KR102159366B1 - Method for producing a single protective polarizing film with a transparent resin layer, a method for producing a polarizing film with an adhesive layer, and a method for producing an image display device - Google Patents

Abstract

The present invention is a method for producing a single protective polarizing film having a protective film only on one side of the polarizer and a transparent resin layer having a transparent resin layer provided on the polarizer surface of the single protective polarizing film, which protects only one side of the polarizer Step (1) of preparing a piece of protective polarizing film having a film (1), a step of applying an aqueous coating solution containing a resin component to the polarizer surface of the piece (2), and drying the obtained coating film to form a transparent resin layer In this order, the polarizer includes a polyvinyl alcohol-based resin, has a thickness of 10 μm or less, and the deviation of the water contact angle of the surface forming the transparent resin layer of the polarizer is an average water contact angle. It is characterized by being within the range of ±20°. According to the present invention, even when the piece protective polarizing film with a transparent resin layer using a thin polarizer is exposed under a humidified environment, occurrence of uneven appearance can be suppressed.

Description

Method for producing a single protective polarizing film with a transparent resin layer, a method for producing a polarizing film with an adhesive layer, and a method for producing an image display device

The present invention relates to a method for producing a single protective polarizing film with a transparent resin layer. In addition, the present invention relates to a method for producing a polarizing film with a pressure-sensitive adhesive layer including the single protective polarizing film with a transparent resin layer and a pressure-sensitive adhesive layer. In addition, the present invention relates to a method of manufacturing an image display device such as a liquid crystal display (LCD) and an organic EL display using a single protective polarizing film with a transparent resin layer or a polarizing film with an adhesive layer obtained by the above manufacturing method.

In watches, cell phones, PDAs, notebook computers, PC monitors, DVD players, and TVs, liquid crystal displays are rapidly expanding the market. In a liquid crystal display device, a polarization state by switching of a liquid crystal is visualized, and a polarizer is used from the display principle.

As the polarizer, since it has high transmittance and high polarization, for example, an iodine polarizer having a structure in which iodine is adsorbed and stretched on a polyvinyl alcohol film is most commonly used. Such a polarizer has a disadvantage in that the mechanical strength is extremely weak and the polarization function is remarkably deteriorated due to shrinkage by heat or moisture. Therefore, the obtained polarizer is immediately bonded to each other via an adhesive-coated protective film and an adhesive, and is used as a polarizing film.

On the other hand, image display devices, such as a liquid crystal display, are progressing thinning, and thinning is also required for a polarizing film. Therefore, thinning is also achieved for the polarizer. In addition, thinning can be achieved by using a protective film provided only on one side of the polarizer and a protective film not provided on the other side of the polarizer. As compared with a positive polarizing film provided with a protective film on both sides of a polarizer, this single protective polarizing film has one less protective film, and thus can achieve thinning.

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

[Prior technical literature]

[Patent Literature]

Patent Document 1: Japanese Unexamined Patent Publication No. 2010-009027

Patent document 2: Japanese Unexamined Patent Publication No. 2013-160775

As described above, it is known that the durability of the piece protective polarizing film can be improved by forming a transparent resin layer on the polarizer. However, when a transparent resin layer is formed on the polarizer of the piece protective polarizing film using a thin polarizer having a thickness of 10 μm or less, when the piece protective polarizing film with the transparent resin layer is exposed under a humidified environment, the transparent water after the humidification test It was newly found this time that the appearance unevenness is easy to be recognized when affixed on both sides of an image display panel or the like so that the absorption axis of the piece protective polarizing film with the formation layer is orthogonal.

Therefore, the present invention is to provide a method for producing a single protective polarizing film with a transparent resin layer capable of suppressing the occurrence of uneven appearance even when a single protective polarizing film with a transparent resin layer using a thin polarizer is exposed under a humidified environment. The purpose. In addition, the present invention provides a method of manufacturing a polarizing film with an adhesive layer using the transparent resin layer-attached single protective polarizing film, and a method of manufacturing an image display device using the single protective polarizing film with the transparent resin layer or a polarizing film with an adhesive layer It aims to do.

As a result of intensive examination, the inventors of the present invention discovered that the above problem could be solved by the method for producing a single protective polarizing film with a transparent resin layer described below, and reached the present invention.

That is, the present invention is a method for producing a single protective polarizing film having a protective film only on one side of the polarizer, and a single protective polarizing film with a transparent resin layer having a transparent resin layer provided on the polarizer surface of the single protective polarizing film,

Step (1) of preparing a single protective polarizing film having a protective film only on one side of the polarizer,

A step (2) of applying an aqueous coating solution containing a resin component to the polarizer surface of the piece protective polarizing film, and

It includes step (3) of drying the obtained coating film to form a transparent resin layer, in this order,

The polarizer includes a polyvinyl alcohol-based resin, and has a thickness of 10 μm or less,

It relates to a method of manufacturing a single protective polarizing film with a transparent resin layer, wherein the deviation of the water contact angle of the surface of the polarizer forming the transparent resin layer is within a range of an average water contact angle of ±20°.

Before the step (2) of applying the aqueous coating solution,

A step of attaching a surface protective film to the polarizer surface of the piece protective polarizing film and then peeling the surface protective film from the piece protective polarizing film, and

The step of performing an activation treatment on the surface protective film peeling surface of the piece protective polarizing film may be included in this order.

Before the step (2) of applying the aqueous coating solution,

A step of performing an activation treatment on the polarizer surface of the piece protective polarizing film, and

The step of attaching a surface protective film to the activated surface of the piece protective polarizing film and then peeling the surface protective film from the piece protective polarizing film may be included in this order.

It is preferable that the activation treatment is corona treatment and/or plasma treatment.

It is preferable that the deviation of the water contact angle is within the range of the average water contact angle ±15°.

It is preferable that the average water contact angle is 90° or less.

Further, the present invention relates to a method for producing a polarizing film with a pressure-sensitive adhesive layer, comprising a step of forming a pressure-sensitive adhesive layer on the transparent resin layer of the piece protective polarizing film with a transparent resin layer obtained by the above-described production method.

In addition, the present invention relates to a method for manufacturing an image display device, which is formed using a single protective 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.

The method of manufacturing a single protective polarizing film with a transparent resin layer of the present invention provides a single protective polarizing film with a transparent resin layer capable of suppressing the occurrence of uneven appearance even when exposed to a humidified environment despite the use of a thin polarizer. I can.

This is because the deviation of the water contact angle of the transparent resin layer formation surface of the polarizer used in the present invention is controlled within a predetermined range, and the thickness nonuniformity of the transparent resin layer is suppressed. In other words, when exposed to a humidified environment, a component near the surface of the polarizer may seep into the transparent resin layer in the case of a single protective polarizing film with a transparent resin layer.If a polarizer with a thickness of 10 μm or less is used, the number of transparent polarizers is transparent to the total amount of the polarizer. When the proportion of components that seep into the stratum is large, and there is a variation in the thickness of the transparent resin layer, due to this, there is also a variation in the amount of components that seep out from the polarizer into the transparent resin layer. I think.

Moreover, since the manufacturing method of the image display device of this invention uses the transparent resin layer-attached polarizing film or the polarizing film with a pressure-sensitive adhesive layer obtained by the manufacturing method of this invention, it can provide an image display device with high reliability.

1 is an example of a schematic cross-sectional view of a piece protective polarizing film with a transparent resin layer obtained by the production method of the present invention.
Fig. 2 is an example of a schematic cross-sectional view of a polarizing film with an adhesive layer obtained by the production method of the present invention.
FIG. 3 is a diagram in which (a) Example 1, (b) Example 3, and (c) the film thickness deviation of the transparent resin layer obtained in Comparative Example 1 were measured using an interference type optical film thickness meter. to be.
Fig. 4 is a photograph showing the visibility of appearance irregularities in samples for humidified environment tests obtained in (a) Example 1, (b) Example 3, and (c) Comparative Example 1. FIG.

1. Method for producing a single protective polarizing film with a transparent resin layer

The method for producing a single protective polarizing film with a transparent resin layer of the present invention includes a single protective polarizing film having a protective film only on one side of the polarizer, and a transparent resin layer having a transparent resin layer provided on the polarizer surface of the single protective polarizing film. As a manufacturing method of a polarizing film,

Step (1) of preparing a single protective polarizing film having a protective film only on one side of the polarizer,

A step (2) of applying an aqueous coating solution containing a resin component to the polarizer surface of the piece protective polarizing film, and

It includes step (3) of drying the obtained coating film to form a transparent resin layer, in this order,

The polarizer includes a polyvinyl alcohol-based resin, and has a thickness of 10 μm or less,

It is characterized in that the deviation of the water contact angle of the surface forming the transparent resin layer of the polarizer is within the range of the average water contact angle ±20°.

The piece protective polarizing film with the transparent resin layer will be described with reference to FIG. 1. However, the present invention is not limited to these drawings.

The single 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 may be laminated through an intervening layer (not shown) such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). The piece protective polarizing film 10 with a transparent resin layer obtained by the production method of the present invention is transparent to the polarizer side (the side not having the protective film 2 of the polarizer 1) of the piece protective polarizing film 3 It has a strata (4).

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

(1) Process of preparing a piece protection polarizing film (1)

In step (1), a single protective polarizing film 3 having a protective film 2 on only one surface 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 even 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. This thin polarizer 1 has little thickness unevenness, excellent visibility, and little dimensional change, so it has excellent durability against thermal shock.

As the polarizer 1, a polyvinyl alcohol-based resin is used. As the polarizer (1), for example, a dichroic substance such as iodine or a dichroic dye is adsorbed to a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene/vinyl acetate copolymer-based partially saponified film. Uniaxially stretched, polyene-based oriented films such as polyvinyl alcohol dehydration treatment and polyvinyl chloride dehydrochloric acid treatment, and the like. Among these, a polarizer made 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 it can be produced by, for example, dyeing by immersing polyvinyl alcohol in an aqueous iodine solution and stretching it 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 such as potassium iodide. Further, if necessary, before dyeing, the polyvinyl alcohol-based film may be immersed in water and washed with water. By washing the polyvinyl alcohol-based film with water, it is possible to wash the surface of the polyvinyl alcohol-based film with an anti-contamination or blocking agent, and by swelling the polyvinyl alcohol-based film, there is an effect of preventing unevenness such as staining. Stretching may be performed after dyeing with iodine, stretching may be performed while dyeing, or may be dyed with iodine after stretching. It can also be stretched in an aqueous solution such as boric acid or potassium iodide or in a water bath.

It is preferable from the viewpoint of stretching stability and optical durability that the polarizer 1 contains boric acid. In addition, the content of boric acid contained in the polarizer 1 is preferably 25% by weight or less, more preferably 20% 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 the occurrence of penetration cracks and nano slits and suppression of expansion. It is more preferable that it is less than %, and it is especially preferable that it is 16 weight% or less. On the other hand, from the viewpoint of stretch stability and optical durability of the polarizer 1, the boric acid content with respect to the total amount of the polarizer is preferably 10% by weight or more, and more preferably 12% by weight or more.

The polarizer 1 has an optical characteristic represented by a single transmittance (T) and a polarization degree (P), in the following formula P> -(10 ^0.929T-42.4 -1) × 100 (however, T <42.3) or, It is preferable to be configured to satisfy the condition of P ≥ 99.9 (however, T ≥ 42.3). The polarizer configured to satisfy the above condition has a performance required as a display for a liquid crystal TV using a large display element, in a sense. Specifically, the contrast ratio is 1000:1 or more, and the maximum luminance is 500 cd/m2 or more. As another application, for example, it is pasted on the viewer side of an organic EL display device.

The material constituting the protective film 2 is preferably those having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropic properties, 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, polystyrene or acrylonitrile-styrene copolymer ( AS resin), and the like, and polycarbonate-based polymers. In addition, polyethylene, polypropylene, polyolefins having a cyclo-based or norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon or aromatic polyamide, imide-based polymers, and sulfone-based Polymer, polyethersulfone polymer, polyetheretherketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy Polymers or blends of the polymers are also exemplified as examples of polymers forming the protective film.

Moreover, one or more types of arbitrary suitable additives may be contained in the protective film 2. Examples of the additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and coloring agents. The content of the thermoplastic resin in the protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the protective film 2 is less than 50% by weight, there is a fear that the high transparency inherent in the thermoplastic resin may not be sufficiently expressed.

As the protective film 2, a retardation film, a brightness improving film, a diffusion film, or the like can also be used. Examples of the retardation film include those having a front retardation of 40 nm or more and/or a retardation in the thickness direction of 80 nm or more. The front retardation is typically controlled in the range of 40 to 200 nm, and the thickness direction retardation is typically controlled in the range of 80 to 300 nm. When using a retardation film as a protective film, since the said retardation film also functions as a polarizer protective film, thinning can be aimed at.

As the retardation film, a birefringent film obtained by uniaxially or biaxially stretching a thermoplastic resin film is exemplified. The stretching temperature, stretching ratio, and the like are appropriately set according to the retardation value, the material of the film, and the thickness.

The thickness of the protective film 2 can be appropriately determined, but in general, it is preferably 3 to 200 µm, and further preferably 3 to 100 µm from the viewpoints of workability such as strength and handling, thin layer properties, etc. . In particular, the thickness of the protective film (when a film is formed in advance) is preferably 10 to 60 µm, further preferably 10 to 50 µm from the viewpoint of transportability. On the other hand, the thickness of the protective film (when formed by application or curing) is preferably 3 to 25 µm, further preferably 3 to 20 µm from the viewpoint of transportability. The protective film can also be used in plural or plural layers.

Functional layers, such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, and a diffusion layer or an anti-glare layer, may be provided on the surface of the protective film 2 to which the polarizer 1 is not adhered. In addition, functional layers such as the hard coat layer, anti-reflection layer, anti-sticking layer, diffusion layer or anti-glare layer may be installed separately from the protective film in addition to being installed on the protective film 2 itself. May be.

The protective film 2 and the polarizer 1 may be laminated through an intervening layer such as an adhesive layer, an adhesive layer, and an undercoat layer (primer layer). At this time, it is preferable to stack both with an intervening layer without air gap. In addition, the interposition layer of the polarizer 1 and the protective film 2 is not shown in the drawing.

The adhesive layer is formed by the adhesive. The type of adhesive is not particularly limited, and various types of adhesives may be used. The adhesive layer is not particularly limited as long as it is optically transparent, and various types of adhesives such as water-based, solvent-based, hot-melt-based, active energy ray-curable type are used, but water-based adhesives or active energy ray-curable adhesives are preferable.

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

The active energy ray-curable adhesive is an adhesive that undergoes curing by an active energy ray such as an electron beam or an ultraviolet ray (radical curing type, cation curing type), and can be used, for example, in an electron beam curing type or an ultraviolet curing type. As the active energy ray-curable adhesive, for example, a photo radical curable adhesive may 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 or the desired 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, and a rod coater. In addition, a method such as a dipping method can be appropriately used for coating.

In addition, the coating of the adhesive is preferably made so that the thickness of the finally formed adhesive layer is 30 to 300 nm when a water-based adhesive or the like is used. The thickness of the adhesive layer is more preferably 60 to 150 nm. On the other hand, in the case of using an active energy ray-curable adhesive, it is preferable that the thickness of the adhesive layer is 0.2 to 20 μm.

In addition, in the lamination of the polarizer 1 and the protective film 2, a tooth (易) adhesive layer can be provided between the protective film and the adhesive layer. The easily adhesive layer can be formed of various resins having, for example, a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone system, 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 to the formation of the easily adhesive layer. Specifically, stabilizers, such as a tackifier, an ultraviolet absorber, an antioxidant, and a heat-resistant stabilizer, etc. are mentioned.

The easily adhesive layer is usually provided in advance on the protective film, and the easily adhesive layer side of the protective film and the polarizer are laminated by an adhesive layer. The formation of the easily-adhesive layer is performed by coating and drying a material for forming the easily-adhesive layer on a protective film by a known technique. The forming material of the easily adhesive layer is usually adjusted as a solution diluted to an appropriate concentration in consideration of the thickness after drying and smoothness of coating. The easily adhesive layer has a thickness after drying of preferably 0.01 to 5 µm, more preferably 0.02 to 2 µm, and more preferably 0.05 to 1 µm. In addition, although a plurality of easily adhesive layers may be provided, it is preferable that the total thickness of the easily adhesive layer is within the above range even in this case.

The adhesive layer is formed from an adhesive. As the pressure-sensitive adhesive, various pressure-sensitive adhesives can be used, for example, rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives, vinylalkyl ether-based pressure-sensitive adhesives, polyvinylpyrrolidone-based pressure-sensitive adhesives, polyacrylamide-based pressure-sensitive adhesives, and cellulose-based pressure-sensitive adhesives Can be lifted. 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 in that they have excellent optical transparency, appropriate wettability, cohesiveness and adhesive properties, and excellent 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 is a material that exhibits some degree of strong adhesion to both the polarizer 1 and the protective film 2. For example, a thermoplastic resin having excellent transparency, thermal stability, stretchability and the like is used. Examples of the thermoplastic resin include acrylic resins, polyolefin resins, polyester resins, polyvinyl alcohol resins, or mixtures thereof.

The single protective polarizing film 3 used in the present invention can be prepared by a manufacturing method of laminating the protective film 2 only on one side of the polarizing plate 1, but as a specific manufacturing method, for example,

Step (1-1) of forming a laminate (a) having a polarizer (1) having a thickness of 10 μm or less containing a transport film and a polyvinyl alcohol-based resin formed on one side of the transport film,

Step (1-2) of forming the protective film 2 on the side of the polarizer 1 of the laminate (a) obtained in the step (1-1), and,

Formed by a manufacturing method including the step (1-3) of peeling the transport film from the layered product (protective film (2) / polarizer (1) / transport film) obtained in the step (1-2) It is desirable. Hereinafter, each step of the preferred manufacturing method will be described.

(1-1) Step of forming laminate (a) (1-1)

The laminate (a) is, for example, at least a stretching step on the 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 side of the transport film. And it is obtained by performing a dyeing process. The transport film can form a long PVA resin layer by using a long material, and is advantageous for continuous production.

Various thermoplastic resin films can be used as the transport film. Examples of the material for forming the thermoplastic resin film include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polyethylene and polypropylene, polyamide resins, and polycarbonate resins. Resins and copolymer resins thereof. Among these, ester-based resins are preferred from the viewpoints 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 may be used. In addition, the thickness of the thermoplastic resin film is preferably thick in view of the avoidance of fracture in the stretching process and the ease of transport of the laminate (a), and the thickness before the stretching process is preferably 20 to 200 μm, and 30 to 150 μm. It is more preferable.

In addition, as a transport film, a peelable pressure-sensitive adhesive layer can be used on the thermoplastic resin film. As the pressure-sensitive adhesive layer, the same ones used for the surface protective films described later and the like 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 thin polarizer (1) is likely to cause defects on the surface of the thin polarizer (1) when peeling the transport film from the laminate (a) in the step (1-3), and the transparent resin layer of the polarizer (1) (4) Unevenness may occur in the surface condition of the formed surface.

Typical examples of the thin polarizer include Japanese Patent No. 4771486, Japanese Patent No. 44751481, Japanese Patent No. 4815544, Japanese Patent No. 5048120, International Publication No. 2014/077599, and International The thin polarizer described in Unexamined Publication No. 2014/077636 pamphlets or the like, or the thin polarizer obtained from the manufacturing method described in these may be mentioned.

As the thin polarizer, it is possible to stretch at a high magnification among the manufacturing methods including a stretching process and a dyeing process in the state of a laminate (a') and to improve polarization performance. It is preferably obtained by a manufacturing method comprising a step of stretching in an aqueous boric acid solution as described in the specification of Patent No. 44751481 and Specification of Japanese Patent No. 4815544. In particular, the specification of Japanese Patent No. 44751481 and No. 4815544 of Japanese Patent It is preferably obtained by a manufacturing method including a step of auxiliary air stretching before stretching in an aqueous boric acid solution described in the specification. Such a thin polarizer can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin layer and a transport film for stretching in the state of a laminate and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it is possible to extend without problems such as fracture due to stretching by being supported by the transport film for stretching.

The laminated body (a') can be formed, for example, by applying an aqueous solution of a PVA-based resin to a transport film, followed by drying. Further, the PVA-based resin layer in the laminate (a') can be formed on the transport film by extrusion molding. Further, the PVA-based resin layer can also be formed by laminating a PVA-based resin film prepared in advance on a transport film. The thickness of the PVA-based resin layer is appropriately determined in consideration of a draw ratio or 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 so that the total stretch ratio of the PVA-based resin layer is in the range of 3 to 10 times the total stretch ratio. The total draw ratio is preferably 4 to 8 times, more preferably 5 to 7 times. The total draw ratio is preferably made to be 5 times or more. The stretching process can also be performed in a dyeing process or another process. The total draw ratio refers to the cumulative draw ratio including the draw in such a process when drawing is involved in a process other than the drawing process.

The dyeing step performed on the laminate (a') is performed by adsorbing and orienting a dichroic dye or iodine to the PVA-based resin layer. The dyeing process can be done with the stretching process. The dyeing process is generally performed, for example, by immersing the layered product (a') in an iodine solution for an arbitrary time. As the iodine aqueous solution used as the iodine solution, an aqueous solution containing iodine ions with iodine and an iodide compound serving as a dissolution aid is used. As the iodide compound, for example, potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like are used. As the iodide compound, potassium iodide is preferable. The iodination compound used in the present invention is the same as above also when used in other steps.

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 concentration of the iodide compound is about 0.1 to 10% by weight, preferably 0.2 to 8% by weight. In iodine dyeing, the temperature of the iodine solution is usually about 20 to 50°C, preferably 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, the layered product (a') may be subjected to, for example, an insolubilization process, a crosslinking process, a drying (water content adjustment) process, in addition to the above process.

The insolubilization process and the crosslinking process are performed using a boron compound as a crosslinking agent. The order of these steps is not particularly limited. The crosslinking process may be performed together with the dyeing process and the stretching process. The insolubilization process and the crosslinking process may be performed multiple times. Boric acid, borax, etc. are mentioned as a boron compound. The boron compound is generally used in the form of an aqueous solution or a water-organic solvent mixed solution. Usually, boric acid aqueous solution is used. The boric acid concentration in the aqueous boric acid solution is about 1 to 10% by weight, preferably 2 to 7% by weight. In order to impart heat resistance by the degree of crosslinking or to suppress damage during peeling of the transport film, it is preferable to use the boric acid concentration. The aqueous boric acid solution and the like can contain iodide compounds such as potassium iodide. When the aqueous boric acid solution 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) Process of forming a protective film (1-2)

In the process (1-2), a protective film 2 is formed on the side of the polarizer 1 of the obtained laminate (a). By the said process (1-2), the single protective polarizing film (A') with the film for conveyance which has the protective film 2 only on one side of the polarizer 1 is obtained. About the intervening layer used when laminating the protective film 2 and the protective film 2, what was mentioned above can be used.

(1-3) Process of peeling the film for transport (1-3)

In the process (1-3), the transport film is peeled from the piece protective polarizing film (A') with the transport film. There is no particular limitation on the peeling method of the transport film. When peeling the film for conveyance, you may put an angle on the polarizer 1 (or piece protective polarizing film) side, and you may peel by putting an angle on the film side for conveyance. Further, it may be peeled off at an angle on both sides. In either case, damage due to peeling of the transport film is likely to occur in the thin polarizer 1. The angle when peeling the film for conveyance is set arbitrarily. When peeling the film for conveyance, there exists an angle at which the peeling force weakens most. The angle at which the peeling force is weakened can be appropriately determined because it depends on the configuration, peeling speed, humidity at the time of peeling, and the rigidity of the film to be peeled.

(2) Process of applying an aqueous coating solution containing a resin component (2)

In step (2), a water-based coating solution containing a resin component is applied to the polarizer (1) side of the polarizer (1) side of the polarizer (1) side of the polarizer (1) prepared in step (1) and has a protective film (2) only on one side. . The surface of the polarizer (1) forming the transparent resin layer 4 is a surface from which the transport film of the piece protective polarizing film 3 obtained in the step (1) is peeled off.

The deviation of the water contact angle of the surface of the polarizer 1 forming the transparent resin layer 4 (the surface without the protective film 2 of the polarizer 1) is within the range of the average water contact angle ±20°.

The deviation of the water contact angle refers to the deviation width of each water contact angle measured at a plurality of locations of the polarizer 1 with respect to the average water contact angle. Specifically, water contact angles of 25 points in the width direction of the polarizer 1 and 5 points in the stretching direction (transport direction) of the polarizer 1 are measured at an arbitrary point of the polarizer 1, and their average value (average Water contact angle) is calculated, and it means that each measured water contact angle is within the range of ±20° of the average water contact angle. Therefore, for example, when the average value of the water contact angle measured in the width direction at an arbitrary point of the polarizer 1 is 90°, each water contact angle measured in the width direction is 90°±20° (70 to 110°) Means within the range of. In addition, 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 (transport direction) of the polarizer 1.

The deviation of the water contact angle is preferably within the range of the average water contact angle ±20°, the average water contact angle is preferably within the range ±15°, and more preferably within the range of the average water contact angle ±10°. In the present invention, by making the deviation of the water contact angle of the surface of the polarizer 1 forming the transparent resin layer 4 (the surface not having the protective film 2 of the polarizer 1) within the above range, the polarizer 1 Since occurrence of unevenness in the thickness of the transparent resin layer 4 formed on) is suppressed, it is possible to suppress visual recognition of uneven appearance even when exposed to a humidified 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, more preferably 80° or less from the viewpoint of affinity with an aqueous coating solution. , More preferably 60° or less.

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

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

As the aqueous coating solution (hereinafter, also referred to as a forming material), a coating solution containing a resin component dissolved or dispersed in water may be mentioned. A resin component dissolved or dispersed in water refers to a resin dissolved in water or a resin soluble in water at room temperature (25°C) dissolved in an aqueous solvent. In the present invention, since an aqueous coating liquid (aqueous or water dispersion system) is used, the affinity with the surface of the polarizer 1 in which the deviation of the water contact angle is controlled is excellent. In addition, when a damaged portion (a damaged portion generated on the surface of the polarizer 1 before forming the transparent resin layer) is present on the surface of the polarizer 1, the surface of the polarizer 1 swells to cause the water system in the damaged portion. It is advantageous because the coating liquid soaks in. That is, by using an aqueous coating solution, 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. Even if the thickness of (4) is small (for example, 3 μm or less, preferably 2 μm or less), 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, resol-type phenol resin, polyethylene oxide, carboxymethyl. Cellulose, etc. are mentioned. These may be used alone or may be used in combination. As the resin component, polyvinyl alcohol-based resin, poly(meth)acrylic acid, and methylolated melamine are preferably used. In particular, from the viewpoint of adhesion to the polyvinyl alcohol-based resin constituting the polarizer, the resin component is preferably a polyvinyl alcohol-based resin. 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 a "polyvinyl alcohol-based resin".

As said polyvinyl alcohol resin, polyvinyl alcohol is mentioned, for example. Polyvinyl alcohol is obtained by saponifying polyvinyl acetate. Further, examples of the polyvinyl alcohol-based resin include saponified products of a copolymer of vinyl acetate and a copolymerizable monomer. When the copolymerizable monomer is ethylene, an ethylene-vinyl alcohol copolymer is obtained. Further, examples of the monomer having the copolymer include unsaturated carboxylic acids such as (anhydride) maleic acid, fumaric acid, crotonic acid, itaconic acid, and (meth)acrylic acid, and esters thereof; Α-olefins such as ethylene and propylene, (meth)allylsulfonic acid (soda), sulfonic acid soda (monoalkyl maleate), disulfonic acid sodaalkyl maleate, N-methylolacrylamide, acrylamide alkylsulfonic acid alkali salt , N-vinylpyrrolidone, N-vinylpyrrolidone derivatives, and the like. These polyvinyl alcohol-based resins may 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, but from the viewpoint of satisfying moist heat resistance and water resistance, the saponification degree is preferably 99 mol% or more, and further 99.7 mol% or more. desirable. The degree of saponification represents the ratio of units that are actually saponified into vinyl alcohol units among units that can be converted into vinyl alcohol units by saponification, and the residue is a vinyl ester unit. The degree of saponification can be obtained according to JIS K 6726-1994.

The average polymerization degree of the polyvinyl alcohol-based resin can be, for example, 500 or more, but from the viewpoint of satisfying moist heat resistance and water resistance, the average polymerization degree is preferably 1000 or more, more preferably 1500 or more, and furthermore 2000 or more. desirable. The average degree of polymerization 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 the side chain of the polyvinyl alcohol or its copolymer can be used. As said hydrophilic functional group, an acetoacetyl group, a carbonyl group, etc. are mentioned, for example. In addition, a modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, phosphoric acid esterification, etc. of a polyvinyl alcohol-based resin may be used.

The ratio of the polyvinyl alcohol-based resin in the transparent resin layer 4 or the aqueous coating solution (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 aqueous coating solution is prepared as a solution obtained by dissolving the polyvinyl alcohol-based resin in an aqueous solvent.

Examples of the aqueous solvent include water or a mixed solvent consisting of water and a water-soluble organic solvent. Among these, an aqueous solvent consisting only of water is preferable. As water, distilled water, ion-exchanged water, ultrapure water, etc. are mentioned, for example. Methanol, ethanol, acetone, 1-propanol, 2-propanol, etc. are mentioned as a water-soluble organic solvent. When the water-soluble organic solvent is contained in the aqueous 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 still more preferably 10% by weight or less.

The concentration of the polyvinyl alcohol-based resin in the forming material (for example, an aqueous solution) is not particularly limited, but in consideration of coating properties and standing stability, 0.1 to 15% by weight is preferable, and 0.5 to 10% by weight is More preferable.

In addition, an additive may be added to the coating liquid (for example, an aqueous solution). As said additive, a plasticizer, surfactant, etc. are mentioned, for example. As a plasticizer, polyhydric alcohols, such as ethylene glycol and glycerin, are mentioned, for example. As a surfactant, a nonionic surfactant is mentioned, for example. In addition, a stabilizer such as a silane coupling agent and a titanium coupling agent, various tackifiers, ultraviolet absorbers, antioxidants, heat-resistant stabilizers, and hydrolysis-resistant stabilizers may be blended.

The coating solution is advantageous in that it has a low viscosity because it is easy to penetrate the damaged part when the damaged part exists on the surface of the polarizer 1. The viscosity, as 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 coating of the water-based coating solution onto the surface of the polarizer 1 of the piece protective polarizing film 3 is preferably made such that the thickness of the dried coating film (transparent resin layer 4) 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, when the transparent resin layer 4 becomes 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 further preferably 2 μm or less. .

Various methods are used as a method of applying the coating solution. Specifically, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, die coater, etc. Methods, such as an extrusion coating method, are mentioned.

(3) Process of forming a transparent resin layer (3)

In step (3), the coating film obtained in step (2) is dried to form a transparent resin layer (4).

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. In addition, the drying time is preferably 10 to 500 seconds, more preferably 20 to 400 seconds.

In the manufacturing method of the present invention, since the deviation of the water contact angle on the surface of the polarizer 1 forming the transparent resin layer 4 is controlled within a specific range, the water-based coating solution is applied on the surface of the polarizer 1 The occurrence of nonuniformity in the film thickness of the transparent resin layer 4 obtained by forming a film and drying is suppressed, and occurrence of uneven appearance in a humidified environment can be suppressed.

(4) Other processes

In the manufacturing method of the piece protective polarizing film with a transparent resin layer of this invention, before the process (2) of applying the said aqueous coating liquid,

On the polarizer side of the piece protective polarizing film

A step of bonding a surface protective film and then peeling the surface protective film from the piece protective polarizing film, and

It is preferable to include at least one step selected from the group consisting of a step of performing an activation treatment, because it is possible to control the deviation of the water contact angle of the surface of the polarizer 1 on which the transparent resin layer 4 is formed.

(4-1) Surface protection film affixing and peeling process

The surface protective film usually has a base film and an adhesive layer, and protects the piece protective polarizing film 3 through the adhesive layer. The said surface protection film temporarily protects the piece protective polarizing film with an adhesive layer, and is peeled when actually used.

As the base film of the surface protection film, a film material having isotropic property or close to isotropic property is selected from the viewpoint of inspection property and manageability. Examples of the film material include polyester resins such as polyethylene terephthalate films, cellulose resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, and polyolefin resins. Transparent polymers such as resin and acrylic resin are mentioned. Among these, polyester resins are preferred. The base film may be used as a laminate of one or two or more film materials, or a stretched product of the film may be used. The thickness of the base film is generally 500 μm or less, preferably 10 to 200 μm.

As the pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer of the surface protection film, a pressure-sensitive adhesive made of a (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as the base polymer can be appropriately selected and used. have. From the viewpoint of transparency, weather resistance, heat resistance, and the like, an acrylic pressure-sensitive adhesive having an acrylic polymer as a base polymer is preferable. The thickness of the pressure-sensitive adhesive layer (dry film thickness) is determined according to the required adhesion. It is usually about 1 to 100 µm, preferably 5 to 50 µm.

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

As the surface protection film, commercially available ones can be preferably used, and for example, Torretec 7832C #30 manufactured by Tore Film Processing Co., Ltd. can be preferably used.

In addition, the time until the said surface protection film is attached and the said surface protection film is peeled is not specifically limited, For example, it is preferable that it is 1 hour or more, and it is more preferable that it is 12 hours or more.

By attaching and peeling the surface protective film to the polarizer 1 surface (transparent resin layer 4 formation surface) of the piece protective polarizing film 3, the transparent resin layer 4 formation surface of the polarizer 1 This is preferable because it can suppress variations in water contact angle.

(4-2) Activation treatment process

Corona treatment and/or plasma treatment may be mentioned as the activation treatment. As the corona treatment, for example, a method of discharging in normal pressure air by a corona treatment device may be mentioned. Plasma treatment includes, for example, a method of discharging in atmospheric air with a plasma discharger.

The corona output in the corona treatment is not particularly limited, but is preferably about 0.5 to 8.0 kW, more preferably about 0.5 to 7.0 kW, and even more preferably about 0.5 to 6.0 kW, for example. .

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

The plasma output in the plasma treatment is not particularly limited, for example, it is preferably about 0.5 to 5.0 kW, more preferably about 0.5 to 3.0 kW, and even more preferably about 0.5 to 1.5 W. .

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

In the case of performing the corona treatment or plasma treatment, the treatment may be performed once, but it is more preferable to perform the treatment twice or more. Further, both corona treatment and plasma treatment may be performed. For example, corona treatment is applied to the polarizer (1) surface (transparent resin layer (4) formation surface) of the piece protective polarizing film (3), and then plasma treatment is performed to apply the water-based coating solution to the treated surface. The form to apply is mentioned.

It is considered that the hydrophilicity of the polarizer 1 surface (transparent resin layer 4 formation surface) of the piece protective polarizing film 3 is increased by the corona treatment or plasma treatment. Accordingly, the affinity between the polarizer (1) surface (transparent resin layer (4) formation surface) of the piece protective polarizing film 3 and the aqueous coating solution is improved, and the polarizer (1) of the piece protective polarizing film 3 ) The wettability of the aqueous coating solution to the surface (the surface where the transparent resin layer 4 is formed) is improved. In addition, variations in the water contact angle of the polarizer 1 surface (transparent resin layer 4 formation surface) can be suppressed by the corona treatment or plasma treatment.

In the production method of the present invention, it is preferable to perform the various treatments alone or in combination before the step (2). When performing in combination, for example

(Combination 1) A surface protection film is attached to the surface of the polarizer (1) of the piece protection polarizing film 3, and then the surface protection film is peeled from the piece protection polarizing film 3, and then the piece protection A method of performing activation treatment on the surface protective film peeling surface of the polarizing film 3, and

(Combination 2) The polarizer (1) side of the piece protective polarizing film (3) was subjected to an activation treatment, and thereafter, a surface protective film was bonded to the activated side of the piece-protected polarizing film (3), and thereafter The method of peeling the said surface protection film from the said piece protection polarizing film 3, etc. are mentioned.

2. Manufacturing method of polarizing film with adhesive layer

The manufacturing method of the polarizing film with a pressure-sensitive adhesive layer of the present invention is characterized by including a step of forming an adhesive layer on the transparent resin layer of the single protective polarizing film with a transparent resin layer obtained by any of the above manufacturing methods.

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

(1) adhesive layer

For the formation of the pressure-sensitive adhesive layer, an appropriate pressure-sensitive adhesive may be used, and there is no particular limitation on the kind. Examples of the adhesive include rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives.

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

As a method of forming the pressure-sensitive adhesive layer, for example, a method of transferring the pressure-sensitive adhesive onto the transparent resin layer 4 after forming the pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive to a peel-treated separator or the like and drying and removing the polymerization solvent, or the transparent resin layer ( It is produced by a method of forming a pressure-sensitive adhesive layer on the transparent resin layer 4 by applying the pressure-sensitive adhesive to 4) and drying and removing the polymerization solvent. In addition, in the application of the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be appropriately added.

As a peeling-treated separator, a silicone peeling liner is preferably used. As a method of drying the pressure-sensitive adhesive in the process of forming the pressure-sensitive adhesive layer by applying and drying the pressure-sensitive adhesive on such a liner, a suitable and appropriate method may be employed depending on the purpose. Preferably, a method of heating and drying the coating film is used. The heating drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and still more preferably 70°C to 170°C. By setting the heating temperature in the above range, an adhesive having excellent adhesive properties can be obtained.

The drying time is suitable and an appropriate time can be adopted. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and even more preferably 10 seconds to 5 minutes.

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

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 even more preferably 5 to 35 μm.

When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a peel-treated sheet (separator) until it is provided for actual use.

As a constituent material of the separator, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film, porous materials such as paper, fabric, and non-woven fabric, nets, foam sheets, metal foils, and laminates thereof, etc. Although a thin leaf body etc. are mentioned, a plastic film is used preferably from the point which is excellent in surface smoothness.

The plastic film is not particularly limited as long as it is a film capable of protecting the pressure-sensitive adhesive layer, and for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, chlorinated A vinyl copolymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene-vinyl acetate copolymer film, etc. are mentioned.

The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. The separator may be subjected to release and antifouling treatment with silicone, fluorine, long-chain alkyl or fatty acid amide release agents, silica powder, etc., or antistatic treatment such as coating, kneading, and evaporation, if necessary. . 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 peelability from the pressure-sensitive adhesive layer can be further improved.

(2) surface protection film

A surface protective film can be provided in the polarizing film of the present invention (including a single protective polarizing film with a transparent resin layer and a polarizing film with an adhesive layer). As for the surface protection film, the thing mentioned above is mentioned.

3. Method of manufacturing an image display device

The manufacturing method of the image display device of this invention is characterized by forming using the polarizing film with the transparent resin layer obtained by the said manufacturing method, or the polarizing film with an adhesive layer obtained by the said manufacturing method.

A single 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 an optical laminate obtained by laminating it with an optical member, such as a liquid crystal display (LCD) and an organic EL display. It is possible to form an image display device.

The optical member is not particularly limited, for example, a reflective plate, a transflective plate, a retardation plate (including a wavelength plate such as 1/2 or 1/4), a liquid crystal display device such as a visual compensation film, etc. One layer or two or more layers that may be used for can be used. As an optical laminate, in particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by laminating a reflecting plate or a semi-transmissive reflecting plate in addition to a single protective polarizing film with a transparent resin layer or a polarizing film with a pressure-sensitive adhesive layer of the present invention, and the transparent water of the present invention Visual compensation in addition to the elliptically polarizing film or circularly polarizing film formed by laminating a retardation plate in addition to the polarizing film with a stratum layer or a polarizing film with an adhesive layer, the polarizing film with a transparent resin layer or the polarizing film with an adhesive layer of the present invention A polarizing film in which a luminance enhancing film is further laminated on a wide viewing angle polarizing film formed by laminating films or a single protective polarizing film with a transparent resin layer or a polarizing film with an adhesive layer of the present invention is preferable.

The optical laminate in which the optical member is laminated on a single 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 sequentially and separately laminated in the manufacturing process of a liquid crystal display device. Although it can also be formed, what was laminated beforehand and made into an optical laminated body has an advantage of being able to improve the manufacturing process of a liquid crystal display device etc. because it is excellent in stability of quality, assembly work, etc. When two or more optical members are laminated, an appropriate adhesive means such as an adhesive layer can be used. When adhering the above-mentioned single protective polarizing film with a transparent resin layer or a polarizing film with a pressure-sensitive adhesive layer, such an optical axis can be set to an appropriate arrangement angle depending on a target retardation characteristic or the like.

The single protective polarizing film with a transparent resin layer, a polarizing film with an adhesive layer, or an optical laminate obtained by the production method of the present invention can be preferably used for formation of various devices such as a liquid crystal display device. A method of manufacturing a liquid crystal display device may be performed according to the conventional method. That is, a liquid crystal display device is generally formed by properly assembling a liquid crystal cell, a polarizing film or an optical film, and constituent parts such as a lighting system as necessary to embed a driving circuit, but in the present invention, the transparent of the present invention Except for using a single protective polarizing film with a resin layer, a polarizing film with a pressure-sensitive adhesive layer, or an optical laminate, it is not particularly limited, and conventionally can be followed. As for the liquid crystal cell, for example, any kind of IPS type, VA type, or the like can be used, but IPS type is particularly preferable.

Using a backlight or a reflecting plate in a liquid crystal display device or lighting system in which a transparent resin layer-attached polarizing film or a polarizing film with a pressure-sensitive adhesive layer obtained by the production method of the present invention or an optical laminate is disposed on one side or both sides of a liquid crystal cell It is possible to form an appropriate liquid crystal display device such as one. In that case, a single protective polarizing film with a transparent resin layer, a polarizing film with an adhesive layer, or an optical laminate obtained by the production method of the present invention can be provided on one side or both sides of a liquid crystal cell. When a single protective polarizing film with a transparent resin layer of the present invention, a polarizing film with an adhesive layer, or an optical laminate of the present invention is provided on both sides, they may be the same or different. In addition, when forming a liquid crystal display, for example, a diffusion plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, etc. Can be placed more than one layer.

[Example]

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. In addition, both parts and% in each example are based on weight. Unless otherwise specified below, the conditions for standing at room temperature are all 23°C and 65% R.H.

Manufacturing Example 1 (Production of a polarizer)

An amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having an absorption rate of 0.75% and a glass transition temperature (Tg) of 75°C was subjected to corona treatment on one side of the substrate, and on this corona treated side, poly Vinyl alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (trade name: Gosefmer Z200, degree of polymerization: 1200, degree of acetoacetyl modification: 4.6%, degree of saponification: 99.0 mol% or more, Nippongaseiga An aqueous solution containing (manufactured by Kakugo Co., Ltd.) in a ratio of 9:1 was applied and dried at 25°C to form a PVA-based resin layer having a thickness of 11 μm to prepare a laminate.

The obtained laminate was uniaxially stretched at the free end 2.0 times in the longitudinal direction (length direction) between rolls having different circumferential speeds in an oven at 120°C (air auxiliary stretching treatment).

Next, the laminate was immersed for 30 seconds in an insolubilization bath having a liquid temperature of 30°C (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds (insolubilization treatment).

Subsequently, the polarizing plate was immersed in a dyeing bath having a liquid temperature of 30° C. while adjusting the iodine concentration and immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 parts by weight of iodine was blended with respect to 100 parts by weight of water, and 1.0 part by weight of potassium iodide was blended and immersed in an aqueous iodine solution for 60 seconds (dyeing treatment).

Subsequently, it was immersed for 30 seconds in a crosslinking bath having 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 (crosslinking treatment).

Thereafter, the laminate was 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, and between rolls having different circumferential velocity. Uniaxial stretching was performed so that the total stretching ratio was 5.5 times in the longitudinal direction (longitudinal direction) (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath having a liquid temperature of 30°C (an aqueous solution obtained by blending 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) (washing treatment).

By the above, an optical film layered product including a 5 µm-thick polarizer was obtained.

Manufacturing Example 2 (Production of a polarizer)

A polyvinyl alcohol film having an average polymerization degree of 2400 and a saponification degree of 99.9 mol% and a thickness of 30 μm was immersed in hot water at 30° C. for 60 seconds to swell. Subsequently, it was immersed in an aqueous solution having a concentration of 0.3% of iodine/potassium iodide (weight ratio = 0.5/8), and the film was dyed while stretching to 3.5 times. Thereafter, stretching was performed so that the total stretching ratio was 6 times in an aqueous boric acid ester solution at 65°C. 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 (Preparation of a single protective polarizing film)

What subjected to corona treatment to the easily-adhesive treatment surface of a (meth)acrylic resin film having a lactone ring structure having a thickness of 40 μm was used as a protective film.

An ultraviolet curable adhesive was prepared by mixing 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO), and 3 parts by weight of a photo initiator (brand name: IRGACURE 819, manufactured by BASF). . This was used as an adhesive for protective films.

On the surface of the polarizer of the optical film laminate obtained in Production Example 1, the protective film was bonded while applying the UV-curable adhesive so that the thickness of the cured adhesive layer became 1 μm, and then irradiated with ultraviolet rays as an active energy ray to form the adhesive. Cured. Ultraviolet irradiation is a gallium-enclosed metal halide lamp (irradiation device: Light HAMMER 10 manufactured by Fusion UV Systems, Inc., valve: V valve, peak illuminance: 1600 mW/cm ² , integrated irradiation amount: 1000/mJ/cm 2 (wavelength 380 to 440 nm) )) was used, and the irradiance of ultraviolet rays was measured using a Solatell's Sola-Check system. The amorphous IPA copolymerized PET film substrate was left as it is without peeling. The total thickness of the single 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 single protective polarizing film were 42.8% of single transmittance and 99.99% of polarization degree.

<Single transmittance (T) and polarization degree (P)>

The single-piece transmittance (T) and polarization degree (P) of the obtained piece protective polarizing film were measured using a spectral transmittance meter with an integrating sphere (Dot-3c of Murakami Color Technology Research Institute).

In addition, the degree of polarization (P) is the transmittance (parallel transmittance: Tp) when two identical polarizing films are superimposed so that their transmission axes are parallel to each other, and transmittance (orthogonal transmittance: It is obtained by applying Tc) to the following equation.

Polarization degree (P)(%) = {(Tp-Tc)/(Tp+Tc)} ^1/2 × 100

Each transmittance is expressed as a Y value obtained by making 100% of the perfect polarization obtained through a Glan Taylor prism polarizer and correcting the visibility according to the second degree field of view (C light source) of JIS Z8701.

Production Example 4 (Preparation of a coating solution for forming a 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 concentration of 4% by weight and a viscosity of 60 mPa·s (25°C).

<Viscosity measurement>

The viscosity of the coating liquid was measured under the following conditions using a VISCOMETER R85 viscometer RE85L (manufactured by Toki Industries, Ltd.).

Measurement temperature: 25℃

Number of revolutions: 0.5 to 100 rpm

Cone rotor: 1°34'×R24

Example 1 (Preparation of a single protective polarizing film with a transparent resin layer)

From the piece protective polarizing film obtained in Production Example 3, the amorphous IPA copolymerized PET film substrate was peeled off, and a surface protective film (trade name: Toray Tech 7832C #30 manufactured by Toray Processed Film) was pasted on the exposed polarizer. In that state, after leaving to stand for 24 hours, the surface protective film was peeled off, and the coating solution obtained in Production Example 4 (a material for forming a transparent resin layer) was applied to the surface of the polarizer (the surface of the polarizer on which the protective film was not provided). It was applied to a thickness of 25 μm using a roll. After coating, hot air drying was performed at 95° C. for 30 seconds using a floating oven to form a 1 μm-thick transparent resin layer to prepare a single protective polarizing film with a transparent resin layer.

Example 2

In Example 1, after peeling the amorphous IPA copolymerized PET film substrate from the piece protection polarizing film obtained in Preparation Example 3, corona treatment on the exposed polarizer surface (discharge amount: 0.038 W min/m 2, output: 2.0 kW, treatment Speed: 25 m/min). Thereafter, a surface protection film (trade name: Toray Tech 7832C #30, manufactured by Toray Process Film Co., Ltd.) was bonded. Other than that, it carried out similarly to Example 1, and produced the piece protective polarizing film with a transparent resin layer.

Example 3

In Example 1, after peeling the surface protective film, corona treatment (discharge amount: 0.038 W·min/m 2, output: 2.0 kW, treatment speed: 25 m/min) was performed on the exposed polarizer surface. Thereafter, a surface protection film (trade name: Toray Tech 7832C #30, manufactured by Toray Process Film Co., Ltd.) was bonded. Further, the surface protective film was peeled off, and plasma treatment (discharge amount: 0.024 W·min/m 2, output: 1.0 kW, treatment speed: 20 m/m) on the surface of the polarizer (polarizer surface on which the protective film was not provided) Minutes), and in the same manner as in Example 1, a single protective polarizing film with a transparent resin layer was produced.

Example 4

In Example 1, the surface protective film was peeled off, and plasma treatment (discharge amount: 0.024 W·min/m ² , output: 1.0 kW, processing speed) on the surface of the polarizer (polarizer surface on which the protective film is not provided) : 20 m/min), and it carried out similarly to Example 1, and produced the piece protective polarizing film with a transparent resin layer.

Comparative Example 1

In Example 1, after peeling the amorphous IPA copolymerized PET film substrate from the piece protective polarizing film obtained in Production Example 3, plasma treatment on the exposed polarizer surface (discharge amount: 0.048 W·min/m ² , output: 2.0 kW , Treatment speed: 20 m/min), and in the same manner as in Example 1, a single protective polarizing film with a transparent resin layer was produced.

Comparative Example 2

In Example 1, after peeling the amorphous IPA copolymerized PET film substrate from the piece protective polarizing film obtained in Production Example 3, the coating solution obtained in Production Example 4 (former for forming a transparent resin layer) was applied to the exposed polarizer surface. Except having done, it carried out similarly to Example 1, and produced the piece protective polarizing film with a transparent resin layer.

Reference Example 1

Except having used the polarizer obtained in Production Example 2, it carried out similarly to Production Example 3, and produced the piece protective polarizing film.

Except having used the said piece protective polarizing film, it carried out similarly to Example 1, and produced the piece protective polarizing film with a transparent resin layer.

The following evaluation was performed using the piece protective polarizing film with a transparent resin layer obtained in an Example and a comparative example. The evaluation results are shown in Table 1.

<Water contact angle>

The contact angle of water on the surface of the transparent resin layer formation surface of the polarizer used in Examples and Comparative Examples was measured using DM-501 manufactured by Kyowa Interfacial Chemical Co., Ltd., with a production liquid volume of 3 μL and a waiting time to measurement of 1000 ms. I did.

In addition, the water contact angle is 25 points in the width direction of the polarizer, and 5 points in the stretching direction (transport direction) at an arbitrary plurality of points of the polarizer, and the water contact angle is measured, and the average water contact angle in the width direction, and The deviation of the water contact angle was evaluated. In addition, since the water contact angle changes with the passage of time, it was measured immediately after plasma treatment or corona treatment (specifically, within 5 minutes).

<Average film thickness>

In Examples and Comparative Examples, the film thickness of the coating film formed by coating an aqueous coating solution (a material for forming a transparent resin layer) was an optical spectrometer (USB2000+ manufactured by Ocean Optics, light source: HL-2000, optical fiber: ZFQ). It was measured using -12796 (200 μm reflective fiber)). The measurement conditions were as follows, and the measurement measured 25 points in the width direction of a polarizer, and 5 points in the extending direction (transport direction), and calculated|required the average value.

(Measuring conditions)

Measurement wavelength: 450nm to 800nm

Transparent resin layer refractive index: 1.51

<Film thickness deviation>

In Examples and Comparative Examples, the deviation of the film thickness of the coating film formed by coating an aqueous coating solution (a material for forming a transparent resin layer) was measured using an optical spectrometer (USB2000+ manufactured by Ocean Optics, light source: HL-2000, optical fiber: ZFQ-). It was measured using 12796 (200 μm reflective fiber)). Samples having a size of 1200 mm×100 mm were measured at 1 mm intervals, and film thickness variations were evaluated. 3(a), (b), and (c) are 100 mm (absorption axis direction, longitudinal direction of the drawing) × 100 mm (transmission axis direction, transverse direction of the drawing) for Examples 1 and 3 and Comparative Example 1, respectively. The results of the in-plane film thickness variation of are shown.

(Measuring conditions)

Measurement wavelength: 450nm to 800nm

Transparent resin layer refractive index: 1.51

<Humidification environment test (confirmation of appearance stain visibility)>

The single protective polarizing film with a transparent resin layer obtained in Examples and Comparative Examples was cut to a size of 300 mm (absorption axis direction) x 300 mm (transmission axis direction). Two pieces of the piece protective polarizing film (sample) were prepared, and affixed to both surfaces of an alkali-free glass so that their absorption axis might become orthogonal, and the sample for humidification environment test was produced. The obtained sample for a humidified environment test was put in a humidified environment (an environment of 60°C/90% RH) for 300 hours. Thereafter, a sample for a humidification environment test was placed on a backlight unit (uniform light emission surface illumination, TWN series, manufactured by I-Tech Systems), and the visibility of appearance irregularities was confirmed. 4A, 4B, and 4C are photographs in which the visibility of external irregularities was observed in Examples 1 and 3 and Comparative Example 1, respectively.

○: Appearance unevenness is not visually recognized.

X: Appearance unevenness was visually recognized.

[Table 1]

In Examples 1 to 4, the deviation of the water contact angle of the transparent resin layer formation surface of the polarizer is the average water contact angle ±20°, and the deviation of the water contact angle is small, so that the film thickness deviation of the obtained transparent resin layer is small, and humidification environment test The subsequent appearance unevenness was suppressed. On the other hand, in Comparative Examples 1 and 2 in which the variation in the water contact angle of the transparent resin layer formation surface of the polarizer was large, the film thickness variation of the obtained transparent resin layer was large, and appearance unevenness occurred after the humidification environment test. In addition, in Reference Example 1, since the thickness of the polarizing plate was 12 μm, even if the deviation of the water contact angle was large, the appearance unevenness was not visually recognized after the humidification environment test.

[Explanation of code]

1: polarizer

2: protective film

3: single protection polarizing film

4: transparent resin layer

5: adhesive layer

10: single protective polarizing film with transparent resin layer

11: Polarizing film with adhesive layer

A: the width direction of the polarizing film

Claims (9)

A method for producing a single protective polarizing film having a protective film only on one side of the polarizer, and a single protective polarizing film with a transparent resin layer having a transparent resin layer provided on the polarizer surface of the single protective polarizing film,
Step (1) of preparing a single protective polarizing film having a protective film only on one side of the polarizer,
A step (2) of applying an aqueous coating solution containing a resin component to the polarizer surface of the piece protective polarizing film, and
It includes step (3) of drying the obtained coating film to form a transparent resin layer, in this order,
The polarizer includes a polyvinyl alcohol-based resin, and has a thickness of 10 μm or less,
A method for producing a single protective polarizing film with a transparent resin layer, characterized in that the deviation of the water contact angle of the surface of the polarizer forming the transparent resin layer is within a range of an average water contact angle of ±20°. The method of claim 1,
Before the step (2) of applying the aqueous coating solution,
A step of bonding a surface protection film to the polarizer surface of the piece protection polarizing film and then peeling the surface protection film from the piece protection polarizing film, and
A method for producing a single protective polarizing film with a transparent resin layer, comprising a step of performing an activation treatment on the surface protective film peeling surface of the single protective polarizing film in this order. The method of claim 1,
Before the step (2) of applying the aqueous coating solution,
The step of performing an activation treatment on the polarizer surface of the piece protective polarizing film, and
A piece with a transparent resin layer, characterized in that it comprises a step of attaching a surface protection film to the activated surface of the piece protection polarizing film and then peeling the surface protection film from the piece protection polarizing film in this order The manufacturing method of a protective polarizing film. The method of claim 2,
The method for producing a single protective polarizing film with a transparent resin layer, characterized in that the activation treatment is a corona treatment and/or a plasma treatment. The method of claim 1,
A method for producing a single protective polarizing film with a transparent resin layer, characterized in that the deviation of the water contact angle is within a range of an average water contact angle ±15°. The method of claim 1,
The method for producing a single protective polarizing film with a transparent resin layer, characterized in that the average water contact angle is 90° or less. A method for producing a polarizing film with a pressure-sensitive adhesive layer, comprising a step of forming a pressure-sensitive adhesive layer on the transparent resin layer of the piece protective polarizing film with a transparent resin layer obtained by the production method according to claim 1. It is characterized by forming using a single protective polarizing film with a transparent resin layer obtained by the production method according to any one of claims 1 to 6, or a polarizing film with an adhesive layer obtained by the production method according to claim 7 A method of manufacturing an image display device. The method of claim 3,
The method for producing a single protective polarizing film with a transparent resin layer, characterized in that the activation treatment is a corona treatment and/or a plasma treatment.

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