JP2014119501A - Manufacturing method of polarizing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polarizing film with excellent conveyability.SOLUTION: A method for manufacturing a polarizing-type film includes: a step (1) of applying an activation treatment on a polarizer with moisture percentage of 11 wt. % or less to make a surface-roughness (Ra) 0.6 nm or more, a step (2) of conveying the polarizer subjected to the activation treatment while causing the surface thereof to have contact with a guide roll; a step (3) of coating the polarizer and/or the transparent protective film with an adhesive agent; and a step (4) of laminating the polarizer and the transparent protective film through the adhesive agent.

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 TVs, higher brightness, higher contrast, and wider viewing angles are required, and in polarizing films, higher transmittance, higher degree of polarization, and higher color reproducibility are also required.

  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, the obtained polarizer is immediately bonded to the transparent protective film coated with the adhesive via the adhesive and used as a polarizing film.

  Further, in order to further improve the adhesive strength between the polarizer and the transparent protective film, the surface of the polarizer on which the adhesive layer is provided is subjected to an activation treatment, and then the polarizer and the transparent protective film are bonded together to form a polarizing film. Has been proposed (Patent Document 1). Since a polarizer is generally manufactured from a hydrophilic polymer film such as a polyvinyl alcohol film, the polarizer has a certain water content. Patent Document 1 describes that the polarizer has a moisture content of preferably 20% by weight or less, more preferably 0 to 17% by weight, and still more preferably 1 to 16% by weight.

JP 2009-008660 A

  Conventionally, the polarizer has been transported by a guide roll, but since the moisture content of the polarizer exceeded 11% by weight, there was no problem in transportability even when transported in contact with the guide roll. . In recent years, a polarizer having a moisture content of 11% by weight or less has been manufactured. However, when the moisture content of the polarizer is 11% by weight or less, the clipping force with the guide roll that transports the polarizer is increased, resulting in poor transportability and subsequent transparency. Defects may occur in pasting with the protective film. In particular, when the surface of the polarizer is transported while being in contact with a guide roll, the transportability tends to be poor.

  An object of this invention is to provide the method which can manufacture the polarizing film by which the transparent protective film is provided in the at least single side | surface of the polarizer through the adhesive bond layer with sufficient transportability.

  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 a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer,
A step (1) of setting the surface roughness (Ra) of the surface of the polarizer to 0.6 nm or more by subjecting at least one surface of the polarizer having a moisture content of 11% by weight or less to an activation treatment;
A step (2) of transporting the activated polarizer while bringing the surface of the activated polarizer into contact with a guide roll;
A step (3) of applying an adhesive to the surface of the polarizer that is conveyed by the guide roll and the surface of the polarizer that forms the adhesive layer and / or the surface of the transparent protective film that forms the adhesive layer;
The manufacturing method of the polarizing film characterized by having the process (4) which bonds a polarizer and a transparent protective film together through the said adhesive agent.

  The manufacturing method of the said polarizing film can be applied suitably, when the thickness of a polarizer is 10 micrometers or less.

  The method for producing the polarizing film includes: a polyvinyl alcohol film formed on a thermoplastic resin substrate, wherein the polarizer is a continuous web polarizing film made of a polyvinyl alcohol resin in which a dichroic substance is oriented. It can be suitably applied to the case where the laminate including the system resin layer is obtained by stretching in a two-stage stretching process consisting of air-assisted stretching and boric acid-water stretching.

  In the manufacturing method of the polarizing film, corona treatment or plasma treatment can be adopted as the activation treatment.

In the manufacturing method of the said polarizing film, it is preferable that the activation process by the said activation process is a corona treatment, and the discharge amount in a corona treatment is 250-1000 W / m < ² > / min.

  In the method for producing a polarizing film of the present invention, a low moisture content polarizer having a moisture content of 11% by weight or less is used, and the surface of the polarizer is guided before the polarizer and the transparent protective film are bonded together with an adhesive. It is conveyed while being in contact with the roll. On the other hand, in the method for producing a polarizing film of the present invention, before bringing the surface of the polarizer into contact with the guide roll, the surface of the polarizer in contact with the guide roll is subjected to an activation treatment so that the surface roughness of the polarizer (Ra ) Is controlled to be 0.6 nm or more. Thus, if the polarizer is controlled so that the surface roughness (Ra) is 0.6 nm or more, it can be transported satisfactorily even when the polarizer with a low moisture content is in contact with the guide roll. I found out that As a result, the subsequent bonding by the adhesive between the polarizer and the transparent protective film becomes good, and the polarizing film can be produced efficiently.

It is a conceptual diagram which shows an example of embodiment which concerns on the manufacturing method of the polarizing film of this invention.

  Below, the manufacturing method of the polarizing film of this invention is demonstrated. In the polarizing film of the present invention, a transparent protective film is provided on at least one surface of the polarizer via an adhesive layer. Such a polarizing film of the present invention can be obtained by sequentially performing the steps (1) to (4). Hereinafter, steps (1) to (4) will be described with reference to FIG. In FIG. 1, steps (1) to (4) are applied to a single-sided protective polarizing film F1 in which a transparent protective film T1 is provided on one side of a polarizer P via an adhesive layer A1. The case where the protective polarizing film F2 is manufactured is illustrated.

<Step (1)>
In the step (1), the surface roughness (Ra) of the surface of the polarizer is set to 0.6 nm or more by performing an activation treatment on at least one surface of the polarizer having a moisture content of 11% by weight or less. In FIG. 1, in the treatment roll R <b> 1, the surface of the polarizer P of the polarizing film F <b> 1 with single-side protection is activated by activation processing means C.

<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. The thickness of the polarizer is preferably 30 μm or less, more preferably 20 μm or less, and still more preferably 10 μm or less.

  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 polarization degree 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 amorphous polyethylene containing copolymerized polyethylene terephthalate copolymerized with isophthalic acid, copolymerized polyethylene terephthalate copolymerized with cyclohexanedimethanol, or other copolymerized polyethylene terephthalate. It can be terephthalate and is preferably made of a transparent resin, and the thickness thereof can be 7 times or more the thickness of the PVA resin layer to be formed. 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.

  The polarizer used in the method for producing a polarizing film of the present invention is a low moisture content polarizer having a moisture content of 11% by weight or less. However, since the polarizer is subjected to the step (1), the process ( In 2), the transportability is also good when the surface of the polarizer is brought into contact with the guide roll and transported. The moisture content of the polarizer within 6 hours after drying may be 6% by weight or less, and further 2% by weight or less. If the moisture content is too low, there is a problem such as the polarizer cracking during transportation. Therefore, the moisture content of the polarizer is preferably 1% by weight or more. In particular, in the case of the above-mentioned thin polarizer, it is effective when the moisture content is 2% by weight or less, and further, the present invention is suitable at 1 to 1.5% by weight.

  What is necessary is just to adjust the moisture content of the polarizer of this invention by arbitrary appropriate methods. For example, the method of controlling by adjusting the conditions of the drying process in the manufacturing process of a polarizer is mentioned.

  The moisture content of the polarizer is measured by the following method. That is, the polarizer was cut out to a size of 100 × 100 mm, and the initial weight of this sample was measured. Subsequently, this sample was dried at 120 ° C. for 2 hours, the dry weight was measured, and the moisture content was measured by the following formula. Moisture content (% by weight) = {(initial weight−dry weight) / initial weight} × 100. The weight was measured three times, and the average value was used.

  Examples of the activation treatment include corona treatment, plasma treatment, glow treatment, and ozone treatment. The corona treatment can be performed, for example, by a method in which discharge is performed in normal pressure air using a corona treatment machine manufactured by Kasuga Electric. The plasma treatment can be performed, for example, by a method in which discharge is performed in atmospheric pressure air or an inert gas atmosphere such as nitrogen or argon using a plasma discharger manufactured by Sekisui Chemical Co., Ltd. Glow treatment and ozone treatment can also be performed according to a conventional method. Among these, corona treatment or plasma treatment is preferable in terms of equipment costs and processing costs.

  The activation treatment is performed so that the surface roughness (Ra) of the surface of the polarizer is 0.6 nm or more. The surface roughness (Ra) is preferably 0.8 nm or more, and more preferably 1 nm or more. When the surface roughness (Ra) is 0.6 nm or more, the moisture content of the polarizer is 11% by weight or less, and the surface of the polarizer is brought into contact with the guide roll in step (2). In this case, the polarizer can be transported well. The surface roughness (Ra) is preferably 10 nm or less, and more preferably 5 nm or less, because when the surface roughness (Ra) becomes too large, the hot water resistance deteriorates.

  The measurement of the surface roughness (Ra) is a parameter representing the surface roughness by the calculated average roughness (average value of surface irregularities). The measurement of the surface roughness (Ra) is a value measured in a tapping mode using an atomic force microscope (AFM) Nanoscope IV manufactured by Beco. As the cantilever, for example, a metrology probe: Tap300 (RTESP type) was used. The measurement range is 1 μm square.

As the activation treatment, treatment conditions are set so that the polarizer has the surface roughness (Ra) according to the activation treatment. For example, the corona treatment is preferably discharged amount is 250~1000W ^/ m 2 ^/ min, more preferably 250~800W ^/ m 2 ^/ min, still preferably 250~600W ^/ m 2 ^/ min Yes, more preferably 250 to 500 W / m ² / min. Calculation formula of activation treatment amount (discharge amount: W / m ² / min) = output (W) / line speed (m / min) / electrode length (m). The gap between the electrode and the sample (polarizer) is preferably 1 mm to 2 mm. The dielectric roll for the activation treatment (corona treatment) is preferably an aluminum roll or a ceramic roll. The earth roll is preferably a Si roll or a metal roll.

  In the method for producing a polarizing film of the present invention, in step (1), at least one side of the polarizer is subjected to activation treatment. In step (2), when both sides of the polarizer are in contact with the guide roll, It is preferable to perform activation treatment on both sides.

  In addition, in the manufacturing method of the polarizing film of this invention, the polarizer used as the object of an activation process in a process (1) should just activate at least one surface, and as shown in FIG. A transparent protective film may be bonded to the other surface of the polarizer that is not subject to the above through an adhesive layer. Further, when the above thin polarizer is used as the polarizer, in FIG. 1, instead of providing the transparent protective film T1 on one side of the polarizer P via the adhesive layer A1, a resin base material (amorphous ester) A thin high-performance polarizing film (polarizer P) formed integrally with a thermoplastic resin).

<Step (2)>
In step (2), the polarizer subjected to the activation treatment is conveyed while the surface of the polarizer subjected to the activation treatment is brought into contact with a guide roll. In the step (2), the surface of the polarizer is brought into contact with the guide roll and conveyed, but the surface of the polarizer in contact with the guide roll has a predetermined surface roughness (Ra) in the step (1). Since it is activated, the transportability is good. In FIG. 1, a single-sided protective polarizing film F <b> 1 whose surface of the polarizer P has been activated is conveyed while the activation surface of the polarizer P is in contact with the guide rolls G <b> 1 and G <b> 2.

<Step (3)>
Next, in step (3), an adhesive is applied to the surface of the polarizer that is transported by the guide roll and the surface of the polarizer that forms the adhesive layer and / or the surface of the transparent protective film that forms the adhesive layer. In FIG. 1, the polarizing film F <b> 1 with single-side protection is activated, but the surface of the polarizer P is coated with the adhesive A <b> 2 on the coating means D in the coating roll R <b> 2.

  The adhesive used for laminating the polarizer and the transparent protective film is not particularly limited as long as it is optically transparent, and water-based, solvent-based, hot-melt-based, and radical-curing types can be used. Adhesives or radical curable adhesives are preferred. In addition, the same adhesive agent can be used also about adhesive layer A1 which bonds the transparent protective film T1 and the polarizer P in the polarizing film F of the single-sided protection of FIG.

  Although it does not specifically limit as an aqueous adhesive, For example, a vinyl polymer type | system | group, a gelatin type, a vinyl type latex type, a polyurethane type, an isocyanate type, a polyester type, an epoxy type etc. can be illustrated. In such an aqueous adhesive, a catalyst such as a crosslinking agent, other additives, and an acid can be blended as necessary. As the water-based adhesive, an adhesive containing a vinyl polymer is preferably used, and the vinyl polymer is preferably a polyvinyl alcohol resin. The polyvinyl alcohol-based resin can contain a water-soluble crosslinking agent such as boric acid, borax, glutaraldehyde, melamine, or oxalic acid. In particular, when a polyvinyl alcohol polymer film is used as the polarizer, it is preferable from the viewpoint of adhesiveness to use an adhesive containing a polyvinyl alcohol resin. Furthermore, an adhesive containing a polyvinyl alcohol-based resin having an acetoacetyl group is more preferable from the viewpoint of improving durability.

  The polyvinyl alcohol-based resin is not particularly limited, but an average degree of polymerization of about 100 to 3000 and an average degree of saponification of about 85 to 100 mol% are preferable from the viewpoint of adhesiveness. Further, the concentration of the aqueous adhesive solution may be appropriately determined according to the target thickness of the adhesive layer, and is not particularly limited, but is preferably 0.1 to 15% by weight, More preferably, it is 0.5 to 10% by weight. If this solution concentration is too high, the viscosity will increase too much, and streaky unevenness will tend to occur. If the solution concentration is too low, the coating properties will be poor and unevenness will tend to occur.

  Polyvinyl alcohol resin is polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability; Examples thereof include modified polyvinyl alcohols that have been converted into ethers, ethers, grafts, or phosphoric esters. Examples of the monomer include (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, unsaturated carboxylic acids such as (meth) acrylic acid and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins can be used singly or in combination of two or more.

  A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto, and a polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Moreover, the method of making diketene gas or liquid diketene contact directly to polyvinyl alcohol is mentioned.

  The degree of acetoacetyl group modification of the polyvinyl alcohol-based resin containing an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is inappropriate. The degree of acetoacetyl group modification is preferably about 0.1 to 40 mol%, more preferably 1 to 20 mol%, and particularly preferably 2 to 7 mol%. When the degree of acetoacetyl modification exceeds 40 mol%, the number of reaction points with the cross-linking agent decreases, and the effect of improving water resistance is small. Such a modification degree of acetoacetyl group can be measured using a nuclear magnetic resonance apparatus (NMR).

  As a crosslinking agent, what is generally used for an adhesive can be used without any particular limitation. For example, in the case of an adhesive using a polyvinyl alcohol resin as described above, a functional group having reactivity with a polyvinyl alcohol resin. A compound having at least two groups can be preferably used. For example, ethylenediamine, triethylenediamine, hexamethylenediamine and other alkyl diamines having two alkylene groups and two amino groups; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (Isocyanates such as 4-phenylmethane triisocyanate, isophorone diisocyanate and ketoxime block product or phenol block product thereof; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexane Diol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycol Epoxys such as dianiline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; Aminoformaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylol melamine, acetoguanamine, benzoguanamine and formaldehyde condensates; sodium, potassium, magnesium, calcium, aluminum, iron, nickel, etc. And divalent or trivalent metal salts and oxides thereof, among which amino-formaldehyde resins, Methylol compounds having Chiroru groups are preferred.

  The compounding amount of the crosslinking agent is generally about 0.1 to 35 parts by weight with respect to 100 parts by weight of the resin, and 10 to 25 parts by weight are preferably used. , 30 to 46 parts by weight, more preferably 32 to 40 parts by weight of a cross-linking agent in exchange for shortening the time (pot life) from preparation of the adhesive to the adhesive layer. Mixing is also effective.

  Moreover, active energy ray-curable adhesives such as an electron beam curable type and an ultraviolet curable type can also be exemplified. In particular, an active energy ray curable adhesive that can be cured in a short time is preferable, and an ultraviolet curable adhesive that can be cured with low energy is more preferable.

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

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

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

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

  Moreover, as a compound which has (meth) acryloyl group other than the above, hydroxyethyl acrylamide, N-methylol acrylamide, N-methoxymethyl acrylamide (SP value 22.9), N-ethoxymethyl acrylamide, (meth) acrylamide, etc. Examples thereof include amide group-containing monomers. Moreover, nitrogen-containing monomers, such as acryloyl morpholine, etc. are mentioned.

  Examples of the curable component of the radical polymerization curable adhesive include compounds having a plurality of polymerizable double bonds such as a (meth) acryloyl group and a vinyl group, and the compound can be used as a crosslinking component. It can also be mixed with the adhesive component. Examples of the curable component that becomes such a crosslinking component include tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, and EO. Modified diglycerin tetraacrylate, Aronix M-220 (manufactured by Toagosei Co., Ltd.), light acrylate 1,9ND-A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DGE-4A (manufactured by Kyoeisha Chemical Co., Ltd.), light acrylate DCP-A (kyoeisha) Chemicals), SR-531 (Sartomer), CD-536 (Sartomer) and the like. Moreover, various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate monomers, and the like are included as necessary.

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

  Examples of the curable component of the cationic polymerization curable adhesive include compounds having an epoxy group or an oxetanyl group. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various generally known curable epoxy compounds can be used. Preferred epoxy compounds include compounds having at least two epoxy groups and at least one aromatic ring in the molecule (hereinafter referred to as “aromatic epoxy compounds”), and having at least two epoxy groups in the molecule. Examples of the compound include at least one compound formed between two adjacent carbon atoms constituting the alicyclic ring (hereinafter referred to as “alicyclic epoxy compound”). .

<Epoxy compound>
The aromatic epoxy compound is not particularly limited as long as the effects of the present invention are not hindered, but bisphenol-type epoxy such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and brominated bisphenol A diglycidyl ether. Resin; novolac epoxy resin such as phenol novolac type epoxy resin and cresol novolac type epoxy resin; biphenyl type epoxy resin, hydroquinone diglycidyl ether, resorcin diglycidyl ether, terephthalic acid diglycidyl ester, phthalic acid diglycidyl ester Of styrene-butadiene copolymer, styrene-isoprene copolymer epoxide, terminal carboxylic acid polybutadiene and bisphenol A type epoxy resin Pressurized reactant, etc. as an example.

  Here, the epoxy resin means a compound or polymer having an average of two or more epoxy groups in the molecule and cured by reaction. In accordance with the custom in this field, in this specification, a monomer may be referred to as an epoxy resin as long as it has two or more curable epoxy groups in the molecule.

  The alicyclic epoxy compound is not particularly limited as long as the effects of the present invention are not hindered, but dicyclopentadiene dioxide, limonene dioxide, 4-vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl, Examples include compounds having at least one epoxidized cyclohexyl group such as epoxycyclohexanecarboxylate and bis (3,4-epoxycyclohexylmethyl) adipate.

  In addition to the above, aliphatic epoxy compounds such as 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and polytetramethylene glycol diglycidyl ether; hydrogenated bisphenol A An epoxy compound having a hydrogenated aromatic ring, such as diglycidyl ether; a compound in which both ends of polybutadiene having hydroxyl groups at both ends are glycidyl etherified, an internal epoxidized product of polybutadiene, and a double bond of styrene-butadiene copolymer A partially epoxidized compound (for example, “Epofriend” manufactured by Daicel Chemical Industries, Ltd.) and a compound in which the isoprene unit of a block copolymer of ethylene-butylene copolymer and polyisoprene is partially epoxidized ( Eg to such KRATON manufactured by the "L-207"), an epoxy compound of the polymer system, etc. also can be an epoxy compound of the component (A).

  Among these, the aromatic epoxy compound is preferable because it is excellent in durability and the like when used as a polarizing plate, and is particularly excellent in adhesion to a polarizer and a protective film. Furthermore, preferred examples of the aromatic epoxy compound include glycidyl ethers of aromatic compounds or glycidyl esters of aromatic compounds. Specific examples of glycidyl ethers of aromatic compounds include bisphenol-type epoxy resins; phenol novolac-type epoxy resins, and cresols, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of brominated bisphenol A. Preferred examples include novolak type epoxy resins such as novolak type epoxy resins; biphenyl type epoxy resins; hydroquinone diglycidyl ether; resorcin diglycidyl ether. Specific examples of the glycidyl ester of the aromatic compound include terephthalic acid diglycidyl ester and phthalic acid diglycidyl ester.

  Among them, glycidyl ether of an aromatic compound is particularly preferable because it is more excellent in adhesion when a polarizer and a protective film are bonded and durability when used as a polarizing plate. Among the glycidyl ethers of aromatic compounds, particularly preferable compounds include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and phenol novolac type epoxy resin.

  An epoxy compound can also be used individually by 1 type, and can also be used in mixture of 2 or more types. For example, two or more types of aromatic epoxy compounds can be mixed and used, or an aromatic epoxy compound as a main component and an alicyclic epoxy compound can also be mixed.

<Oxetane compound>
The oxetane compound is not particularly limited as long as it has at least one oxetanyl group in the molecule, and various compounds having an oxetanyl group can also be used. As the oxetane compound (B), a compound having one oxetanyl group in the molecule (hereinafter referred to as “monofunctional oxetane”) and a compound having two or more oxetanyl groups in the molecule (hereinafter referred to as “polyfunctional oxetane”) Is a preferred example.

  The monofunctional oxetane includes an aromatic group-containing monofunctional group such as an alkoxyalkyl group-containing monofunctional oxetane such as 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane and 3-ethyl-3-phenoxymethyloxetane. Preferred examples include a hydroxyl group-containing monofunctional oxetane such as oxetane and 3-ethyl-3-hydroxymethyloxetane.

Examples of the polyfunctional oxetane include 3-ethyl-3-[(3-ethyloxetane-3-yl) methoxymethyl] oxetane and 1,4-bis [(3-ethyloxetane-3-yl) methoxymethyl] benzene. 1,4-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, 1,2-bis [(3- Ethyloxetane-3-yl) methoxy] benzene, 4,4'-bis [(3-ethyloxetane-3-yl) methoxy] biphenyl, 2,2'-bis [(3-ethyloxetane-3-yl) methoxy ] Biphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-bis [(3-ethyloxetane-3-yl) methoxy] biphenyl, 2,7-bis [(3-ethyl Xetane-3-yl) methoxy] naphthalene, bis [4-{(3-ethyloxetane-3-yl) methoxy} phenyl] methane, bis [2-{(3-ethyloxetane-3-yl) methoxy} phenyl] Etherified modification of methane, 2,2-bis [4-{(3-ethyloxetane-3-yl) methoxy} phenyl] propane, novolak type phenol-formaldehyde resin with 3-chloromethyl-3-ethyloxetane, 3 (4), 8 (9) -bis [(3-ethyloxetane-3-yl) methoxymethyl] -tricyclo [5.2.1.0 ^2,6 ] decane, 2,3-bis [(3-ethyl Oxetane-3-yl) methoxymethyl] norbornane, 1,1,1-tris [(3-ethyloxetane-3-yl) methoxymethyl] propane, 1-butoxy -2,2-bis [(3-ethyloxetane-3-yl) methoxymethyl] butane, 1,2-bis [{2- (3-ethyloxetane-3-yl) methoxy} ethylthio] ethane, bis [{ 4- (3-Ethyloxetane-3-yl) methylthio} phenyl] sulfide, 1,6-bis [(3-ethyloxetane-3-yl) methoxy] -2,2,3,3,4,4,5 , 5-octafluorohexane, hydrolysis condensate of 3-[(3-ethyloxetane-3-yl) methoxy] propyltriethoxysilane, condensate of tetrakis [(3-ethyloxetane-3-yl) methyl] silicate Etc.

  The oxetane compound is preferably liquid at room temperature with a molecular weight of 500 or less from the viewpoint of coating properties and adhesion to a protective film when forming a polarizing plate. Further, in terms of the durability of the polarizing plate, a monofunctional oxetane is more preferably an aromatic ring in the molecule or a polyfunctional oxetane. Examples of such particularly preferred oxetane compounds include 3-ethyl-3-phenoxymethyloxetane, 3-ethyl-3-[(3-ethyloxetane-3-yl) methoxymethyl] oxetane, and 1,4-bis [ (3-ethyloxetane-3-yl) methoxymethyl] benzene and the like.

  One oxetane compound can be used alone, or two or more oxetane compounds can be used in combination.

<Ratio of epoxy compound and oxetane compound>
The use ratio of the epoxy compound and the oxetane compound is 90/10 to 10/90 in weight ratio. If this ratio is excessive or insufficient, the effect of curing in a short time is not sufficiently exhibited. A suitable weight ratio of the two is about 70/30 to 20/80, since it has a low viscosity before curing and excellent coating properties, and can exhibit sufficient adhesion and flexibility after curing. The weight ratio is about 60/40 to 25/75.

<Photocationic polymerization initiator>
The cationic polymerization curable adhesive contains the epoxy compound and the oxetane compound described above as curable components, and these are cured by cationic polymerization, and therefore, a photocationic polymerization initiator is blended therein. This cationic photopolymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and starts a polymerization reaction of an epoxy group or an oxetanyl group.

  By blending the cationic photopolymerization initiator, curing at room temperature is possible, and the necessity of considering the heat resistance of the polarizer and the distortion due to expansion or contraction is reduced, and the protective film can be satisfactorily adhered. In addition, since the cationic photopolymerization initiator acts catalytically upon irradiation with active energy rays, it is excellent in storage stability and workability even when mixed with an epoxy compound and an oxetane compound. Examples of compounds that generate cation species and Lewis acids upon irradiation with active energy rays include onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes.

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate, diphenyl [4- (Phenylthio) phenyl] sulfonium hexafluoroantimonate, 4,4′-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] Diphenyl sulfide bishexafluoroantimonate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfur 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) Borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenylsulfide hexafluoroantimonate, 4- (p -Tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

  Examples of iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) -tris. And (trifluoromethylsulfonyl) methanide.

  Each of these cationic photopolymerization initiators may be used alone or in combination of two or more. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.

  As the cationic photopolymerization initiator, commercially available products can be easily obtained. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd.) ), “UVI-6992” (manufactured by Dow Chemical Company), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA Corporation), “CI-5102”, “CIT” -1370 "," CIT-1682 "," CIP-1866S "," CIP-2048S "," CIP-2064S "(above, manufactured by Nippon Soda Co., Ltd.)," DPI-101 "," DPI-102 " “DPI-103”, “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI-103”, “BBI” 105 ”,“ TPS-101 ”,“ TPS-102 ”,“ TPS-103 ”,“ TPS-105 ”,“ MDS-103 ”,“ MDS-105 ”,“ DTS-102 ”,“ DTS-103 ” (Midori Chemical Co., Ltd.), “PI-2074” (Rhodia Co., Ltd.), “Irgacure 250”, “Irgacure PAG103”, Irgacure PAG108 ”, Irgacure PAG121”, Irgacure PAG203 ”(above, Ciba) “CPI-100P”, “CPI-101A”, “CPI-200K”, “CPI-210S” (manufactured by San Apro Co., Ltd.) and the like, and in particular, diphenyl [4- (phenylthio) phenyl] sulfonium "UVI-6992" manufactured by Dow Chemical Co., Ltd. "CPI-100P" of, "CPI-101A", "CPI-200K", "CPI-210S" is preferable.

  The blending ratio of the photo cationic polymerization initiator is in the range of 0.5 to 20% by weight based on the whole cationic polymerization curable adhesive. When the proportion is less than 0.5% by weight, the adhesive is not sufficiently cured, and the mechanical strength and adhesive strength are lowered. On the other hand, when the proportion exceeds 20% by weight, the ionic substance in the cured product is obtained. Since the hygroscopic property of the cured product is increased and the durability performance is likely to be reduced due to the increase in the amount of selenium, it is not preferable.

  The adhesive may contain a metal compound filler. With the metal compound filler, the fluidity of the adhesive layer can be controlled, the film thickness can be stabilized, and a polarizing plate having a good appearance, uniform in-plane and no adhesive variation can be obtained.

  As an adhesive, a dry laminating method that can be bonded in a solventless or low solvent state can be used. As this dry laminating method, conventionally known dry laminating adhesives and laminating methods may be used, but this method can be used in addition to the present invention. As a result, there is an effect of further reducing the stripe-shaped unevenness and the like.

  Examples of the dry laminating adhesive include a two-component curable adhesive, a two-component solvent-type adhesive, and a one-component solventless adhesive. Two-component curable adhesives are acrylic, and two-component solvent-based adhesives are polyester, aromatic polyester, aliphatic polyester, polyester / polyurethane, polyether / polyurethane, one-component solventless adhesive. As the agent (moisture curable type), a polyether / polyurethane resin or the like can be used.

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

  The adhesive coating method is appropriately selected depending on the viscosity of the adhesive 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.

  Moreover, when using an aqueous adhesive etc., it is preferable to apply the adhesive so that the thickness of the finally formed adhesive layer is 30 to 300 nm. The thickness of the adhesive layer is more preferably 60 to 250 nm. On the other hand, when a curable adhesive is used, the thickness of the adhesive layer is preferably 0.1 to 200 μm. More preferably, it is 0.5-50 micrometers, More preferably, it is 0.5-10 micrometers.

<Process (4)>
At a process (4), the said polarizer and a transparent protective film are bonded together through the said adhesive agent. The polarizer and the transparent protective film can be bonded together using a roll laminator or the like. In FIG. 1, a polarizing film F2 having a double-side protection is obtained by laminating a polarizer P of a polarizing film F1 with a single-side protection and a transparent protective film T2 with an adhesive A2 using laminate rolls R3 and R4.

<Transparent protective film>
As the material constituting the 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, a coloring inhibitor, 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 thickness of the transparent protective film can be appropriately determined, 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.

  In addition, when providing a transparent protective film on both surfaces of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the transparent protective film which consists of a different polymer material etc. may be used. For example, as shown in FIG. 1, when the double-sided protective polarizing film F2 is manufactured by applying the steps (1) to (4) to the single-sided protective polarizing film F1, the transparent single-sided protective polarizing film F1 is transparent. The protective film T1 is preferably selected from a cellulose polymer (such as triacetyl cellulose), a polyolefin having a norbornene structure, an acrylic polymer, a polyester polymer, or a polyolefin polymer (such as polypropylene). In this case, it is preferable that the transparent protective film T2 is appropriately selected from a cellulose polymer (triacetyl cellulose or the like), a polyolefin having a norbornene structure, an acrylic polymer, a polyester polymer, or a polyolefin polymer (polypropylene or the like). .

  An adhesive layer is formed after the bonding step. The formation of the adhesive layer is performed according to the type of adhesive. In the case of a water-based adhesive, bonding can be performed in step (4) with an adhesive layer previously formed in step (3).

  When the adhesive is a water-based adhesive or a solvent-based adhesive, a drying step is performed after the bonding step to form an adhesive layer. When using a water-based adhesive, the drying step is preferably performed at a drying temperature of about 20 to 80 ° C., preferably 40 to 80 ° C. for about 1 to 10 minutes, preferably 1 to 5 minutes.

  When the adhesive is a radical curable adhesive, a curing process is performed after the bonding process to form an adhesive layer. When the radical curable adhesive is electron beam curable, it is cured by electron beam irradiation, when it is ultraviolet curable, by ultraviolet treatment, and when it is thermosetting, it is cured by heat treatment. In these curing treatments, each condition is appropriately set according to the type of curing, the type of adhesive, and the thickness of the adhesive layer.

  In addition, although the manufacturing method of the polarizing film of this invention has the said process (1) thru | or a process (4), other processes other than the said process can be included.

  For example, when bonding a polarizer and a transparent protective film, 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 a transparent protective film on one or both sides of the polarizer is obtained, but on the surface of the transparent protective film on which the polarizer is not adhered, a hard coat layer, an antireflection layer, an antisticking layer, A functional layer such as 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 in water at a stretching temperature of 65 degrees. Then, drying was performed at 50 ° C. for 4 minutes to produce an optical film laminate including a 4 μm thick PVA layer. 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. Furthermore, after applying a saponified 40 μm thick triacetyl cellulose film (transparent protective film) while applying a polyvinyl alcohol adhesive on the surface of the polarizing film of the optical film laminate, an amorphous PET group The material was peeled off. This is referred to as a thin piece protective polarizing film (1). The moisture content of the polarizing film (polarizer) in the piece protective polarizing film (1) was 1.8%.

<Creation of a single-protective polarizing film (2)>
A polyvinyl alcohol film having a thickness of 80 μm was stretched up to 3 times while being dyed for 1 minute in an iodine solution of 0.3% concentration at 30 ° C. between rolls having different speed ratios. Thereafter, the total draw ratio was stretched to 6 times while being immersed in an aqueous solution containing 60% at 4% concentration of boric acid and 10% concentration of potassium iodide for 0.5 minutes. Next, after washing by immersing in an aqueous solution containing potassium iodide at 30 ° C. and 1.5% concentration for 10 seconds, drying was performed at 50 ° C. for 4 minutes to obtain a polarizer having a thickness of 20 μm. A saponified 40 μm-thick triacetyl cellulose film (transparent protective film) was bonded to both surfaces of the polarizer with a polyvinyl alcohol-based adhesive to prepare a polarizing film. Hereinafter, this is referred to as a piece protective polarizing film (2). The moisture content of the polarizing film (polarizer) in the piece protective polarizing film (2) was 11%.

<Transparent protective film>
A norbornene-based film (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 HEAA: 50 parts, ACMO: 50 parts, IRGACURE 819: 3 parts and stirred at 50 ° C. for 1 hour to obtain an active energy ray-curable adhesive.
HEAA (hydroxyethylacrylamide), Kojin Co., Ltd. ACMO (acryloylmorpholine), Kojin Co., Ltd. IRGACURE819 (bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, manufactured by Ciba Japan Co., Ltd.)

  Example 1

(Process 1)
The piece protection polarizing film (1) was conveyed by the aspect of FIG. 1 so that the transparent protection film side of the piece protection polarizing film (1) might become the process roll side. The activation treatment was performed by corona treatment with a corona irradiator (Kasuga Denki Co., Ltd., CT-0212) on one side of the polarizer at a discharge amount of 250 W / m ² / min. The surface roughness (Ra) of the surface of the polarizer subjected to the activation treatment was 0.62 nm.

(Process 2)
Next, the piece protective polarizing film (1) having the surface of the polarizer activated is conveyed in the form of FIG. 1 so that the polarizer side is the guide roll side. did.

(Process 3)
Next, the adhesive (active energy ray-curable adhesive) was applied to the polarizer surface of the piece protective polarizing film (1) using a micro gravure coater.

(Process 4)
Next, after the adhesive was applied, the transparent protective film was bonded with a roll machine through the adhesive. From the bonded transparent protective film side, ultraviolet rays were irradiated to obtain a polarizing film having a transparent protective film on both sides. Bonding was performed at a line speed of 20 m / min.

Examples 2-3 and Comparative Examples 1-4
In Example 1, the polarizing film was produced like Example 1 except having changed the kind of piece protection polarizing film, and the amount of corona discharge treatment to a polarizer as shown in Table 1. In addition, the moisture content of the piece protection polarizing film was controlled by the drying temperature.

[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.

<Transportability>
The transportability in the step (2) was evaluated according to the following criteria.
○: Good sliding, no breakage or flaws during transportation.
X: The clip force with the roll is too high, and the film is broken, scratched, or poorly laminated.

P Polarizer T1, T2 Transparent protective film A1, A2 Adhesive F1 Single-sided protective polarizing film F2 Double-sided protective polarizing film

JP 2009-008860 A

Claims (5)

A method for producing a polarizing film, wherein a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer,
A step (1) of setting the surface roughness (Ra) of the surface of the polarizer to 0.6 nm or more by subjecting at least one surface of the polarizer having a moisture content of 11% by weight or less to an activation treatment;
A step (2) of transporting the activated polarizer while bringing the surface of the activated polarizer into contact with a guide roll;
A step (3) of applying an adhesive to the surface of the polarizer that is conveyed by the guide roll and the surface of the polarizer that forms the adhesive layer and / or the surface of the transparent protective film that forms the adhesive layer;
A method for producing a polarizing film, comprising a step (4) of laminating a polarizer and a transparent protective film via the adhesive.   The method for producing a polarizing film according to claim 1, wherein the polarizer has a thickness of 10 μm or less.   The polarizer is a continuous web polarizing film made of a polyvinyl alcohol resin in which a dichroic material is oriented, and a laminate including a polyvinyl alcohol resin layer formed on a thermoplastic resin substrate. 3. The method for producing a polarizing film according to claim 1, wherein the polarizing film is obtained by stretching in a two-stage stretching process comprising air-assisted stretching and boric acid-water stretching.   The method for producing a polarizing film according to claim 1, wherein the activation treatment is a corona treatment or a plasma treatment. The method for producing a polarizing film according to claim 1, wherein the activation treatment is a corona treatment, and a discharge amount in the corona treatment is 250 to 1000 W / m ² / min.

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