet, a paper, a cloth, a nonwoven fabric, a net, a foam sheet, a metal foil and a laminate thereof may be used, And a material obtained by coating with an appropriate stripping agent such as an alkyl-based, fluorine-based or molybdenum sulfide, may be used.

The polarizing film or optical film of the present invention can be suitably used for the formation of various devices such as a liquid crystal display device. The formation of the liquid crystal display device can be carried out conventionally. That is, the 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 needed, and mounting a driving circuit. In the present invention, Or an optical film is used, and there is no particular limitation, and it is possible to comply with the conventional method. As the liquid crystal cell, for example, any type of TN type, STN type, π type, or the like can be used.

A suitable liquid crystal display device 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 the liquid crystal cell and a backlight or a reflector is used in the illumination system can be formed. In this case, the polarizing film or optical film according to the present invention can be provided on one side or both sides of the liquid crystal cell. When polarizing films or optical films are formed on both sides, they may be the same or different. In forming a liquid crystal display device, a suitable part such as a diffusion plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, Or more.

Example

Hereinafter, embodiments of the present invention will be described, but the embodiments of the present invention are not limited thereto. The &quot; parts by weight &quot; 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

&Lt; Preparation of active energy ray-curable adhesive composition &gt;

, 38.5 parts by weight of HEAA (hydroxyethyl acrylamide) (Kyogin Kasei), 20.0 parts by weight of Aronix M-220 (tripropylene glycol diacrylate) [manufactured by Toa Synthetic Chemical Industry], ACMO (acryloylmorpholine) 38.5 parts by weight of KAYACURE DETX-S (diethylthioxanthone) [manufactured by Nippon Kayaku Co., Ltd.], 1.5 parts by weight of IRGACURE 907 (2-methyl-1- (4-methylthiophenyl) 1-one) [manufactured by BASF Co., Ltd.] were mixed and stirred at 50 ° C for 1 hour to obtain an active energy ray curable adhesive.

(2) Fabrication of thin polarizer

In order to produce a thin polarizer, first, a laminate having a PVA layer of 24 占 퐉 thickness formed on an amorphous PET substrate was subjected to air-assisted stretching at a stretching temperature of 130 占 폚 to form a stretched laminate, The colored layered product was further colored by dying to obtain a colored layered product comprising a PVA layer having a thickness of 10 탆 which is integrally stretched with an amorphous PET base so that the total stretch ratio is 5.94 times by stretching in boric acid water at a stretching temperature of 65 ° C To thereby produce an optical film laminate. By such two-step stretching, PVA molecules of the PVA layer formed on the amorphous PET substrate are highly oriented and the iodine adsorbed by dyeing constitutes a thin polarizer in which the poly iodide ion complex is highly oriented in one direction, An optical film laminate (second film (total thickness of 40 mu m)) including a PVA layer having a thickness of 5 mu m could be produced.

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

Example 1

In the line shown in Figs. 1 and 2, a gravure roll coating system 10A (MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb pattern, number of cell lines of gravure roll: 1000 The liquid film was applied to both the coplanar surface of the first film 1 and the coplanar surface of the second film 2 by using the two rolls of the first film 1 and the second film 2, Next, the adhesive composition (3) is applied to the concave surface of the second film (2) by using the gravure roll coating system (10B) to remove foreign substances and bubbles, The adhesive composition (3) was applied to the second film (2) composed of the PET base material and the thin polarizer so that the thin polarizing film surface was a cohesive surface. The adhesive composition (3) To be 1 占 퐉 in thickness 1 was applied to the film and the second film was used provided with a gravure roll coating method (10A and 10B), the (foreign matter removing method using a filter) is also the foreign material removing function shown in Fig.

<Active energy ray>

(Gallium-encapsulated metal halide lamp) irradiating apparatus as an active energy ray after passing through the line shown in Fig. 1: Light HAMMER10 valve manufactured by Fusion UV Systems, Inc. V valve peak intensity: 1600 mW / / mJ / cm &lt; 2 &gt; (wavelength: 380-440 nm), and the adhesive composition (3) was cured to prepare an optical film. The illuminance of the ultraviolet ray was measured using a Sola-Check system manufactured by Solatell.

Examples 2 to 9 and Comparative Examples 1 to 2

The same procedure as in Example 1 was carried out except that the application of the adhesive composition to the first film and / or the second film, the type of the after-weight application method, the viscosity and the composition of the liquid material were changed to those shown in Table 1, . In the bar coater application method and the air knife application method, a commercially available coating device was used.

&Lt; Method of counting the number of foreign substances in the adhesive layer &gt;

The number of appearance defects (number of external defects originating from foreign matters and appearance defects originating from (bonded) bubbles (number / m 2)) in the adhesive layer of the polarizing film was counted by visual inspection and reflection inspection using an automatic inspection apparatus. The results are shown in Table 1.

Claims (13)

A process for producing an optical film comprising a laminate 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 layer of an adhesive composition or a pressure-
And a first coating step of removing foreign matter by applying a liquid material having a viscosity of 1 to 10,000 cP to the concave surface of the first film and the concave surface of the second film using a post metering coating method By weight based on the total weight of the optical film. The method according to claim 1,
And a second coating step of removing foreign substances and / or air bubbles by applying the adhesive composition or the pressure-sensitive adhesive composition to the adhesion surface of at least one of the films using the post-metering coating method. 3. The method according to claim 1 or 2,
Wherein the liquid material contains at least 50% by weight of water. 4. The method according to any one of claims 1 to 3,
Wherein the liquid material further contains an alcohol. 5. The method according to any one of claims 1 to 4,
Wherein the adhesive composition or the pressure-sensitive adhesive composition is applied by circulating the adhesive composition or the pressure-sensitive adhesive composition in a post-metering application system, and the foreign substance mixed into the adhesive composition or the pressure-sensitive adhesive composition from the first film and / And removing the foreign substance from the pressure-sensitive adhesive composition. 6. The method according to any one of claims 1 to 5,
Wherein the coating method is a gravure roll coating method using a gravure roll. The method according to claim 6,
Wherein the rotating direction of the gravure roll and the traveling direction of the first film and the second film are opposite to each other. 8. The method according to claim 6 or 7,
Wherein the pattern formed on the surface of the gravure roll is a honeycomb pattern. 9. The method according to any one of claims 6 to 8,
Wherein the rotating speed ratio of the gravure roll to the advancing speed of the first film and the second film is 100 to 300%. 10. The method according to any one of claims 1 to 9,
Wherein the first film is a transparent protective film and the second film is a polarizer. 11. The method of claim 10,
Wherein the thickness of the polarizer is 10 占 퐉 or less. An optical film produced by the manufacturing method according to any one of claims 1 to 11. An image display apparatus characterized by using the optical film according to claim 12.

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