JP2014199284A - Manufacturing method of polarizing plate, polarizing plate, optical film, and image display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a polarizing plate capable of preventing bubble generation when causing a polarizer and a transparent protective film to adhere to each other by an active energy ray curable adhesive to form a polarizing plate, and also to provide an optical film including a polarizing plate obtained by the manufacturing method.SOLUTION: A manufacturing method of a polarizing plate comprises: a step of applying a desiccation treatment after at least applying a coloring treatment, a crosslinking treatment, and a drawing treatment to a polyvinyl alcohol film, to produce a polarizer; and a step of laminating a transparent protective film at least on one surface of a polarizer via an activation energy ray curable adhesive layer. The desiccation treatment is a treatment of applying heat to the polyvinyl alcohol film having been subjected to at least the coloring treatment, the crosslinking treatment, and the drawing treatment, while being conveyed by a plurality of rolls in a prescribed direction. A ratio (L/W) of a distance Lbetween the rolls and a width Wof the polyvinyl alcohol film immediately before the desiccation treatment is 0.4 or less.

Description

  The present invention relates to a method for manufacturing a polarizing plate, a polarizing plate obtained by the manufacturing method, an optical film on which the polarizing plate is laminated, and an image display device including the optical film.

  A polarizing plate widely used in image display devices such as a liquid crystal display device and an organic EL display device is usually produced by laminating a transparent protective film on at least one surface of a polarizer. The polarizer is manufactured by orienting a dichroic substance such as iodine or dichroic dye having dichroism on a polyvinyl alcohol (PVA) film.

  In recent years, with an increase in size, function, and brightness of a liquid crystal display device, the polarizing plate used for the liquid crystal display device is also required to be increased in size and at the same time, improved in optical characteristics and in-plane uniformity. However, in order to obtain a large polarizing plate, it is necessary to uniformly and uniaxially stretch the wide raw film of the PVA-based film. However, this is a very difficult process in practice. The optical characteristics tend to deteriorate at the same time as the uniformity.

Various methods have been proposed for manufacturing the polarizer. For example, it is a manufacturing method of a polarizing film (polarizer) including the wet extending process of the film performed while conveying in a predetermined direction with a pair of conveyance rolls, Comprising: Between the pair of conveyance rolls, the conveyance direction of the film is bathed. A guide roll to be changed is provided, and a method is known in which the ratio (L ₁ / W) of the distance L ₁ between the guide rolls and the width W of the film immediately before stretching is 1.2 or less ( For example, see Patent Document 1). In Patent Document 1, it is possible to produce a wide optical film while maintaining good optical characteristics as a polarizing film by setting the ratio between the distance between the guide rolls and the width of the film immediately before stretching within a specific range. It describes what you can do.

  Moreover, in the manufacturing method of the polarizer which performs a drying process after giving a dyeing process, a bridge | crosslinking process, and an extending | stretching process at least to a PVA-type film, the said drying process has a specific rapid drying stage, It is characterized by the above-mentioned. A method for manufacturing a polarizer is disclosed (for example, see Patent Document 2). Patent Document 2 describes that, by having a specific rapid drying step, the iodine complex can be stably fixed to the molecular chain of PVA, and a polarizer having good durability can be obtained.

JP 2009-15277 A JP 2009-163202 A

  However, in the optical film (polarizer) obtained by the methods of Patent Documents 1 and 2, when the transparent protective film is bonded to the optical film (polarizer) via the active energy ray-curable adhesive layer, May occur.

  In the case of using a water-based adhesive such as a PVA-based adhesive that has been conventionally used for bonding between a polarizer and a transparent protective film, it takes a certain amount of time from application of the adhesive to curing. Even if the child had some wrinkles, the wrinkles were eased in the meantime. However, with active energy ray curable adhesives such as UV curable adhesives, the time from application to curing is short, and there is no relaxation like the aforementioned aqueous adhesives, so when attaching a polarizer and a transparent protective film In addition, there is a problem that bubbles (poor appearance) are formed.

  Then, this invention provides the manufacturing method of the polarizing plate which can suppress bubble generation, when a polarizer and a transparent protective film are bonded together through an active energy ray hardening-type adhesive bond layer, and it is set as a polarizing plate. For the purpose. Another object of the present invention is to provide an optical film including a polarizing plate obtained by the production method.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above object can be achieved by the production method shown below, and have completed the present invention.

That is, the present invention is a process for producing a polarizer by subjecting a polyvinyl alcohol film to at least a dyeing treatment, a crosslinking treatment, and a stretching treatment, followed by a drying treatment,
A method for producing a polarizing plate comprising a step of laminating a transparent protective film via an active energy ray-curable adhesive layer on at least one surface of the polarizer,
The drying process is a process of heating while conveying a polyvinyl alcohol film subjected to at least a dyeing process, a crosslinking process, and a stretching process in a predetermined direction by a plurality of rolls,
Method for producing a polarizing plate ratio of the width W ₁ of the polyvinyl alcohol film of the distance L ₁ and dried immediately before between the rolls (L 1 _{/ W 1)} is equal to or less than 0.4 relates.

  The active energy ray curable adhesive is preferably a radical curable adhesive, and is an adhesive containing a photopolymerization initiator and N-hydroxyethylacrylamide and / or N-acryloylmorpholine. Is more preferable.

  The transparent protective film preferably contains at least one resin selected from the group consisting of a cellulose resin, a (meth) acrylic resin, a cyclic olefin resin, a polyolefin resin, and a polyester resin.

  Further, the present invention includes a polarizing plate obtained by the production method, an optical film characterized in that at least one polarizing plate is laminated, and the optical film. The present invention relates to an image display device.

  In the method for producing a polarizing plate of the present invention, the distance between the rolls is reduced with respect to the width of the polarizer in the drying process of the polarizer, thereby suppressing neck-in of the PVA-based film during drying, and the obtained polarizer As a result, it is possible to suppress the generation of bubbles when the polarizer and the transparent protective film are bonded to each other through the active energy curable adhesive layer to form a polarizing plate.

(A) It is a conceptual diagram which shows the one aspect | mode of the drying process of the polarizer in the manufacturing process of this invention. (B) It is a conceptual diagram which shows the one aspect | mode of the drying process of the polarizer in the manufacturing process of this invention. It is a conceptual diagram which shows the one aspect | mode of the manufacturing method of this invention.

The method for producing a polarizing plate of the present invention comprises a step of producing a polarizer by subjecting a polyvinyl alcohol (PVA) film to at least a dyeing treatment, a crosslinking treatment, and a stretching treatment, followed by a drying treatment,
Including a step of laminating a transparent protective film on at least one surface of the polarizer via an active energy ray-curable adhesive layer;
The drying process is a process of heating while conveying a polyvinyl alcohol film subjected to at least a dyeing process, a crosslinking process, and a stretching process in a predetermined direction by a plurality of rolls,
The ratio (L ₁ / W ₁ ) between the distance L ₁ between the rolls and the width W ₁ of the polyvinyl alcohol film immediately before the drying treatment is 0.4 or less.

1. Polarizer The PVA film applied to the polarizer used in the production method of the present invention has translucency in the visible light region and disperses and adsorbs dichroic substances such as iodine and dichroic dyes. Can be used without any particular limitation. Usually, the PVA film used as the raw material has a thickness of about 10 to 300 μm, and preferably about 20 to 100 μm. The width of the PVA film used as the original fabric is usually about 100 to 5000 mm.

  As a PVA-type film, the PVA-type film conventionally used for the polarizer is used suitably, for example. Examples of the material for the PVA film include PVA and derivatives thereof. Derivatives of PVA include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and alkyl esters thereof, acrylamide and the like. Can be mentioned. The degree of polymerization of PVA is preferably about 100 to 10,000, and more preferably 1000 to 10,000. A saponification degree of about 80 to 100 mol% is generally used.

  In addition to the above, PVA films include hydrophilic polymer films such as partially saponified ethylene / vinyl acetate copolymer systems, polyene-based oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products. Can be mentioned.

  The PVA film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but is preferably 20% by weight or less in the PVA film.

  In the present invention, at least a dyeing process, a crosslinking process, and a stretching process are performed on the PVA-based film.

  The dyeing treatment is performed by adsorbing or orienting iodine or a dichroic dye on the PVA film. The dyeing process can be performed together with the stretching process. Dyeing is usually performed by immersing the film in a dyeing solution. As a dyeing solution, an iodine solution is common. As the iodine solution, an aqueous solution containing iodine ions with iodine and an iodide compound which is a dissolution aid is used. Examples of the iodide compound include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Titanium or the like is used. As the iodide compound, potassium iodide is preferred. The iodide compound used in the present invention is the same as described above when used in other treatments.

  Although the iodine concentration in an iodine solution is not specifically limited, For example, it is preferable that it is about 0.01 to 1 weight%, and it is more preferable that it is 0.01 to 0.5 weight%. The concentration of the iodide compound is not particularly limited, but is preferably about 0.1 to 10% by weight, and more preferably 0.2 to 8% by weight. In iodine staining, the temperature of the iodine solution is usually preferably about 20 to 50 ° C, and more preferably 25 to 40 ° C. The immersion time is usually preferably about 10 to 300 seconds, and more preferably 20 to 240 seconds.

  The crosslinking treatment is usually performed using a boron compound as a crosslinking agent. The order of the crosslinking treatment is not particularly limited. The crosslinking treatment can be performed together with the stretching treatment. The crosslinking treatment can be performed multiple times. Examples of the boron compound include boric acid and borax. The boron compound is generally used in the form of an aqueous solution or a water-organic solvent mixed solution. Usually, an aqueous boric acid solution is used. The boric acid concentration of the boric acid aqueous solution is preferably about 2 to 15% by weight, and more preferably 3 to 13% by weight. In order to impart heat resistance depending on the degree of crosslinking, the boric acid concentration is preferably used. The boric acid aqueous solution or the like can contain an iodide compound such as potassium iodide. When the iodide compound is contained in the boric acid aqueous solution, the iodide compound concentration is preferably about 0.1 to 10% by weight, more preferably 0.2 to 5% by weight.

  The crosslinking treatment can be performed by immersing the PVA film in a boric acid aqueous solution or the like. In addition, a boron compound or the like can be applied to the PVA film by a coating method, a spraying method, or the like. The treatment temperature in the crosslinking treatment is usually preferably 25 ° C. or higher, more preferably 30 to 85 ° C., and further preferably 30 to 70 ° C. The treatment time is usually preferably 5 to 800 seconds, and more preferably about 8 to 500 seconds.

  The stretching treatment is usually performed by uniaxial stretching. This stretching method can be applied together with a dyeing process and a crosslinking process. As the stretching method, either a wet stretching method or a dry stretching method can be employed. In the present invention, it is preferable to use a wet stretching method. As a wet stretching method, for example, it is common to perform stretching after a dyeing treatment. Moreover, it can extend | stretch with a crosslinking process. On the other hand, in the case of dry stretching, examples of the stretching means include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In the stretching means, the unstretched film is usually heated. The stretching process can be performed in multiple stages.

  An iodide compound can be contained in the treatment liquid used in the wet stretching method. When the treatment compound contains an iodide compound, the iodide compound concentration is preferably about 0.1 to 10% by weight, and more preferably 0.2 to 5% by weight. In general, the treatment temperature in the wet stretching method is preferably 25 ° C. or higher, more preferably 30 to 85 ° C., and further preferably 30 to 60 ° C. Further, the immersion time is preferably 10 to 800 seconds, more preferably 30 to 500 seconds.

  In the stretching treatment, the total stretching ratio is preferably 3 to 17 times as the total stretching ratio with respect to the original length of the PVA film, more preferably 4 to 10 times, and more preferably 4 to 8 times. Is more preferable. That is, the total stretch ratio refers to a cumulative stretch ratio including stretching in those treatments when stretching is involved in the swelling treatment described later, the dyeing treatment, the crosslinking treatment or the like other than the stretching treatment. If the total draw ratio is low, the orientation tends to be insufficient, and a polarizer having high optical properties (polarization degree) tends to be difficult to obtain. On the other hand, if the total draw ratio is too high, stretch breakage tends to occur. May become too thin, and the workability in the subsequent process may be reduced.

Further, in the wet stretching treatment of the film, for example, as described in JP-A-2009-15277, the ratio (L ₀₎ between the distance L ₀ between the guide rolls in the bath and the film width W ₀ just before stretching. / W ₀ ) can be 1.2 or less. Thereby, since shrinkage | contraction in the width direction of a film can be suppressed, it is preferable from a viewpoint that a wide polarizing film can be manufactured, maintaining the optical characteristic as a polarizing film favorably.

  In the method for producing a polarizing plate of the present invention, the PVA film is at least subjected to the dyeing treatment, the crosslinking treatment, and the stretching treatment, but before the dyeing treatment, the swelling treatment can be performed. In addition to washing the surface of the PVA-based film and the anti-blocking agent by the swelling treatment, the PVA-based film is also swollen so as to prevent unevenness such as uneven coloring.

  As the treatment liquid used in the swelling treatment, water, distilled water, or pure water is usually used. If the main component is water, the treatment solution may contain a small amount of an iodide compound, an additive such as a surfactant, alcohol, or the like. Moreover, when an iodide compound is contained in the treatment liquid, the iodide compound concentration is preferably about 0.1 to 10% by weight, and more preferably 0.2 to 5% by weight.

  The treatment temperature in the swelling treatment is usually preferably adjusted to about 20 to 45 ° C, more preferably 25 to 40 ° C. In addition, if there is swelling unevenness, the portion becomes uneven coloring in the dyeing process, so that swelling unevenness is not generated. The immersion time is preferably about 10 to 300 seconds, and more preferably 20 to 240 seconds. Moreover, in a swelling process, it can extend | stretch suitably and the draw ratio is normally made into 6.5 times or less with respect to the original length of a PVA-type film.

  In the manufacturing method of the polarizing plate of this invention, a metal ion process can be given other than the said process. The metal ion treatment is performed by immersing the PVA film in an aqueous solution containing a metal salt. Various metal ions can be contained in the PVA film by the metal ion treatment.

  Moreover, in the manufacturing method of the polarizing plate of this invention, after performing the said process as mentioned above, a washing process can be performed. As the cleaning process, a water cleaning process can be performed. The water washing treatment is usually performed by immersing a PVA film in pure water such as ion exchange water or distilled water. The water washing temperature is usually 5 to 50 ° C., and the immersion time is usually 10 to 300 seconds. Further, the order of the cleaning treatment is not particularly limited as long as it is before the drying treatment.

The PVA-based film after the above treatments is dried to produce a polarizer. The drying step is performed by heating the PVA-based film subjected to at least the dyeing treatment, the crosslinking treatment, and the stretching treatment while being conveyed in a predetermined direction by a plurality of rolls, and a distance L between the rolls. ₁ and the ratio (L ₁ / W ₁ ) of the width W ₁ of the polyvinyl alcohol film immediately before the drying treatment is 0.4 or less. By setting L ₁ / W ₁ to 0.4 or less, neck-in at the time of drying can be suppressed, and wrinkles can be prevented from entering the polarizer. As a result, the active energy curable adhesive layer is When a polarizer and a transparent protective film are bonded to form a polarizing plate, the generation of bubbles can be suppressed.

The ratio (L ₁ / W ₁ ) between the distance L ₁ between the rolls and the width W ₁ of the PVA-based film immediately before the drying treatment is preferably 0.3 or less, more preferably 0.2 or less. . Further, the lower limit value of the ratio (L ₁ / W ₁ ) between the distance L ₁ between the rolls and the width W ₁ of the polarizer immediately before the drying treatment is not particularly limited. I just need it. The distance L ₁ between the rolls, the PVA-based film is separated position from the upstream side of the roll, the distance of the PVA-based film on the downstream side of the roll until the first contact position (Figure 1). Further, the width W ₁ of the polarizer immediately before the drying treatment is at least the drying treatment after performing the dyeing treatment, the crosslinking treatment, and the stretching treatment, and, if necessary, the swelling treatment. It represents the width of the PVA film immediately before processing.

The drying process in the present invention will be described more specifically with reference to the drawings. For example, as shown in FIG. 1 (a), when having two rolls in the heating furnace 2 such as an oven, and the distance L ₁ between the rolls, PVA-based film 1 is separated from the upstream roller R1 position d _1, the distance of the PVA-based film 1 of the downstream roller R2 to the position d ₂ initially contact is the distance L ₁ between the rolls. Further, for example, as shown in FIG. 1 (b), in the case where three rolls arranged consecutively in the heating furnace 2 is present, the distance between the rolls L ₁₁ between the rolls R3 and R4, roll R4 and one of the distance between the rolls _{L 12} between the roll R5 is _as long L 1 / _W at ₁ ≦ 0.4, the roll distance _{L 11} between the rolls R3 and R4 satisfy the relation It is preferable that both L ₁₁ and L ₁₂ satisfy the above relationship. In FIGS. 1A and 1B, two and three rolls are provided in the heating furnace 2, respectively, but there is no particular limitation as long as the number of rolls is plural. Usually, the number of rolls is preferably about 2 to 40, and more preferably 4 to 30. The number of rolls is preferably an even number so that both surfaces of the film can be evenly dried. When there are a plurality of rolls and there are a plurality of inter-roll distances L ₁ , any one of the inter-roll distances L ₁ may be L ₁ / W ₁ ≦ 0.4. between the side of the roll distance (i.e., distance between one th roll and the second roll in the oven) is preferably satisfies the relationship, it is preferable that all of L ₁ satisfies the relationship.

  The roll has a rotatable roll shape. Moreover, although those diameters are not specifically limited, For example, it is preferable that it is 50-300 mm, and it is more preferable that it is 100-200 mm. The diameters of the plurality of rolls may be the same or different. The rotation speed of the roll is not particularly limited, but is preferably 3 to 100 m / min, and more preferably 6 to 100 m / min, for example.

As the distance _{L 1} between the rolls, but are not particularly limited, is preferably not more than 2000 mm, more preferably 500mm or less, more preferably 150mm or less. Further, the lower limit is not particularly limited, and an optimum condition can be selected depending on the diameter of the roll or the like. For example, it may be 10 mm or more. L ₁ is preferably in the above range from the viewpoint of reducing bubbles.

Drying the width W ₁ of the previous PVA-based film is not particularly limited, is due to the width of the PVA-based film to be used as raw. For example, it is preferable that it is about 40 to 60% of the width | variety (width | variety of the initial PVA-type film) of the PVA-type film original fabric used as an original fabric. That is, since the width of the PVA film used as the original fabric is usually about 100 to 5000 mm as described above, the width W ₁ of the PVA film immediately before the drying treatment is about 40 to 3000 mm.

  Although the drying temperature in a drying process can be set suitably, it is preferable that it is 20-100 degreeC, for example, and it is more preferable that it is 50-90 degreeC. The roll may be a hot roll. In the case of a hot roll, the temperature is preferably set to be equal to or higher than the temperature of the dry atmosphere.

  Although the time of the said drying process is not specifically limited, For example, it is preferable that it is about 10 to 240 seconds, it is more preferable that it is 15 to 110 seconds, and it is further more preferable that it is 20 to 100 seconds.

  Moreover, it is preferable that the inner wall in a heating furnace is provided with the some hot air vent which can blow a hot air toward the surface of the PVA-type film which passes each roll. The blowing means is not particularly limited, and those normally used for a heating furnace or the like can be used without limitation.

  Moreover, since the said each process is normally performed in a series of continuous processes, the dry process can also be performed as a continuous process following the said each process. For example, in the present invention, as shown in FIG. 2, a series of continuous steps including a swelling treatment step 6, a dyeing treatment step 7, a crosslinking treatment step 8, and a drying treatment step 9, wherein the dyeing treatment step 7, crosslinking It can carry out in the continuous process which performs an extending | stretching process in the process process 8. Specifically, the PVA film drawn out from the raw film 3 of the PVA film is conveyed by the pinch roll 4 and the guide roll 5, and the swelling treatment process 6, the dyeing treatment process 7, the crosslinking treatment process 8, and the drying process. Step 9 is performed, and finally the polarizer 10 is obtained. In FIG. 2, although it is set as the roll of the polarizer 10, it can also be set as the process of manufacturing a polarizing plate continuously, without winding up the polarizer 10, being conveyed to the bonding process with a transparent protective film as it is. . Further, after the cross-linking treatment step 8, a separate stretching treatment step (not shown) may be provided, and further, the cleaning treatment step (not shown) may be appropriately provided.

  Although the thickness of the polarizer obtained by the said method is not specifically limited, It is preferable that it is 2-50 micrometers, and it is more preferable that it is 10-30 micrometers.

  In the production method of the present invention, since the specific drying treatment is performed, neck-in during drying can be suppressed and wrinkles can be prevented from entering the polarizer. As a result, an active energy curable adhesive described later can be used. Also, when the polarizer and the transparent protective film are bonded together to form a polarizing plate, the generation of bubbles can be suppressed.

2. Transparent protective film The polarizing plate of the present invention is obtained by laminating a transparent protective film on at least one surface of the obtained polarizer via an active energy ray-curable adhesive layer.

  Examples of the material constituting the transparent protective film include thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate (PET), polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, Examples thereof include a polyimide resin, a polyolefin resin, a cyclic olefin resin, a (meth) acrylic resin, a polyarylate resin, a polystyrene resin, a PVA resin, and a mixture thereof. Further, thermosetting resins such as (meth) acrylic resins, urethane resins, acrylic urethane resins, epoxy resins, and silicone resins, or ultraviolet curable resins may be used. Among these, at least one resin selected from the group consisting of a cellulose resin, a (meth) acrylic resin, a cyclic olefin resin, and a polyester resin is preferable, and a cellulose resin and a (meth) acrylic resin are preferable. Is more preferable.

  Further, the transparent protective film may contain one or more arbitrary appropriate additives. 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 weight, more preferably 50 to 99% by weight, further preferably 60 to 98% by weight, 70 It is particularly preferred that it is ˜97% by weight. When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  The thickness of the transparent protective film can be appropriately determined, but is generally about 1 to 500 μm, preferably 1 to 300 μm from the viewpoints of workability such as strength and handleability, and thin layer properties. 200 μm is more preferable, and 5 to 150 μm is particularly preferable.

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

  The transparent protective film of the present invention is preferably a film containing at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin.

  The cellulose resin is an ester of cellulose and a fatty acid. Specific examples of such cellulose ester resins include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetylcellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available products of triacetylcellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-60UL” manufactured by FUJIFILM Corporation. , “TD-TAC”, “UZ-TAC”, “KC series” manufactured by Konica, and the like.

  A specific example of the cyclic polyolefin resin is preferably a norbornene resin. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And the graft polymer which modified these with unsaturated carboxylic acid or its derivative (s), and those hydrides, etc. are mentioned. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, trade names “ARTON” manufactured by JSR Corporation, “TOPASS” manufactured by TICONA, and products manufactured by Mitsui Chemicals, Inc. Product name “APEL”.

  On the other hand, as the transparent protective film, a retardation plate having a retardation having a front retardation of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced.

  Examples of the phase difference plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include PVA, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, Polyethersulfone, polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary and ternary systems A polymer, a graft copolymer, a blend, etc. are mentioned. These polymer materials become an oriented product (stretched film) by stretching or the like.

  In addition, the film which has the said phase difference can be separately bonded to the transparent protective film which does not have a phase difference, and the said function can also be provided.

  Further, the surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat treatment, an antireflection treatment, an antisticking treatment, a brightness enhancement treatment, a treatment for diffusion or antiglare, and these treatment layers. Can be provided as an optical layer separately from the transparent protective film.

  The transparent protective film may be subjected to surface modification treatment before applying the adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

3. Active energy ray curable adhesive The polarizer and the transparent protective film are laminated via an active energy ray curable adhesive layer. The active energy ray curable type is an adhesive that is cured by an active energy ray such as an electron beam or ultraviolet ray, and can be used in, for example, an electron beam curable type or an ultraviolet ray curable type. As the active energy ray curable adhesive used in the present invention, an ultraviolet curable adhesive is preferable.

  Moreover, as the active energy ray-curable adhesive used in the present invention, either a cationic curable type or a radical curable type can be used, but a radical curable type is preferable.

  Examples of the curable component of the radical 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 (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.

  Examples of the compound having a (meth) acryloyl group other than the above include amide group-containing monomers such as N-hydroxyethylacrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, and (meth) acrylamide. Is mentioned. Moreover, nitrogen-containing monomers, such as acryloyl morpholine, etc. are mentioned.

  Examples of the curable component of the radical curable adhesive include a compound having a plurality of polymerizable double bonds such as a (meth) acryloyl group and a vinyl group, and the compound is bonded as a crosslinking component. It can also be mixed with the agent 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 Examples thereof include acrylate DCP-A (manufactured by Kyoeisha Chemical Co., Ltd.), SR-531 (manufactured by Sartomer), CD-536 (manufactured by 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 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 for the adhesive to contain a radical polymerization initiator, but when used as an ultraviolet curable type, a photopolymerization initiator is used. . The usage-amount of a photoinitiator is about 0.1-10 weight part normally per 100 weight part of sclerosing | hardenable components, and 0.5-5 weight part is preferable. 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, and it is preferable that it is 0.01-3 weight part.

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

  Examples of the active energy ray-curable adhesive used in the present invention include an active energy ray-curable adhesive composition containing a photopolymerization initiator and N-hydroxyethylacrylamide and / or N-acryloylmorpholine. An active energy ray-curable adhesive composition containing a photopolymerization initiator, N-hydroxyethyl acrylamide, and N-acryloylmorpholine is more preferable.

  If necessary, the adhesive forming the adhesive layer 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 films, acryloxy group compounds and hydrocarbons (Natural and synthetic resins) and other additives that improve mechanical strength and processability, UV absorbers, anti-aging agents, dyes, processing aids, ion trapping agents, antioxidants, tackifiers, Stabilizers such as fillers (other than metal compound fillers), plasticizers, leveling agents, foaming inhibitors, antistatic cracks, heat stabilizers, hydrolysis stabilizers, and the like.

  The thickness of the adhesive layer made of an active energy ray-curable adhesive is not particularly limited, but is preferably controlled to be 0.01 to 7 μm, more preferably 0.01 to 5 μm, and 0.01 to 2 μm. Is more preferable, and 0.01 to 1 μm is particularly preferable. When the thickness of the adhesive layer is smaller than 0.01 μm, the cohesive force of the adhesive force itself cannot be obtained, and the adhesive strength may not be obtained. On the other hand, if the thickness of the adhesive layer exceeds 7 μm, the polarizing plate cannot satisfy the durability.

4). Polarizing plate In the method for producing a polarizing plate of the present invention, an active energy ray-curable adhesive is applied to the surface on which the adhesive layer of the polarizer is formed and / or the surface of the transparent protective film on which the adhesive layer is formed. After the processing, a step of bonding the polarizer and the transparent protective film, and then a step of curing the active energy ray-curable adhesive by irradiation with active energy rays to form an adhesive layer can be included.

  The coating method of the active energy ray-curable adhesive is appropriately selected depending on the viscosity of the composition and the target thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, and the like. In addition, for coating, a method such as a dapping method can be appropriately used.

  A polarizer and a transparent protective film are bonded together through the adhesive applied as described above. The polarizer and the transparent protective film can be bonded together using a roll laminator or the like.

  After bonding a polarizer and a transparent protective film, an active energy ray (an electron beam, ultraviolet rays, etc.) is irradiated, an active energy ray hardening type adhesive is hardened, and an adhesive layer is formed. The irradiation direction of active energy rays (electron beam, ultraviolet ray, etc.) can be irradiated from any appropriate direction. Preferably, it irradiates from the transparent protective film side. When irradiated from the polarizer side, the polarizer may be deteriorated by active energy rays (electron beams, ultraviolet rays, etc.).

  In the polarizing plate obtained by the production method of the present invention, the polarizer and the transparent protective film are bonded through an adhesive layer formed by a cured product layer of the active energy ray-curable adhesive. 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, stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers, and the like may be used.

4). Optical Film The optical film of the present invention can be obtained by laminating the polarizing plate obtained by the production method of the present invention with another optical layer in practical use. The optical layer is not particularly limited. For example, it is used 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 optical layer or two or more optical layers may be used. In particular, the polarizing plate obtained by the production method of the present invention is further provided with a reflective plate, or a reflective polarizing plate obtained by laminating a transflective plate, or a transflective polarizing plate, and a retardation plate. Is preferably an elliptical polarizing plate, a circular polarizing plate, a wide viewing angle polarizing plate in which a viewing angle compensation film is further stacked on the polarizing plate, or a polarizing plate in which a brightness enhancement film is further stacked on the polarizing plate. .

  The polarizing plate or the optical film obtained by the production method 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 assembling a liquid crystal cell and a polarizing plate, or an optical film, and, if necessary, a component such as an illumination system and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate obtained by the method, or an optical film, and it can apply according to the former. As the liquid crystal cell, any type of liquid crystal cell such as a TN type, STN type, or π type can be used.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.

<Measurement of glass transition temperature>
The glass transition temperature (Tg) was measured using a dynamic viscoelasticity measuring device RSAIII (manufactured by TA Instruments) under the following measurement conditions.
Sample size: width 10mm, length 30mm,
Clamp distance 20mm,
Measurement mode: Tensile, Frequency: 1 Hz, Temperature rising rate: 5 ° C./min Dynamic viscoelasticity was measured and adopted as the temperature Tg of tan δ peak top.

Production Example 1 Production of active energy ray-curable adhesive composition 38.3 parts of N-hydroxyethylacrylamide (trade name: HEAA, manufactured by Kojin Co., Ltd.), Tripropylene glycol diacrylate (trade name: Aronix M-220, Tojo) Synthetic Co., Ltd.) 19.1 parts, acryloylmorpholine (trade name: ACMO, manufactured by Kojin Co., Ltd.) 38.3 parts, as a photopolymerization initiator, diethylthioxanthone (trade name: KAYACURE DETX-S, Nippon Kayaku ( 1.4 parts, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE907, manufactured by BASF) 2.9 parts, It stirred at 50 degreeC for 1 hour, and the active energy ray hardening-type adhesive composition was obtained.

Example 1
(Manufacture of polarizers)
A PVA film (thickness: 75 μm, width: 2900 mm) having an average polymerization degree of 2400 and a saponification degree of 99.9 mol% was immersed in warm water at 30 ° C. for 60 seconds to swell.

  Next, the draw ratio with respect to the original length is immersed for 120 seconds in a dye bath filled with an iodine dyeing aqueous solution (30 ° C.) having a concentration of 0.3% iodine / potassium iodide (weight ratio = 0.5 / 8). The film was dyed while being uniaxially stretched up to 3.5 times.

Next, uniaxial stretching was performed while immersing in a crosslinking bath filled with a 3.25% boric acid ester aqueous solution at 60 ° C. for 20 seconds so that the total stretching ratio was 6 times the original length. The ratio (L ₀ / W ₀ ) between the distance L ₀ between the guide rolls in the bath and the film width W ₀ immediately before stretching was 3.

Next, the treated PVA film (W ₁ : 1500 mm) was dried using a heating furnace (oven) as shown in FIG. Fourteen rolls (roll diameter: 100 mm, rotation speed: 20 m / min) were alternately arranged up and down as in FIG. Between the respective roll distance _{L 1} is 300 _mm, it was L ₁ / W ₁ = 0.2. In the oven, as a blowing means, a temperature of 50 ° C. and a wind speed of 15 m / s were blown. The temperature in the oven was 50 ° C., and the drying time was 117 seconds. The thickness of the obtained polarizer was 20 μm.

(Manufacture of polarizing plates)
On Production Example 1 on a TAC film (trade name: TD-60UL, manufactured by FUJIFILM Corporation) having a thickness of 60 μm and a cyclic polyolefin resin film (trade name: ZEONOR, manufactured by ZEON Corporation) having a thickness of 52 μm. MCD coater (cell shape: honeycomb, gravure roll wire number: 1000 / inch, rotational speed 140% / line speed, manufactured by Fuji Machine Industry Co., Ltd.) was applied to the obtained active energy ray-curable adhesive composition. It was used and coated to a thickness of 0.7 μm. The surface of the TAC film coated with the active energy ray curable adhesive composition is applied to one surface of the polarizer, and the surface of the cyclic polyolefin resin film coated with the active energy ray curable adhesive composition is used as the polarizer. The other side of the film was bonded by a roll machine. Then, from the laminated transparent protective film side (both sides), it heated to 50 degreeC using IR heater, and irradiated the ultraviolet-ray of the following conditions on both surfaces, and the said active energy ray hardening-type adhesive composition was hardened. Then, it dried with hot air at 70 degreeC for 3 minute (s), and the polarizing plate which has a transparent protective film on both sides of a polarizer was obtained.

<Active energy rays>
As an active energy ray, an ultraviolet (gallium filled metal halide lamp) irradiation device (product name: Light HAMMER 10, bulb: V bulb, peak illuminance: 1600 mW / cm ² , integrated irradiation amount: 1000 / mJ / cm ² (wavelength: 380 to 440 nm) Fusion UV Systems, Inc.). In addition, the illumination intensity of the ultraviolet-ray was measured using the Sola-Check system by Solatell.

Examples 2-4, Comparative Examples 1-3
Example 1 with the exception that the distance L ₀ between rolls in the stretching process, the film width W ₀ , and the heating temperature, the distance L ₁ between rolls, and the film width W ₁ in the drying process were changed to the values shown in Table 1. A polarizing plate was produced in the same manner.

<Appearance>
About the polarizing plate obtained in Examples 1-4 and Comparative Examples 1-3, the presence or absence of the bubble was confirmed visually and the following evaluation criteria evaluated. The evaluation results are shown in Table 1.
○: Bubbles could not be visually confirmed by transmission and reflection, and no bubbles were seen even when the panel was mounted.
X: Bubbles could be visually confirmed by transmission and reflection, and bubbles were seen even when the panel was displayed.

  As is clear from Table 1 above, in the examples, it was possible to obtain a polarizing plate with a good appearance and a sufficient width. On the other hand, in the comparative example, bubbles were generated frequently and did not function as a polarizing plate.

1 PVA-based film 2 furnace 3 raw film 4 pinch roll 5 guide rolls 6 swelling step 7 dyeing step 8 crosslinking step 9 drying step 10 polarizer R1~R5 roll _{L 1,} L 11, between _{L 12} rolls Distance d Position where PVA film leaves ₁ roll R1 d Position where PVA film first contacts ₂ roll R2

Claims (7)

A step of producing a polarizer by subjecting a polyvinyl alcohol film to at least a dyeing treatment, a crosslinking treatment, and a stretching treatment, followed by a drying treatment,
A method for producing a polarizing plate comprising a step of laminating a transparent protective film via an active energy ray-curable adhesive layer on at least one surface of the polarizer,
The drying process is a process of heating while conveying a polyvinyl alcohol film subjected to at least a dyeing process, a crosslinking process, and a stretching process in a predetermined direction by a plurality of rolls,
The method for producing a polarizing plate, wherein a ratio (L ₁ / W ₁ ) between the distance L ₁ between the rolls and the width W ₁ of the polyvinyl alcohol film immediately before the drying treatment is 0.4 or less.   The method for producing a polarizing plate according to claim 1, wherein the active energy ray curable adhesive is a radical curable adhesive.   The polarizing plate according to claim 1 or 2, wherein the active energy ray-curable adhesive contains a photopolymerization initiator and N-hydroxyethylacrylamide and / or N-acryloylmorpholine. Production method.   The transparent protective film includes at least one resin selected from the group consisting of a cellulose resin, a (meth) acrylic resin, a cyclic olefin resin, a polyolefin resin, and a polyester resin. The manufacturing method of the polarizing plate of Claims 1-3.   A polarizing plate obtained by the production method according to claim 1.   6. An optical film, wherein at least one polarizing plate according to claim 5 is laminated.   An image display device comprising the optical film according to claim 6.

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