TW201809756A - Laminated film - Google Patents

Abstract

An object of the present invention is to provide a laminated film capable of maintaining a high polarization degree even in a wet heat environment. The laminated film comprises a polarizer layer in which dichroic dye is oriented in polyvinyl alcohol resin, a stretched film which comprises a resin film having a slow axis in a direction with respect to the absorption axis of polarizer layer, and an adhesive layer for adhering the polarizer layer and the stretched film, wherein the glass transition temperature of the adhesive layer is 60 DEG C or higher.

Description

Laminated film

The invention relates to a laminated film.

Conventionally, a polarizing plate has been widely used as a supply element for polarized light in a display device such as a liquid crystal display device, and as a detection element for polarized light. A polarizing plate is known in which a protective film is bonded to one or both sides of a polarizing film (polarizer layer) using an adhesive or the like.

As a polarizing film, a film containing a polyvinyl alcohol-based resin is known in which a dichroic dye such as iodine is aligned. The iodine system in the polarizing film exists as an iodine complex, and the iodine complex itself is also aligned depending on the orientation of the polyvinyl alcohol resin. It is known that this iodine complex absorbs light in the visible light region, whereby the polarizing film exhibits polarization characteristics (polarization degree).

When a polarizing plate is applied to a display device, various optical layers such as a retardation film and an optical compensation film having optical characteristics are bonded to a polarizing film provided with a protective film as required. Depending on the application of the polarizing plate, the stretched film constituting the retardation film may be required to have a slow axis with respect to the direction in which the longitudinal axis of the polarizing film is oblique. In such a display device, it is necessary to arrange the slow axis of the retardation film and the absorption axis of the polarizing film at a desired angle.

Since a conventional retardation film is manufactured by longitudinally extending or laterally extending, the slow axis is, in principle, 0 ° or 90 ° with respect to the longitudinal axis direction of the film. Therefore, in order to set the desired angle as described above, the production is performed in a batch manner, that is, the film sheets cut out from the long stretch film roll at a specific angle are laminated to each other. However, this method not only has low productivity, but also has a problem of a large loss of chips and the like.

In contrast, various manufacturing methods of long retardation films have been proposed, which extend at a desired angle in the oblique direction, and can freely control the slow axis to be neither 0 ° nor 90 with respect to the longitudinal direction of the film ° direction (for example, refer to Patent Document 1). By using such an elongated film whose slant axis is oblique, instead of the conventional batch-type lamination, the roll-to-roll lamination can be performed, so the productivity can be greatly improved and the loss can be greatly reduced.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-80674

However, when the polarizing plate using the stretched film obtained by the method described in Patent Document 1 is placed in a hot and humid environment (for example, an environment at a room temperature of 60 ° C. and a humidity of 95%), the degree of polarization may decrease. .

The present invention is made in view of such a situation, and an object thereof is to provide a laminated film capable of maintaining a high degree of polarization even in a hot and humid environment. By.

In order to solve the above-mentioned problems, the inventors repeated the results of careful research, and concluded that in a hot and humid environment, the stretched film stretches in an oblique direction with respect to the longitudinal axis of the film, causing the polarization axis of the polarizer to collapse. As a result, the degree of polarization is reduced. In contrast, by setting the glass transition temperature of the adhesive layer interposed between the polarizing film and the optical layer to 60 ° C. or higher, it is expected that the stretching of the stretched film in the oblique direction can be suppressed, and the present invention has been completed.

According to one aspect of the present invention, there is provided a laminated film having: a polarizer layer, which is aligned with a dichroic pigment in a polyvinyl alcohol resin; and an extension film, which is inclined with respect to an absorption axis of the polarizer layer. A resin film having a slow axis in the intersection direction is used as a material forming material; and an adhesive layer is an adhesive layer that connects a polarizer layer and an extension film; wherein the glass transition temperature of the adhesive layer is 60 ° C or higher.

In one aspect of the present invention, both the polarizer layer and the extension film may be elongated.

According to one aspect of the present invention, it is possible to provide a laminated film capable of maintaining a high degree of polarization even in a hot and humid environment.

1, 2‧‧‧ laminated film

11‧‧‧Polarizer layer

21‧‧‧ stretch film

23‧‧‧ protective film

31, 33‧‧‧ Adhesive layer

FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of a laminated film according to this embodiment.

FIG. 2 is a schematic cross-sectional view showing a modified example of the layer structure of the laminated film according to this embodiment.

<Laminated film>

FIG. 1 is a schematic cross-sectional view showing an example of a layer structure of a laminated film according to this embodiment. As shown in FIG. 1, the laminated film 1 according to the present embodiment includes a polarizer layer 11, an extension film 21, and an adhesive layer 31 that connects the polarizer layer 11 and the extension film 21. In other embodiments, the protective film may be further laminated on the polarizer layer 11 on the side opposite to the extension film 21.

The laminated film of this embodiment may be a long sheet, or it may be a sheet-like body obtained by cutting the long laminated film into a predetermined length. The long laminated film system includes a long polarizer layer and a long stretch film. The long polarizer layer and the long stretched film will be described later.

[Polarizer layer]

The polarizer layer refers to an optical film having a property of absorbing linearly polarized light having a vibration plane parallel to the optical axis and transmitting linearly polarized light having a vibration plane orthogonal to the optical axis. Specifically, the polarizer layer 11 of this embodiment is a film having a dichroic pigment aligned in a polyvinyl alcohol-based resin (hereinafter referred to as a “PVA-based resin”).

The thickness of the polarizer layer 11 is preferably 30 μm or less, more preferably It is preferably 25 μm or less, more preferably 15 μm or less, particularly preferably 10 μm or less, and particularly preferably 7 μm or less.

When the polarizer layer 11 is a film having a dichroic pigment in a PVA-based resin, the polarizer layer 11 can also be obtained by stretching a base film containing a PVA-based resin. When the thickness of the polarizer layer 11 is 7 μm or less, the coating film containing a PVA-based resin formed on the substrate may be stretched together with the substrate, and then the substrate may be peeled off to obtain the polarizer layer 11.

Examples of the substrate that can be used in this embodiment include a polypropylene film, a polyethylene terephthalate film, a polycarbonate film, a cellulose triacetate film, a norbornene film, a polyester film, Polystyrene film, etc.

Examples of the PVA-based resin used in this embodiment include those obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers that can be copolymerized therewith can also be mentioned. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamide having an ammonium group.

The saponification degree of the PVA-based resin is preferably 80 mol% or more, more preferably 90 mol% or more and 99.5 mol% or less, and still more preferably 94 mol% or more and 99 mol% or less. When the degree of saponification is 80 mol% or more, the heat resistance of the obtained laminated film 1 can be improved. When the degree of saponification is 99.5 mol% or less, the laminated film 1 having sufficient polarizing performance can be obtained.

The PVA-based resin may be a modified polyvinyl alcohol partially modified. For example, olefins modified by ethylene, propylene, etc. Those modified by unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; those modified by alkyl esters of unsaturated carboxylic acids, acrylamide, etc.

The modification ratio of the PVA-based resin is preferably less than 30 mole%, and more preferably less than 10 mole%. When a PVA-based resin having a modification ratio of less than 30 mol% is used, a dichroic pigment can be sufficiently adsorbed, and a polarizer having sufficient polarizing performance can be obtained.

The average degree of polymerization of the PVA-based resin is preferably 100 to 10,000, more preferably 1,500 to 8,000, and even more preferably 2,000 to 5,000. When the average degree of polymerization is 100 or more, a polarizer having sufficient polarization performance can be obtained. When the average degree of polymerization is 10,000 or less, the solubility in a solvent becomes good, and the formation of a film containing a PVA-based resin becomes easy.

PVA-based resins can easily obtain commercially available products. As the preferred examples of commercially available products, they are all listed by product name: "PVA124" and "PVA117" (made by Sauramin Sakata: 98 to 99 Mo) Ear%), "PVA624" (Saponification degree: 95 to 96 mole%), "PVA617" (Saponification degree: 94.5 to 95.5 mole%); "N-300" and "Made by Japan Synthetic Chemical Industry Co., Ltd." "NH-18" (degree of saponification: 98 to 99 mole%), "AH-22" (degree of saponification: 97.5 to 98.5 mole%), "AH-26" (degree of saponification: 97 to 98.8 mole%) ); "JC-33" (degree of saponification: 99 mol% or more), "JF-17", "JF-17L" and "JF-20" (all saponification degrees: 98 by VAM & POVAL Co., Ltd.) To 99 mol%), "JM-26" (degree of saponification: 95.5 to 97.5 mol%), "JM-33" (degree of saponification: 93.5 to 95.5 mol) %), "JP-45" (degree of saponification: 86.5 to 89.5 mole%), etc.

Examples of the dichroic dye used in this embodiment include iodine or a dichroic organic dye. Examples of the dichroic organic dye include red BR, red LR, red R, pink LB, crimson (RUBIN) BL, claret GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, and purple LB, Purple B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Bright Purple BK, S Super Blue G, Super Blue GL, Super Orange GL, Direct Sky Blue, Direct FAST ORANGE S, FAST BLACK.

A dichroic pigment may be used individually by 1 type, and may use 2 or more types together.

[Stretch film]

The stretch film 21 according to this embodiment is a resin film having a slow axis in an oblique direction with respect to the absorption axis of the polarizer layer 11 as a forming material. Such a resin film system can be manufactured through a stretching process, and the resin film system has tensile stress remaining in an oblique direction with respect to the absorption axis of the polarizer layer 11.

The extension film 21 has a slow axis in the oblique direction with respect to the absorption axis of the polarizer layer 11. For example, the angle of the slow axis with respect to the absorption axis of the polarizer layer 11 is preferably 45 ± 10 ° or 135 ± 10 °. By making the angle of the slow axis into the above range, the difference between the phase of the light rays in the fast axis direction and the phase of the light rays in the slow axis direction becomes π / 2. Because the phase difference between the fast axis and the slow axis is π / 2, when the multilayer film 1 of this embodiment is applied to a display device, the light passing through the multilayer film 1 can be circularly polarized. Accordingly, even when viewed through polarized sunglasses, it can be configured to have excellent visibility.

The stretched film 21 of this embodiment is preferably a retardation layer having retardation characteristics and wavelength dispersion characteristics satisfying the following formulae (1) to (4). When the stretch film 21 satisfies the expressions (1) to (4), when the multilayer film 1 of this embodiment is mounted on a display device, it is possible to effectively suppress viewing from various directions (azimuth angle and polar angle) through polarized sunglasses. The hue changes during the picture. This can improve the visibility of the image display device.

(1) 100nm ≦ R _e (590) ≦ 180nm, (2) 0.5 <R _th (590) / R _e (590) ≦ 0.8, (3) 0.85 ≦ R _e (450) / R _e (550) <1.00 , And (4) 1.00 <R _e (630) / R _e (550) ≦ 1.1

_{Wherein, R e (590), R} e (450), R e (550), R e (630) each represent a measurement wavelength 590nm, 450nm, 550nm, 630nm within the in-plane retardation value, R _th (590) Shows the retardation value in the thickness direction at the measurement wavelength of 590 nm. These in-plane retardation values and thickness direction retardation values refer to values measured under an environment of a temperature of 23 ° C and a relative humidity of 55%.

The in-plane retardation value R _e and the thickness direction retardation value R _{th are} set to the refractive index of the in-plane slow axis direction as n _x and the in-plane fast axis direction (a direction orthogonal to the in-plane slow axis direction). When the refractive index of is set to n _y , the refractive index in the thickness direction is set to n _z , and the thickness of the optical film is set to d, it is defined by the following formulae (S1) and (S2).

(S1) R _e = (n _x -n _y ) × d

(S2) R _th = [((n _x + n _y ) / 2) -n _z ] × d

From the viewpoint of more effectively suppressing a change in hue in the laminated film 1, it is preferable that R _e (590) in the formula (1) is 105 to 170 nm. R _th (590) / R _e (590) in the formula (2) is preferably 0.6 to 0.75. The formula R _e (3) in the _{(450) / R e (550} ) preferably 0.86 to 0.98. R _e (630) / R _e (550) in the formula (4) is preferably 1.01 to 1.06.

For example, the stretched film 21 can be manufactured by stretching the film containing the resin mentioned later. Examples of the stretching treatment include uniaxial stretching and biaxial stretching.

Examples of the stretching direction include a mechanical flow direction (MD) of an unstretched film, a direction orthogonal to this (TD), and a direction oblique to the mechanical flow direction (MD). Here, the unstretched film refers to a film in a state where it is not stretched. Uniaxial stretching means stretching the unstretched film in any of these directions. On the other hand, biaxial extension may be simultaneous biaxial extension in two extension directions, or successive biaxial extension in other directions after extending in a predetermined direction.

The stretching process can be performed in the longitudinal direction (machine flow direction: MD) by using two or more pairs of nip rollers having an increased peripheral speed on the exit side, or by holding a non-stretched film by using a chuck, for example. The two sides are enlarged in a direction orthogonal to the direction of mechanical flow (TD). get on. In this case, the phase difference value and the wavelength dispersion can be controlled within the ranges of the above-mentioned formulas (1) to (4) by adjusting the thickness of the film or adjusting the stretching ratio.

In addition, by adding a wavelength dispersion adjusting agent to the resin, it is possible to control the wavelength dispersion value within the range of the above formulas (3) to (4).

Generally, a long polarizing film (polarizer layer) has an absorption axis in the longitudinal direction. The two are arranged in a roll-to-roll manner such that the elongated stretched film and the elongated polarizer layer can be laminated, and the angle formed by the absorption axis of the polarizer layer and the slow axis of the stretched film falls within the above range. In other words, the stretched film 21 is preferably manufactured by oblique stretching by biaxial stretching.

Examples of the resin forming the resin film include a cellulose acetate-based resin, a cycloolefin-based resin, a polyolefin-based resin, an acrylic resin, a polyimide-based resin, a polycarbonate-based resin, and a polyester-based resin.

The cellulose acetate-based resin is composed of cellulose acetate partially or completely. Examples of the cellulose acetate resin include cellulose triacetate and cellulose diacetate.

Resin films containing cellulose acetate-based resins are commercially available products. As a good example of commercially available products, they are listed under the trade name: "FUJITAC (registered trademark) TD80" sold by Fuji Film Co., Ltd. "," FUJITAC (registered trademark) TD80UF "and" FUJITAC (registered trademark) TD80UZ "," KC8UX2M "and" KC8UY "sold by Konica Minolta Opto Co., Ltd., etc.

Cycloolefin-based resins forming a resin film are, for example, thermoplastic amorphous resins (also referred to as non-cyclic resins) having monomer units containing cyclic olefins (cycloolefins) such as norbornene and polycyclic norbornene-based monomers. Crystalline polyolefin resin). The cycloolefin-based resin may be a hydride of a ring-opening polymer of the above-mentioned cyclic olefin, or a hydride of a ring-opening copolymer using two or more kinds of cyclic olefins; it may also be a cyclic olefin and a chain olefin and / or an aromatic having a vinyl group Additive copolymers of family compounds and the like. A polar group may be introduced.

When a resin film is formed using a copolymer of a cyclic olefin and a chain olefin and / or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene, propylene, and the like. Examples of the aromatic compound having a vinyl group include styrene, α-methylstyrene, and styrene having an alkyl group substituted on a benzene ring. In such a copolymer, the monomer unit containing a cyclic olefin is preferably 50 mol% or less, more preferably 15 to 50 mol%.

In particular, when a terpolymer of an aromatic compound having a cyclic olefin, a chain olefin, and a vinyl group is used, the monomer unit containing the cyclic olefin can be made as small as described above. In this terpolymer, the unit of the monomer composed of a chain olefin is preferably 5 to 80 mol%. The monomer unit containing an aromatic compound having a vinyl group is preferably 5 to 80 mole%.

Cycloolefin-based resins can easily obtain commercially available products. As preferred examples of commercially available products, they are listed under the trade name: "TOPAS (registered by TOPAS ADVANCED POLYMERS GmbH) and sold by POLY PLASTICS Co., Ltd. in Japan. (Trademark) "," ARTON (registered trademark) "sold by JSR Co., Ltd., and Japan Zeon Co., Ltd. "ZEONOR (registered trademark)" and "ZEONEX (registered trademark)" sold by the company, "APEL (registered trademark)" sold by Mitsui Chemicals Co., Ltd., etc.

When the stretched film 21 of this embodiment is a retardation layer, the thickness of the retardation layer is preferably 10 μm or more and 50 μm or less.

The stretched film 21 of this embodiment may contain a plasticizer in addition to the resin forming the resin film, in order to impart flexibility to the resin film and facilitate stretching. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane.

The plasticizer may be used alone or in combination of two or more. Particularly suitable are ethylene glycol and glycerol.

[Adhesive layer]

The adhesive layer 31 of this embodiment has a glass transition temperature of 60 ° C or higher. When the glass transition temperature is 60 ° C. or higher, the hardness of the adhesive layer 31 can be sufficiently increased. Thereby, in a hot and humid environment (for example, an environment of a room temperature of 60 ° C. and a humidity of 95%), it is possible to suppress stretching in the diagonal direction of the stretched film 21. The upper limit is not particularly limited, and may be about 400 ° C.

In this specification, the glass transition temperature of the adhesive layer 31 is a value measured by the following method.

When an active energy ray-curable adhesive composition (to be described later) is used, two stretched cyclic olefin-based resin films with a thickness of 50 μm [trade name "ZEONOR (registered trademark)" manufactured by Japan Zeon Corporation] are prepared. Then, each prepared curable resin composition was coated on one surface of the film with a rod coater so that the cured film thickness became 2 μm, and another film was superposed on the coating surface. This laminated body was irradiated with ultraviolet rays from one side so that the cumulative light amount became 250 mJ / cm ² to harden the adhesive composition.

Next, the film stuck to both sides of this hardened | cured material is peeled. Then, 5 mg of the cured product was collected and placed in an aluminum button-type container, which was then closed and sealed to prepare a measurement sample.

Next, a differential scanning calorimeter (DSC) "EXSTAR-6000 DSC6220" sold by SII NanoTechnology Co., Ltd. was provided with a container in which the above-mentioned measurement sample was placed. Then, while flowing in nitrogen, the temperature was lowered from 20 ° C to -60 ° C. After reaching -60 ° C and holding for 1 minute, the temperature was increased from -60 ° C to 200 ° C at a heating rate of 10 ° C / min, and immediately after reaching 200 ° C, the temperature was lowered. To 20 ° C. Then, from the DSC curve when the temperature was raised from -60 ° C to 200 ° C, the intermediate point glass transition temperature specified in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics" was obtained. This temperature was set as the glass transition temperature of the adhesive layer 31 (hardened | cured material).

On the other hand, in the case of a water-based adhesive composition (described later), one piece of cellulose triacetate film [Konica Minolta Opto Co., Ltd.'s trade name "KC4UY"] was prepared. An aqueous adhesive composition was coated on one side of the cellulose triacetate film, and dried at 80 ° C. for 5 minutes. At this time, the coating was repeated so that the film thickness after drying became 2 μm and dried. Subsequently, a specimen for measurement was prepared for the cured product obtained by peeling the film by the same method as described above, and the glass transition temperature was measured.

The thickness of the adhesive layer 31 is preferably 0.01 μm or more and 5 μm or less, more preferably 0.01 μm or more and 2 μm or less, and still more preferably 0.01 μm or more and 1 μm or less. When the thickness of the adhesive layer 31 is 0.01 μm or more, sufficient adhesiveness can be obtained. When the thickness of the adhesive layer 31 is 5 μm or less, the appearance of the laminated film 1 is difficult to form.

The material for forming the adhesive layer 31 is not particularly limited as long as the glass transition temperature is 60 ° C. or higher, and a cured product of a curable resin composition can be used. Examples of the curable resin composition include a water-based adhesive composition and an active energy ray-curable adhesive composition.

Here, the "active energy ray-curable adhesive composition" refers to an adhesive composition that is hardened by irradiating an active energy ray (for example, ultraviolet rays, visible light, electron rays, X-rays, etc.).

[Aqueous adhesive composition]

Examples of the water-based adhesive composition include a polyvinyl alcohol-based resin aqueous solution and an aqueous two-liquid urethane-based emulsion adhesive composition, and the like is preferably a polyvinyl alcohol-based resin aqueous solution. When a polyvinyl alcohol-based resin aqueous solution is used, the polyvinyl alcohol-based resin used as the adhesive composition includes a vinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate, which is a homopolymer of vinyl acetate. In addition to the compounds, there may be a vinyl alcohol copolymer obtained by saponifying a copolymer of vinyl acetate and another monomer copolymerizable therewith, and a modified polymer obtained by partially modifying these hydroxyl groups. Vinyl alcohol-based polymers and the like. As a modification Examples of the polyvinyl alcohol-based polymer include carboxyl-modified polyvinyl alcohol, acetoacetamyl-modified polyvinyl alcohol, methylol-modified polyvinyl alcohol, and amino-modified polyvinyl alcohol. In the present embodiment, the adhesive layer 31 is preferably a hardened product of a polyvinyl alcohol-based resin modified with an acetamidine group, as a forming material.

Polyvalent aldehydes, water-soluble epoxy compounds, melamine-based compounds, zirconia compounds, zinc compounds, and the like may be added to this adhesive composition as additives.

The adhesive agent composition using polyvinyl alcohol resin as an adhesive agent component is preferably a hardening component such as a metal salt of glyoxylic acid, glyoxal, and a water-soluble epoxy resin, and / or cross-linking in order to improve adhesion. Agent. The metal salt of glyoxylic acid is preferably an alkali metal salt or an alkaline earth metal salt, and examples thereof include sodium glyoxylate, potassium glyoxylate, magnesium glyoxylate, and calcium glyoxylate. As the water-soluble epoxy resin, for example, polyamideamine (polyamideamine) obtained by reacting polyalkylene polyamines such as paraethylene triamine and triethylene tetraamine with dicarboxylic acids such as adipic acid is preferably used. ), A polyamine epoxy resin obtained by reacting with epichlorohydrin.

Examples of commercially available metal salts of such glyoxylic acid include "SPM-01" (manufactured by Nippon Synthetic Chemical Co., Ltd.) and the like. Examples of commercially available products of such polyamine polyamine epoxy resins include "Sumirez Resin 650" (manufactured by Sumika CHEMTEX Co., Ltd.), "Sumirez Resin 675" (manufactured by Sumika CHEMTEX Co., Ltd.), " "WS-525" (manufactured by Japan PMC Co., Ltd.), etc.

The amount of these hardening components and / or cross-linking agents added to 100 parts by mass of the polyvinyl alcohol-based resin (the total is added together) Amount) is, for example, 1 to 100 parts by mass, and preferably 1 to 50 parts by mass. When the addition amount of the said hardening component and / or a crosslinking agent exists in the said range, adhesiveness can be improved and the adhesive layer which shows favorable adhesiveness can be formed.

When the water-based adhesive composition contains a urethane resin, a mixture of a polyester-based ionic polymer-type urethane resin and a compound having an epoxypropyloxy group is preferably used.

Here, the so-called polyester-based ionic polymer-type urethane resin is a urethane resin having a polyester skeleton, with a small amount of ionic components (hydrophilic components) introduced into the skeleton. Since such an ionic polymer-type urethane resin is directly emulsified in water without using an emulsifier to become an emulsion, it is suitable for use as an aqueous adhesive composition.

The polyester ionic polymer urethane resin itself is well known, for example, Japanese Patent Laid-Open No. 7-97504, and describes an example of a polymer dispersant for dispersing a phenol resin in an aqueous medium. . Also, in Japanese Patent Application Laid-Open No. 2005-70140 and Japanese Patent Application Laid-Open No. 2005-208456, a mixture of a polyester-based ionic polymer-type urethane resin and a compound having an epoxypropyloxy group is disclosed as The adhesive is a form in which a cyclic olefin-based resin film is bonded to a polarizer made of a polyvinyl alcohol-based resin.

When a polyvinyl alcohol-based resin aqueous solution is used, the content of the polyvinyl alcohol-based resin is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of water.

[Active energy ray-curable adhesive composition]

As the active-energy-ray-curable compound contained in the active-energy-ray-curable adhesive composition, a cationically polymerizable compound or a radically polymerizable compound is preferred, and a cationically polymerizable compound and a radically polymerizable compound are more preferred. . When a cationically polymerizable compound and a radically polymerizable compound are contained, the hardness of the adhesive layer 31 can be expected to be increased, and the viscosity, curing rate, and the like of the active energy ray-curable adhesive composition can be adjusted more easily.

(Cationically polymerizable compound)

Examples of the cationically polymerizable compound used in this embodiment include an oxetane compound and an epoxy compound.

The content of the cationically polymerizable compound with respect to 100 parts by mass of the active energy ray-curable adhesive composition is preferably 10 parts by mass or more and 99 parts by mass, and more preferably 40 parts by mass or more and 99 parts by mass or less.

Examples of the oxetane compound include 3-ethyl-3hydroxymethyloxetane and 1,4-bis [(3-ethyl-3-oxetane) methoxy Methyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, bis [(3-ethyl-3-oxetanyl) methyl] ether, 3- Ethyl-3- (2-ethylhexyloxymethyl) oxetane and the like. Among these, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene and di [(3-ethyl-3-oxa Cyclobutyl) methyl] ether.

These oxetane compounds can be easily obtained in the market, and as the marketers, they can be listed by Toa Synthetic Co., Ltd. Products sold by the company are "ARON OXETANE (registered trademark) OXT-101", "ARON OXETANE (registered trademark) OXT-121", "ARON OXETANE (registered trademark) OXT-211", "ARON OXETANE (registered trademark) OXT -221 "," ARON OXETANE (registered trademark) OXT-212 ", etc.

The content of the oxetane compound is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 10 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable adhesive composition.

In the active energy ray-curable adhesive composition, an oxetane compound may be used singly or in combination of two or more kinds.

The active-energy-ray-curable adhesive composition may contain an epoxy compound in addition to the oxetane compound described above as necessary. An epoxy compound is one of cationically polymerizable compounds like an oxetane compound, and can be hardened by irradiating an active energy ray. When the active energy ray-curable adhesive composition contains an epoxy compound, the adhesiveness between the stretch film 21 and the polarizer layer 11 can be improved.

Examples of the epoxy compound include an aromatic epoxy compound, a glycidyl ether of a polyhydric alcohol having an alicyclic ring, an aliphatic epoxy compound, and an alicyclic epoxy compound.

Examples of the aromatic epoxy compound include bisphenol-type epoxy resins of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and bisphenol S diglycidyl ether. Resins; such as novolac-type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; such as tetrahydroxyphenylmethane Polyfunctional epoxy resins such as glycidyl ether, glycidyl ether of tetrahydroxydiphenyl ketone, and epoxidized polyvinyl phenol.

Examples of the glycidyl ether of a polyhydric alcohol having an alicyclic ring include a core obtained by selectively hydrogenating an aromatic ring under pressure in the presence of a catalyst under pressure. A hydrogenated polyhydric compound obtained by etherification of an epoxy group. Examples of the aromatic polyols include bisphenol compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac types such as phenol novolac resin, cresol novolac resin, and hydroxybenzaldehyde phenol novolac resin Resin; such as tetrahydroxydiphenylmethane, tetrahydroxydiphenyl ketone, polyvinylphenol and other polyfunctional compounds.

The alicyclic polyol obtained by hydrogenating an aromatic ring of these aromatic polyols and reacting with epichlorohydrin can be converted into an epoxypropyl ether.

Among the glycidyl ethers of such polyhydric alcohols having an alicyclic ring, preferred is a diglycidyl ether of hydrogenated bisphenol A.

Examples of the "aliphatic epoxy compound" include an aliphatic polyhydric alcohol or poly (propylene oxide ether) of an alkylene oxide adduct thereof. Specific examples include a diglycidyl ether of 1,4-butanediol; a diglycidyl ether of 1,6-hexanediol; a triglycidyl ether of glycerol; and trimethylol Triglycidyl ether of propylene propane; diglycidyl ether of polyethylene glycol; diglycidyl ether of propylene glycol; diglycidyl ether of neopentyl glycol; such as ethylene glycol, propylene glycol or A polyether polyol obtained by adding glycerol aliphatic polyol to one or two or more alkylene oxides (ethylene oxide and propylene oxide). Polyepoxypropyl ether.

The monofunctional epoxy compound represented by the following formula (I) can also be cited as an aliphatic epoxy compound. R ¹ may be a branched alkyl group having 1 to 15 carbon atoms. The carbon number of the alkyl group is preferably 6 or more, and more preferably 6 to 10. Among these, branched alkyl is preferred. Examples of the monofunctional epoxy compound represented by the formula (I) include 2-ethylhexyl glycidyl ether.

An "alicyclic epoxy compound" refers to a compound having at least one carbon atom in the molecule with an alicyclic ring to form an ethylene oxide ring structure. Here, "the ethylene oxide ring structure is formed with the carbon atom of an alicyclic ring" means the structure represented by following formula (II). N in the formula is an integer of 2 to 5.

A group in the form in which one or a plurality of hydrogen atoms in (CH ₂ ) n of the formula (II) is removed is bonded to a compound of another chemical structure to form an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) n forming an alicyclic ring may be substituted by a linear alkyl group such as a methyl group and an ethyl group.

As the epoxy compound, an alicyclic epoxidation is preferred In order to easily obtain a protective layer having more excellent adhesion with the polarizer, it is preferable to have epoxy cyclohexane (in the above formula (II), n = 4) or epoxy cycloheptane ( An epoxy compound of the above formula (II) (n = 5).

The content of the epoxy compound is preferably 1 part by mass or more and 90 parts by mass or less, more preferably 20 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable adhesive composition.

In the active-energy-ray-curable adhesive composition, an epoxy compound may be used individually by 1 type, and may use 2 or more types together.

(Radical Polymerizable Compound)

Further, in addition to the cationically polymerizable compound such as the oxetane compound and the epoxy compound, a radically polymerizable compound may be contained.

Examples of the radical polymerizable compound include a compound having at least one (meth) acryloxy group in the molecule (hereinafter, referred to as a "(meth) acrylic compound"). A compound having at least one (meth) acrylamide group (hereinafter, referred to as a "(meth) acrylamide compound") and the like. In addition, the "(meth) acrylfluorenyloxy" means methacrylhydrazyl or acrylic acid, and the so-called (meth) acrylamide is methacrylamine or acrylamide base.

Examples of the (meth) acrylic compound include a (meth) acrylic acid ester monomer having at least one (meth) acryloxy group in the molecule, and at least two (meth) acrylic acid in the molecule. (Meth) acrylate oligomers of methoxy. These systems can be used individually or in combination. More than that. When two or more kinds are used in combination, the (meth) acrylate monomer may be two or more kinds, and the (meth) acrylate oligomer may be two or more kinds. Of course, the (meth) acrylate monomer 1 may also be used in combination. Or more types and (meth) acrylate oligomers.

Examples of the (meth) acrylamido compound are N-substituted (meth) acrylamido compounds. The N-substituted (meth) acrylamide compound is a (meth) acrylamide compound having a substituent at the N-position. A typical example of this substituent is an alkyl group. The N-position substituents may be bonded to each other to form a ring, and -CH ₂ -constituting the ring may be substituted with an oxygen atom. Further, the carbon atom constituting the ring may be substituted with a substituent such as an alkyl group or a pendant oxygen group (= O). N-substituted (meth) acrylamide can usually be produced by the reaction of (meth) acrylic acid or its chloride with a primary or secondary amine.

The content of the radical polymerizable compound is preferably 1 part by mass or more and 70 parts by mass or less, and more preferably 10 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable adhesive composition.

In the active-energy-ray-curable adhesive composition, a radical polymerizable compound may be used individually by 1 type, and may use 2 or more types together.

(Cationic polymerization initiator)

When the active energy ray-curable adhesive composition contains the cationically polymerizable compound such as the oxetane compound and the epoxy compound, it is preferable to further contain a cation polymerization initiator. Cationic polymerization initiators can generate cation species or Lewis acids by irradiating active energy rays such as visible light, ultraviolet rays, X-rays, and electron rays to start cations. Polymerization of polymerizable compounds. Examples of the cationic polymerization initiator include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, and iron-aromatic hydrocarbon complexes.

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

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

Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium (pentafluorophenyl) borate, and 4,4'-bis [Diphenylfluorenyl] diphenylsulfide bishexafluorophosphate, 4,4'-bis [bis (β-hydroxyethoxy) phenylfluorenyl] diphenylsulfide bishexafluoroantimonate , 4,4'-bis [bis (β-hydroxyethoxy) phenylfluorenyl] diphenylsulfide bishexafluorophosphate, 7- [bis (p-tolylmethyl) fluorenyl] -2- Isopropylthioxanthone hexafluoroantimonate, 7- [bis (p-tolylmethyl) fluorenyl] -2-isopropylthioxanthone (pentafluorophenyl) borate 4-phenylcarbonyl-4'-diphenylfluorenyl-diphenylsulfide hexafluorophosphate, 4- (p-third-butylphenylcarbonyl) -4'-diphenylfluorenyl-diphenyl Sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-bis (p-tolylmethyl) fluorenyl-diphenylsulfide (pentafluorophenyl) borate Wait.

Examples of the iron-arene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and Toluene-cyclopentadienyl iron (II) ginseng (trifluoromethylsulfonium Methyl) and the like.

These cationic polymerization initiators can be easily obtained in the market. For example, "KAYARAD (registered trademark) PCI-220" and "KAYARAD (registered trademark)" sold by Nippon Kayaku Co., Ltd. can be listed under trade names. "PCI-620", "UVI-6990" sold by Dow Chemical, "UVACURE (registered trademark) 1590" sold by DAICEL-CYTEC Co., Ltd., and "ADEKA OPTOMER (registered trademark) SP" sold by ADEKA Corporation -150 "and" ADEKA OPTOMER (registered trademark) SP-170 "," CI-5102 "," CIT-1370 "," CIT-1682 "," CIP-1866S "," CIP " -2048S "and" CIP-2064S "," DPI-101 "," DPI-102 "," DPI-103 "," DPI-105 "," MPI-103 "," MPI "sold by MIDORI Chemical Co., Ltd. -105 "," BBI-101 "," BBI-102 "," BBI-103 "," BBI-105 "," TPS-101 "," TPS-102 "," TPS-103 "," TPS-105 "," MDS-103 "," MDS-105 "," DTS-102 "and" DTS-103 "," PI-2074 "sold by Rhodia, etc.

Among these cationic polymerization initiators, an aromatic sulfonium salt is preferred because it can absorb light having a wavelength of 300 nm or more, has excellent hardenability, and can obtain a hardened material having good mechanical strength and adhesion.

In the active-energy-ray-curable adhesive composition, a cationic polymerization initiator may be used individually by 1 type, and may mix and use 2 or more types.

(Free radical polymerization initiator)

When an active-energy-ray-curable adhesive composition contains the said radically polymerizable compound, it is preferable to further contain a radical polymerization initiator. The radical polymerization initiator may be one capable of starting polymerization of a radical polymerizable compound such as a (meth) acrylic compound by irradiating active energy rays, and a known one can be used.

Examples of the radical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, and 1- (4-isopropylphenyl) -2-hydroxy-2. -Methylpropane-1-one, 2-methyl-1- [4- (methylthio) phenyl-2-morpholine propane-1-one, and 2-hydroxy-2-methyl-1-benzene Acetophenone-based initiators of propan-1-one; such as diphenyl ketones, 4-chlorodiphenyl ketones, and 4,4'-diaminodiphenyl ketones ; Benzoin ether based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone based initiators such as 4-isopropyl thioxanthone; and Ketones, fluorenone, camphor quinone, benzaldehyde, anthraquinone, etc.

The radical polymerization initiator can be easily obtained as a commercially available product. For example, "IRGACURE (registered trademark) 184", "IRGACURE (registered trademark) 907", and "DAROCUR (registered trademark)" manufactured by BASF Corporation can be listed under their respective trade names. ) 1173 "," Lucirin (registered trademark) TPO ", etc.

In this composition, a radical polymerization initiator may be used individually by 1 type, and may use 2 or more types together.

(Other additives)

The active energy ray-curable adhesive composition is in addition to the compounds described above. In addition to the substances, a photosensitizer, a solvent, a leveling agent, an antioxidant, a light stabilizer, an ultraviolet absorber, and the like may be contained as long as the effect of the present invention is not impaired.

Examples of the photosensitizer that can be used in this embodiment include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreductive pigments. .

Examples of solvents that can also be used in this embodiment include, for example, aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; such as methanol, ethanol, propanol, isopropanol, and n-hexane; Alcohols of butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; such as methylcellulose Selenium such as threonine, ethyl selethrol and butylcellulose; such as halogenated hydrocarbons such as methylene chloride and chloroform.

As a leveling agent that can also be used in this embodiment, various compounds such as a polysiloxane-based, a fluorine-based, a polyether-based, an acrylic copolymer-based, and a titanate-based can be used.

Examples of the antioxidant that can be used in this embodiment include, for example, phenol-based and amine-based primary antioxidants and sulfur-based secondary antioxidants.

Examples of the light stabilizer that can be used in this embodiment include a hindered amine light stabilizer (HALS) and the like.

Examples of the ultraviolet absorber that can be used in this embodiment include a diphenyl ketone system, a benzotriazole system, and a benzoate system.

Adjustment of the glass transition temperature of the adhesive layer 31 can be performed according to the following policy, for example.

That is, the glass transition temperature of the adhesive layer depends on the structure of the compound contained in the curable resin composition as the main component and the combination of the compounds. For example, when an adhesive layer is formed from a curable resin composition, the glass transition temperature tends to increase when the composition contains the alicyclic epoxy compound, and the glass transition temperature decreases when the composition contains the aliphatic epoxy compound. The tendency.

The glass transition temperature of the adhesive layer can also be adjusted by the degree of crosslinking of the compound. For example, when the amount of the bifunctional or more hardening compound is increased, the degree of crosslinking tends to increase and the glass transition temperature of the adhesive layer tends to increase. When the amount of the monofunctional hardening compound is increased, the degree of crosslinking decreases. In addition, the glass transition temperature tends to be lower.

[Protective film]

FIG. 2 is a schematic cross-sectional view showing a modified example of the layer structure of the laminated film according to this embodiment. As shown in FIG. 2, in the laminated film 2, the protective film 23 can be further laminated on the polarizer layer 11 on the side opposite to the side where the stretched film 21 is laminated. As a material for forming the protective film 23, the same resin as the material for forming the stretched film 21 can be used. The material for forming the extension film 21 and the material for forming the protective film 23 may be the same or different.

The protective film 23 is capable of being laminated on the polarizer layer 11 through the adhesive layer 33.

Examples of the adhesive layer 33 include an aqueous adhesive and active energy. Examples of the linear curing type adhesive include active energy ray-curable adhesives such as cationic polymerization-type active energy ray-curable adhesives and radical polymerization-type active energy ray-curable adhesives. A pressure-sensitive adhesive layer may be provided instead of the adhesive layer 33. Examples of the adhesive layer include an adhesive containing an acrylic resin.

An adhesive layer (not shown) may be provided on the polarizer layer 11 on the side opposite to the layer laminated with the extension film 21 or on the opposite side of the polarizer layer 11 on the protective film. By providing an adhesive layer, the laminated film 2 can be bonded to a liquid crystal cell of a display device. Examples of the adhesive layer include an adhesive containing an acrylic resin. The laminated film of the present invention is preferably arranged on the visible side of a liquid crystal cell.

[Manufacturing method of laminated film]

The laminated film 1 of this embodiment includes the following steps: (i) forming a cured resin composition layer on one side of the stretched film 21 having a slow axis (hereinafter referred to as a "cured resin composition layer") Step; (ii) the polarizer layer 11 and the above (i) hardened resin composition layer having the stretched film 21 formed, and the slow axis of the stretched film 21 to the absorption axis of the polarizer layer 11 becomes 45 ± 10 ° or 135 Laminating in a manner of ± 10 ° to obtain a laminated body having the polarizer layer 11, the hardened resin composition layer, and the stretched film 21 in order; Active energy rays (such as ultraviolet, visible light, electron rays, X-rays, etc.) and / or heating The compound resin composition layer is hardened to obtain an adhesive layer 31. Hereinafter, specific examples will be described for each step.

In the step shown in (i) above, first, a stretched film 21 having a slow axis is prepared.

When the polarizer layer 11 is continuously manufactured, the long polarizer layer may have an absorption axis in the flow direction. The stretched film is from the viewpoint that a laminated body (laminated film) can be manufactured by a roll-to-roll method, and both can be arranged so that the angle formed by the absorption axis and the slow axis of the stretched film 21 is within the above range. 21 is preferably made obliquely.

As a stretching machine used for diagonal stretching, a tenter type stretching machine is mentioned, for example. The tenter type stretching machine can perform feeding force, tensile force or traction force at different speeds in the horizontal or vertical direction or in both directions. Examples of such a tenter type stretcher include a horizontal uniaxial stretcher and a simultaneous biaxial stretcher. Any appropriate stretcher can be used as long as the resin film can be continuously diagonally stretched.

As a method of forming a hardened resin composition layer on one side of the stretched film 21, a method of directly applying a hardening resin composition and drying as required. Moreover, as another method, the method of apply | coating a curable resin composition to a base film, drying as needed, and transferring this coating layer to the polarizer layer 11 is mentioned. In the latter case, the substrate film is removed before the step shown in (ii) above. As the base film system, the same resin as described above can be used. In addition, in the base film, the coating surface of the curable resin composition may be previously subjected to a peeling treatment.

As a method for applying the curable resin composition, A well-known coating method is used, and examples thereof include a doctor blade, a wire rod, a die coater, a comma coater, and a gravure coater.

In the step shown in (ii) above, the polarizer layer 11 can be bonded to the hardened resin composition layer in which the stretch film 21 is formed in the above (i), so that the polarizer layer 11 is sequentially laminated. A laminated body of the cured resin composition layer and the stretched film 21.

In the step shown in the above (iii), the laminated body obtained in the above (ii) is irradiated with active energy rays such as visible light, ultraviolet rays, X-rays, or electron rays and / or the above (ii) The obtained laminated body is dried, and the cured resin composition layer is cured to become the adhesive layer 31 to obtain a laminated film 1.

When an active energy ray-curable adhesive composition is used as the curable resin composition, the adhesive composition is hardened by irradiating the active energy ray. The light source system used to irradiate the active energy ray is not particularly limited, and a light source having a light emission distribution at a wavelength of 400 nm or less can be used. Examples of such a light source include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, and a metal halide lamp.

The irradiation intensity of the active energy ray varies depending on the composition of the adhesive to be cured. The irradiation intensity in the wavelength region effective for activating the cationic polymerization initiator is preferably set to a range of 10 to 2500 mW / cm ² .

The irradiation time of the active energy ray is different depending on the composition of the adhesive to be hardened. The cumulative light amount expressed as the product of the irradiation intensity and the irradiation time is preferably set to a range of 10 to 2500 mJ / cm ² .

When an aqueous adhesive composition is used as the curable resin composition, the adhesive composition is hardened by heat treatment after bonding. This drying process can be performed by blowing hot air, for example. The temperature of the drying process is, for example, 30 to 200 ° C, preferably 35 to 150 ° C, more preferably 40 to 100 ° C, and still more preferably 60 to 100 ° C. The drying time is, for example, 20 to 1200 seconds.

After drying, the adhesive layer may be aged at least half a day, preferably several days or more, at a temperature of room temperature or higher to obtain sufficient adhesive strength. The aging temperature is preferably in the range of 30 to 50 ° C, and more preferably in the range of 35 to 45 ° C. When the aging temperature is within the aforementioned range, the so-called "winding tightness" is unlikely to occur in a rolled state. The humidity at the time of aging is not particularly limited, and the relative humidity may be in the range of 0 to 70% RH. The aging time is, for example, 1 to 10 days, preferably 2 to 7 days.

In the above-mentioned manufacturing example, the cured resin composition layer is formed on one side of the stretched film 21, but may be formed on one side of the polarizer layer 11 or may be formed on both sides. As shown in FIG. 2, the protective film 23 may be laminated on the polarizer layer 11 and the side to which the extension film 21 is attached, and an adhesive layer (not shown) may be provided to adhere to the liquid crystal cell.示).

According to the laminated film configured as described above, it is possible to maintain a high degree of polarization even in a hot and humid environment.

<Laminated film blank film>

In this embodiment, both the polarizer layer and the extension film may be long. The laminated film blank (long laminated film) of this embodiment has a strip-shaped polarizing film blank (long-shaped polarizer layer); a strip-shaped resin film blank (long-stretched film); and a polarizing film Adhesive layer followed by the green film and the resin film.

A polarizing film base film is a belt-shaped film using PVA-based resin as a forming material, and a dichroic dye is aligned in the longitudinal direction of the film. The PVA-based resin and the dichroic pigment are the same as those described above.

The resin film blank film is a belt-shaped film made of a thermoplastic resin as a forming material, and is stretched in a direction oblique to the longitudinal axis direction of the film. Thereby, a roll-to-roll method can be used when laminating | stacking with a polarizing film blank film, and a manufacturing process can be simplified.

The thermoplastic resin is the same as described above.

The resin film blank film is preferably a retardation film blank film. The resin film base film is provided with a slow axis at an arbitrary angle with respect to the absorption axis of the polarizing film base film. The arbitrary angle is, for example, 45 ± 10 ° or 135 ± 10 ° with respect to the absorption axis of the polarizing film blank film. By setting the angle of the slow axis to the above range, when the laminated film blank of this embodiment is applied to a display device, it can have a structure with excellent visibility even when viewed through polarized sunglasses.

The adhesive layer contains a cured product of the same curable resin composition as the forming material. The glass transition temperature of the adhesive layer is 60 ° C or higher. When the glass transition temperature is 60 ° C. or higher, the hardness of the adhesive layer 31 can be sufficiently increased. Thereby, it is possible to suppress the The expansion and contraction in the oblique direction of the stretch film 21 under the environment (for example, an environment of a room temperature of 60 ° C. and a humidity of 95%).

When a laminated film having the above structure is used, a high degree of polarization can be maintained even in a hot and humid environment.

[Example]

Hereinafter, the present invention will be described by examples, but the present invention is not limited by these examples. The unstretched film used in this example refers to a film in an unstretched state.

[Measurement of the glass transition temperature of the adhesive layer]

In the case of an active energy ray-curable adhesive composition (described later), two sheets of a 50 µm-thick stretched cyclic olefin resin film [trade name "ZEONOR (registered trademark)" made by Japan Zeon Corporation] were prepared. Then, each of the prepared curable resin compositions was applied to one surface of the film using a rod applicator so that the cured film thickness became 2 μm, and another film was superposed on the application surface. This laminated body was irradiated with ultraviolet rays from one side so that the cumulative light amount became 250 mJ / cm ² to harden the adhesive composition.

Then, the film which stuck to both sides of the hardened | cured material was peeled. Then, 5 mg of the cured product was collected and placed in an aluminum button-type container, which was then closed and sealed to prepare a sample for measurement.

Next, a differential scanning calorimeter (DSC) "EXSTAR-6000 DSC6220" sold by SII NanoTechnology Co., Ltd. was provided with a container in which the above-mentioned measurement sample was placed. Then, inflow At the same time, the nitrogen temperature was reduced from 20 ° C to -60 ° C. After reaching -60 ° C and holding for 1 minute, the temperature was increased from -60 ° C to 200 ° C at a heating rate of 10 ° C / min, and immediately after reaching 200 ° C, it was cooled to 20 ° C . Then, from the DSC curve when the temperature was raised from -60 ° C to 200 ° C, the intermediate point glass transition temperature specified in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics" was obtained. This temperature was set as the glass transition temperature of an adhesive layer (hardened | cured material).

On the other hand, in the case of an aqueous adhesive composition (to be described later), one cellulose acetate film [Konica Minolta Opto Co., Ltd.'s trade name "KC4UY"] was prepared. The water-based adhesive composition was coated on one side and dried at 80 ° C. for 5 minutes. At this time, the coating was repeated so that the film thickness after drying became 2 μm and dried. Then, the hardened | cured material obtained by peeling a film was used to produce the measurement sample by the same method as the above, and the glass transition temperature was measured.

[Evaluation of Moisture and Heat Resistance of Laminated Films]

The laminated films of Examples and Comparative Examples were left for 250 hours in an environment with a temperature of 65 ° C. and a relative humidity of 90%, and the visual acuity before and after the correction was compared to correct the polarization. At this time, the absolute value (ΔPy) of the visual sensitivity-corrected polarized light after the placement minus the visual sensitivity-corrected polarized light before the placement was 0.3 or less, and was evaluated as ○, and those with ΔPy greater than 0.3 were determined as ×. The visual acuity correction polarization degree was measured using the following method. The results are shown in Tables 2 to 5.

(Measurement of visual sensitivity correction polarization)

For laminated films of Examples and Comparative Examples, the points with integrating spheres were used. A spectrophotometer (manufactured by JASCO Corporation, "V7100") measures MD transmittance and TD transmittance in a range of 380 nm to 780 nm. Next, the polarization degree at each wavelength was calculated based on the following formula (T1) using MD transmittance and TD transmittance.

Here, the "MD transmittance" means the transmittance when the polarization direction from Glan-Thomson is parallel to the transmission axis of the laminated film sample. The "TD transmittance" means the transmittance when the polarization direction from Glan-Thomson is orthogonal to the transmission axis of the laminated film sample.

[Production Example (Preparation of Adhesive Composition)]

The adhesive compositions of Examples and Comparative Examples were prepared according to the blending amounts shown in Tables 2 to 5. However, the names of the compounds used in the preparation may be expressed by abbreviations.

The cation polymerization initiator "ADEKA OPTOMER (registered trademark) SP-150" is a propylene carbonate solution. Tables 2 to 4 show the active ingredient amounts.

For each component of the adhesive composition, the following compounds were used.

[Active energy ray-curable adhesive composition] (Cationically polymerizable compound)

"CELLOXIDE (registered trademark) 2021P": 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, purchased from Daicel Chemical Co., Ltd.

"TECHMORE (registered trademark) VG3101L": 2- [4- (2,3-glycidoxy) phenyl] -2- [4- [1,1-bis [4-([2,3-cyclo Oxypropoxy] phenyl] ethyl] phenyl] propane was purchased from Printec Corporation.

"ARON OXETANE (registered trademark) OXT-101": 3-ethyl-3-hydroxymethyloxetane, purchased from East Asia Synthetic Corporation.

"ARON OXETANE (registered trademark) OXT-221": bis [(3-ethyl-3-oxetanyl) methyl] ether, purchased from East Asia Synthesis Co., Ltd.

"ARON OXETANE (registered trademark) OXT-212": 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, purchased from East Asia Synthetic Corporation.

Table 1 shows the structure of the oxetane compound.

(Radical Polymerizable Compound)

"A-DCP": Tricyclodecane dimethanol diacrylate, purchased from Shin Nakamura Chemical Industry Co., Ltd.

(Cationic polymerization initiator)

"ADEKA OPTOMER (registered trademark) SP-150": 4,4'-bis [diphenylfluorenyl] diphenylsulfide dihexafluorophosphate-based photocationic polymerization initiator, in the form of a propylene carbonate solution Acquired from ADEKA Corporation.

(Free radical polymerization initiator)

"DAROCUR (registered trademark) 1173": 2-hydroxy-2-methyl-1-phenyl-propane-1-one, purchased from BASF Japan Co., Ltd.

[Aqueous adhesive composition] (Polyvinyl alcohol)

"Z-200": Ethyl acetofluorenyl modified polyvinyl alcohol, purchased from Japan Synthetic Chemical Co., Ltd.

(Epoxy-based crosslinking agent)

"SPM-01": purchased from Japan Synthetic Chemical Co., Ltd.

[Other ingredients]

"SH710": Silicone leveling agent, purchased from TORAY. DOW CORNING Co., Ltd.

[Examples 1 to 13, Comparative Example 1] (a) Manufacturing of polarizer layer

A polyvinyl alcohol film having an average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more, and a thickness of 30 μm was subjected to dry uniaxial stretching to about 5 times, and kept in a state of tension, immersed in pure water at 60 ° C. 1 After 15 minutes, the solution was immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C for 60 seconds. Subsequently, an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 was immersed at 72 ° C. for 300 seconds. Next, it was washed with pure water at 26 ° C. for 20 seconds, and then dried at 65 ° C. to produce a uniaxially stretched polyvinyl alcohol film with a polarizer layer having iodine. The thickness of the polarizer is 12 μm.

(b) Preparation of stretch film

As a stretched film, a cellulose triacetate film produced by diagonally stretching was prepared. A hard coat layer is formed on one side of the cellulose triacetate film. The angle of the slow axis to the longitudinal axis direction of the stretched film was about 45 ° on average.

The following materials were used as the cellulose triacetate film produced by diagonally extending.

Manufactured by obliquely extending cellulose triacetate film: Konica Minolta Co., Ltd., KC4UGR-HC, thickness _{= 44μm, R e (590)} = 106nm, R th (590) = 75nm, R th (590 ) / R _e (590) = 0.71, Re _e (450) / R _e (550) = 0.96, Re _e (630) / R _e (550) = 1.02)

In _{addition, R e (590), R} e (450), R e (550), R e (630) lines each shows a measurement wavelength 590nm, 450nm, 550nm, 630nm within the plane retardation value, R _th (590) Shows the retardation value in the thickness direction at the measurement wavelength of 590 nm.

(c) Manufacturing of laminated film

Next, the adhesive composition obtained in the manufacturing example was applied to the surface of the stretched film (b) on which the hard coat layer was not formed to form an adhesive composition layer. Specifically, the adhesive composition was applied using a rod applicator (manufactured by Daiichi Chemical Co., Ltd.) so that the cured film thickness became about 2 μm. In addition, a corona discharge treatment was performed on one side of a non-stretched film of a norbornene-based resin [trade name "ZEONOR (registered trademark)" manufactured by Japan Zeon Corporation] having a thickness of 23 μm as a forming material. The adhesive composition was applied to the corona discharge treated surface in the same manner as the stretched film to form an adhesive composition layer. In addition, the raw material of the protective film in the film-based laminated film is not stretched.

One side of the polarizer layer manufactured in (a) above was bonded to the adhesive composition layer in which the stretched film was formed in (b), and the other side of the polarizer layer was bonded to the adhesive in which an unstretched film was formed. The layers are laminated to produce a laminate. The bonding system used a bonding device (Fujipla Co., Ltd., "LPA3301"). At the time of bonding, the angle formed between the absorption axis of the polarizer layer and the slow axis of the stretched film was 45 °.

Next, an ultraviolet irradiation device with a conveyor belt was used [the lamp system uses "D Bulb" manufactured by Fusionv UV Systems], and ultraviolet rays were irradiated from the unstretched film side of the obtained laminate so that the accumulated light amount became 250 mJ / cm ² To harden the adhesive composition layer. In this way, a multilayer film including a protective film, a polarizer layer, an adhesive layer, an extension film, and a hard coat layer was manufactured.

[Example 14]

(c) Except that the following operations were performed in the production of the laminated film, the laminated film of Example 14 was produced in the same manner as in Example 1.

The resin layer prepared in the above (b) was passed through the water-based adhesive composition obtained in the production example, and bonded to one surface of the polarizer layer produced in the above (a). Subsequently, after drying at 80 ° C for 5 minutes, aging was performed at 40 ° C and 23% RH for 72 hours to produce a laminated film.

From the results in Tables 2 to 5, it can be seen that when the glass transition temperature is 60 ° C or higher, ΔPy is 0.3 or lower, and a high degree of polarization can be maintained even in a hot and humid environment.

From the above, it can be confirmed that the present invention is useful.

[Industrial availability]

The present invention can be used as a polarized light supply element or a polarized light detection element in a display device such as a liquid crystal display device.

1‧‧‧ laminated film

11‧‧‧Polarizer layer

21‧‧‧ stretch film

31‧‧‧ Adhesive layer

Claims (2)

A laminated film comprising: a polarizer layer, which is oriented with a dichroic pigment in a polyvinyl alcohol resin; and an extension film, which is a resin film having a slow axis in an oblique direction with respect to an absorption axis of the polarizer layer. A forming material; and an adhesive layer, which connects the polarizer layer and the stretched film; wherein the glass transition temperature of the adhesive layer is 60 ° C. or higher. The laminated film according to item 1 of the scope of patent application, wherein the polarizer layer and the stretched film are both elongated.