KR20180131390A - Method for manufacturing optical film - Google Patents

Abstract

The present invention relates to a method for manufacturing an optical film comprising a laminated structure in which at least a first film and a second film are bonded, which comprises a coating step of applying a coating liquid to both of the first film and the second film on laminated surfaces via a gravure roll coating method using a gravure roll. In the coating step, the bead width which is the film advancing direction width of a liquid gathering portion of the coating liquid formed between the first film and the second film and the gravure roll is set to 4-20 mm.

Description

METHOD FOR MANUFACTURING OPTICAL FILM [0001]

The present invention relates to a process for producing 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- .

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. A liquid crystal display device is one obtained 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 applied 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 that does not contain water or an organic solvent, in view of advantages such as omission of a drying step and less dimensional change.

When an optical film is produced by combining a plurality of films by 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, and a polarizer or the like is applied from such an adhered surface side, It is common to produce an optical film containing the structure. However, in the conventional manufacturing method, when foreign substances such as dust or dust adhere to the surface of a polarizer or transparent protective film before application of an adhesive composition or the like, or when the adhesive composition contains minute foreign matters, Foreign matter remains, 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 inventor of the present invention, it has been found that, in the technique described in Patent Document 1, since foreign substances are already present on a transparent support or the like, they are tried to be crushed and removed by calendering 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 appearance defect due to a foreign substance is prevented even if the optical film is thin.

As a result of diligent studies for solving the above problems, the present inventors have found that when producing an optical film comprising a laminate structure in which at least two films are laminated, the present inventors have found that, It has been found that removal of foreign matters and application of the adhesive composition or the pressure-sensitive adhesive composition can be performed at once by applying the coating liquid to the joint surface. The present invention is obtained as a result of the study of this example, and has the following constitutions.

That is, the present invention is a method for producing an optical film comprising a laminated structure in which at least a first film and a second film are bonded, characterized in that a gravure roll coating method using a gravure roll is used, And a coating step of applying a coating liquid to both of the concaved surfaces, wherein in the coating step, the film advancing direction width of the liquid impregnated portion of the coating liquid formed between the first film and the second film and the gravure roll And the bead width is set to all 4 to 20 mm.

In the above production method, the coating liquid is at least one coating liquid selected from the group consisting of an adhesive composition, a pressure-sensitive adhesive composition, and a liquid material having a viscosity of 0.5 to 10,000 cP, And a laminate structure in which at least a first film and a second film are bonded to each other via an adhesive layer or a pressure-sensitive adhesive layer comprising a cured layer of the pressure-sensitive adhesive composition.

Wherein the coating step comprises a first coating step of applying the adhesive composition or the pressure-sensitive adhesive composition onto the concave surface of the first film, and a second coating step of applying the pressure-sensitive adhesive composition or the pressure- And a second coating step of applying a phosphorus-containing water to the concave surface of the second film.

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

In the above manufacturing method, it is preferable that the gravure roll has a diameter of 80? To 140 ?.

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

In the above manufacturing method, 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%.

In the above manufacturing method, the gravure roll coating method is a method in which the coating liquid is circulated and applied, and a foreign substance mixed into the coating liquid from the first film and / or the second film by coating is applied to the coating liquid It is preferable to have a foreign substance removing function for removing the foreign substance from the foreign substance removing function.

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

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

When two films are laminated to produce an optical film having a laminated structure, it is general to manufacture an optical film by coating an adhesive composition or a pressure-sensitive adhesive composition on one side of two films and then laminating the film on the other side (Hereinafter, also referred to as " single-side coating method "). However, in the present invention, the coating liquid is applied to both the coplanar surface of the first film and the coplanar surface of the second film, and such coating is carried out while removing foreign substances using a gravure roll coating method using a gravure roll do. Concretely, by using a gravure roll coating system, gels and agglomerates derived from an adhesive composition or a pressure-sensitive adhesive composition are scraped off while scraping foreign matters such as dust and dust present on both of the two adjoining faces of the two films to be laminated, The coating liquid is applied to both of the two side surfaces of the film while scraping off the both sides of the film. As a result, in the method of producing an optical film according to the present invention, the possibility that foreign matter exists on both of the two films is very low. As a result, in the method for producing an optical film according to the present invention, it is possible to produce an optical film in which the occurrence of appearance defects due to foreign substances is prevented.

On the other hand, in the single-side coating method, foreign substances existing on the cohesive surface of the film not coated with the adhesive composition or the pressure-sensitive adhesive composition can not be removed, so that the possibility of foreign matter remaining in the adhesive layer (or pressure- .

The term "gravure roll coating system" in the present invention means a system in which a gravure roll scrapes a coating liquid from a container containing a coating liquid and forms a liquid droplet of the coating liquid between the gravure roll and the film to be coated, The coating liquid is applied to the surface of the substrate. The width in the film advancing direction of the coating liquid in the film advancing direction is referred to as the bead width and a frictional force is generated between the film and the liquid repelling portion in the inner portion of the bead width, Effect. In the present invention, particularly, by setting the bead width to 4 to 20 mm, it is possible to perform stable production while further improving the effect of removing the foreign matters on the coplanar surface of the film.

In the method of producing an optical film according to the present invention, it is possible to efficiently remove foreign matter present in both of the two adhered surfaces of the laminated film and the adhesive composition or the adhesive composition, and therefore, 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.

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.
Fig. 3 is an example of a schematic view of the liquid suspension of the coating liquid formed between the first film and the gravure roll.

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 characterized in that at least one coating liquid selected from the group consisting of an adhesive composition, a pressure-sensitive adhesive composition, and a liquid having a viscosity of 0.5 to 10000 cP is applied by a gravure roll coating method, 1 < / RTI > film and the second film.

The liquid material used as the coating liquid is one having a viscosity of 0.5 to 10,000 cP. 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, 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 water containing 50 to 100% More preferably 50% by weight of alcohol, and particularly preferably 50 to 70% by weight of water and 30 to 50% by weight of alcohol. The adhesive composition and the pressure-sensitive adhesive composition as a coating liquid will be described later.

Fig. 1 shows an example of a schematic view of a production method of an optical film related to the present invention. In this embodiment, a gravure roll coating method using a gravure roll is used, and both of the first and second films, As the coating liquid, all of the adhesive compositions are used. 1, the first film 1 is transported toward the right direction in FIG. 1 at the time when the adhesive composition 3 is applied using the gravure roll coating system 10, and on the other hand, The gravure roll provided in the system 10 rotates clockwise. In other words, the rotational direction of the gravure roll and the advancing direction of the first film are opposite. Similarly, in the relationship between the second film 2 and the gravure roll, the rotational direction of the gravure roll and the advancing direction of the second film 2 are opposite to each other. In this case, the effect of scraping foreign substances 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, is effectively increased, It is possible to more effectively prevent appearance defects of the finally obtained optical film.

In this embodiment, the application step includes a first application step of applying the adhesive composition to the application surface of the first film and a second application step of applying the adhesive composition to the application surface of the second film in the same manner However, the present invention is not limited to the present embodiment, and it is possible to apply an adhesive composition, a pressure-sensitive adhesive composition, and a liquid material having a viscosity of 0.5 to 10000 cP as a coating liquid to be applied to both of the first and second film- At least one kind of coating liquid selected from the group consisting of: For example, the following pattern is illustrative.

Wherein the coating step comprises a first coating step of applying the adhesive composition to the concave surface of the first film and a second coating step of applying a liquid material having a viscosity of 0.5 to 10,000 cP to the concave surface of the second film. Further, in this pattern, a third coating step of applying the adhesive composition to the concave surface of the second film may be further provided after the second coating step, if necessary.

Wherein the coating step comprises a first coating step of applying a liquid material having a viscosity of 0.5 to 10000 cP to the concave surface of the first film and a second coating step of applying a liquid material having a viscosity of 0.5 to 10000 cP to the concave surface of the second film A pattern comprising a second application step. Further, in this pattern, after the first coating step and / or the second coating step, the third coating step and / or the fourth coating step of further applying the adhesive composition to the concave surface of the first film and / or the second film Respectively.

The rotational 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% in order to more effectively prevent appearance defects of the finally obtained optical film, It is preferably 150 to 250%.

2 shows an example of a schematic view of the gravure roll coating system used in the present invention and particularly shows a state in which the adhesive composition 3 is applied to the first film 1 by using the gravure roll coating system 10 Respectively. As shown in Fig. 2, when the gravure roll 4 is pressed against the first film 1 to remove foreign matter, foreign substances such as dust and dust present 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 roll coating system 10 includes at least a gravure roll 4. 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 improve the surface accuracy of the coated surface after applying the adhesive composition or the pressure-sensitive adhesive composition, it is preferable that the cell pitch per inch of the roll is 200 to 2000 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 raising the adhesive composition (coating liquid) 3.

In the present invention, in the coating step, the bead width, which is the width in the film advancing direction of the liquid impregnated portion of the coating liquid formed between the first film and the gravure roll, and the width of the bead which is further formed between the second film and the gravure roll, Is set to be 4 to 20 mm. This makes it possible to perform stable production while further improving the effect of removing foreign matter on the coplanar surface of the film. Fig. 3 shows a schematic view of the liquid suspension of the coating liquid (adhesive composition) 3 formed between the first film 1 and the gravure roll 4. 3, d represents the bead width which is the film advancing direction width of the liquid suspension of the coating liquid formed between the first film 1 and the gravure roll 4. In the present invention, when the bead width in the coating step is 5 mm or more, the effect of removing foreign substances on the coplanar surface of the film is further improved, which is preferable. Further, even if the bead width is widened to exceed 20 mm, the effect of removing foreign matters on the coplanar surface of the film is largely unchanged. On the other hand, as the bead width becomes wider, the coating property of the coating liquid is remarkably lowered, Due to the inability to apply the liquid, the coated surface of the film is roughened and appearance defects occur. In the present invention, the adjustment of the width of the beads can be appropriately performed by adjusting the gravure roll position relative to the film. Concretely, for example, when the gravure roll is moved in the pushing direction with respect to the film, the bead width can be widened. On the other hand, when the film and the gravure roll are separated from each other, the bead width can be narrowed.

In order to set the bead width which is the film advancing direction width of the liquid suspension of the coating liquid formed between the first film and the second film and the gravure roll to 4 to 20 mm in the application step, To 140 [phi].

In the present invention, in order to prevent foreign matter from being mixed into the adhesive composition (3), it is preferable that the adhesive coating 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 the aggregate derived from the adhesive composition 3 are scraped off by the gravure roll 4, It may be transferred into the container 5 containing the composition 3 and then applied again to the concave surface of the first film by the gravure roll 4. [ Therefore, in the case where the gravure roll coating system 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 likely to increase. However, in the case where the gravure roll coating system 10 has a function of removing a foreign substance 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- , 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 may be of any number. The mesh size of the filter 7 can be appropriately changed depending on 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.

After the adhesive composition 3 is applied to both the coplanar surface of the first film 1 and the coplanar surface of the second film 2 by the gravure roll coating method shown in Fig. 1, for example, the nip roll 9 , The first film (1) and the second film (2) are bonded via an adhesive composition (adhesive layer).

When the optical film is produced 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), preferably 1 to 500 m / min Preferably 5 to 300 m / min, and more preferably 10 to 100 m / min. When the line speed is too small, it is not possible to produce an optical film which is insufficient in productivity or excessively large in damage to the first film and / or the second film and which can withstand durability tests and the like. When 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 >

The adhesive layer or the pressure-sensitive adhesive layer is not particularly limited as far as it is optically transparent, 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 the optical film, a transparent curing type adhesive layer can be preferably used.

≪ Transparent curable adhesive layer >

As the adhesive composition, for example, a radical-curable adhesive is preferably used for forming the transparent curing-type 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 ultraviolet curable adhesive which is preferably curable in a short time, is preferably an active energy ray curable type, and further curable with a low energy.

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 curing 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 cycloalkyl (meth) acrylate (for example, cyclohexyl (meth) acrylate, cyclopentyl (meth) 2-norbornylmethyl (meth) acrylate (e.g., benzyl (meth) acrylate, etc.), polycyclic (meth) Acrylate, 5-norbornene-2-yl-methyl (meth) acrylate and 3-methyl- (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropylmethyl-butyl (meth) acrylate and the like), an alkoxy group or a phenoxy group- Methacrylic acid esters (such as 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 curing component of the radical polymerization curing adhesive include compounds having a plurality of polymerizable double bonds such as (meth) acryloyl groups and vinyl groups, and the compounds are mixed with an adhesive component as a crosslinking component You may. 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, di (Manufactured by Kyowa Chemical Industry Co., Ltd.), light acrylate DGE-4A (manufactured by Kyowa Chemical Industry Co., Ltd.), acrylic acid monoacrylate SR-531 (manufactured by Sartomer), CD-536 (manufactured by Sartomer), and the like can be given. 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 includes the above-mentioned curable component, and 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. In the case of using an ultraviolet hardening type or a 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 curing component. In addition, a photo-sensitizer may be added to the radical polymerization curable adhesive, if necessary, to increase the curing rate and sensitivity by electron beams typified by carbonyl compounds and the like. The amount of the photosensitizer 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 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 forming 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. When preparing the aqueous solution, a catalyst such as a crosslinking agent, other additives, or an acid can 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, boric acid or borax, carboxylic acid compounds, alkyldiamines; Isocyanates; Epoxies; Monoaldehydes; Dialdehydes; Amino-formaldehyde resins; Further, a divalent metal, a salt of a trivalent metal, and an oxide thereof can be mentioned.

The adhesive forming the curable adhesive layer may suitably contain an additive if necessary. 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 derived from the foreign material 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 of a pressure-sensitive adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used. Examples of the pressure-sensitive adhesive include a pressure sensitive adhesive such as a rubber pressure sensitive adhesive, an acrylic pressure sensitive adhesive, a silicone pressure sensitive adhesive, a urethane pressure sensitive adhesive, a vinyl alkyl ether pressure sensitive adhesive, a polyvinyl pyrrolidone pressure sensitive adhesive, a polyacrylamide pressure sensitive adhesive, . Depending on the type of the pressure-sensitive adhesive, a tacky base polymer is selected. Among these pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they exhibit excellent optical transparency, appropriate wettability, cohesiveness and adhesiveness, and excellent 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. When the acceleration voltage is less than 5 kV, the electron beam does not reach the adhesive and there is a risk of insufficient curing. If the acceleration voltage exceeds 300 kV, the penetration force passing through the sample is too strong, which may damage the transparent protective film or the polarizer . 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 insufficient in curing. When the irradiation dose exceeds 100 kGy, the transparent protective film or the polarizer is damaged and mechanical strength is lowered, yellowing occurs, 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. Although oxygen depends on the material of the transparent protective film, oxygen is forcibly inhibited on the surface of the transparent protective film which is first exposed to the electron beam, and damage to the transparent protective film can be prevented, .

On the other hand, when a transparent protective film imparted with ultraviolet ray absorbing ability is used in the ultraviolet ray curing type, light having a wavelength shorter than 380 nm is absorbed by light of shorter wavelength than 380 nm, and therefore light of shorter wavelength than 380 nm does not reach the active energy ray curable adhesive composition, It does not contribute to the polymerization reaction. Further, the light having a wavelength shorter than 380 nm absorbed by the transparent protective film is converted into heat, and the transparent protective film per se 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 is less likely to be visually observed and the appearance defects are unlikely to be problematic. On the other hand, the thinner the adhesive layer (or the pressure-sensitive adhesive layer) is, the thinner the thinner the total thickness of the optical film, the more likely the foreign substance becomes visible, and 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, , In particular when the first film is a transparent protective film and the second film is a polarizer or the second film is a transparent protective film and the first film is a polarizer, Especially useful. The manufacturing method according to the present invention is capable of preventing occurrence of appearance defects due to foreign matter in the adhesive layer (or the pressure-sensitive adhesive layer), particularly when the thickness of the polarizer is 10 m or less, It is possible to produce a thin polarizing film.

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, 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 a solution diluted to a proper 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. Further, although a plurality of layers can be formed for facilitating the adhesion, it is preferable that the total thickness of the easy-to-adhere layer is also in the above range.

Hereinafter, a polarizing film will be described as an example of the optical film. 1, a polarizing film including a laminated structure in which at least a first film and a second film are bonded is formed on a first film (1) as a transparent protective film, a transparent protective film or a PET substrate, And a second laminated film (2) in which a polarizer is laminated with an adhesive layer interposed therebetween as needed, 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 produce an optical film in which foreign substances are effectively prevented from being generated in the adhesive layer, and therefore, an optical film having a particularly thin thickness, It is suitable for manufacturing. 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. If the total thickness of the polarizing film is 100 m or less, the thickness of the polarizing film is thin, so that appearance defects caused by 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 50 μm 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 a hydrophilic polymer film such as a polyvinyl alcohol film, a partially porous polyvinyl alcohol film and a partially saponified ethylene / vinyl acetate copolymer film, And polyene-based oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochloric acid treated products. Among them, a polyvinyl alcohol film and a polarizer made of a dichroic material such as iodine are preferable. The thickness of these polarizers is not particularly limited, but is generally about 80 占 퐉 or less.

A polarizer obtained by dying a polyvinyl alcohol film with iodine and uniaxially stretching can be produced, for example, by dying polyvinyl alcohol in an aqueous solution of iodine and stretching it to 3 to 7 times its 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, followed by stretching while dyeing, or after stretching, followed by dyeing with iodine. 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 is preferable because it is excellent in durability because the thickness deviation is small, the visibility is excellent, the dimensional change is small, 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.

As the thin polarizer, it is possible to use the thin film polarizer described in WO2010 / 100917 pamphlet, PCT / JP2010 / 001460 In the aqueous boric acid solution described in the specification of Japanese Patent Application No. 2010-269002 or Japanese Patent Application No. 2010-263692, and in particular, Japanese Patent Application No. 2010-269002 Or in a boric acid aqueous solution described in the specification of Japanese Patent Application No. 2010-263692.

The thin, high-performance polarizer disclosed in the specification of PCT / JP2010 / 001460 is a thin, highly functional polarizer made of a PVA-based resin in which a dichroic substance is aligned and formed integrally on a resin substrate, And a polarization degree of 99.95% or more.

The thin type 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 resultant PVA resin layer in a dyeing solution of a dichroic substance , The PVA resin layer in which the dichroic substance is adsorbed to the PVA resin layer and the PVA resin layer in which the dichroic substance is adsorbed is stretched so as to have a total draw ratio of 5 times or more of the original length integrally with the resin base in the aqueous solution of boric acid, Can be manufactured.

Also disclosed is a method for producing a laminated film comprising a thin, highly functional polarizer in which a dichroic substance is oriented, comprising the steps of: applying a resinous base material having a thickness of at least 20 mu m and an aqueous solution containing a PVA- And a PVA resin layer formed on one side of the resin base material is immersed in a dyeing solution containing a dichroic substance to form a laminate film comprising a PVA resin layer formed by forming a resin film A step of adsorbing a dichroic material to a PVA resin layer contained in the laminate film and a step of forming a laminate film comprising a PVA resin layer on which a dichroic substance is adsorbed by a laminate film having a total draw ratio A step of stretching the PVA resin layer so as to be at least five times the original length, and a step in which the PVA resin layer on which the dichroic substance is adsorbed is integrally stretched with the resin substrate, A laminated film having a thickness of 7 탆 or less, a single-layer transmittance of 42.0% or more, and a polarization degree of 99.95% or more and having a thin-shaped high-performance polarizer formed on a single face of the asphaltic material by a PVA- The thin, highly functional polarizer can be produced.

Specification of Japanese Patent Application No. 2010-269002 and Japanese Patent Application No. 2010-263692 The thin polarizer is a polarizer of a continuous web made of a PVA resin in which a dichroic material is oriented, and is a polarizer of a PVA formed on an amorphous ester thermoplastic resin base The laminate including the base resin layer is stretched in a two-step stretching process comprising air-assisted stretching and boric acid in-water stretching, resulting in a thickness of 10 占 퐉 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 that the optical characteristics satisfy 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 boric acid in water on 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 colored intermediate product is preferably immersed in an aqueous boric acid solution having a liquid temperature not exceeding 40 캜 desirable. The amorphous ester-based thermoplastic resin base material may be made of copolymerized polyethylene terephthalate copolymerized with isophthalic acid, copolymerized polyethylene terephthalate copolymerized with cyclohexanedimethanol, or 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.

To prepare a continuous web of isophthalic acid copolymerized polyethylene terephthalate (amorphous PET) copolymerized with 6 mol% of isophthalic acid. 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. The glass transition temperature of PVA is 80 ° C.

An amorphous PET substrate having a thickness of 200 μm and a PVA aqueous solution having a polymerization degree of 1000 or more and a PVA powder having a degree of saponification of 99% or more dissolved in water at a concentration of 4 to 5% are 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, the drawn laminate was obtained by putting a laminate including a PVA layer having a thickness of 7 탆 on a stretching device provided in an oven set at a temperature of 130 캜 for stretching, . 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 캜 and a PVA layer constituting the ultimately produced high-performance polarizer with a transmittance of 40 to 44% So that the PVA layer contained in the oriented 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% by weight and a potassium iodide concentration of 2.1% by weight for 60 seconds to obtain a colored laminate in which iodine was adsorbed on a PVA layer having a thickness of 5 탆 .

Further, the colored laminate is further stretched integrally with the amorphous PET substrate by a boric acid in-water stretching step of the second stage to produce an optical film laminate including a PVA layer constituting a highly functional polarizer having a thickness of 3 占 퐉 . Specifically, this optical film laminate was obtained by putting the colored laminate on a stretching apparatus provided in a treatment apparatus set in an aqueous solution of boric acid having a liquid temperature range of 60 to 85 DEG C containing boric acid and potassium iodide and having a stretching magnification of 3.3 times It is stretched to the free end single axis. More specifically, the liquid temperature of the aqueous solution of boric acid is 65 캜. It also has a boric acid content of 4 parts by weight based on 100 parts by weight of water and a potassium iodide content of 5 parts by weight based on 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. Thereafter, the colored laminate is passed through a plurality of sets of rolls having different main axes, which are the drawing apparatus provided in the processing apparatus as it is, and the uniaxial stretching is carried out for 30 to 90 seconds so that the draw magnification is 3.3 times. By this stretching treatment, the PVA layer contained in the colored laminate is changed to a PVA layer having a thickness of 3 탆 which is oriented in a higher order in one direction as adsorbed iodine 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 PVA layer of 3 占 퐉 thickness formed on the amorphous PET substrate is treated with potassium iodide It is preferable to wash it with an aqueous solution. Then, the cleaned 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, while not being an indispensable step in the production of an optical film laminate, an adhesive is applied to the surface of a PVA layer having a thickness of 3 占 퐉 formed on an amorphous PET substrate by an adhesion and / or a transferring process, After the acetylcellulose film is laminated, the amorphous PET substrate is peeled off, and the PVA layer having a thickness of 3 占 퐉 may be transferred to a triacetylcellulose film having a thickness of 80 占 퐉.

[Other processes]

The manufacturing method of the thin polarizer may include other steps in addition to the steps described above. 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 performing the crosslinking step after the dyeing step, it is preferable to further 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 polymer, a polyether sulfone-based polymer, a polyether ether ketone-based polymer, a polyphenylene sulfide-based polymer, a vinyl alcohol polymer, a vinylidene chloride polymer, a vinyl butyral polymer, an arylate polymer, a polyoxymethylene polymer, 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 an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment and a colorant. 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 a substituted and / or unsubstituted phenyl and nitrile groups in the side chain of the resin (B). 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 suitably determined, and generally it is about 1 to 500 占 퐉 from the viewpoints 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 anti-glare layer can be formed on the transparent protective film itself or may be formed separately from the transparent protective film It is possible.

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 two or more optical layers 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. And the like are advantageous in that the manufacturing process of the liquid crystal display device and the like can be improved. Appropriate adhesive means such as a pressure-sensitive adhesive layer can be used for the lamination. When the polarizing film or other optical film is adhered, the optical axis thereof can be set at a suitable arrangement angle in accordance with the desired retardation characteristics and the like.

A pressure-sensitive adhesive layer for bonding to another member 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 having excellent optical transparency, suitable wettability, cohesiveness and adhesiveness, and excellent 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 adhered and covered with a separator for the purpose of preventing contamination 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 as the separator, Such as a fluorine-based or molybdenum sulfide-coated material, or a coating material treated with a suitable release agent such as a fluorine-based or molybdenum sulfide.

The polarizing film or optical film of the present invention can be suitably used for forming various devices such as a liquid crystal display device. The formation of the liquid crystal display device can be carried out conventionally. In other words, 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 needed, and mounting a driving circuit. In the present invention, There is no particular limitation, except that a polarizing film or an optical film is used. For the liquid crystal cell, any type of TN type, STN type, or π type, for example, 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 or 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 the 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, the 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 (hydroxyethylacrylamide) (manufactured by Kojinsha), 20.0 parts by weight of Aronix M-220 (tripropylene glycol diacrylate) [manufactured by TOAGOSEI Co., Ltd.], 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) were mixed and stirred at 50 캜 for 1 hour to obtain an active energy ray-curable adhesive composition (simply referred to as "adhesive composition" in Table 1).

(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 subjected to stretching in boric acid water at a stretching temperature of 65 ° C to give a total stretch ratio of 5.94, and a layer of PVA 10 μm thick integrally stretched with the amorphous PET substrate To thereby produce an optical film laminate. In such a two-stage stretching, the PVA molecules of the PVA layer formed on the amorphous PET substrate are highly oriented, and the iodine adsorbed by the dyeing is a polyiodide ion complex, which constitutes a thin polarizer in which the thin polarizer is highly oriented in one direction. An optical film laminate (second film (total thickness of 40 mu m)) including the PVA layer 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, the gravure roll coating system 10 (MCD coater (manufactured by Fuji Machinery Co., Ltd.) (cell shape: honeycomb pattern, cell player of gravure roll: 1000 The adhesive composition 3 was applied to both of the concave surface of the first film 1 and the concave surface of the second film 2 by using the bead widths in Table 1 The bead width of the first film and the gravure roll was set to L1 (mm), the width of the beads of the second film and the gravure roll was set to L2 (mm), and the width of the bead of the second film and the gravure roll was set to L2 Next, 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) The first film and the second film were laminated so that the thickness of the adhesive layer was 1 占 퐉 The gravure roll coating system 10 was provided with a foreign substance removing function (a foreign substance removing method using a filter) shown in Fig.

<Active energy ray>

(Gallium-encapsulated metal halide lamp) 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 to 440 nm) was used to cure the adhesive composition (3) to prepare an optical film. The illuminance of the ultraviolet ray was measured using a Sola-Check system manufactured by Solatell.

Examples 2 to 12 and Comparative Examples 1 to 18

An optical film was produced in the same manner as in Example 1 except that the kind of coating liquid and the bead width to which the first film and the second film were laminated were changed to those shown in Table 1. [ In Table 1, the water used as the liquid material was 100 weight% of water and 1 cP of viscosity.

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

The number of appearance defects (number of appearance defects (number of defects due to foreign substances (number / square meter)) in the adhesive layer of the polarizing film was counted by visual inspection and reflection inspection using an automatic inspection device. The results are shown in Table 1.

&Lt; Evaluation of Appearance on Coating Surface of Coating Solution &gt;

A case where appearance defects in which a coated surface after applying a coating liquid was visually observed and a defective outer appearance occurred were defined as &quot; Yes &quot;; and a case where appearance defects did not occur was defined as &quot; none &quot;. The results are shown in Table 1.

Claims (11)

A method for producing an optical film comprising a laminated structure in which at least a first film and a second film are bonded,
And a coating step of applying a coating liquid to both of the first and second films and the concave surface of the first film and the second film using a gravure roll coating method using a gravure roll,
In the coating step, the bead width which is the film advancing direction width of the liquid suspension of the coating liquid formed between the first film and the second film and the gravure roll is set to 4 to 20 mm , And a method for producing an optical film. The method according to claim 1,
Wherein the coating liquid is at least one coating liquid selected from the group consisting of an adhesive composition, a pressure-sensitive adhesive composition, and a liquid material having a viscosity of 0.5 to 10,000 cP, and the optical film is a liquid composition comprising the adhesive composition or the cured product And a laminate structure in which at least a first film and a second film are bonded to each other via an adhesive layer or a pressure-sensitive adhesive layer. 3. The method of claim 2,
Wherein the coating step comprises a first coating step of applying the adhesive composition or the pressure-sensitive adhesive composition to the concave surface of the first film,
And a second coating step of applying the adhesive composition or the pressure-sensitive adhesive composition or a liquid material having a viscosity of 0.5 to 10000 cP to an adhesion surface of the second film. 3. The method according to claim 1 or 2,
Wherein the rotational direction of the gravure roll and the advancing direction of the first film and the second film are opposite to each other. 5. The method according to any one of claims 1 to 4,
Wherein the gravure roll has a diameter of 80? To 140 ?. 6. The method according to any one of claims 1 to 5,
Wherein the pattern formed on the surface of the gravure roll is a honeycomb pattern. 7. The method according to any one of claims 1 to 6,
Wherein the rotating speed ratio of the gravure roll to the traveling speed of the first film and the second film is 100 to 300%. 8. The method according to any one of claims 1 to 7,
Wherein the gravure roll coating method is a method in which the coating liquid is circulated and applied, and a foreign matter mixed in the coating liquid from the first film and / or the second film by coating is removed from the coating liquid Wherein the optical film has a refractive index of not less than 0.1. 9. The method according to any one of claims 1 to 8,
Wherein the first film is a transparent protective film and the second film is a polarizer. 9. The method according to any one of claims 1 to 8,
Wherein the second film is a transparent protective film, and the first film is a polarizer. 11. The method according to claim 9 or 10,
Wherein the thickness of the polarizer is 10 占 퐉 or less.

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