JP6636367B2 - Method for manufacturing one-sided protective polarizing film with transparent resin layer, method for manufacturing polarizing film with adhesive layer, and method for manufacturing image display device - Google Patents

Description

  The present invention relates to a method for producing a piece-protected polarizing film provided with a transparent resin layer. The present invention also relates to a method for producing a polarizing film with an adhesive layer including the one-sided protective polarizing film with a transparent resin layer and an adhesive layer. Further, the present invention provides an image display device such as a liquid crystal display device (LCD) or an organic EL display device using the one-sided protective polarizing film with a transparent resin layer or the polarizing film with an adhesive layer obtained by the above manufacturing method. It relates to a manufacturing method.

  For watches, mobile phones, PDAs, notebook computers, monitors for personal computers, DVD players, TVs, and the like, liquid crystal display devices are rapidly developing in the market. The liquid crystal display device visualizes a polarization state by switching of liquid crystal, and a polarizer is used from the display principle.

  As a polarizer, for example, an iodine-based polarizer having a structure in which iodine is adsorbed on a polyvinyl alcohol film and stretched is most widely used because of its high transmittance and high degree of polarization. Such a polarizer has a disadvantage that the mechanical strength is extremely weak, and the polarizer shrinks due to heat or moisture and the polarizing function is significantly reduced. Therefore, the obtained polarizer is immediately bonded to a protective film coated with an adhesive via an adhesive, and is used as a polarizing film.

  On the other hand, an image display device such as a liquid crystal display device is becoming thinner, and a polarizing film is also required to be thinner. For this reason, the thickness of the polarizer has been reduced. Further, the thickness can be reduced by providing a protective film only on one side of the polarizer and using a single protective polarizing film not provided with the protective film on the other side. Such a single-sided protective polarizing film has one less protective film than a double-sided protective polarizing film in which protective films are provided on both surfaces of a polarizer, so that a thinner type can be achieved.

  On the other hand, since the one-sided protective polarizing film has insufficient durability due to thermal shock, a film provided with a protective layer (transparent resin layer) on the polarizer side has been proposed (for example, see Patent Documents 1 and 2).

JP 2010-009027 A JP 2013-160775 A

  As described above, it is known that the durability of a single-sided protective polarizing film can be improved by forming a transparent resin layer on a polarizer. However, when the transparent resin layer is formed on the polarizer of the one-sided protective polarizing film using a thin polarizer having a thickness of 10 μm or less, when the one-sided protective polarizing film with the transparent resin layer is exposed to a humid environment, This time, it was newly found that when the one-sided protective polarizing film with the transparent resin layer after the humidification test was attached to both sides of an image display panel or the like such that the absorption axes were orthogonal, the appearance unevenness was easily visually recognized.

  Accordingly, the present invention provides a piece with a transparent resin layer, which can suppress the appearance unevenness even when the piece-protected polarizing film with a transparent resin layer using a thin polarizer is exposed to a humid environment. An object of the present invention is to provide a method for producing a protective polarizing film. The present invention also provides a method for producing a polarizing film with an adhesive layer using the one-sided protective polarizing film with the transparent resin layer, and an image using the one-sided protective polarizing film with the transparent resin layer or the polarizing film with the adhesive layer. Another object is to provide a method for manufacturing a display device.

  Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by the following method for producing a single-sided protective polarizing film with a transparent resin layer, and have accomplished the present invention.

That is, the present invention provides a one-sided protective polarizing film having a protective film only on one side of a polarizer, and a one-sided protective polarizing film with a transparent resin layer having a transparent resin layer provided on the polarizer surface of the one-sided protective polarizing film. The method of manufacturing
Step (1) of preparing a one-sided protective polarizing film having a protective film only on one side of a polarizer,
A step (2) of applying an aqueous coating solution containing a resin component to the polarizer surface of the one-sided protective polarizing film, and a step (3) of drying the obtained coating film to form a transparent resin layer. Include this order,
The polarizer includes a polyvinyl alcohol-based resin, has a thickness of 10 μm or less,
The present invention relates to a method for producing a one-sided protective polarizing film provided with a transparent resin layer, wherein the water contact angle of the surface of the polarizer on which the transparent resin layer is formed is in the range of an average water contact angle of ± 20 °.

Before the step (2) of applying the aqueous coating liquid,
A step of bonding a surface protective film to the polarizer surface of the one-sided protective polarizing film, and then peeling the surface protective film from the one-sided protective polarizing film, and
A step of performing an activation treatment on the surface protective film peeling surface of the one-side protective polarizing film can be included in this order.

Before the step (2) of applying the aqueous coating liquid,
A step of performing an activation treatment on the polarizer surface of the one-side protection polarizing film, and
A step of bonding a surface protective film to the activated surface of the one-sided protective polarizing film, and then peeling off the surface-protective film from the one-sided protective polarizing film,
Can be included in this order.

  Preferably, the activation treatment is a corona treatment and / or a plasma treatment.

  The variation of the water contact angle is preferably within a range of an average water contact angle ± 15 °.

  The average water contact angle is preferably 90 ° or less.

  Further, the present invention provides a polarizing film with an adhesive layer, comprising a step of forming an adhesive layer on the transparent resin layer of the one-sided protective polarizing film with a transparent resin layer obtained by the production method. It relates to a manufacturing method.

  Further, the present invention provides an image display device formed by using a one-sided protective polarizing film with a transparent resin layer obtained by the above-mentioned manufacturing method, or a polarizing film with an adhesive layer obtained by the above-mentioned manufacturing method. And a method for producing the same.

  The method for producing a piece-protected polarizing film with a transparent resin layer of the present invention can suppress the occurrence of appearance unevenness even when exposed to a humidified environment despite using a thin polarizer. A one-sided protective polarizing film with a resin layer can be provided.

  This is because the variation in the water contact angle of the transparent resin layer forming surface of the polarizer used in the present invention is controlled within a predetermined range, and the thickness unevenness of the transparent resin layer is suppressed. That is, a piece protective polarizing film with a transparent resin layer, when exposed to a humidified environment, the components near the polarizer surface may seep into the transparent resin layer, and a polarizer with a thickness of 10 μm or less was used. In the case, the proportion of the component that oozes out into the transparent resin layer with respect to the total amount of the polarizer is large, and furthermore, when the thickness variation of the transparent resin layer occurs, the polarizer causes the transparent resin layer to lose its thickness. It is considered that the amount of the components that seep into the inside also varies, so that it is likely to be visually recognized as uneven appearance.

  Further, in the method for manufacturing an image display device of the present invention, since a one-sided protective polarizing film with a transparent resin layer or a polarizing film with an adhesive layer obtained by the manufacturing method of the present invention is used, a highly reliable image display device is used. Can be provided.

FIG. 1 is an example of a schematic cross-sectional view of a one-sided protective polarizing film with a transparent resin layer obtained by a production method of the present invention. FIG. 1 is an example of a schematic cross-sectional view of a polarizing film with a pressure-sensitive adhesive layer obtained by a production method of the present invention. (A) Example 1, (b) Example 3, (c) It is the figure which measured the thickness variation of the transparent resin layer obtained by the comparative example 1 using the interference type optical thickness meter. (A) Example 1, (b) Example 3, (c) It is the photograph which observed the visibility of the external appearance unevenness in the sample for the humidification environment test obtained by the comparative example 1.

1. Method for producing a one-sided protective polarizing film with a transparent resin layer The method for producing a one-sided protective polarizing film with a transparent resin layer of the present invention comprises: a one-sided protective polarizing film having a protective film on only one side of a polarizer; A method for producing a one-sided protective polarizing film with a transparent resin layer having a transparent resin layer provided on the polarizer surface of the film,
Step (1) of preparing a one-sided protective polarizing film having a protective film only on one side of a polarizer,
A step (2) of applying an aqueous coating solution containing a resin component to the polarizer surface of the one-sided protective polarizing film, and a step (3) of drying the obtained coating film to form a transparent resin layer. Include this order,
The polarizer includes a polyvinyl alcohol-based resin, has a thickness of 10 μm or less,
The variation of the water contact angle of the surface of the polarizer on which the transparent resin layer is formed is within the range of the average water contact angle ± 20 °.

  The one-sided protective polarizing film provided with the transparent resin layer will be described with reference to FIG. However, the present invention is not limited to these figures.

  The one-sided protective polarizing film 3 used in the present invention has the protective film 2 only on one side of the polarizer 1. The polarizer 1 and the protective film 2 can be laminated via an intervening layer (not shown) such as an adhesive layer, a pressure-sensitive adhesive layer, and an undercoat layer (primer layer). The one-sided protective polarizing film 10 provided with the transparent resin layer obtained by the production method of the present invention includes the transparent resin layer 4 on the polarizer surface of the one-sided protective polarizing film 3 (the surface without the protective film 2 of the polarizer 1). It has.

  Hereinafter, each step of the production method of the present invention will be described.

(1) Step of preparing a piece-protected polarizing film (1)
In the step (1), a single-sided protective polarizing film 3 having the protective film 2 on only one side of the polarizer 1 is prepared.

  As the polarizer 1, a polarizer 1 having a thickness of 10 μm or less is used. The thickness of the polarizer 1 is preferably 8 μm or less, more preferably 7 μm or less, and still more preferably 6 μm or less. On the other hand, the thickness of the polarizer is preferably 2 μm or more, and more preferably 3 μm or more. Such a thin polarizer 1 has less thickness unevenness, is excellent in visibility, and has little dimensional change, and thus has excellent durability against thermal shock.

  As the polarizer 1, one using a polyvinyl alcohol-based resin is used. Examples of the polarizer 1 include a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, an ethylene / vinyl acetate copolymer-based partially saponified film, and two colors of iodine and a dichroic dye. And a polyene-based oriented film such as a uniaxially stretched product obtained by adsorbing a hydrophilic substance, a dehydration product of polyvinyl alcohol, and a dehydrochlorination product of polyvinyl chloride. Among these, a polarizer composed of a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferable.

  A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching can be produced by, for example, dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching the film to 3 to 7 times its original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution of potassium iodide or the like. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, dirt on the surface of the polyvinyl alcohol-based film and an anti-blocking agent can be washed off.Also, by swelling the polyvinyl alcohol-based film, the effect of preventing unevenness such as uneven dyeing can be obtained. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. Stretching can be performed in an aqueous solution of boric acid or potassium iodide or in a water bath.

  It is preferable that the polarizer 1 contains boric acid from the viewpoint of stretching stability and optical durability. Further, the content of boric acid contained in the polarizer 1 is preferably 25% by weight or less, more preferably 20% by weight or less with respect to the total amount of the polarizer, from the viewpoint of suppressing generation of penetration cracks and nanoslits, and suppressing expansion. It is more preferably at most 18% by weight, particularly preferably at most 16% by weight. On the other hand, from the viewpoint of the stretching stability and the optical durability of the polarizer 1, the boric acid content based on the total amount of the polarizer is preferably 10% by weight or more, more preferably 12% by weight or more.

The polarizer 1 has an optical property represented by a single transmittance T and a degree of polarization P of the following formula: P>-(10 ^0.929T-42.4 -1) × 100 (where T <42.3). Or
P ≧ 99.9 (however, T ≧ 42.3)
It is preferable to satisfy the above condition. A polarizer configured to satisfy the above conditions has the performance required primarily as a display for a liquid crystal television using a large display element. Specifically, the contrast ratio is 1000: 1 or more and the maximum luminance is 500 cd / m ² or more. As another application, for example, it is bonded to the viewing side of the organic EL display device.

  The material constituting the protective film 2 is preferably a material having excellent transparency, mechanical strength, heat stability, moisture barrier properties, isotropy, and the like. 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, and styrene such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Polymers, polycarbonate polymers and the like. In addition, polyethylene, polypropylene, polyolefin having a cyclo- or norbornene structure, polyolefin polymers such as ethylene-propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, and 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 Blends of polymers and the like are also examples of polymers forming the protective film.

  The protective film 2 may contain one or more optional additives. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the protective film is preferably from 50 to 100% by mass, more preferably from 50 to 99% by mass, further preferably from 60 to 98% by mass, and particularly preferably from 70 to 97% by mass. When the content of the thermoplastic resin in the protective film 2 is less than 50% by mass, the high transparency and the like inherent to the thermoplastic resin may not be sufficiently exhibited.

  As the protective film 2, a retardation film, a brightness enhancement film, a diffusion film, or the like can be used. Examples of the retardation film include those having a front retardation of 40 nm or more and / or a thickness direction retardation of 80 nm or more. 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 film is used as the protective film, the thickness can be reduced because the retardation film also functions as a polarizer protective film.

  Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a thermoplastic resin film. The stretching temperature, stretching ratio, and the like are appropriately set depending on the retardation value, the material and thickness of the film.

  The thickness of the protective film 2 can be appropriately determined, but is generally preferably from 3 to 200 μm, and more preferably from 3 to 100 μm from the viewpoint of workability such as strength and handleability, thinness and the like. Is preferred. In particular, the thickness of the protective film (when the film is formed in advance) is preferably from 10 to 60 μm, and more preferably from 10 to 50 μm, from the viewpoint of transportability. On the other hand, the thickness of the protective film (when formed by coating and curing) is preferably 3 to 25 μm, and more preferably 3 to 20 μm, from the viewpoint of transportability. The protective film can be used in plural or plural layers.

  A functional layer such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer can be provided on the surface of the protective film 2 where the polarizer 1 is not bonded. The functional layers such as the hard coat layer, the antireflection layer, the anti-sticking layer, the diffusion layer and the antiglare layer can be provided on the protective film 2 itself, or separately provided separately from the protective film. Can also.

  The protective film 2 and the polarizer 1 can be laminated via an intervening layer such as an adhesive layer, a pressure-sensitive adhesive layer, and an undercoat layer (primer layer). At this time, it is preferable that both layers are laminated without an air gap by the intervening layer. The intervening layer between the polarizer 1 and the protective film 2 is not shown in the figure.

  The adhesive layer is formed by an adhesive. The type of the adhesive is not particularly limited, and various adhesives can be used. The adhesive layer is not particularly limited as long as it is optically transparent. Examples of the adhesive include water-based, solvent-based, hot-melt, and active energy ray-curable adhesives. Alternatively, an active energy ray-curable adhesive is suitable.

  Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex-based adhesive, and an aqueous-based polyester. The water-based adhesive is usually used as an adhesive composed of an aqueous solution, and usually contains a solid content of 0.5 to 60% by weight.

  The active energy ray-curable adhesive is an adhesive whose curing progresses with an active energy ray such as an electron beam or an ultraviolet ray (radical-curable or cationically-curable). Can be used. As the active energy ray-curable adhesive, for example, a photo-radical curable adhesive can be used. When a photo-radical curable active energy ray-curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

  The method of applying the adhesive is appropriately selected depending on the viscosity of the adhesive and the desired thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse and offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, and the like. In addition, a method such as a dipping method can be appropriately used for coating.

  In the case where a water-based adhesive or the like is used, the application of the adhesive is preferably performed 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 150 nm. On the other hand, when using an active energy ray-curable adhesive, it is preferable that the thickness of the adhesive layer be 0.2 to 20 μm.

  In laminating the polarizer 1 and the protective film 2, an easy-adhesion layer can be provided between the 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. Further, other additives may be added for forming the easy-adhesion layer. Specific examples include stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, and heat stabilizers.

  Usually, the easy-adhesion layer is provided in advance on the protective film, and the easy-adhesion layer side of the protective film and the polarizer are laminated with an adhesive layer. The easy-adhesion layer is formed by applying and drying the material for forming the easy-adhesion layer on the protective film by a known technique. The material for forming the easily adhesive layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying, the smoothness of coating, and the like. 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. In addition, although a plurality of easy-adhesion layers can be provided, it is preferable that the total thickness of the easy-adhesion layers be in the above range also in this case.

  The pressure-sensitive adhesive layer is formed from a pressure-sensitive adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used, for example, a rubber-based pressure-sensitive adhesive, an acrylic-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a vinylalkyl ether-based pressure-sensitive adhesive, a polyvinylpyrrolidone-based pressure-sensitive adhesive, An acrylamide-based pressure-sensitive adhesive, a cellulose-based pressure-sensitive adhesive, and the like can be given. An adhesive base polymer is selected according to the type of the adhesive. Among the pressure-sensitive adhesives, acrylic pressure-sensitive adhesives are preferably used because they have excellent optical transparency, exhibit appropriate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties, and are excellent in weather resistance and heat resistance. .

  The undercoat layer (primer layer) is formed to improve the adhesion between the polarizer 1 and the protective film 2. The material constituting the primer layer is not particularly limited as long as it exhibits a certain level of strong adhesion to both the polarizer 1 and the protective film 2. For example, a thermoplastic resin excellent in transparency, thermal stability, stretchability and the like is used. Examples of the thermoplastic resin include an acrylic resin, a polyolefin resin, a polyester resin, a polyvinyl alcohol resin, and a mixture thereof.

The one-sided protective polarizing film 3 used in the present invention can be prepared by a manufacturing method in which the protective film 2 is laminated only on one side of the polarizer 1, and specific manufacturing methods include, for example,
A step (1-1) of forming a laminate (a) having a transport film and a polarizer 1 having a thickness of 10 μm or less containing a polyvinyl alcohol-based resin formed on one surface of the transport film;
A step (1-2) of forming a protective film 2 on the side of the polarizer 1 of the laminate (a) obtained in the step (1-1), and
Step (1-3) of peeling the transport film from the laminate (protective film 2 / polarizer 1 / transport film) obtained in the step (1-2)
It is preferable to form by the manufacturing method containing. Hereinafter, each step of the preferable manufacturing method will be described.

(1-1) Step of Forming Laminate (a) (1-1)
The laminate (a) is, for example, at least a laminate (a ′) having a transport film and a polyvinyl alcohol-based resin (hereinafter, also referred to as a PVA-based resin) layer formed on one surface of the transport film. It is obtained by performing a stretching step and a dyeing step. By using a long material, the transport film can form a long PVA-based resin layer, which is advantageous for continuous production.

Various thermoplastic resin films can be used as the transport film. As the material for forming the thermoplastic resin film, for example, ester-based resins such as polyethylene terephthalate resin, a cycloolefin-based resin such as norbornene-based resin, polyethylene, olefin resin such as polypropylene, polyamide resins, polycarbonate resins, these And the like. Among them, ester resins are preferred from the viewpoint of ease of production and cost reduction. As the ester-based thermoplastic resin film, an amorphous ester-based thermoplastic resin film or a crystalline ester-based thermoplastic resin film can be used. Further, the thickness of the thermoplastic resin film is preferably thicker from the viewpoint of avoiding breakage in the stretching step and facilitating transportation of the laminate (a), and usually the thickness before the stretching step is 20 to 200 μm. Is preferably 30 to 150 μm.

  Further, as the transport film, a film provided with a peelable pressure-sensitive adhesive layer on the thermoplastic resin film can be used. As the pressure-sensitive adhesive layer, those similar to those used for a surface protective film and the like described later can be used.

  The polarizer in the laminate (a) contains a polyvinyl alcohol-based resin and has a thickness of 10 μm or less. The preferable range of the thickness of the polarizer and the polyvinyl alcohol-based resin are as described above. Such a thin polarizer 1 is liable to cause defects on the surface of the thin polarizer 1 when the transporting film is peeled from the laminate (a) in the step (1-3). In some cases, unevenness may occur in the surface state of the surface on which the transparent resin layer 4 is formed.

As a thin polarizer, typically,
Patent No. 4751486,
Patent No. 4,751,481,
Patent No. 4815544,
Patent No. 5048120,
WO 2014/077759 pamphlet,
International Publication No. 2014/077636 pamphlet,
And the like, or a thin polarizer obtained by the production method described therein.

  The thin polarizer is described in Japanese Patent No. 4751486 because it can be stretched at a high magnification and the polarization performance can be improved in a production method including a stretching step and a dyeing step in the state of a laminate (a ′). And those obtained by a production method including a step of stretching in a boric acid aqueous solution as described in Japanese Patent Nos. 4,751,481 and 4,815,544, and in particular, Patent Nos. 4,751,481 and 4,815,544. And those obtained by a production method including a step of auxiliary stretching in the air before stretching in a boric acid aqueous solution described in (1). These thin polarizers can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin layer and a transporting film for stretching in a laminated state, and a step of dyeing. According to this production method, even if the PVA-based resin layer is thin, it can be stretched without any trouble such as breakage due to stretching because it is supported by the stretch-conveying film.

  The laminate (a ′) can be formed, for example, by applying an aqueous solution of a PVA-based resin to a transport film and then drying. Further, the PVA-based resin layer in the laminate (a ′) can be formed on a transport film by extrusion molding. Furthermore, the PVA-based resin layer can be formed by laminating a PVA-based resin film prepared in advance on a transporting film. The thickness of the PVA-based resin layer is appropriately determined in consideration of the stretching ratio and the like so that the thickness of the polarizer obtained after stretching is 10 μm or less. In addition, if the PVA-based resin film is dyed, the dyeing step performed on the laminate (a ′) can be omitted.

  The stretching step performed on the laminate (a ′) is preferably performed, for example, so that the total stretching ratio of the PVA-based resin layer is in the range of 3 to 10 times in total stretching ratio. The total stretching ratio is preferably 4 to 8 times, more preferably 5 to 7 times. It is desirable that the total stretching ratio be 5 times or more. The stretching step can be performed in a dyeing step or other steps. When the stretching is performed in a process other than the stretching process, the total stretching ratio refers to a cumulative stretching ratio including the stretching in those processes.

  The dyeing step performed on the laminate (a ′) is performed by adsorbing and orienting a dichroic dye or iodine on the PVA-based resin layer. The dyeing step can be performed together with the stretching step. The dyeing step is generally performed, for example, by immersing the laminate (a ′) in an iodine solution for an arbitrary time. As the iodine aqueous solution used as the iodine solution, an aqueous solution containing iodine and iodine ions by an iodide compound as a dissolution aid is used. Examples of the iodide compound include, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and tin iodide. Titanium or the like is used. As the iodide compound, potassium iodide is preferable. The same applies to the case where the iodide compound used in the present invention is used in another step.

  The iodine concentration in the iodine solution is about 0.01 to 10% by weight, preferably 0.02 to 5% by weight, and more preferably 0.02 to 0.5% by weight. The iodide compound concentration is about 0.1 to 10% by weight, preferably 0.2 to 8% by weight. In the iodine dyeing, the temperature of the iodine solution is usually preferably about 20 to 50 ° C and 25 to 40 ° C. The immersion time is usually about 10 to 300 seconds, preferably in the range of 20 to 240 seconds.

  In addition to the above steps, the laminate (a ′) may be subjected to, for example, an insolubilization step, a crosslinking step, a drying (adjustment of moisture content) step, and the like.

  The insolubilizing step and the crosslinking step are performed using a boron compound as a crosslinking agent. The order of these steps is not particularly limited. The crosslinking step can be performed together with the dyeing step and the stretching step. The insolubilizing step and the cross-linking step can be performed plural 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 mixed solution of water and an organic solvent. Usually, an aqueous boric acid solution is used. The boric acid concentration of the boric acid aqueous solution is about 1 to 10% by weight, preferably 2 to 7% by weight. In order to impart heat resistance depending on the degree of cross-linking or to suppress damage at the time of peeling of the transporting film, the boric acid concentration is preferably used. An aqueous boric acid solution or the like can contain an iodide compound such as potassium iodide. When the aqueous solution of boric acid contains an iodide compound, the concentration of the iodide compound is about 0.1 to 10% by weight, preferably 0.5 to 8% by weight.

(1-2) Step of Forming Protective Film (1-2)
In the step (1-2), a protective film 2 is formed on the polarizer 1 side of the obtained laminate (a). Through the step (1-2), a one-sided protective polarizing film A ′ with a transport film having the protective film 2 on only one side of the polarizer 1 is obtained. As the protective film 2 and the intervening layer used for laminating the protective film 2, those described above can be used.

(1-3) Step of peeling off transport film (1-3)
In the step (1-3), the transport film is peeled off from the one-sided protective polarizing film A ′ with the transport film. There is no particular limitation on the method of peeling the transfer film. When peeling the transporting film, the polarizer 1 (or one-sided protective polarizing film) may be angled, or the transporting film may be peeled at an angle. Moreover, you may peel at an angle on both sides. In any case, the thin polarizer 1 is likely to be damaged by peeling of the transport film. The angle at which the transport film is peeled off is set arbitrarily. When peeling the transporting film, there is an angle at which the peeling force becomes the weakest. The angle at which the peeling force is weakened depends on the configuration, the peeling speed, the humidity at the time of peeling, and the rigidity of the film to be peeled, and can be appropriately determined.

(2) Step of applying an aqueous coating liquid containing a resin component (2)
In the step (2), an aqueous coating liquid containing a resin component is applied to one surface of the polarizer 1 of the one-sided protective polarizing film 3 having the protective film 2 only on one side of the polarizer 1 prepared in the step (1). I do. The surface of the polarizer 1 on which the transparent resin layer 4 is formed is a surface from which the transporting film of the one-side protection polarizing film 3 obtained in the step (1) is peeled off.

  The variation in the water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed (the surface of the polarizer 1 without the protective film 2) is within the range of the average water contact angle ± 20 °.

  The variation in the water contact angle means a fluctuation width of each water contact angle measured at a plurality of locations at an arbitrary location of the polarizer 1 with respect to the average water contact angle. Specifically, at any point of the polarizer 1, the water contact angles of 25 points in the width direction of the polarizer 1 and 5 points in the stretching direction (conveying direction) of the polarizer 1 are measured, and their average values ( Average water contact angle), and each measured water contact angle is within ± 20 ° of the average water contact angle. Therefore, for example, when the average value of the water contact angles measured in the width direction is 90 ° at an arbitrary position of the polarizer 1, each water contact angle measured in the width direction is 90 ° ± 20 ° (70 to 110 °). °). This operation is performed at a plurality of arbitrary locations of the polarizer 1. Here, the width direction of the polarizer 1 means a direction orthogonal to the stretching direction (conveying direction) of the polarizer 1.

  The variation in the water contact angle is within a range of an average water contact angle of ± 20 °, preferably within a range of an average water contact angle of ± 15 °, and is within a range of an average water contact angle of ± 10 °. Is more preferred. In the present invention, the variation of the water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed (the surface of the polarizer 1 without the protective film 2) is set within the above range, whereby the polarizer 1 Since the occurrence of unevenness in the thickness of the transparent resin layer 4 formed thereon is suppressed, the appearance unevenness can be suppressed from being visually recognized even when exposed to a humid environment.

  The average water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed is not particularly limited, but is preferably 90 ° or less from the viewpoint of affinity with an aqueous coating solution, and is preferably 80 ° or less. ° or less, more preferably 60 ° or less.

  The water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed can be appropriately controlled by the material of the polarizer 1, various processes, and the like. Various processes and the like will be described later.

  The aqueous coating liquid used in the present invention contains a resin component, and the transparent resin layer 4 is formed from the aqueous coating liquid.

  Examples of the aqueous coating liquid (hereinafter, also referred to as a forming material) include a coating liquid containing a resin component dissolved or dispersed in water. The resin component dissolved or dispersed in water refers to a resin dissolved in water or a resin soluble in water dissolved in an aqueous solvent at normal temperature (25 ° C.). In the present invention, since an aqueous coating liquid (water-based or water-dispersed) is used, the affinity with the surface of the polarizer 1 in which the variation of the water contact angle is controlled is excellent. Further, when there is a damaged portion (a damaged portion generated on the surface of the polarizer 1 before forming the transparent resin layer) on the surface of the polarizer 1, the damaged portion is formed by swelling of the surface of the polarizer 1. This is advantageous because the aqueous coating liquid is compatible. That is, by using the aqueous coating liquid, the orientation of the polyvinyl alcohol molecules around the damaged portion constituting the polarizer 1 can be partially relaxed, and the boric acid content around the damaged portion can be reduced. Therefore, even if the thickness of the transparent resin layer 4 is small (for example, less than 3 μm, and preferably 2 μm or less), the expansion of the damaged portion can be effectively suppressed.

  Representative examples of the resin component include, for example, polyvinyl alcohol (PVA) resin, poly (meth) acrylic acid, polyacrylamide, methylolated melamine resin, methylolated urea resin, resole type phenol resin, polyethylene oxide, carboxymethyl cellulose, and the like. Is mentioned. These may be used alone or in combination. As the resin component, a polyvinyl alcohol-based resin, poly (meth) acrylic acid, or methylolated melamine is preferably used. In particular, a polyvinyl alcohol-based resin is preferable as the resin component from the viewpoint of adhesion to the polyvinyl alcohol-based resin constituting the polarizer. Hereinafter, a case where a polyvinyl alcohol-based resin is used will be described.

  The transparent resin layer 4 is preferably formed from a forming material (coating liquid) containing a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin forming the transparent resin layer may be the same as or different from the polyvinyl alcohol-based resin contained in the polarizer, as long as it is “polyvinyl alcohol-based resin”.

  Examples of the polyvinyl alcohol-based resin include polyvinyl alcohol. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. Examples of the polyvinyl alcohol-based resin include a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability. When the copolymerizable monomer is ethylene, an ethylene-vinyl alcohol copolymer is obtained. Examples of the copolymerizable monomer include unsaturated carboxylic acids such as maleic acid, fumaric acid, crotonic acid, itaconic acid, and (meth) acrylic acid, and esters thereof; and ethylene and propylene. α-olefin, (meth) allyl sulfonic acid (soda), sodium sulfonic acid (monoalkylmalate), sodium alkyl sulfonate, N-methylolacrylamide, alkali salt of acrylamidoalkylsulfonic acid, N-vinylpyrrolidone, N- And vinylpyrrolidone derivatives. These polyvinyl alcohol-based resins can be used alone or in combination of two or more.

  The saponification degree of the polyvinyl alcohol-based resin may be, for example, 95 mol% or more. From the viewpoint of satisfying the wet heat resistance and the water resistance, the saponification degree is preferably 99 mol% or more. Is preferably 99.7 mol% or more. The degree of saponification indicates the ratio of units actually converted to vinyl alcohol units among units that can be converted into vinyl alcohol units by saponification, and the residue is a vinyl ester unit. The saponification degree can be determined according to JIS-K6726-1994.

  The average degree of polymerization of the polyvinyl alcohol-based resin may be, for example, 500 or more, but from the viewpoint of satisfying wet heat resistance and water resistance, the average degree of polymerization is preferably 1,000 or more, more preferably 1500 or more. Preferably, 2000 or more is more preferable. The average polymerization degree of the polyvinyl alcohol-based resin is measured according to JIS-K6726.

  Further, as the polyvinyl alcohol-based resin, a modified polyvinyl alcohol-based resin having a hydrophilic functional group in a side chain of the polyvinyl alcohol or a copolymer thereof can be used. Examples of the hydrophilic functional group include an acetoacetyl group and a carbonyl group. In addition, modified polyvinyl alcohol obtained by acetalizing, urethanizing, etherifying, grafting, phosphoric esterifying, or the like a polyvinyl alcohol-based resin can be used.

  The proportion of the polyvinyl alcohol-based resin in the transparent resin layer 4 or the aqueous coating liquid (solid content) is preferably 80% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more.

The water-based coating liquid is adjusted to the polyvinyl alcohol resin as a solution dissolved in an aqueous solvent.

  Examples of the aqueous solvent include water and a mixed solvent of water and a water-soluble organic solvent. Of these, an aqueous solvent composed of only water is preferable. Examples of the water include distilled water, ion-exchanged water, and ultrapure water. Examples of the water-soluble organic solvent include methanol, ethanol, acetone, 1-propanol, 2-propanol and the like. When the aqueous solvent contains a water-soluble organic solvent, the content of the water-soluble organic solvent in the aqueous solvent is preferably 40% by weight or less, more preferably 20% by weight or less, and more preferably 10% by weight or less. Is more preferable.

  The concentration of the polyvinyl alcohol-based resin in the forming material (e.g., aqueous solution) is not particularly limited, but is preferably 0.1 to 15% by weight in consideration of coatability, storage stability, and the like. 5 to 10% by weight is more preferred.

  Note that an additive can be added to the coating liquid (for example, an aqueous solution). Examples of the additive include a plasticizer and a surfactant. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol and glycerin. Examples of the surfactant include a nonionic surfactant. Further, coupling agents such as silane coupling agents and titanium coupling agents, various tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers, stabilizers such as hydrolysis stabilizers, and the like can be added.

  It is advantageous for the coating liquid to have a lower viscosity because the coating liquid easily penetrates the damaged portion when the damaged portion exists on the surface of the polarizer 1. The viscosity measured at 25 ° C. is preferably 2000 mPa · s or less, more preferably 1000 mPa · s or less, further preferably 500 mPa · s or less, and particularly preferably 100 mPa · s or less.

  The application of the aqueous coating liquid to the one-side protective polarizer film 3 on the polarizer 1 is preferably performed so that the thickness of the coating film (transparent resin layer 4) after drying is 0.2 μm or more. The thickness of the transparent resin layer 4 is more preferably 0.5 μm or more, and even more preferably 0.7 μm or more. On the other hand, if the transparent resin layer 4 is too thick, the optical reliability and water resistance decrease, so the thickness of the transparent resin layer 4 is preferably 3 μm or less, more preferably less than 3 μm, and more preferably 2 μm or less. More preferably, there is.

  Various methods are used for applying the coating liquid. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. A method such as an extrusion coating method may be used.

(3) Step of forming transparent resin layer (3)
In step (3), the transparent resin layer 4 is formed by drying the coating film obtained in step (2).

  The drying temperature is not particularly limited, and is usually about 60 to 150 ° C, preferably 80 to 120 ° C, and more preferably 90 to 120 ° C. The drying time is preferably from 10 to 500 seconds, more preferably from 20 to 400 seconds.

  In the manufacturing method of the present invention, since the variation in the water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed is controlled within a specific range, an aqueous coating liquid is applied on the surface of the polarizer 1. Of the transparent resin layer 4 obtained by forming and drying the coating film is suppressed, and it is possible to suppress the appearance unevenness from occurring in a humid environment.

(4) Other Steps In the method for producing a piece-protected polarizing film with a transparent resin layer of the present invention, before the step (2) of applying the aqueous coating liquid,
On the polarizer surface of the one-sided protective polarizing film,
Laminating a surface protection film, then, peeling the surface protection film from the one-side protection polarizing film, and,
A step of performing an activation process,
It is preferable to include one or more steps selected from the group consisting of: since the variation in the water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed can be controlled.

(4-1) Affixing / peeling step of surface protection film The surface protection film usually has a base film and an adhesive layer, and protects the one-side protection polarizing film 3 via the adhesive layer. The surface protection film temporarily protects the piece-protecting polarizing film with the pressure-sensitive adhesive layer, and is peeled off during actual use.

  As the base film of the surface protection film, a film material having or close to isotropic is selected from the viewpoints of testability and manageability. Examples of the film material include a polyester resin such as a polyethylene terephthalate film, a cellulose resin, an acetate resin, a polyether sulfone resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a polyolefin resin, and an acrylic resin. A transparent polymer such as a resin may be used. Among these, polyester resins are preferred. The base film may be used as a laminate of one or more film materials, or a stretched product of the film. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

  Examples of the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer of the surface protective film include pressure-sensitive adhesives containing (meth) acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as a base polymer. Can be appropriately selected and used. From the viewpoints of transparency, weather resistance, heat resistance, and the like, an acrylic pressure-sensitive adhesive containing an acrylic polymer as a base polymer is preferable. The thickness (dry film thickness) of the pressure-sensitive adhesive layer is determined according to the required pressure-sensitive adhesive strength. Usually, it is about 1 to 100 μm, preferably 5 to 50 μm.

  In addition, on the surface protective film, a release treatment layer can be provided on the surface opposite to the surface on which the pressure-sensitive adhesive layer of the base film is provided, using a low-adhesion material such as silicone treatment, long-chain alkyl treatment, or fluorine treatment. .

  As the surface protective film, commercially available ones can also be suitably used, and for example, Tretec 7832C # 30 manufactured by Toray Film Processing Co., Ltd. can be suitably used.

  Further, the time until the surface protective film is bonded and the surface protective film is peeled off is not particularly limited, but is preferably, for example, 1 hour or more, and more preferably 12 hours or more.

  The water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed varies by attaching and detaching the surface protective film on the surface of the polarizer 1 (the surface on which the transparent resin layer 4 is formed) of the one-side protection polarizing film 3. This is preferable because it can suppress

(4-2) Activation Treatment Step The activation treatment may include a corona treatment and / or a plasma treatment. As the corona treatment, for example, a method of discharging in a normal pressure air by a corona treatment machine may be mentioned. The plasma treatment includes, for example, a method in which a discharge is performed in normal-pressure air by a plasma discharge machine.

  The corona output in the corona treatment is not particularly limited, but is preferably, for example, about 0.5 to 8.0 kW, more preferably about 0.5 to 7.0 kW, and 0.5 to 6 kW. More preferably, it is about 0.0 kW.

  The processing speed in the corona treatment is preferably about 5 to 100 m / min, more preferably about 5 to 90 m / min, and still more preferably about 5 to 80 m / min.

  The plasma output in the plasma processing is not particularly limited, but is, for example, preferably about 0.5 to 5.0 kW, more preferably about 0.5 to 3.0 kW, and more preferably about 0.5 to 1 kW. More preferably, it is about 0.5 W.

  The processing speed in the plasma processing is preferably about 5 to 100 m / min, more preferably about 5 to 90 m / min, and still more preferably about 5 to 80 m / min.

  When performing the corona treatment or the plasma treatment, the treatment may be performed once, but more preferably two or more times. Further, both corona treatment and plasma treatment may be performed. For example, a mode in which a corona treatment is performed on one polarizer surface (the surface on which the transparent resin layer 4 is formed) of the one-side protection polarizing film 3 and then a plasma treatment is performed, and the water-based coating liquid is applied to the treated surface. be able to.

  It is considered that the corona treatment or the plasma treatment increases the hydrophilicity of the polarizer 1 surface (the surface on which the transparent resin layer 4 is formed) of the one-side protection polarizing film 3. For this reason, the affinity between the polarizer 1 surface (the surface on which the transparent resin layer 4 is formed) of the one-side protective polarizing film 3 and the aqueous coating solution is improved, and the polarizer 1 surface (the transparent resin layer) of the one-side protective polarizing film 3 is improved. 4) The wettability of the water-based coating liquid on the forming surface is improved. In addition, the corona treatment or the plasma treatment can suppress the variation in the water contact angle of one polarizer (the surface on which the transparent resin layer 4 is formed).

In the production method of the present invention, it is preferable that the various treatments are performed alone or in combination before the step (2). When performing in combination, for example,
(Combination 1) A surface protective film is stuck to one polarizer of the one-sided protective polarizing film 3, and then the surface-protective film is peeled off from the one-sided protective polarizing film 3. A method of performing an activation treatment on the surface protective film release surface,
(Combination 2) The polarizer 1 of the one-sided protective polarizing film 3 is subjected to an activation treatment, and then the surface of the one-sided protective polarizing film 3 that has been subjected to the activation treatment is bonded to a surface protective film. A method of peeling the surface protective film from the one-side protective polarizing film 3 and the like can be mentioned.

2. Method for producing a polarizing film with a pressure-sensitive adhesive layer The method for producing a polarizing film with a pressure-sensitive adhesive layer of the present invention comprises the steps of: A step of forming an agent layer.

  As shown in FIG. 2, the polarizing film 11 with the pressure-sensitive adhesive layer obtained by the production method of the present invention further comprises a pressure-sensitive adhesive layer 5 on the transparent resin layer 4 of the one-sided protective polarizing film 10 with the transparent resin layer. It is characterized by having.

(1) Pressure-sensitive adhesive layer An appropriate pressure-sensitive adhesive can be used for forming the pressure-sensitive adhesive layer, and the type thereof is not particularly limited. As the adhesive, a rubber-based adhesive, an acrylic-based adhesive, a silicone-based adhesive, a urethane-based adhesive, a vinylalkyl ether-based adhesive, a polyvinyl alcohol-based adhesive, a polyvinylpyrrolidone-based adhesive, a polyacrylamide-based adhesive, Cellulose-based adhesives and the like can be mentioned.

  Among these pressure-sensitive adhesives, those having excellent optical transparency, exhibiting appropriate wettability, cohesiveness and adhesive pressure-sensitive adhesive properties and having excellent weather resistance and heat resistance are preferably used. An acrylic pressure-sensitive adhesive is preferably used to exhibit such characteristics.

  As a method of forming the pressure-sensitive adhesive layer, for example, a method in which the pressure-sensitive adhesive is applied to a separator or the like that has been subjected to a release treatment, a polymerization solvent or the like is removed by drying to form a pressure-sensitive adhesive layer, and then transferred onto the transparent resin layer 4. Alternatively, it is produced by a method in which the pressure-sensitive adhesive is applied to the transparent resin layer 4 and a polymerization solvent or the like is dried and removed to form a pressure-sensitive adhesive layer on the transparent resin layer 4. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be newly added as appropriate.

  As the release-treated separator, a silicone release liner is preferably used. In the step of forming a pressure-sensitive adhesive layer by applying and drying a pressure-sensitive adhesive on such a liner, an appropriate method can be appropriately adopted as a method for drying the pressure-sensitive adhesive depending on the purpose. Preferably, a method of heating and drying the coating film is used. The heating and drying temperature is preferably from 40C to 200C, more preferably from 50C to 180C, and even more preferably from 70C to 170C. By setting the heating temperature within the above range, a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties can be obtained.

  As the drying time, an appropriate time can be appropriately used. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, even more preferably 10 seconds to 5 minutes.

  Various methods are used for forming the pressure-sensitive adhesive layer. Specifically, for example, by roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. A method such as an extrusion coating method may be used.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, preferably 2 to 50 μm, more preferably 2 to 40 μm, and still more preferably 5 to 35 μm.

  When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected by a sheet (separator) that has been subjected to a release treatment until it is practically used.

  As a constituent material of the separator, for example, a plastic film such as polyethylene, polypropylene, polyethylene terephthalate, or a polyester film, a porous material such as paper, cloth, or nonwoven fabric, a net, a foamed sheet, a metal foil, and a laminate of these, as appropriate. Although a thin leaf body and the like can be mentioned, a plastic film is preferably used because of its excellent surface smoothness.

As the plastic film is not particularly limited as long as a film capable of protecting the pressure-sensitive adhesive layer, for example, polyethylene film, polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene off I Lum, polyvinyl chloride film, chloride Examples include a vinyl copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. The separator may be, if necessary, a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, a release and antifouling treatment with silica powder or the like, a coating type, a kneading type, a vapor deposition type. And the like. In particular, by appropriately performing a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the separator, the releasability from the pressure-sensitive adhesive layer can be further improved.

(2) Surface Protective Film A surface protective film can be provided on the polarizing film of the present invention (including a one-sided protective polarizing film with a transparent resin layer and a polarizing film with an adhesive layer). Examples of the surface protective film include those described above.

3. Manufacturing method of image display device The manufacturing method of the image display device of the present invention uses a piece-protected polarizing film with a transparent resin layer obtained by the above manufacturing method, or a polarizing film with an adhesive layer obtained by the above manufacturing method. It is characterized by being formed by.

  The one-sided protective polarizing film with a transparent resin layer and the polarizing film with a pressure-sensitive adhesive layer obtained by the production method of the present invention may be used alone or as an optical laminate obtained by laminating this with an optical member, a liquid crystal display (LCD), An image display device such as an organic EL display device can be formed.

  The optical member is not particularly limited, but for example, a liquid crystal display such as a reflection plate, a semi-transmission plate, a retardation plate (including a wavelength plate such as や or ４), or a viewing angle compensation film. One layer or two or more layers that may be used for forming a device or the like can be used. As the optical laminate, in particular, a reflective polarizing film or a transflective film obtained by laminating a reflective plate or a transflective reflective plate on a one-sided protective polarizing film with a transparent resin layer or a polarizing film with an adhesive layer of the present invention. Type polarizing film, a one-sided protective polarizing film with a transparent resin layer or a polarizing film with an adhesive layer of the present invention, further, an elliptically polarizing film or a circularly polarizing film obtained by laminating a retardation plate, with a transparent resin layer of the present invention A wide viewing angle polarizing film obtained by laminating a viewing angle compensation film on the one-sided polarizing film or the polarizing film with an adhesive layer, or the one-sided polarizing film with the transparent resin layer of the present invention or the polarized light with an adhesive layer. A polarizing film obtained by further laminating a brightness enhancement film on the film is preferable.

  An optical laminate obtained by laminating the above optical member on a one-sided protective polarizing film with a transparent resin layer or a polarizing film with a pressure-sensitive adhesive layer obtained by the production method of the present invention is separately laminated in the process of producing a liquid crystal display device or the like. Although it can be formed by a method, an optical laminate obtained by laminating in advance has an advantage in that it is excellent in quality stability, assembling work, and the like, and can improve a manufacturing process of a liquid crystal display device and the like. When two or more optical members are laminated, an appropriate adhesive means such as a pressure-sensitive adhesive layer can be used. When bonding the one-sided protective polarizing film with the transparent resin layer or the polarizing film with the pressure-sensitive adhesive layer, the optical axis thereof can be set at an appropriate angle according to the target retardation characteristic or the like.

  The one-sided protective polarizing film with a transparent resin layer, the polarizing film with a pressure-sensitive adhesive layer, or the optical laminate 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 method for manufacturing the liquid crystal display device can be performed according to a conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell and a polarizing film or an optical film, and an illumination system as necessary, and incorporating a drive circuit. Except for using the one-sided protective polarizing film with a transparent resin layer, the polarizing film with a pressure-sensitive adhesive layer, or the optical laminate of the present invention, there is no particular limitation, and it can be in accordance with the conventional method. The liquid crystal cell can be of any type, such as an IPS type or a VA type, but is particularly suitable for the IPS type.

  One side or both sides of a liquid crystal cell, a one-sided protective polarizing film with a transparent resin layer or a polarizing film with an adhesive layer obtained by the production method of the present invention, or a liquid crystal display device or an illumination system in which an optical laminate is disposed, An appropriate liquid crystal display device such as one using a light or a reflection plate can be formed. In that case, the one-sided protective polarizing film with the transparent resin layer, the polarizing film with the pressure-sensitive adhesive layer, or the optical laminate obtained by the production method of the present invention can be installed on one side or both sides of the liquid crystal cell. When the one-sided protective polarizing film with a transparent resin layer, the polarizing film with an adhesive layer, or the optical laminate of the present invention is provided on both sides, they may be the same or different. Further, in forming the liquid crystal display device, for example, appropriate components such as a diffusion plate, an anti-glare layer, an antireflection film, a protection plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight are placed in one layer at an appropriate position. Alternatively, two or more layers can be arranged.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples described below. In addition, all parts and% in each example are based on weight. The room temperature storage conditions not particularly specified below are all 23 ° C., 65% R.D. H. It is.

Production Example 1 (production of polarizer)
One side of an amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) substrate having a water absorption of 0.75% and a glass transition temperature (Tg) of 75 ° C. was subjected to a corona treatment. On the corona-treated surface, polyvinyl alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (trade name: Gosefimer Z200, degree of polymerization: 1200, degree of acetoacetyl modification: 4.6) %, Saponification degree: 99.0 mol% or more, an aqueous solution containing 9: 1 ratio (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) at 25 ° C. is applied and dried to form a 11 μm thick PVA-based resin layer. Then, a laminate was produced.
The obtained laminate was uniaxially stretched 2.0 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 120 ° C. (free-air auxiliary stretching treatment).
Next, the laminate was immersed in an insolubilizing bath at a liquid temperature of 30 ° C. (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilizing treatment).
Next, it was immersed in a dyeing bath at a liquid temperature of 30 ° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was added to 100 parts by weight of water, and the resultant was immersed in an aqueous solution of iodine obtained by mixing 1.0 part by weight of potassium iodide for 60 seconds (dyeing treatment). .
Next, it was immersed in a crosslinking bath at a liquid temperature of 30 ° C. (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds. (Crosslinking treatment).
Thereafter, the laminate is immersed in an aqueous solution of boric acid at a liquid temperature of 70 ° C. (an aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water). Meanwhile, uniaxial stretching was performed between rolls having different peripheral speeds in the longitudinal direction (longitudinal direction) so that the total stretching ratio was 5.5 times (underwater stretching treatment).
Thereafter, the laminate was immersed in a washing bath at a liquid temperature of 30 ° C. (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) (washing treatment).
Thus, an optical film laminate including a 5 μm-thick polarizer was obtained.

Production Example 2 (production of polarizer)
A 30 μm thick polyvinyl alcohol film 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 film was immersed in a 0.3% aqueous solution of iodine / potassium iodide (weight ratio = 0.5 / 8), and the film was dyed while being stretched to 3.5 times. Thereafter, the film was stretched in an aqueous borate solution at 65 ° C. so that the total stretching ratio became 6 times. After stretching, drying was performed in an oven at 40 ° C. for 3 minutes to obtain a PVA-based polarizer. The thickness of the obtained polarizer was 12 μm.

Production Example 3 (Production of one-sided protective polarizing film)
A (meth) acrylic resin film having a lactone ring structure having a thickness of 40 μm and subjected to a corona treatment on an easily-adhesive treated surface was used as a protective film.

  40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO) and 3 parts by weight of a photoinitiator (trade name: IRGACURE 819, manufactured by BASF) were mixed to prepare an ultraviolet-curable adhesive. . This was used as the protective film adhesive.

The protective film was adhered to the surface of the polarizer of the optical film laminate obtained in Production Example 1, while applying the ultraviolet curable adhesive so that the thickness of the adhesive layer after curing was 1 μm. Thereafter, ultraviolet rays were irradiated as active energy rays to cure the adhesive. The ultraviolet irradiation is performed by using a gallium-filled metal halide lamp (irradiation apparatus: Light HAMMER10 manufactured by Fusion UV Systems, Inc., bulb: V bulb, peak illuminance: 1600 mW / cm ² , integrated irradiation amount: 1000 / mJ / cm ² (wavelength 380 to 380). 440 nm)), and the illuminance of ultraviolet light was measured using a Sola-Check system manufactured by Solatell. The amorphous IPA copolymerized PET film substrate was not peeled off and was left as it was. The total thickness of the one-sided protective polarizing film (not including the amorphous IPA copolymerized PET film substrate) using the thin polarizer was 46 μm. The optical properties of the obtained one-sided protective polarizing film were a single transmittance of 42.8% and a degree of polarization of 99.99%.

<Single transmittance T and degree of polarization P>
The single transmittance T and the degree of polarization P of the obtained one-sided protective polarizing film were measured using a spectral transmittance meter with an integrating sphere (Dot-3c of Murakami Color Research Laboratory).
The degree of polarization P is such that the transmittance (parallel transmittance: Tp) when two identical polarizing films are overlapped so that their transmission axes are parallel and that the two transmission films are orthogonal to each other. It is determined by applying the combined transmittance (orthogonal transmittance: Tc) to the following equation.
Degree of polarization P (%) = {(Tp−Tc) / (Tp + Tc)} ^1/2 × 100
Each transmittance is represented by a Y value obtained by adjusting luminosity by a 2-degree field of view (C light source) according to JIS Z8701, with 100% of completely polarized light obtained through a Glan-Teller prism polarizer.

Production Example 4 (Production of coating liquid for forming transparent resin layer)
A polyvinyl alcohol resin having a degree of polymerization of 2500 and a degree of saponification of 99.7 mol% was dissolved in pure water to prepare an aqueous solution (coating liquid) having a solid content of 4% by weight and a viscosity of 60 mPa · s (25 ° C.).

<Viscosity measurement>
The viscosity of the coating liquid was measured using a VISCOMTER R85 type viscometer RE85L (manufactured by Toki Sangyo Co., Ltd.) under the following conditions.
Measurement temperature: 25 ° C
Rotation speed: 0.5-100 rpm
Cone rotor: 1 ° 34 '× R24

Example 1 (Production of one-sided protective polarizing film with transparent resin layer)
The amorphous IPA copolymerized PET film substrate was peeled off from the piece-protected polarizing film obtained in Production Example 3, and a surface protective film (trade name: Tretec 7832C # 30, Toray processing) was placed on the exposed polarizer. (Manufactured by Film Co., Ltd.). In this state, after standing for 24 hours, the surface protective film was peeled off, and the surface of the polarizer (the surface of the polarizer on which the protective film was not provided) was coated with the coating liquid obtained in Production Example 4 (the transparent resin layer). Forming material) was applied using a gravure roll so as to have a thickness of 25 μm. After the application, the film was dried with hot air at 95 ° C. for 30 seconds using a floating type oven to form a transparent resin layer having a thickness of 1 μm, thereby producing a one-sided protective polarizing film with a transparent resin layer.

Example 2
In Example 1, after exfoliating the amorphous IPA copolymerized PET film substrate from the one-sided protective polarizing film obtained in Production Example 3, the exposed polarizer surface was subjected to corona treatment (discharge amount: 0.038 W). (Min / m ² , output: 2.0 kW, processing speed: 25 m / min). Thereafter, a surface protective film (trade name: Tretec 7832C # 30, manufactured by Toray Industries Film Co., Ltd.) was laminated. Otherwise, in the same manner as in Example 1, a one-sided protective polarizing film with a transparent resin layer was produced.

Example 3
In Example 1, after the surface protective film was peeled off, the exposed polarizer surface was subjected to corona treatment (discharge amount: 0.038 W · min / m ² , output: 2.0 kW, processing speed: 25 m / min). gave. Thereafter, a surface protective film (trade name: Tretec 7832C # 30, manufactured by Toray Industries Film Co., Ltd.) was laminated. Further, the surface protective film was peeled off, and plasma treatment (discharge amount: 0.024 W · min / m ² , output: 1.0 kW, treatment) was performed on the surface of the polarizer (the surface of the polarizer on which the protective film was not provided). (Speed: 20 m / min), and a one-sided protective polarizing film with a transparent resin layer was produced in the same manner as in Example 1.

Example 4
In Example 1, the surface protective film was peeled off, and the surface of the polarizer (the surface of the polarizer on which the protective film was not provided) was subjected to plasma treatment (discharge amount: 0.024 W · min / m ² , output: 1. (0 kW, processing speed: 20 m / min), and a single-sided protective polarizing film with a transparent resin layer was produced in the same manner as in Example 1.

Comparative Example 1
In Example 1, after the amorphous IPA copolymerized PET film substrate was peeled from the one-sided protective polarizing film obtained in Production Example 3, the exposed polarizer surface was subjected to plasma treatment (discharge amount: 0.048 W). Min / m ² , output: 2.0 kW, processing speed: 20 m / min), and a single-sided protective polarizing film with a transparent resin layer was produced in the same manner as in Example 1.

Comparative Example 2
In Example 1, after the amorphous IPA copolymerized PET film substrate was peeled from the one-sided protective polarizing film obtained in Production Example 3, the exposed polarizer surface was coated on the exposed polarizer surface. A one-sided protective polarizing film with a transparent resin layer was produced in the same manner as in Example 1 except that a working liquid (a material for forming a transparent resin layer) was applied.

Reference Example 1
A one-sided protective polarizing film was produced in the same manner as in Production Example 3, except that the polarizer obtained in Production Example 2 was used.
A one-sided protective polarizing film with a transparent resin layer was produced in the same manner as in Example 1 except that the one-sided protective polarizing film was used.

  The following evaluation was performed using the one-sided protective polarizing film with the transparent resin layer obtained in the examples and comparative examples. The evaluation results are shown in Table 1.

<Water contact angle>
The contact angle of water on the transparent resin layer forming surface of the polarizer used in Examples and Comparative Examples was 3 μL using DM-501 manufactured by Kyowa Interface Chemical Co., Ltd., and the waiting time until measurement was measured. It was measured as 1000 ms.
The water contact angle was measured at 25 points in the width direction of the polarizer and 5 points in the stretching direction (conveying direction) at arbitrary plural positions of the polarizer, and the water contact angle was measured. The water contact angle and the variation in the water contact angle were evaluated. Since the water contact angle changes over time, the water contact angle was measured immediately after the plasma treatment or corona treatment (specifically, within 5 minutes).

<Average film thickness>
In Examples and Comparative Examples, the thickness of a coating film formed by applying a water-based coating liquid (material for forming a transparent resin layer) is an optical spectroscope (USB2000 + manufactured by Ocean optics), a light source: HL-2000, and an optical fiber. : ZFQ-12796 (200 μm reflection fiber)). The measurement conditions were as follows. The measurement was performed at 25 points in the width direction of the polarizer and at 5 points in the stretching direction (transport direction), and the average value was obtained.
(Measurement condition)
Measurement wavelength: 450 nm to 800 nm
Transparent resin layer refractive index: 1.51

<Thickness variation>
In Examples and Comparative Examples, variation in the thickness of a coating film formed by applying a water-based coating liquid (forming material for a transparent resin layer) was measured using an optical spectroscope (USB2000 + manufactured by Ocean optics, light source: HL-2000, Optical fiber: measured using ZFQ-12796 (200 μm reflection fiber). A sample having a size of 1200 mm × 100 mm was measured at a pitch of 1 mm, and the variation in film thickness was evaluated. 3 (a), (b), and (c) show 100 mm (absorption axis direction, vertical direction in the figure) × 100 mm (transmission axis direction, horizontal direction in the figure) for Examples 1 and 3, and Comparative Example 1, respectively. 3 shows the results of the in-plane film thickness variation.
(Measurement condition)
Measurement wavelength: 450 nm to 800 nm
Transparent resin layer refractive index: 1.51

<Humidification environmental test (confirmation of appearance unevenness)>
The one-sided protective polarizing film with a transparent resin layer obtained in each of Examples and Comparative Examples was cut into a size of 300 mm (absorption axis direction) × 300 mm (transmission axis direction). Two single-sided protective polarizing films (samples) were prepared and attached to both surfaces of non-alkali glass such that their absorption axes were orthogonal to each other, to prepare a sample for a humid environment test. The obtained sample for a humid environment test was thrown into a humid environment (60 ° C / 90% RH environment) for 300 hours. Thereafter, the sample for the humidification environment test was placed on a backlight unit (uniform light emitting surface illumination, TWN series, manufactured by ITEC System Co., Ltd.), and the visibility of the appearance unevenness was confirmed. FIGS. 4A, 4B, and 4C are photographs obtained by observing the visibility of uneven appearance in Examples 1, 3, and Comparative Example 1, respectively.
〇: No uneven appearance is observed.
X: The appearance unevenness is visually recognized.

  In Examples 1 to 4, the dispersion of the water contact angle on the transparent resin layer forming surface of the polarizer was an average water contact angle ± 20 °, and the dispersion of the water contact angle was small. The thickness variation was small, and the appearance unevenness after the humid environment test was suppressed. On the other hand, in Comparative Examples 1 and 2 in which the water contact angle on the surface of the polarizer on which the transparent resin layer was formed was large, the thickness of the obtained transparent resin layer was large and uneven appearance occurred after the humid environment test. Further, in Reference Example 1, since the polarizer thickness was 12 μm, even when the water contact angle had a large variation, the appearance unevenness was not visually recognized after the humidification environment test.

DESCRIPTION OF SYMBOLS 1 Polarizer 2 Protective film 3 One-sided protective polarizing film 4 Transparent resin layer 5 Adhesive layer 10 One-sided protective polarizing film with a transparent resin layer 11 Polarized film with an adhesive layer A The width direction of a polarizing film

Claims (6)

A method for producing a one-sided protective polarizing film having a protective film only on one side of a polarizer, and a one-sided protective polarizing film with a transparent resin layer having a transparent resin layer provided on a polarizer surface of the one-sided protective polarizing film. ,
Step (1) of preparing a one-sided protective polarizing film having a protective film only on one side of a polarizer,
A step (2) of applying an aqueous coating solution containing a resin component to the polarizer surface of the one-sided protective polarizing film, and a step (3) of drying the obtained coating film to form a transparent resin layer. Include this order,
Further, before the step (2) of applying the aqueous coating liquid,
A step of performing an activation treatment on the polarizer surface of the one-side protection polarizing film, and
A step of bonding a surface protective film to the activated surface of the one-sided protective polarizing film, and then peeling off the surface-protective film from the one-sided protective polarizing film,
In this order,
The polarizer includes a polyvinyl alcohol-based resin, has a thickness of 10 μm or less,
A method for producing a one-sided protective polarizing film with a transparent resin layer, wherein the water contact angle of the surface of the polarizer on which the transparent resin layer is formed is in the range of an average water contact angle of ± 20 °. The method for producing a one-sided protective polarizing film with a transparent resin layer according to claim 1, wherein the activation treatment is a corona treatment and / or a plasma treatment. The method for producing a one-sided protective polarizing film with a transparent resin layer according to claim 1 or 2 , wherein the variation in the water contact angle is within a range of an average water contact angle ± 15 °. The method for producing a one-sided protective polarizing film with a transparent resin layer according to any one of claims 1 to 3 , wherein the average water contact angle is 90 ° or less. On the transparent resin layer piece protective polarizing film with a transparent resin layer obtained by the process according to any one of claims 1-4, the pressure-sensitive adhesive layer and having a step of forming an adhesive layer Manufacturing method of a polarizing film with an adhesive. A one-sided protective polarizing film with a transparent resin layer obtained by the production method according to any one of claims 1 to 4 , or a polarizing film with an adhesive layer obtained by the production method according to claim 5. A method for manufacturing an image display device, comprising: