JP2019023759A - Production method of polarizing film - Google Patents

Abstract

To provide a production method of a polarizing film having a transparent protective film disposed on both surfaces of a polarizer, by which a polarizing film having a good appearance can be produced even when the polarizer and the transparent protective film are bonded by use of an active energy ray-curable adhesive.SOLUTION: The production method of a polarizing film includes: a step (1) of applying an active energy ray-curable adhesive on a second surface of a polarizer of a one-side protection polarizing film having a first transparent protective film disposed on a first surface of the polarizer; (2) a step of bonding a second transparent protective film to the polarizing film via the active energy ray-curable adhesive; and (3) a step of irradiating the active energy ray-curable adhesive with active energy rays to form an adhesive layer.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a polarizing film. The polarizing film obtained by the production method can form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, or a PDP alone or as an optical film obtained by laminating the polarizing film.

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

  As the polarizer, since it has a high transmittance and a high degree of polarization, for example, an iodine-type polarizer having a stretched structure in which iodine is adsorbed on polyvinyl alcohol is most widely used. Such a polarizer has a disadvantage that the mechanical strength is extremely weak, and the polarizing function is remarkably lowered due to contraction due to heat and moisture. Therefore, usually, the obtained polarizer is immediately coated with a water-based adhesive, and is used as a polarizing film in which a transparent protective film is simultaneously bonded to both sides of the polarizer via this adhesive. As the transparent protective film, triacetyl cellulose having a high moisture permeability is used. On the other hand, in order to suppress a dimensional change, the moisture content of a polarizer can be reduced or a transparent protective film with low moisture permeability can be used.

  However, when producing a polarizing film, when a water-based adhesive is used (so-called wet lamination), a high-productivity cannot be expected because a drying process is required after the polarizer and the transparent protective film are bonded together. . Moreover, when a transparent protective film with low moisture permeability is used, the drying efficiency is further deteriorated and high productivity cannot be expected.

  In order to solve the above-mentioned problems in wet lamination, an active energy ray-curable adhesive that does not contain water or an organic solvent has been proposed (Patent Documents 1 and 2). Such active energy ray-curable adhesives are roughly classified into a photocationic polymerization type and a photoradical polymerization type. Since the active energy ray-curable adhesive does not require a drying step like a water-based adhesive, the productivity of the polarizing film can be increased even when a transparent protective film having low moisture permeability is used.

JP 2010-286754 A JP 2008-233874 A

  In the wet lamination using the water-based adhesive, there is no particular problem in terms of appearance with respect to a polarizing film obtained by laminating a polarizer and a transparent protective film. That is, when an aqueous adhesive is used, the polarizer and the transparent protective film are bonded together with a wet adhesive, and then the adhesive is dried to gradually remove water. For this reason, it is difficult for air bubbles to bite into the bonding surface, and the appearance problem caused by the air bubbles did not occur. However, when an active energy ray-curable adhesive was used, the new polarizing film faced a new problem in that it was poor in appearance.

  The present invention is a method for producing a polarizing film in which a transparent protective film is provided on both surfaces of a polarizer, and the polarizer and the transparent protective film are bonded together using an active energy ray-curable adhesive. It aims at providing the method which can manufacture a polarizing film with a favorable external appearance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a method for producing the following polarizing film and completed the present invention.

That is, the present invention is a method for producing a polarizing film in which the first and second transparent protective films are provided on the first and second surfaces of the polarizer,
A step (1) of applying an active energy ray-curable adhesive to the second surface of the polarizer in the one-side protective polarizing film in which the first transparent protective film is provided on the first surface of the polarizer;
A step (2) of bonding the second transparent protective film via the active energy ray-curable adhesive;
The manufacturing method of the polarizing film characterized by including the process (3) of irradiating an active energy ray with respect to the said active energy ray hardening-type adhesive agent, and forming an adhesive bond layer.

  In the method for producing the polarizing film, the polarizer is a continuous web polarizing film made of a polyvinyl alcohol resin in which a dichroic material is oriented, and the piece protective polarizing film is a thermoplastic resin substrate. It can be suitably applied when the laminate including the polyvinyl alcohol-based resin layer formed on is obtained by stretching in a two-stage stretching process consisting of air-assisted stretching and boric acid-water stretching.

  In the step (1), the manufacturing method of the polarizing film, after applying the active energy ray-curable adhesive to the second surface of the polarizer in the one-side protective polarizing film, after passing 2 seconds or more, It is preferable to perform step (2).

  In the method for producing the polarizing film, the active energy ray-curable adhesive preferably has a viscosity of 10 to 350 cps (25 ° C.).

  In the method for producing the polarizing film, the active energy ray-curable adhesive preferably contains a radical polymerizable compound.

  In the method for producing a polarizing film, the step (1) allows the second surface of the polarizer to be dried before applying the active energy ray-curable adhesive to the second surface of the polarizer in the one-side protective polarizing film. It is preferable to include the process of giving a process.

  In the manufacturing method of the said polarizing film, it is preferable to perform irradiation of the active energy ray in the said process (3) from the 2nd transparent protective film side.

  In the manufacturing method of the said polarizing film, it is preferable that the thickness of the adhesive bond layer formed by the said process (3) is 300 nm-1.3 micrometers.

  When manufacturing a polarizing film, it is very difficult to handle a polarizer due to strength problems. For this reason, when using an active energy ray-curable adhesive (hereinafter sometimes referred to simply as an adhesive), the adhesive is applied not to the polarizer side but to the transparent protective film side. It is thought that it is preferable to stick together. However, since the surface of the polarizer has streaks with a pitch of several μm and irregularities of several hundreds of nanometers, the adhesive is applied to the transparent protective film side with a relatively smooth surface, and then applied to the polarizer. When combined, it was found that the unevenness and streaks on the surface of the polarizer could hardly be filled with an adhesive. Therefore, it was found that many bubbles were generated in the obtained polarizing film, resulting in poor appearance. That is, when the polarizer and the transparent protective film are bonded to each other with the active energy ray curable adhesive, the inventors have found that the cause of the bubble entrapment is affected by the surface roughness of the polarizer.

  Therefore, in the present invention, the active energy ray-curable adhesive is applied not to the transparent protective film side but to the polarizer side. Generally, the surface roughness of the polarizer is larger than the surface roughness of the transparent protective film. Therefore, it is more dramatic to apply the adhesive to the polarizer side and apply the adhesive to the polarizer than to apply the active energy ray-curable adhesive to the transparent protective film. Can be reduced. In other words, by applying an adhesive to the polarizer side, the adhesive can be bonded to the transparent protective film with the unevenness on the surface of the polarizer being filled to some extent, so that the generation of air bubbles is suppressed. The appearance can be improved.

  As described above, the polarizer is very difficult to handle, and when an adhesive is applied directly to the polarizer, there is a risk that the production line stops. In particular, when a polarizer obtained through the stretching process is bonded to a transparent protective film with a continuous line, it is the most dangerous, difficult and unsuitable for production. In the present invention, when the adhesive is applied, the one-side protective polarizing film in which the first transparent protective film is already provided on the first surface of the polarizer opposite to the second surface of the polarizer to be coated is provided. Used. Since the single-protective polarizer is strong, the adhesive coating on the second surface of the single-protective polarizer applies the adhesive directly to a single polarizer that does not have a transparent protective film on both sides of the polarizer. Compared with the case where it does, the stabilized coating can be implement | achieved.

Below, the manufacturing method of the polarizing film of this invention is demonstrated. In the polarizing film of the present invention, a first transparent protective film is provided on one surface (first surface) of the polarizer, and a second transparent protective film is provided on the other surface (second surface). Such a polarizing film of the present invention can be obtained by sequentially performing the steps (1) to (3).

<Step (1)>
In the step (1), an active energy ray-curable adhesive is applied to the second surface of the polarizer in the single-protective polarizing film in which the first transparent protective film is provided on the first surface of the polarizer.

<Single protective polarizing film>
The single protective polarizing film is a film in which the first transparent protective film is provided only on the first surface of the polarizer, but the first surface of the polarizer and the first transparent protective film are bonded via an adhesive layer. May be combined.

  Examples of the adhesive used for the adhesive treatment between the first surface of the polarizer and the first transparent protective film include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex adhesives, aqueous polyesters, and the like. It can be illustrated. The said adhesive agent is normally used as an adhesive agent which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content normally. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include active energy ray curable adhesives such as an ultraviolet curable adhesive and an electron beam curable adhesive. The adhesive used in the present invention can contain a metal compound filler.

  In the case of using a water-based adhesive as the adhesive, the thickness of the adhesive layer is preferably about 10 to 300 nm. The thickness of the adhesive layer is more preferably from 10 to 200 nm, particularly preferably from 20 to 150 nm, from the viewpoint of obtaining a uniform in-plane thickness and obtaining sufficient adhesive strength. The thickness of the adhesive layer when an active energy ray-curable adhesive is used as the adhesive is preferably controlled in the same range as the thickness of the adhesive layer according to the second surface described later.

  In the case where the first transparent protective film is provided on the first surface of the polarizer alone, it is difficult to apply the adhesive directly to the polarizer alone. In this case, the adhesive is applied to the first transparent protective film. It is preferable to work. On the other hand, as described in a thin polarizer described later, a thin high-performance polarizing film integrally formed on a resin base material has good handleability. Therefore, when using a thin and highly functional polarizing film integrally formed on a resin base material, it is possible to apply an adhesive directly to the first surface of the polarizer, resulting in a surface roughness larger than that of the surface protective film. It is good for suppressing the entrapment of bubbles by the polarizer having the.

<Polarizer>
The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 1 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be prepared, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution such as boric acid or potassium iodide or in a water bath.

≪Thin polarizer≫
As the polarizer, a thin polarizer having a thickness of 10 μm or less can be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer is preferable in that the thickness unevenness is small, the visibility is excellent, the dimensional change is small, the durability is excellent, and the thickness of the polarizing film can be reduced.

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

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

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

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

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

  In the present invention, as a polarizer having a thickness of 10 μm or less, it is a continuous web polarizing film made of a PVA-based resin in which a dichroic material is oriented, and is formed on a thermoplastic resin substrate. What was obtained by extending | stretching the laminated body containing this by the two-stage extending | stretching process which consists of an air auxiliary | assistant extending | stretching and boric-acid-water extending | stretching can be used. The thermoplastic resin substrate is preferably an amorphous ester thermoplastic resin substrate or a crystalline ester thermoplastic resin substrate.

The thin polarizing film in the above-mentioned Japanese Patent Application Nos. 2010-269002 and 2010-263692 is a continuous web polarizing film made of a PVA resin in which a dichroic material is oriented, and is amorphous. The laminate including the PVA-based resin layer formed on the ester-based thermoplastic resin base material was stretched in a two-stage stretching process consisting of air-assisted stretching and boric acid-water stretching, so that the thickness was 10 μm or less. Is. Such a thin polarizing film has P> − (10 ^0.929 T ^−42.4 −1) × 100 (where T <42.3) and P ≧, where T is the single transmittance and P is the polarization degree. It is preferable that the optical properties satisfy 99.9 (where T ≧ 42.3).

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

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

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

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

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

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

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

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

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

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

<First transparent protective film>
As a material constituting the first transparent protective film, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or the above Examples of the polymer that forms the transparent protective film include polymer blends. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, an anti-coloring agent, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by mass, more preferably 50 to 99% by mass, further preferably 60 to 98% by mass, and particularly preferably 70 to 97% by mass. . When content of the said thermoplastic resin in a transparent protective film is 50 mass% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed. The first transparent protective film can be appropriately selected and used.

  The thickness of the first transparent protective film can be determined as appropriate, but is generally about 1 to 500 μm from the viewpoints of workability such as strength and handleability, and thin layer properties. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.

<Active energy ray-curable adhesive>
The active energy ray-curable adhesive according to the present invention is an adhesive that is cured by an active energy ray such as an electron beam or ultraviolet ray, and can be used, for example, in an electron beam curable type or an ultraviolet ray curable type. As the active energy ray curable adhesive in the present invention, an ultraviolet curable adhesive is preferable because it can be easily experimented with general-purpose equipment. On the other hand, since electron beam curable adhesives do not use photoinitiators, they can be used with materials that do not transmit light (metal films and high-concentration pigments), and are characterized by improved adhesion. There are equipment limitations compared to adhesives.

  The active energy ray-curable adhesive used in the present invention can be either a photocationic polymerization type or a photoradical polymerization type, but the active energy ray-curable adhesive of the present invention is a photoradical polymerization type. The adhesive is preferably used because it cures quickly and is suitable for high-speed production.

  When the photo radical polymerization type active energy ray curable adhesive is used as the ultraviolet curable type, the adhesive contains (A) a radical polymerizable compound and (B) a photo radical generator.

≪ (A) Radical polymerizable compound≫
The (A) radical polymerizable compound can be used without particular limitation as long as it is a compound having a vinyl group containing at least one carbon-carbon double bond, a (meth) acryloyl group, and the like. In the present invention, (A) Among the radical polymerizable compound represented by the following general formula ^{_{(1): CH 2 = C}} (R 1) -CONH 2-m - (X-O-R 2) m (1)
(R ¹ represents a hydrogen atom or a methyl group, X represents a —CH ₂ — group or a —CH ₂ CH ₂ — group, R ² represents a — (CH ₂ ) _n —H group (where n is 0, 1 Or an N-substituted amide monomer represented by 2) and m represents 1 or 2.

  Specific examples of the N-substituted amide monomer represented by the general formula (1) include, for example, N-hydroxyethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-ethoxyethyl (meth) acrylamide, etc. are mentioned. These N-substituted amide monomers can be used singly or in combination of two or more.

  As the N-substituted amide monomer represented by the general formula (1), commercially available products can also be suitably used. Specifically, for example, N-hydroxyethyl acrylamide (trade name “HEAA”, manufactured by Kojin Co., Ltd.), N-methoxymethyl acrylamide (trade name “NMMA”, manufactured by MRC Unitech Co., Ltd.), N-butoxymethyl acrylamide (trade name) “NBMA” (manufactured by MRC Unitech), N-methoxymethylmethacrylamide (trade name “Wassmer 2MA”, manufactured by Kasano Kosan Co., Ltd.), and the like.

  As the N-substituted amide monomer represented by the general formula (1), N-hydroxyethyl (meth) acrylamide is suitable. The N-substituted amide-based monomer exhibits good adhesion to a transparent protective film using a low moisture content polarizer or a material with low moisture permeability. Among the monomers exemplified above, N- Hydroxyethyl acrylamide exhibits particularly good adhesion.

The active energy ray-curable adhesive (A) is a monofunctional compound having an N-substituted amide monomer other than that represented by the general formula (1), various aromatic rings and a hydroxy group as a radical polymerizable compound. You may contain the compound etc. which have (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, various (meth) acryloyl groups. However, when considering the adhesiveness and water resistance of the adhesive layer, the ratio of the N-substituted amide monomer represented by the general formula (1) to the total amount of the (A) radical polymerizable compound is 30 to 95. It is preferable that it is mass%, and it is more preferable that it is 35-90 mass%.

  Examples of N-substituted amide monomers other than those represented by the general formula (1) include N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, and N, N-diethyl (meth) acrylamide. , N-isopropylacrylamide, N-butyl (meth) acrylamide, N-hexyl (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercaaptomethyl (meth) acrylamide, mercaptoethyl (meth) acrylamide N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like.

  As the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group, various monofunctional (meth) acrylates having an aromatic ring and a hydroxy group can be used. The hydroxy group may exist as a substituent of the aromatic ring, but in the present invention, it exists as an organic group (bonded to a hydrocarbon group, particularly an alkylene group) that bonds the aromatic ring and the (meth) acrylate. Those that do are preferred.

  Examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group include a reaction product of a monofunctional epoxy compound having an aromatic ring and (meth) acrylic acid. Examples of the monofunctional epoxy compound having an aromatic ring include phenyl glycidyl ether, t-butylphenyl glycidyl ether, and phenyl polyethylene glycol glycidyl ether. Specific examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group include, for example, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-t-butylphenoxypropyl (meth) Acrylate, 2-hydroxy-3-phenyl polyethylene glycol propyl (meth) acrylate, etc. are mentioned.

  Moreover, as said urethane (meth) acrylate, the hydroxyl group of the one end of diol compounds, such as (meth) acrylate which has an isocyanate group, and polyalkylene glycols, such as polyurethane diol, polyester diol, polyether diol, polyethylene glycol, polypropylene glycol, etc. And a reaction product thereof.

As a compound having a (meth) acryloyl group, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate C 1-12 alkyl (meth) acrylates such as lauryl (meth) acrylate; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; ) 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, (meta Acrylic acid Hydroxyl group-containing monomers such as 0-hydroxydecyl, 12-hydroxylauryl (meth) acrylate and (4-hydroxymethylcyclohexyl) -methyl acrylate; Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; acrylic acid Caprolactone adducts: styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid And sulfonic acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate and the like. (Meth) acrylamide; maleimide, N-cyclohexylmaleimide, N-phenylmaleimide, etc .; aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate , (Meth) acrylic acid alkylaminoalkyl monomers such as (meth) acrylic acid t-butylaminoethyl, 3- (3-pyridinyl) propyl (meth) acrylate; N- (meth) acryloyloxymethylene succinimide and N- ( And nitrogen-containing monomers such as succinimide monomers such as (meth) acryloyl-6-oxyhexamethylene succinimide and N- (meth) acryloyl-8-oxyoctamethylene succinimide.

  In the case where the active energy ray-curable adhesive further contains a monomer having two or more carbon-carbon double bonds, particularly preferably a polyfunctional (meth) acrylate monomer, as the radically polymerizable compound (A). It is preferable because the water resistance of the adhesive layer is improved. In consideration of the water resistance of the adhesive layer, the monomer having two or more carbon-carbon double bonds is more preferably hydrophobic. Monomers having two or more hydrophobic carbon-carbon double bonds, particularly hydrophobic polyfunctional (meth) acrylate monomers include, for example, tricyclodecane dimethanol diacrylate, divinylbenzene, N, N′-methylene. Bisacrylamide, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) Acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol glycol di (meth) acrylate, glycerin di (meth) acrylate, EO modified glycerin tri (meth) acrylate, EO modified diglycerin tetra ( (Meth) acrylate, (meth) acrylic acid 2- (2-vinyloxyethoxy) ethyl, bisphenol A-EO adduct di (meth) acrylate, trimethylolpropane tri (meth) acrylate, hydroxypivalate neopentyl glycol (meth) Acrylic acid adduct, EO-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, iso Anuric acid EO-modified di (meth) acrylate, isocyanuric acid EO-modified tri (meth) acrylate, ε-caprolactone-modified tris ((meth) acryloxyethyl) isocyanurate, 1,1-bis ((meth) acryloyloxymethyl) ethyl Examples include isocyanate, a polymer of 2-hydroxyethyl (meth) acrylate and 1,6-diisocyanate hexane, 9,9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl] fluorene, and the like.

  (A) It is preferable that the ratio of the monomer which has a 2 or more carbon-carbon double bond with respect to the total amount of a radically polymerizable compound is 5-70 mass%, and it is more preferable that it is 10-65 mass%. . When this ratio is less than 5% by mass, sufficient water resistance may not be obtained. On the other hand, when it exceeds 50% by mass, sufficient adhesion may not be obtained.

<< (B) Photoradical generator >>
(B) The photo radical generator generates radicals by irradiating active energy rays. (B) Examples of the photo radical generator include a hydrogen abstraction type photo radical generator and a cleavage type photo radical generator.

  Examples of the hydrogen abstraction type photo radical generator include 1-methylnaphthalene, 2-methylnaphthalene, 1-fluoronaphthalene, 1-chloronaphthalene, 2-chloronaphthalene, 1-bromonaphthalene, 2-bromonaphthalene, 1-iodonaphthalene. , 2-iodonaphthalene, 1-naphthol, 2-naphthol, 1-methoxynaphthalene, 2-methoxynaphthalene, naphthalene derivatives such as 1,4-dicyanonaphthalene, anthracene, 1,2-benzanthracene, 9,10-dichloroanthracene , 9,10-dibromoanthracene, 9,10-diphenylanthracene, 9-cyanoanthracene, 9,10-dicyanoanthracene, 2,6,9,10-tetracyanoanthracene, anthracene derivatives, pyrene derivatives, carbazole 9-methylcarbazole, 9-phenylcarbazole, 9-prop-2-ynyl-9H-carbazole, 9-propyl-9H-carbazole, 9-vinylcarbazole, 9H-carbazole-9-ethanol, 9-methyl-3-nitro -9H-carbazole, 9-methyl-3,6-dinitro-9H-carbazole, 9-octanoylcarbazole, 9-carbazolemethanol, 9-carbazolepropionic acid, 9-carbazolepropionitrile, 9-ethyl-3,6 -Dinitro-9H-carbazole, 9-ethyl-3-nitrocarbazole, 9-ethylcarbazole, 9-isopropylcarbazole, 9- (ethoxycarbonylmethyl) carbazole, 9- (morpholinomethyl) carbazole, 9-acetylcarbazole, 9- Allyl Rubazole, 9-benzyl-9H-carbazole, 9-carbazoleacetic acid, 9- (2-nitrophenyl) carbazole, 9- (4-methoxyphenyl) carbazole, 9- (1-ethoxy-2-methyl-propyl) -9H -Carbazole, 3-nitrocarbazole, 4-hydroxycarbazole, 3,6-dinitro-9H-carbazole, 3,6-diphenyl-9H-carbazole, 2-hydroxycarbazole, 3,6-diacetyl-9-ethylcarbazole, etc. Carbazole derivatives, benzophenone, 4-phenylbenzophenone, 4,4'-bis (dimethoxy) benzophenone, 4,4'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, methyl 2-benzoylbenzoate Ester, 2- Benzophenone derivatives such as methylbenzophenone, 3-methylbenzophenone, 4-methylbenzophenone, 3,3′-dimethyl-4-methoxybenzophenone, 2,4,6-trimethylbenzophenone, aromatic carbonyl compounds, [4- (4-methyl Phenylthio) phenyl] -phenylmethanone, xanthone, thioxanthone, 2-chlorothioxanthone, 4-chlorothioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 1- Examples include thioxanthone derivatives such as chloro-4-propoxythioxanthone and coumarin derivatives.

  The cleavage type photo radical generator is a type of photo radical generator that generates radicals by cleavage of the compound upon irradiation with active energy rays. Specific examples thereof include arylalkyls such as benzoin ether derivatives and acetophenone derivatives. Examples include, but are not limited to, ketones, oxime ketones, acylphosphine oxides, S-phenyl thiobenzoates, titanocenes, and derivatives obtained by increasing the molecular weight thereof. Commercially available cleavage type photo radical generators include 1- (4-dodecylbenzoyl) -1-hydroxy-1-methylethane, 1- (4-isopropylbenzoyl) -1-hydroxy-1-methylethane, 1-benzoyl. -1-hydroxy-1-methylethane, 1- [4- (2-hydroxyethoxy) -benzoyl] -1-hydroxy-1-methylethane, 1- [4- (acryloyloxyethoxy) -benzoyl] -1-hydroxy- 1-methylethane, diphenyl ketone, phenyl-1-hydroxy-cyclohexyl ketone, benzyldimethyl ketal, bis (cyclopentadienyl) -bis (2,6-difluoro-3-pyryl-phenyl) titanium, (η6-isopropylbenzene) -(Η5-cyclopentadienyl) -iron (II) hexaf Fluorophosphate, trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxy-benzoyl)-(2,4,4-trimethyl-pentyl) -phosphine oxide, bis (2,4,6-trimethylbenzoyl) -2, 4-dipentoxyphenylphosphine oxide or bis (2,4,6-trimethylbenzoyl) phenyl-phosphine oxide, (4-morpholinobenzoyl) -1-benzyl-1-dimethylaminopropane, 4- (methylthiobenzoyl) -1 -Methyl-1-morpholinoethane may be mentioned, but is not limited thereto.

  (B) The photoradical generator, that is, the hydrogen abstraction type or cleavage type photoradical generator can be used alone or in combination, but the stability of the photoradical generator alone is also possible. In addition, the combination of one or more cleavage type photoradical generators is more preferable in terms of curability of the composition in the present invention. Among the cleavage type photo radical generators, acylphosphine oxides are preferable. More specifically, trimethylbenzoyldiphenylphosphine oxide (trade name “DAROCURE TPO”; manufactured by Ciba Japan), bis (2,6-dimethoxy-benzoyl) )-(2,4,4-trimethyl-pentyl) -phosphine oxide (trade name “CGI 403”; manufactured by Ciba Japan) or bis (2,4,6-trimethylbenzoyl) -2,4-dipen Toxiphenylphosphine oxide (trade name “IRGACURE819”; manufactured by Ciba Japan Co., Ltd.) is preferable.

  (B) The content of the photo radical generator is preferably 0.01 to 10 parts by mass, and 0.05 to 5 parts by mass with respect to the total amount of the active energy ray-curable adhesive. More preferred is 0.1 to 3 parts by mass.

  In addition, when the active energy ray-curable adhesive according to the present invention is used in an electron beam curing type, the above-mentioned (B) photoradical generator can be arbitrarily used as the adhesive. Moreover, you may add the sensitizer which raises the cure rate and sensitivity by an electron beam represented by the carbonyl compound.

  Examples of the sensitizer include anthracene, phenothiazene, perylene, thioxanthone, and benzophenone thioxanthone. Further, sensitizing dyes include thiopyrylium salt dyes, merocyanine dyes, quinoline dyes, styrylquinoline dyes, ketocoumarin dyes, thioxanthene dyes, xanthene dyes, oxonol dyes, cyanine dyes, rhodamine dyes. And pyrylium salt pigments.

  As specific anthracene compounds, dibutoxyanthracene, dipropoxyanthraquinone (Anthracure UVS-1331, 1221 manufactured by Kawasaki Kasei Co., Ltd.) and the like are effective.

  When adding a sensitizer, it is preferable that the content is 0.01-20 mass parts with respect to the active energy ray hardening-type adhesive whole quantity, and it is more preferable that it is 0.01-10 mass parts. Preferably, it is 0.1-3 mass parts.

  Moreover, various additives can be mix | blended with the said active energy ray hardening-type adhesive agent as another arbitrary component in the range which does not impair the objective and effect of this invention. Such additives include polyamide, polyamideimide, polyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene-butadiene block copolymer, petroleum resin, xylene resin, ketone resin, cellulose resin, fluorine-based oligomer, silicone-based oligomer. Polymers such as polysulfide oligomers or oligomers; Polymerization inhibitors such as phenothiazine and 2,6-di-t-butyl-4-methylphenol; polymerization initiators; leveling agents; wettability improvers; UV absorbers; silane coupling agents; inorganic fillers; pigments; dyes and the like. However, in the active energy ray-curable adhesive, the content of the above-described additive is preferably 0.005 to 20 parts by mass with respect to the total amount of the active energy ray-curable adhesive, and 0.01 to 10 masses. More preferably, it is 0.1-5 mass parts.

  In addition, as a photocationic polymerization type active energy ray-curable adhesive, for example, a composition containing a compound having an epoxy group and a photoacid generator can be used.

  The viscosity of the active energy ray-curable adhesive is preferably 10 to 350 cps (25 ° C.), more preferably 20 to 300 cps (25 ° C.), and further preferably 40 to 150 cps (25 ° C.). When the viscosity is 10 cps or less, the viscosity becomes too low, and the applied adhesive turns to the back side of the film (single protective polarizing film), and it becomes difficult to design the thickness of the adhesive layer. Also, if the viscosity exceeds 300 cps, the viscosity becomes too high, and if the line speed is increased, it is not preferable from the viewpoint of productivity because coating of the adhesive cannot be sufficiently performed or coating streaks are easily generated. Absent.

  The method of applying the active energy ray-curable adhesive to the second surface of the polarizer in the piece protective polarizing film is appropriately selected depending on the viscosity of the composition and the target thickness. Examples of coating methods include reverse coaters, gravure coaters (direct, reverse and offset), bar reverse coaters, roll coaters, die coaters, bar coaters, rod coaters and the like. In addition, for coating, a method such as a dapping method can be appropriately used.

  In addition, the adhesive coating improves the adhesion between the second transparent protective film and the polarizer from the viewpoint of filling the streaks and irregularities on the surface of the polarizer and making it difficult for air bubbles to bite into the bonded surface. In view of this, it is preferable that the thickness of the finally formed adhesive layer is 300 nm or more. On the other hand, it is considered that the thicker the adhesive layer is, the more the entrained bubbles can be reduced at the time of bonding. However, if the adhesive layer is too thick, it is not preferable in terms of water resistance. Therefore, the thickness of the adhesive layer is preferably 1.3 μm or less, more preferably 1.2 μm or less, and further preferably 1 μm or less. The thickness of the adhesive layer is preferably controlled to be 300 nm to 1 μm, more preferably 350 to 900 nm, and further preferably 400 to 800 nm.

<Step (2)>
After giving the said process (1), a 2nd transparent protective film is bonded together via the said active energy ray hardening-type adhesive by a process (2). The bonding in the step (2) can be performed by a roll laminator or the like.

  In addition, in the step (2), after applying the active energy ray-curable adhesive on the second surface of the polarizer in the one-side protective polarizing film in the step (1), 2 seconds or more have passed, It is preferable to apply. Although depending on the type and viscosity of the active energy ray-curable adhesive, the adhesive was applied to the second surface of the polarizer in order to allow the adhesive to conform to the second surface of the polarizer with many streaks and irregularities. It is preferable to attach the second transparent protective film after some time later. By setting the time after application of the adhesive to 2 seconds or more, it can be applied to the surface of the polarizer of the adhesive rather than immediately after the application, and the entrained bubbles when the second transparent protective film is bonded are eliminated. It can be further reduced. The elapsed time is more preferably 4 seconds or longer, and further preferably 6 seconds or longer. If the elapsed time is too long, the coating solution penetrates too much into the substrate and the adhesive single layer becomes thin and adhesion cannot be taken. Therefore, the elapsed time is preferably 30 seconds or less.

  In addition, as a 2nd transparent protective film, the same material illustrated in the said 1st transparent protective film can be used, and the film of the same thickness can be used. Moreover, the 2nd transparent protective film may use the same material and thickness as a 1st transparent protective film, and may use a different material and thickness. The second transparent protective film can be appropriately selected and used.

<Step (3)>
Next, after applying the step (2), the active energy ray-curable adhesive is irradiated with active energy rays to form an adhesive layer in the step (3). Examples of the active energy rays include ultraviolet rays and electron beams.

When the ultraviolet curable adhesive is employed, any appropriate condition can be adopted as the ultraviolet irradiation condition as long as the adhesive can be cured. The dose of ultraviolet rays is preferably from 100 to 500 mJ / cm ² in accumulated light quantity, and even more preferably 200 to 400 mJ / cm ^2.

  When the electron beam curable adhesive is employed, any appropriate conditions can be adopted as the irradiation condition of the electron beam as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and may be insufficiently cured. If the acceleration voltage exceeds 300 kV, the penetration force through the sample is too strong and the electron beam rebounds, There is a risk of damaging the polarizer. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy.

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

  Irradiation direction of the active energy ray in the step (3) can be irradiated from any appropriate direction, but in irradiation from the first transparent protective film side, light is absorbed by the polarizer, which is extraneous. Since irradiation is needed, it is preferable to irradiate from the 2nd transparent protective film side from a viewpoint of validation of irradiation light.

  In addition, although the manufacturing method of the polarizing film of this invention has the said process (1) thru | or a process (3), other processes other than the said process can be included. For example, in the step (1), the step of applying a dry treatment to the second surface of the polarizer before applying the active energy ray-curable adhesive to the second surface of the polarizer in the single protective polarizing film. Can be provided. Specific examples of the dry treatment include corona treatment and plasma treatment. By performing the dry treatment, the surface modification treatment of the second surface of the polarizer is performed, which is preferable for improving the wettability and adhesiveness of the adhesive.

  In addition, when the polarizer (for both the first surface and the second surface) and the transparent protective film are bonded, an easy-adhesion layer can be provided between the transparent protective film and the adhesive layer. The easy adhesion layer can be formed of, for example, various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. These polymer resins can be used alone or in combination of two or more. Moreover, you may add another additive for formation of an easily bonding layer. Specifically, a stabilizer such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat resistance stabilizer may be used.

  The easy adhesion layer is usually provided in advance on a transparent protective film, and the easy adhesion layer side of the transparent protective film and the polarizer are bonded together with an adhesive layer. The easy-adhesion layer is formed by coating and drying the material for forming the easy-adhesion layer on the transparent protective film by a known technique. The material for forming the easy-adhesion layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying and the smoothness of coating. The thickness of the easy adhesion layer after drying is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and still more preferably 0.05 to 1 μm. Note that a plurality of easy-adhesion layers can be provided, but also in this case, the total thickness of the easy-adhesion layers is preferably in the above range.

  When the polarizing film of the present invention is produced in a continuous line, the line speed depends on the curing time of the adhesive, but is preferably 1 to 500 m / min, more preferably 5 to 300 m / min, and still more preferably 10 to 100 m / min. It is. When the line speed is too low, the productivity is poor, or the damage to the transparent protective film is too great, and a polarizing film that can withstand the durability test cannot be produced. When the line speed is too high, the adhesive is not sufficiently cured, and the target adhesiveness may not be obtained.

  As described above, a polarizing film having the first transparent protective film and the second transparent protective film on both surfaces of the polarizer is obtained. On the surface of the transparent protective film to which the polarizer is not adhered, a hard coat layer and antireflection are provided. Functional layers such as a layer, an anti-sticking layer, a diffusion layer or an antiglare layer can be provided. The functional layers such as the hard coat layer, antireflection layer, antisticking layer, diffusion layer and antiglare layer can be provided on the transparent protective film itself, and separately provided separately from the transparent protective film. You can also.

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

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

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

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing film or an optical film as an overlapping layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of a polarizing film or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 1 to 200 μm, and particularly preferably 1 to 100 μm.

  The exposed surface of the adhesive layer is temporarily covered with a separator for the purpose of preventing contamination until it is put into practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foamed sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate ones according to the prior art, such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based or molybdenum sulfide, can be used.

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

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

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. A protective polarizing film was produced.

<Production of single-protective polarizing film (1)>
In order to produce a thin polarizing film, first, a laminated body in which a PVA layer having a thickness of 9 μm is formed on an amorphous PET substrate is produced by air-assisted stretching at a stretching temperature of 130 ° C., and then stretched. A colored laminate is produced by dyeing the laminate, and the colored laminate is further stretched integrally with an amorphous PET substrate so that the total draw ratio is 5.94 times by stretching in boric acid water at a stretching temperature of 65 degrees. An optical film laminate including a 4 μm thick PVA layer was produced. The PVA molecules in the PVA layer formed on the amorphous PET substrate by such two-stage stretching are oriented in the higher order, and the iodine adsorbed by the dyeing is oriented in the one direction as the polyiodine ion complex. It was possible to produce an optical film laminate including a PVA layer having a thickness of 4 μm and constituting a highly functional polarizing film. Further, a saponified 40 μm-thick triacetyl cellulose film (first transparent protective film) was bonded while applying a polyvinyl alcohol-based adhesive on the surface (first surface) of the polarizing film of the optical film laminate. After that, the amorphous PET substrate was peeled off. Hereinafter, this is referred to as a thin piece protective polarizing film (1).

<Second transparent protective film>
A ZEONOR film (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 60 μm and subjected to corona treatment was used.

(Adjustment of active energy ray-curable adhesive)
The following components were mixed at a ratio of 40 parts of compound (a), 20 parts of compound (b), 40 parts of compound (c) and 3 parts of photopolymerization initiator and stirred at 50 ° C. for 1 hour to cure active energy rays. A mold adhesive was obtained.
Radical polymerizable compound (a): HEAA (hydroxyethylacrylamide), manufactured by Kojinsha;
Radical polymerizable compound (b): Light acrylate BP-4EAL (EP adduct diacrylate of bisphenol A), manufactured by Kyoei Chemical Co., Ltd .;
Radical polymerizable compound (c): ACMO (acryloylmorpholine), manufactured by Kojinsha;
Photopolymerization initiator: IRGACURE 819 (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide), manufactured by BASF.

<Measurement of adhesive viscosity>
The viscosity of the adhesive was measured with a precision rotary viscometer.

Example 1
(Process 1)
Using the microgravure coater (gravure roll: # 180, rotational speed 140% / line speed) on the second surface of the piece protective polarizing film (1), the thickness of the final adhesive layer Was applied so as to be 600 nm.

(Process 2)
Next, after 10 seconds had elapsed after the adhesive was applied, the second transparent protective film was pasted with a roll machine via the adhesive.

(Process 3)
Next, ultraviolet light was irradiated from the bonded second transparent protective film side to obtain a polarizing film having a transparent protective film on both sides. The line speed was 20 m / min, and the amount of UV irradiation was 700 mJ / cm ² in terms of integrated light quantity.

Examples 2 to 5 and Comparative Example 1
In Example 1, except that the coated surface of the adhesive, the thickness of the adhesive layer, the time until pasting after coating, the ratio of each compound of the adhesive, and the viscosity were changed as shown in Table 1. In the same manner as in Example 1, a polarizing film was produced.

[Evaluation]
The following evaluation was performed about the polarizing film obtained by the Example and the comparative example. The results are shown in Table 1.

<Appearance evaluation>
The appearance of the obtained polarizing film was observed with an optical microscope, and bubbles having a maximum diameter of 5 μm to 200 μm were counted. The results are shown in Table 1.

Claims (7)

A method for producing a polarizing film in which first and second transparent protective films are provided on the first and second surfaces of the polarizer,
The active energy ray-curable adhesive is applied to the second surface of the polarizer in the single-protective polarizing film in which the first transparent protective film is provided on the first surface of the polarizer via the polyvinyl alcohol adhesive layer. Step (1),
A step (2) of bonding the second transparent protective film via the active energy ray-curable adhesive;
A step (3) of forming an adhesive layer having a thickness of 300 nm to 1.3 μm by irradiating the active energy ray-curable adhesive with active energy rays; Production method.   The polarizer is a continuous web polarizing film made of a polyvinyl alcohol resin in which a dichroic material is oriented, and the piece protective polarizing film is formed on a thermoplastic resin substrate. The method for producing a polarizing film according to claim 1, wherein the laminate including the resin layer is obtained by stretching in a two-stage stretching process comprising air-assisted stretching and boric acid-water stretching.   In the step (1), after the active energy ray-curable adhesive is applied to the second surface of the polarizer in the one-side protective polarizing film, the step (2) is performed after 2 seconds or more have elapsed. The method for producing a polarizing film according to claim 1 or 2.   The viscosity of the said active energy ray hardening-type adhesive agent is 10-350 cps (25 degreeC), The manufacturing method of the polarizing film in any one of Claims 1-3 characterized by the above-mentioned.   The said active energy ray hardening-type adhesive agent contains a radically polymerizable compound, The manufacturing method of the polarizing film in any one of Claims 1-4 characterized by the above-mentioned.   The step (1) includes a step of performing a dry treatment on the second surface of the polarizer before applying the active energy ray-curable adhesive to the second surface of the polarizer in the one-side protective polarizing film. The manufacturing method of the polarizing film in any one of Claims 1-5 characterized by the above-mentioned.   The method for producing a polarizing film according to claim 1, wherein the irradiation of active energy rays in the step (3) is performed from the second transparent protective film side.