JP2018025793A - Laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated film capable of maintaining a high degree of polarization even in humid and hot environments.SOLUTION: A laminated film includes: a polarizer layer in which a dichroic dye is oriented in a polyvinyl alcohol-based resin; a stretched film that has a resin film, as a formation material, having a slow axis in direction oblique to an absorption axis of the polarizer layer; and an adhesive layer for adhering between the polarizer layer and the stretched film. The adhesive layer has an elasticity modulus at 23°C that is 2000 N/mor more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laminated film.

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

  As a polarizing film, a film in which a dichroic dye such as iodine is oriented on a film made of a polyvinyl alcohol resin is known. Iodine in the polarizing film exists as an iodine complex, and the iodine complex itself is oriented depending on the orientation of the polyvinyl alcohol resin. It is known that this iodine complex absorbs light in the visible region, so that the polarizing film exhibits polarization characteristics (polarization degree).

  By the way, when applying a polarizing plate to a display device, various optical layers such as a retardation film and an optical compensation film having optical properties are bonded to a polarizing film provided with a protective film, if necessary. The Depending on the use of the polarizing plate, the stretched film constituting the retardation film may be required to have a slow axis in a direction oblique to the longitudinal direction of the polarizing film. In such a display device, it is necessary to dispose the retardation film so that the slow axis of the retardation film and the absorption axis of the polarizing film are at a desired angle.

  Since the conventional retardation film is produced by longitudinal stretching or transverse stretching, the slow axis is in principle 0 ° or 90 ° with respect to the longitudinal direction of the film. Therefore, in order to obtain the desired angle, it has been carried out by a batch method in which film pieces cut out from a long stretched film roll at a specific angle are bonded one by one. However, this method has a problem that not only productivity is low, but there are many losses such as chips.

  On the other hand, there are various methods for producing a long retardation film that can be stretched obliquely at a desired angle and the slow axis can be freely controlled in a direction that is neither 0 ° nor 90 ° with respect to the longitudinal direction of the film. It has been proposed (see, for example, Patent Document 1). By using a stretched film with such a slow axis crossed, it is possible to perform roll-to-roll bonding instead of the conventional batch-type bonding, thus dramatically improving productivity. Loss is also expected to drop significantly.

JP 2008-80674 A

  However, when the polarizing plate using the stretched film obtained by the method described in Patent Document 1 is left in a humid heat environment (for example, at room temperature of 60 ° C. and humidity of 95%), the degree of polarization decreases. was there.

  This invention is made | formed in view of such a situation, Comprising: It aims at providing the laminated | multilayer film which can maintain a high degree of polarization also in a humid heat environment.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have made the stretched film expand and contract in a direction oblique to the longitudinal direction of the film in a wet and heat environment, thereby polarizing the polarizing plate. It was estimated that the axis collapsed, resulting in a decrease in the degree of polarization. On the other hand, in the adhesive layer interposed between the polarizing film and the optical layer, when the elastic modulus at 23 ° C. is 2000 N / m ² or more, expansion and contraction in the oblique direction of the stretched film can be suppressed. As a result, the present invention has been completed.

One embodiment of the present invention is a material for forming a polarizer film in which a dichroic dye is oriented in a polyvinyl alcohol resin, and a resin film having a slow axis in a direction oblique to the absorption axis of the polarizer layer And an adhesive layer that adheres the polarizer layer and the stretched film. The adhesive layer provides a laminated film having an elastic modulus at 23 ° C. of 2000 N / m ² or more.

  In one embodiment of the present invention, the adhesive layer preferably contains a cured product of an acetoacetyl group-modified polyvinyl alcohol resin as a forming material.

  In one embodiment of the present invention, the polarizer layer and the stretched film may both be long.

  According to one embodiment of the present invention, there is provided a laminated film that can maintain a high degree of polarization even in a humid heat environment.

It is a cross-sectional schematic diagram which shows an example of the laminated constitution of the laminated film of this embodiment. It is a cross-sectional schematic diagram which shows the modification of the layer structure of the laminated | multilayer film of this embodiment.

<Laminated film>
FIG. 1 is a schematic cross-sectional view showing an example of the layer configuration of the laminated film of the present embodiment. As shown in FIG. 1, the laminated film 1 of the present embodiment includes a polarizer layer 11, a stretched film 21, and an adhesive layer 31 that bonds the polarizer layer 11 and the stretched film 21. In another embodiment, a protective film may be further laminated on the side of the polarizer layer 11 opposite to the stretched film 21.

  The laminated film of the present embodiment may be long or may be a single sheet obtained by cutting the long laminated film into a predetermined length. The long laminated film includes a long polarizer layer and a long stretched film. The long polarizer layer and the long stretched film will be described later.

[Polarizer layer]
A polarizer layer refers to an optical film having the property of absorbing linearly polarized light having a vibration plane parallel to the optical axis and transmitting linearly polarized light having a vibration plane perpendicular to the optical axis. Specifically, the polarizer layer 11 of this embodiment is a film in which a dichroic dye is oriented in a polyvinyl alcohol-based resin (hereinafter sometimes referred to as “PVA-based resin”).

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

  When the polarizer layer 11 is a film in which a dichroic dye is oriented in a PVA-based resin, the polarizer layer 11 may be obtained by stretching a film original including the PVA-based resin. When the thickness of the polarizer layer 11 is 7 μm or less, the polarizer layer 11 may be obtained by stretching a coating film containing a PVA-based resin formed on the substrate together with the substrate, and then peeling the substrate.

  Examples of the substrate that may be used in the present embodiment include a polypropylene film, a polyethylene terephthalate film, a polycarbonate film, a triacetyl cellulose film, a norbornene film, a polyester film, and a polystyrene film.

  Examples of the PVA resin used in the present embodiment include a saponified polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having ammonium groups.

  The saponification degree of the PVA resin is preferably 80 mol% or more, more preferably 90 mol% or more and 99.5 mol% or less, and further preferably 94 mol% or more and 99 mol% or less. . When the degree of saponification is 80 mol% or more, the moisture and heat resistance of the resulting laminated film 1 is improved. Moreover, the laminated | multilayer film 1 which has sufficient polarization | polarized-light performance as saponification degree is 99.5 mol% or less is obtained.

  The PVA resin may be a modified polyvinyl alcohol partially modified. For example, olefin modification with ethylene, propylene, etc .; unsaturated carboxylic acid modification with acrylic acid, methacrylic acid, crotonic acid, etc .; one modified with an alkyl ester of unsaturated carboxylic acid, acrylamide or the like may be used.

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

  The average degree of polymerization of the PVA resin is preferably 100 or more and 10,000 or less, more preferably 1500 or more and 8000 or less, and further preferably 2000 or more and 5000 or less. When the average degree of polymerization is 100 or more, a polarizer having sufficient polarization performance can be obtained. Moreover, 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 resin is easy.

  Commercially available PVA-based resins can be easily obtained, and preferable examples of commercially available products are trade names, “PVA124” and “PVA117” (both saponification degrees) manufactured by Kuraray Co., Ltd. : 98-99 mol%), "PVA624" (degree of saponification: 95-96 mol%), "PVA617" (degree of saponification: 94.5-95.5 mol%); manufactured by Nippon Synthetic Chemical Industry Co., Ltd. "N-300" and "NH-18" (both saponification degree: 98-99 mol%), "AH-22" (saponification degree: 97.5-98.5 mol%), "AH-26 “(Saponification degree: 97 to 98.8 mol%)” “JC-33” (saponification degree: 99 mol% or more), “JF-17”, “JF-17L” of Nippon Vinegar Poval Co., Ltd. And "JF-20" (both saponification degree: 98-99 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” ( Saponification degree: 86.5 to 89.5 mol%).

  Examples of the dichroic dye used in the present embodiment include iodine or a dichroic organic dye. Dichroic organic dyes include Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B , Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue , Direct First Orange S, and First Black.

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

[Stretched film]
The stretched film 21 of the present embodiment uses a resin film having a slow axis in a direction oblique to the absorption axis of the polarizer layer 11 as a forming material. Such a resin film can be manufactured through a stretching process, and the resin film is left with a tensile stress in a direction oblique to the absorption axis of the polarizer layer 11. This residual stress can cause a decrease in the degree of polarization of the laminated film in a moist heat environment.

  The stretched film 21 has a slow axis in a direction oblique to the absorption axis of the polarizer layer 11. For example, the angle of the slow axis is 45 ± 10 ° or 135 with respect to the absorption axis of the polarizer layer 11. It is preferably ± 10 °. When the angle of the slow axis is in the above range, the difference between the light phase in the fast axis direction and the light phase in the slow axis direction is π / 2. When the phase difference between the fast axis and the slow axis is π / 2, when the laminated film 1 of the present embodiment is applied to a display device, the light that has passed through the laminated film 1 can be made into circularly polarized light. . Therefore, even when viewed through a polarizing glass, a configuration with excellent visibility can be obtained.

  The stretched film 21 of the present embodiment is preferably a retardation layer having retardation characteristics and wavelength dispersion characteristics that satisfy the following formulas (1) to (4). When the stretched film 21 satisfies the formulas (1) to (4), the screen from various directions (azimuth angle and polar angle) through the polarizing glass when the laminated film 1 of the present embodiment is incorporated into a display device. It is possible to effectively suppress the color change when viewing the screen. Thereby, the visibility of the image display device can be improved.

(1) 100 nm ≦ R _e (590) ≦ 180 nm,
(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

In the formula, R _e (590), R _e (450), R _e (550), and R _e (630) represent in-plane retardation values at measurement wavelengths of 590 nm, 450 nm, 550 nm, and 630 nm, respectively, and R _th ( 590) represents a thickness direction retardation value at a measurement wavelength of 590 nm. These in-plane retardation value and thickness direction retardation value are values measured in an environment of a temperature of 23 ° C. and a humidity of 55% RH.

Plane retardation value R _e, and the thickness direction retardation value R _th, refraction of the refractive index in the in-plane slow axis direction n _x, plane fast axis direction (perpendicular to the plane slow axis direction) When the rate is n _y , the refractive index in the thickness direction is n _z , and the thickness of the optical film is d, it is defined by the following formulas (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 the color change in the laminated film 1, R _e (590) in the formula (1) is preferably 105 to 170 nm. R _th (590) / R _e (590) in Formula (2) is preferably 0.6 to 0.75. R _e (450) / R _e (550) in Formula (3) is preferably 0.86 to 0.98. R _e (630) / R _e (550) in Formula (4) is preferably 1.01 to 1.06.

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

  Examples of the stretching direction include a machine flow direction (MD) of an unstretched film, a direction orthogonal to the machine flow direction (TD), and a direction oblique to the machine flow direction (MD). Here, the unstretched film refers to a film that is not stretched. In uniaxial stretching, an unstretched film is stretched in any one of these directions. On the other hand, the biaxial stretching may be simultaneous biaxial stretching that simultaneously stretches in two stretching directions, or may be sequential biaxial stretching that stretches in another direction after stretching in a predetermined direction.

  For the stretching process, for example, two or more pairs of nip rolls with increased peripheral speed on the outlet side are used to stretch in the longitudinal direction (machine flow direction: MD), or the both ends of the unstretched film are gripped with a chuck and machine flow is performed. It can be performed by spreading in a direction (TD) orthogonal to the direction. At this time, the retardation value and the wavelength dispersion can be controlled within the ranges of the above formulas (1) to (4) by adjusting the thickness of the film or adjusting the draw ratio.

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

  In general, a long polarizing film (polarizer layer) has an absorption axis in the long side direction. The long stretched film and the long polarizer layer can be bonded with a roll-to-roll, and the angle formed by the absorption axis and the slow axis of the stretched film is within the above range. It is preferable that the stretched film 21 is manufactured by being obliquely stretched by biaxial stretching.

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

  The cellulose acetate-based resin is composed of a cellulose portion or a complete acetate ester. Examples of the cellulose acetate resin include triacetyl cellulose and diacetyl cellulose.

  A resin film made of a cellulose acetate resin can be easily obtained as a commercial product. As a preferable example of the commercial product, all of them are trade names of “Fujitac (registered)” sold by FUJIFILM Corporation. Trademark) TD80 "," Fujitac (registered trademark) TD80UF "and" Fujitac (registered trademark) TD80UZ "," KC8UX2M "and" KC8UY "sold by Konica Minolta Opto Corporation.

  The cycloolefin resin forming the resin film is, for example, a thermoplastic amorphous resin having a monomer unit composed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer (non-crystalline polyolefin). Also called resin.) The cycloolefin-based resin may be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a hydrogenated product of a ring-opening copolymer using two or more kinds of cycloolefins. It may be an addition copolymer with an olefin and / or an aromatic compound having a vinyl group. In addition, a polar group may be introduced.

  When a resin film is formed using a copolymer of a cycloolefin and a chain olefin and / or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene. Examples of the aromatic compound having a vinyl group include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the unit of the monomer composed of cycloolefin may be 50 mol% or less, and preferably 15 to 50 mol%.

  In particular, when a terpolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group is used, the amount of the monomer unit comprising the cycloolefin can be made relatively small as described above. In such a terpolymer, the monomer unit composed of a chain olefin is preferably 5 to 80 mol%. Moreover, it is preferable that the unit of the monomer which consists of an aromatic compound which has a vinyl group is 5-80 mol%.

Cycloolefin-based resins can be easily obtained as commercial products, and preferred examples of the commercial products are all trade names, TOPAS ADVANCED POLYMERS.
“Topas (registered trademark)” manufactured by Polyplastics Co., Ltd. in Japan, “Arton (registered trademark)” sold by JSR Co., Ltd., and sold by Nippon Zeon Co., Ltd. ZEONOR (registered trademark) "and" ZEONEX (registered trademark) "," Apel (registered trademark) "sold by Mitsui Chemicals, Inc., and the like.

  When the stretched film 21 of the present 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 for the purpose of imparting flexibility to the resin film and facilitating stretching in addition to the resin forming the resin film. Examples of the plasticizer include polyhydric alcohols such as ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane.

  Only one type of plasticizer may be used, or two or more types may be used in combination. In particular, ethylene glycol and glycerin are preferably used.

[Adhesive layer]
The adhesive layer 31 of this embodiment has an elastic modulus at 23 ° C. of 2000 N / m ² or more. When the elastic modulus at 23 ° C. is 2000 N / m ² or more, the hardness of the adhesive layer 31 can be sufficiently increased. Thereby, the expansion-contraction to the direction which crosses the stretched film 21 diagonally can be suppressed in a humid heat environment (for example, the environment of room temperature 60 degreeC and humidity 95%). The upper limit is not particularly limited, but may be 5000 N / m ² .

In this specification, the value measured as follows was adopted for the elastic modulus of the adhesive layer 31.
First, in the case of an active energy ray-curable adhesive composition (described later), two sheets of a cycloolefin resin film (trade name “ZEONOR (registered trademark)” manufactured by Nippon Zeon Co., Ltd.) having a thickness of 50 μm are prepared. . Then, using a bar coater on one film surface, each prepared curable resin composition is applied so that the film thickness after curing is 10 μm, and another film is overlaid on the coated surface. About this laminated body, an ultraviolet-ray is irradiated so that an integrated light quantity may be 250 mJ / cm < ² > from one surface, and an adhesive composition is hardened.

  Next, this cured product layer (adhesive layer) is cut into a 1 cm width × 8 cm length together with the film, and both films are peeled off to obtain a sample. Next, the tensile test is performed at a pulling speed of 10 mm / min by sandwiching both ends of the sample in the long side direction with an upper and lower gripper of an AUTOGRAPH AG-1S tester manufactured by Shimadzu Corporation so that the distance between the grippers is 5 cm. . Then, the elastic modulus is calculated from the slope of the initial straight line in the obtained stress-strain curve.

  On the other hand, in the case of an aqueous adhesive composition (described later), one sheet of triacetyl cellulose film [trade name “KC4UY” manufactured by Comica Minolta Opto Co., Ltd.] is prepared. A water-based adhesive composition is applied to one side and dried at 80 ° C. for 5 minutes. At this time, coating and drying are repeated so that the film thickness after drying becomes 10 μm. Then, an elastic modulus is measured with the method similar to the above with respect to the hardened | cured material obtained by peeling a film.

  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 further preferably 0.01 μm or more and 1 μm or less. Sufficient adhesiveness can be acquired as the thickness of the adhesive bond layer 31 is 0.01 micrometer or more. Moreover, when the thickness of the adhesive layer 31 is 5 μm or less, the laminated film 1 is unlikely to have a poor appearance.

The material for forming the adhesive layer 31 is not particularly limited as long as the elastic modulus at 23 ° C. is 2000 N / m ² or more, and a cured product of the 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 cured by irradiation with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.).

[Water-based adhesive composition]
Examples of the aqueous adhesive composition include an aqueous polyvinyl alcohol resin solution and an aqueous two-component urethane emulsion adhesive composition, and an aqueous polyvinyl alcohol resin solution is preferable. When an aqueous polyvinyl alcohol resin solution is used, the polyvinyl alcohol resin used as the adhesive composition includes a vinyl alcohol homopolymer obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, and vinyl acetate. And vinyl alcohol copolymers obtained by saponifying a copolymer with other monomers copolymerizable therewith, and modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups thereof is there. Examples of the modified polyvinyl alcohol polymer include carboxy group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, methylol group-modified polyvinyl alcohol, and amino group-modified polyvinyl alcohol. In the present embodiment, the adhesive layer 31 preferably contains a cured product of an acetoacetyl group-modified polyvinyl alcohol resin as a forming material.

  To this adhesive composition, a polyvalent aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, or the like may be added as an additive.

  An adhesive composition containing a polyvinyl alcohol resin as an adhesive component may contain a curable component such as a metal salt of glyoxylic acid, glyoxal, and a water-soluble epoxy resin and / or a crosslinking agent in order to improve adhesion. preferable. 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. Examples of water-soluble epoxy resins include polyamide polyamine epoxy resins obtained by reacting polychloropolyamines such as diethylenetriamine and triethylenetetramine with polycarboxylic acid polyamines such as adipic acid and epichlorohydrin. Can be suitably used.

  Examples of commercially available metal salts of glyoxylic acid include “SPM-01” (manufactured by Nippon Synthetic Chemical Co., Ltd.). Commercially available products of the polyamide polyamine epoxy resin include “Smiles Resin 650” (manufactured by Sumika Chemtex Co., Ltd.), “Smiles Resin 675” (manufactured by Sumika Chemtex Co., Ltd.), “WS-525” (Japan PMC shares) Company-made).

  The addition amount of these curable components and / or crosslinking agents (the total amount when added together) is, for example, 1 to 100 parts by mass, preferably 1 to 50 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol resin. It is. Adhesiveness improves that the addition amount of the said sclerosing | hardenable component and / or a crosslinking agent exists in the said range, and the adhesive bond layer which shows favorable adhesiveness can be formed.

When the water-based adhesive composition contains a urethane resin, it is preferable to use a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group.
Here, the polyester ionomer type urethane resin is a urethane resin having a polyester skeleton, and a small amount of an ionic component (hydrophilic component) is introduced into the skeleton. Such an ionomer type urethane resin is suitable as a water-based adhesive composition because it is emulsified directly into water without using an emulsifier to form an emulsion.

  Polyester ionomer-type urethane resins are known per se. For example, JP-A-7-97504 describes an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium. In JP-A-2005-70140 and JP-A-2005-208456, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group is used as an adhesive, and a polarizer made of a polyvinyl alcohol resin is cyclic. The form which bonds an olefin resin film is shown.

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

[Active energy ray-curable adhesive composition]
The active energy ray-curable compound contained in the active energy ray-curable adhesive composition is preferably a cationic polymerizable compound or a radical polymerizable compound, and includes a cationic polymerizable compound and a radical polymerizable compound. It is more preferable. When the cationic polymerizable compound and the radical polymerizable compound are included, an effect of increasing the hardness of the adhesive layer 31 can be expected, and furthermore, the adjustment of the viscosity and the curing rate of the active energy ray-curable adhesive composition is further facilitated. Will be able to do.

(Cationically polymerizable compound)
Examples of the cationic polymerizable compound used in the present embodiment include an oxetane compound and an epoxy compound.

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

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

These oxetane compounds can be easily obtained as commercial products. As commercial products, all of them are trade names sold by Toagosei Co., Ltd., “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 "and the like.

  The content of the oxetane compound is preferably 1 part by mass or more and 50 parts by mass or less, and 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. More preferred.

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

  In addition to the oxetane compound, the active energy ray-curable adhesive composition may contain an epoxy compound as necessary. The epoxy compound is one of cationically polymerizable compounds like the oxetane compound, and can be cured by irradiation with active energy rays. When the active energy ray-curable adhesive composition contains an epoxy compound, the adhesion between the stretched 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 polyol having an alicyclic ring, an aliphatic epoxy compound, and an alicyclic epoxy compound.

  Aromatic epoxy compounds include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins and hydroxybenzaldehyde phenol novolacs Examples thereof include novolak-type epoxy resins such as epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

  As the glycidyl ether of a polyol having an alicyclic ring, a nuclear hydrogenated polyhydroxy compound obtained by selectively hydrogenating an aromatic polyol under pressure in the presence of a catalyst under pressure is used as a glycidyl ether. Can be listed. Examples of aromatic polyols include bisphenol type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac type resins such as phenol novolac resin, cresol novolac resin, hydroxybenzaldehyde phenol novolac resin; tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, A polyfunctional compound such as polyvinylphenol is exemplified.

Glycidyl ether can be obtained by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of these aromatic polyols with epichlorohydrin.
Among these glycidyl ethers of polyols having an alicyclic ring, hydrogenated bisphenol A diglycidyl ether is preferable.

  Examples of the “aliphatic epoxy compound” include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene glycol Diglycidyl ether of neopentyl glycol; by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol or glycerin The polyglycidyl ether of the polyether polyol obtained is mentioned.

Moreover, the monofunctional epoxy compound represented by following formula (I) is also mentioned as an aliphatic epoxy compound. R ¹ is an optionally branched alkyl group having 1 to 15 carbon atoms. The alkyl group preferably has 6 or more carbon atoms, more preferably 6 to 10 carbon atoms. Of these, a branched alkyl group is preferred. Examples of the monofunctional epoxy compound represented by the formula (I) include 2-ethylhexyl glycidyl ether.

  The “alicyclic epoxy compound” refers to a compound having at least one structure in the molecule forming an oxirane ring together with a carbon atom of the alicyclic ring. Here, “a structure in which an oxirane ring is formed together with a carbon atom of an alicyclic ring” means a structure represented by the following formula (II). N in a formula is an integer of 2-5.

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

  As the epoxy compound, an alicyclic epoxy compound is preferable, and an epoxy cyclohexane (n = 4 in the above formula (II)) or epoxy cycloheptane is preferable in that an excellent protective layer can be easily obtained due to adhesion with a polarizer. Epoxy compounds having (with n = 5 in the above formula (II)) are more preferred.

  The content of the epoxy compound is preferably 1 part by mass or more and 90 parts by mass or less, and 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. More preferred.

  In the active energy ray-curable adhesive composition, the epoxy compound may be used alone or in combination of two or more.

(Radically polymerizable compound)
Further, in addition to the cationically polymerizable compound such as the oxetane compound or the epoxy compound, a radical polymerizable compound may be included.

  Examples of the radical polymerizable compound include a compound having at least one (meth) acryloyloxy group in the molecule (hereinafter sometimes referred to as “(meth) acrylic compound”), and at least one ( Examples thereof include compounds having a meth) acrylamide group (hereinafter sometimes referred to as “(meth) acrylamide compounds”). The “(meth) acryloyloxy group” means a methacryloyloxy group or an acryloyloxy group, and the (meth) acrylamide group means a methacryloylamide group or an acryloylamide group.

  (Meth) acrylic compounds include (meth) acrylate monomers having at least one (meth) acryloyloxy group in the molecule and (meth) acrylates having at least two (meth) acryloyloxy groups in the molecule. An oligomer etc. are mentioned. These may be used alone or in combination of two or more. When two or more types are used in combination, two or more (meth) acrylate monomers may be used, two or more (meth) acrylate oligomers may be used, and, of course, one or more (meth) acrylate monomers. One or more (meth) acrylate oligomers may be used in combination.

Examples of (meth) acrylamide compounds include N-substituted (meth) acrylamide compounds. An N-substituted (meth) acrylamide compound is a (meth) acrylamide compound having a substituent at the N-position. A typical example of the 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, a substituent such as an alkyl group or an oxo group (═O) may be bonded to the carbon atom constituting the ring. N-substituted (meth) acrylamides can generally be prepared by 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 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. Is more preferable.

  In the active energy ray-curable adhesive composition, the radical polymerizable compound may be used alone or in combination of two or more.

(Cationic polymerization initiator)
When the active energy ray-curable adhesive composition contains a cationic polymerizable compound such as the oxetane compound or the epoxy compound, it is preferable to further contain a cationic polymerization initiator. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of the cationic polymerizable compound. Examples of the cationic polymerization initiator include aromatic diazonium salts, onium salts such as aromatic iodonium salts and aromatic sulfonium salts, and iron-arene complexes.

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

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

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexa. Fluorophosphate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate, 4,4'-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis Hexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-toluyl) sulfoni O] -2-Isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfo Nio-diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate, and the like.

  Examples of the iron-arene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II) tris ( (Trifluoromethylsulfonyl) methanide and the like.

  These cationic polymerization initiators can be easily obtained from commercial products, for example, “Kayarad (registered trademark) PCI-220” and “Kayarad” sold by Nippon Kayaku Co., Ltd. under the trade names, respectively. (Registered trademark) PCI-620 "," UVI-6990 "sold by Dow Chemical Company," UVACURE (registered trademark) 1590 "sold by Daicel-Cytec Corporation, sold by ADEKA Corporation "Adekaoptomer (registered trademark) SP-150" and "Adekaoptomer (registered trademark) SP-170", "CI-5102", "CIT-1370", "CIT" sold by Nippon Soda Co., Ltd. -1682 "," CIP-1866S "," CIP-2048S "and" CIP-2064S " "DPI-101", "DPI-102", "DPI-103", "DPI-105", "MPI-103", "MPI-105", "BBI-101" sold by Midori Chemical Co., Ltd. "," 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, and the like.

  Among these cationic polymerization initiators, the aromatic sulfonium salt is capable of absorbing light having a wavelength of 300 nm or more, having excellent curability, and obtaining a cured product having good mechanical strength and adhesion. preferable.

  In the active energy ray-curable adhesive composition, one type of cationic polymerization initiator may be used alone, or two or more types may be mixed and used.

(Radical polymerization initiator)
When the active energy ray-curable adhesive composition contains the above-mentioned radical polymerizable compound, it is preferable to further contain a radical polymerization initiator. Any radical polymerization initiator may be used as long as it can initiate polymerization of a radical polymerizable compound such as a (meth) acrylic compound by irradiation with active energy rays, and a known one can be used.

  Examples of the radical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- ( Acetophenone initiators such as methylthio) phenyl-2-morpholinopropan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone and 4,4′-diamino Benzophenone initiators such as benzophenone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; other xanthone, fluorenone, camphorquinone, Lens aldehyde, such as anthraquinone, and the like.

  Commercially available radical polymerization initiators can be easily obtained. For example, “Irgacure (registered trademark) 184”, “Irgacure (registered trademark) 907” and “Darocur (registered trademark)” manufactured by BASF are available. Trademark) 1173 "," Lucirin (registered trademark) TPO ", and the like.

  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 a photosensitizer, a solvent, a leveling agent, an antioxidant, a light stabilizer, an ultraviolet absorber, in the range not impairing the effects of the present invention, in addition to the above compounds. Fine particles (such as colloidal silica) may be included.

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

  Examples of the solvent that may be used in the present embodiment include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; methanol, ethanol, propanol, isopropanol, and n- Alcohols such as butanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as methyl acetate, ethyl acetate and butyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; Halogenated hydrocarbons such as methylene and chloroform.

  As a leveling agent that may be used in the present embodiment, various compounds such as silicone-based, fluorine-based, polyether-based, acrylic acid copolymer-based, and titanate-based compounds can be used.

  Examples of the antioxidant that may be used in the present embodiment include primary antioxidants such as phenols and amines, and sulfur-based secondary antioxidants.

Examples of the light stabilizer that may be used in the present embodiment include hindered amine light stabilizers (HALS).
Examples of ultraviolet absorbers that may be used in this embodiment include benzophenone-based, benzotriazole-based, and benzoate-based compounds.

Adjustment of the elastic modulus of the adhesive layer 31 can be performed, for example, according to the following guidelines. That is, the elastic modulus of the adhesive layer depends on the structure of the compound contained as a main component in the curable resin composition and the combination of the compounds. For example, when forming an adhesive layer from a curable resin composition, when the composition contains the above-described alicyclic epoxy compound, the elastic modulus tends to be high, and when the above-described aliphatic epoxy compound is contained, The elastic modulus tends to be low.
The elastic modulus of the adhesive layer can also be adjusted by the degree of crosslinking of the compound. For example, increasing the amount of bifunctional or higher curable compound increases the degree of cross-linking and increases the elastic modulus of the adhesive layer, and increasing the amount of monofunctional curable compound decreases the degree of cross-linking and decreases the elastic modulus. Tend to be.

  It is also possible to adjust the elastic modulus of the adhesive layer by adding a component other than the main component to the curable resin composition. For example, when a polymer component (such as a thermoplastic resin) is added, the elastic modulus of the adhesive layer tends to be low, and when fine particles (such as colloidal silica) are added, the elastic modulus tends to be high.

[Protective film]
FIG. 2 is a schematic cross-sectional view showing a modification of the layer configuration of the laminated film of the present embodiment. As shown in FIG. 2, in the laminated film 2, a protective film 23 can be further laminated on the side of the polarizer layer 11 opposite to the side on which 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 forming the stretched film 21 and the material forming the protective film 23 may be the same or different.

The protective film 23 can be laminated on the polarizer layer 11 via the adhesive layer 33.
Examples of the adhesive layer 33 include a water-based adhesive and an active energy ray-curable adhesive. Examples of the active energy ray-curable adhesive include a cationic polymerization-type active energy ray-curable adhesive and a radical polymerization-type active energy. A line curable adhesive is mentioned. An adhesive layer may be provided instead of the adhesive layer 33. Examples of the pressure-sensitive adhesive layer include a pressure-sensitive adhesive containing an acrylic resin.

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

[Production method of laminated film]
The laminated film 1 of this embodiment is
(I) forming a layer of a curable resin composition (hereinafter sometimes referred to as a “curable resin composition layer”) on one surface of the stretched film 21 having a slow axis;
(Ii) The polarizer layer 11 and the curable resin composition layer formed on the stretched film 21 in (i) above have a slow axis of 45 ± 10 with respect to the absorption axis of the polarizer layer 11. A step of obtaining a laminate in which the polarizer layer 11, the curable resin composition layer, and the stretched film 21 are laminated in this order by laminating so as to be ° or 135 ± 10 °;
(Iii) The laminate obtained in (ii) above is irradiated with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.) and / or heated to cure the curable resin composition layer. And obtaining the adhesive layer 31. Hereinafter, each process will be described with specific examples.

In the step (i), first, a stretched film 21 having a slow axis is prepared.
When the polarizer layer 11 is continuously manufactured, the elongated polarizer layer may have an absorption axis in the flow direction. A laminate (laminated film) can be produced by roll-to-roll, and both can be arranged so that the angle formed by the absorption axis and the slow axis of the stretched film 21 falls within the above range. The stretched film 21 is preferably manufactured by being stretched obliquely.

  Examples of the stretching machine used for the oblique stretching include a tenter type stretching machine. The tenter type stretching machine can apply a feeding force, a pulling force or a pulling force at different speeds in the left and right directions in the horizontal direction or the vertical direction or in both directions. Examples of such a tenter-type stretching machine include a horizontal uniaxial stretching machine and a simultaneous biaxial stretching machine. Any suitable stretching machine can be used as long as the resin film can be continuously stretched obliquely. it can.

  Examples of the method for forming the curable resin composition layer on one surface of the stretched film 21 include a method in which the curable resin composition is directly applied and dried as necessary. Further, as another method, there is a method in which a curable resin composition is applied to a base film, dried as necessary, and then transferred to the polarizer layer 11. In the latter case, the base film is removed before the step (ii). For the base film, the same resin as described above is used. Moreover, in the base film, the application surface of the curable resin composition may be subjected to a peeling treatment in advance.

  As a coating method of the curable resin composition, a known coating method can be adopted, and examples thereof include a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater.

  In the step shown in (ii) above, the polarizer layer 11 and the adhesive composition layer formed on the stretched film 21 in (i) above are bonded together, and the polarizer layer 11, the curable resin composition layer, and the stretched film are bonded together. A laminate in which 21 is laminated in this order is obtained.

  In the step shown in (iii) above, the laminate obtained in (ii) above is irradiated with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams and / or obtained in (ii) above. By drying the laminated body, the curable resin composition layer is cured to form the adhesive layer 31, and the laminated film 1 is obtained.

  When an active energy ray-curable adhesive composition is used as the curable resin composition, the adhesive composition is cured by irradiating active energy rays. The light source used for irradiation with active energy rays is not particularly limited, but a light source having a light emission distribution at a wavelength of 400 nm or less is used. Examples of such a light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, and a metal halide lamp.

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

Although the irradiation time of an active energy ray changes with adhesive compositions to harden | cure, it is preferable to set the integrated light quantity represented by the product of irradiation intensity | strength and irradiation time to the range of 10-2500 mJ / cm < ² >.

  When using an aqueous adhesive composition as the curable resin composition, the adhesive composition is cured by heat treatment after bonding. This drying process is performed, for example, by blowing hot air. The temperature of a drying process is 30-200 degreeC, for example, Preferably it is 35-150 degreeC, More preferably, it is 40-100 degreeC, More preferably, it exists in the range of 60-100 degreeC. The drying time is, for example, 20 to 1200 seconds.

  After drying, the adhesive layer may be cured for at least half a day, preferably several days or more, at a temperature of room temperature or higher to obtain sufficient adhesive strength. The curing temperature is preferably in the range of 30 to 50 ° C, more preferably in the range of 35 to 45 ° C. When the curing temperature is within the above range, so-called “tightening” in the roll winding state is difficult to occur. The humidity during curing is not particularly limited, and the relative humidity may be in the range of 0 to 70% RH. The curing time is, for example, 1 to 10 days, preferably 2 to 7 days.

  In the above production example, the curable resin composition layer is formed on one surface of the stretched film 21, but may be formed on one surface of the polarizer layer 11 or on both surfaces. As shown in FIG. 2, a protective film 23 may be laminated on the side of the polarizer layer 11 opposite to the side on which the stretched film 21 is bonded, and a pressure-sensitive adhesive for bonding to a liquid crystal cell. A layer (not shown) may be provided.

  According to the laminated film having the above-described configuration, a high degree of polarization can be maintained even in a humid heat environment.

<Laminated film stock>
In this embodiment, the polarizer layer and the stretched film may both be long. The laminated film original fabric (elongated laminated film) of the present embodiment includes a strip-shaped polarizing film original fabric (elongated polarizer layer), a belt-shaped resin film original fabric (long elongated stretched film), and And an adhesive layer that bonds the polarizing film original and the resin film original.

  The polarizing film original fabric is a band-shaped film made of a PVA-based resin, and a dichroic dye is oriented in the longitudinal direction of the film. The PVA resin and the dichroic dye are the same as described above.

The resin film original is formed by stretching a strip-shaped film made of a thermoplastic resin as a forming material in a direction oblique to the longitudinal direction of the film. Thereby, a roll, a toe | roll, and a roll are attained at the time of lamination | stacking with a polarizing film original fabric, and a manufacturing process can be simplified.
The thermoplastic resin is the same as described above.

  The resin film original is preferably a retardation film original. In the resin film original fabric, a slow axis is given at an arbitrary angle with respect to the absorption axis of the polarizing film original fabric. The arbitrary angle is preferably 45 ± 10 ° or 135 ± 10 ° with respect to the absorption axis of the polarizing film original. When the angle of the slow axis is in the above range, when the laminated film original fabric of the present embodiment is applied to a display device, a configuration with excellent visibility can be obtained even when viewed through a polarizing glass.

The adhesive layer contains a cured product of the same curable resin composition as described above as a forming material. The elastic modulus at 23 ° C. of the adhesive layer is 2000 N / m ² or more. When the elastic modulus at 23 ° C. is 2000 N / m ² or more, the hardness of the adhesive layer 31 can be sufficiently increased. Thereby, the expansion-contraction to the direction which crosses the stretched film 21 diagonally can be suppressed in a humid heat environment (for example, the environment of room temperature 60 degreeC and humidity 95%).

  According to the laminated film original fabric having the above-described configuration, a high degree of polarization can be maintained even in a humid heat environment.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The unstretched film used in this example refers to a film that has not been stretched.

[Measurement of elastic modulus of adhesive layer]
First, in the case of an active energy ray-curable adhesive composition (described later), two cycloolefin resin films (trade name “ZEONOR (registered trademark)” manufactured by Nippon Zeon Co., Ltd.) having a thickness of 50 μm were prepared. . Then, using a bar coater on one film surface, each prepared curable resin composition was applied so that the film thickness after curing was 10 μm, and another film was laminated on the coated surface. . About this laminated body, the ultraviolet-ray was irradiated so that an integrated light quantity might be set to 250 mJ / cm < ² > from one surface, and the adhesive composition was hardened.

  Next, the cured product layer (adhesive layer) was cut into a 1 cm width × 8 cm length together with the film, and both films were peeled off to obtain a sample. Next, using the AUTOGRAPH AG-1S tester manufactured by Shimadzu Corporation, the upper and lower grippers are sandwiched at both ends in the long side direction so that the distance between the grippers is 5 cm, and a tensile test is performed at a pulling speed of 10 mm / min. It was. Then, the elastic modulus was calculated from the slope of the initial straight line in the obtained stress-strain curve.

  On the other hand, in the case of an aqueous adhesive composition (described later), one triacetyl cellulose film [trade name “KC4UY” manufactured by Konica Minolta Opto Co., Ltd.] was prepared. A water-based adhesive composition was applied to one side and dried at 80 ° C. for 5 minutes. At this time, coating and drying were repeated so that the film thickness after drying was 10 μm. Then, the elasticity modulus was measured with the method similar to the above with respect to the hardened | cured material obtained by peeling a film.

[Evaluation of heat and humidity resistance of laminated film]
The laminated films of the examples and comparative examples were left in an environment of a temperature of 65 ° C. and a humidity of 90% RH for 250 hours, and the visibility correction polarization degrees before and after being left were compared. At that time, the absolute value (ΔPy) of the value obtained by subtracting the visibility-corrected polarization degree before leaving from the visibility-corrected polarization degree after being left is set to ○, and ΔPy is set to 0. What was larger than 3 was set as x. The visibility correction polarization degree was measured by the following method. The results are shown in Tables 1 and 2.

(Measurement of visibility correction polarization degree)
About the laminated | multilayer film of the Example and the comparative example, MD transmittance | permeability and TD transmittance | permeability in the wavelength range of 380 nm-780 nm were measured with the spectrophotometer with an integrating sphere (the JASCO Corporation make, "V7100"). Next, the degree of polarization at each wavelength was calculated based on the formula (T1) using the MD transmittance and the TD transmittance.
Here, “MD transmittance” indicates the transmittance when the direction of polarized light emitted from the Glan-Thompson prism is parallel to the transmission axis of the laminated film sample. The “TD transmittance” refers to the transmittance when the direction of polarized light emitted from the Glan-Thompson prism is orthogonal to the transmission axis of the laminated film sample.

[Production Example (Preparation of Adhesive Composition)]
According to the compounding amounts shown in Table 1 and Table 2, adhesive compositions of Examples and Comparative Examples were prepared, respectively. However, the names of the compounds used for the preparation may be indicated by abbreviations.
The cationic polymerization initiator “Adekaoptomer (registered trademark) SP-150” uses a propylene carbonate solution, but in Table 1, it is indicated by the amount of the active ingredient. The epoxy-based cross-linking agent “Smileze Resin (registered trademark) 650” is an aqueous solution, but in Table 2, it is indicated by the amount of its active ingredients.

  In addition, the following compounds were used about each component of the adhesive composition.

[Active energy ray-curable adhesive composition]
(Cationically polymerizable compound)
“Celoxide (registered trademark) 2021P”: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, obtained from Daicel Chemical Industries, Ltd.
“YX8000”: Diglycidyl ether of bisphenol, obtained from Mitsubishi Chemical Corporation.
“TECHMORE® VG3101L”: 2- [4- (2,3-epoxypropoxy) phenyl] -2- [4- [1,1-bis [4-([2,3-epoxypropoxy] phenyl]] Ethyl] phenyl] propane, obtained from Printec.
“Aron oxetane (registered trademark) OXT-221”: di [(3-ethyl-3-oxetanyl) methyl] ether, obtained from Toagosei Co., Ltd.

  The structure of the oxetane compound among the cationic polymerizable compounds is shown below.

(Radically polymerizable compound)
“A-DCP”: tricyclodecane dimethanol diacrylate, obtained from Shin-Nakamura Chemical Co., Ltd.

(Cationic polymerization initiator)
“Adekaoptomer (registered trademark) SP-150”: 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator, obtained from ADEKA Corporation in the form of a propylene carbonate solution.

(Radical polymerization initiator)
“Darocur (registered trademark) 1173”: 2-hydroxy-2-methyl-1-phenyl-propan-1-one, obtained from BASF Japan Ltd.

[Water-based adhesive composition]
(Polyvinyl alcohol)
“Z-200”: polyvinyl alcohol modified with acetoacetyl group, obtained from Nippon Synthetic Chemical Co., Ltd.
“Kuraray Poval (registered trademark) KL-318”: a carboxyl group-modified polyvinyl alcohol, obtained from Kuraray Co., Ltd.

(Epoxy-based crosslinking agent)
“SPM-01”: obtained from Nippon Synthetic Chemical Co., Ltd.
“Smilease Resin (registered trademark) 650”: Water-soluble polyamide epoxy resin (aqueous solution with a solid content of 30%), obtained from Sumika Chemtex Co., Ltd.

[Other ingredients]
“SH710”: Silicone leveling agent, obtained from Toray Dow Corning Co., Ltd.

[Examples 1 to 7, Comparative Example 1]
(A) Preparation of polarizer layer A polyvinyl alcohol film having an average polymerization degree of about 2400 and a saponification degree of 99.9 mol% or more and a thickness of 30 μm is uniaxially stretched about 5 times in a dry process, and further kept in a tension state After being immersed in pure water at 60 ° C. for 1 minute, it 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. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, the film was washed with pure water at 26 ° C. for 20 seconds, and then dried at 65 ° C. to prepare a polarizer layer in which iodine was oriented on a uniaxially stretched polyvinyl alcohol film. The thickness of the polarizer layer was 12 μm.

(B) Preparation of stretched film A triacetylcellulose film produced by oblique stretching as a stretched film and containing a plasticizer was prepared. A hard coat layer was formed on one side of the triacetyl cellulose film. Moreover, the angle of the slow axis with respect to the longitudinal direction of the stretched film was about 45 ° on average.
The following materials were used as the triacetyl cellulose film produced by oblique stretching.
Triacetyl cellulose film produced by the oblique stretching: Konica Minolta Co., Ltd., KC4UGR-HC, thickness _{= 44μm, R e (590)} = 106nm, R th (590) = 75nm, R th (590) / R e ( 590) = 0.71, R _e (450) / R _e (550) = 0.96, R _e (630) / R _e (550) = 1.02)
Note that R _e (590), R _e (450), R _e (550), and R _e (630) represent in-plane retardation values at measurement wavelengths of 590 nm, 450 nm, 550 nm, and 630 nm, respectively, and R _th (590 ) Represents a thickness direction retardation value at a measurement wavelength of 590 nm.

(C) Production of Laminated Film Next, the adhesive composition obtained in Production Example was applied to the surface of the stretched film of (b) above where the hard coat layer was not formed to form an adhesive composition layer. . Specifically, the adhesive composition was applied using a bar coater (manufactured by Daiichi Rika Co., Ltd.) so that the film thickness after curing was about 2 μm.

  Separately, a corona discharge treatment was performed on one side of an unstretched film (trade name “ZEONOR (registered trademark)” manufactured by Nippon Zeon Co., Ltd.) using a norbornene resin 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. The unstretched film is used as a protective film in the laminated film.

  While bonding one surface of the polarizer layer prepared in (a) above and the adhesive composition layer formed on the stretched film in (b) above, it is formed on the other surface of the polarizer layer and an unstretched film. The laminated adhesive composition layer was laminated to prepare a laminate. For pasting, a pasting apparatus (manufactured by Fuji Pla Co., Ltd., “LPA3301”) was used. When pasting, the angle formed by the absorption axis of the polarizer layer and the slow axis of the stretched film was set to 45 °.

Next, using an ultraviolet irradiation device with a belt conveyor (the lamp uses a “D bulb” manufactured by Fusion UV Systems), the accumulated light amount is 250 mJ / cm ² from the unstretched film side of the obtained laminate. The adhesive composition layer was cured by irradiating with UV rays. Thus, the laminated film which consists of a protective film / adhesive layer / polarizer layer / adhesive layer / stretched film / hard coat layer was produced.

[Example 8 and Comparative Example 2]
(C) A laminated film of Example 8 and Comparative Example 2 was produced in the same manner as in Example 1 except that the following operation was performed in the production of the laminated film.

  The resin layer prepared in (b) above was bonded to one surface of the polarizer layer prepared in (a) above via the aqueous adhesive composition obtained in the production example. Then, after drying at 80 degreeC for 5 minute (s), it cured at 40 degreeC and 23% RH for 72 hours, and produced the laminated | multilayer film.

From the results of Table 1 and Table 2, when the elastic modulus at 23 ° C. of the adhesive layer is 2000 N / m ² or more, ΔPy is 0.3 or less, and a high degree of polarization is maintained even in a humid heat environment. It has been shown.

  In the following reference examples, it was confirmed that the problem of the present invention occurs when the slow axis of the resin layer is oblique to the absorption axis of the polarizer layer.

[Reference example]
(A-1) Production of Polarizer Layer A polarizer layer having a thickness of 30 μm in which iodine was oriented on a uniaxially stretched polyvinyl alcohol film was produced.

(B-1) Preparation of Resin Layer A film obtained by subjecting a triacetyl cellulose film (“KC4FR-1” manufactured by Konica Minolta Opto Co., Ltd., thickness 43 μm) to saponification was prepared as a resin layer. This film is a stretched film and contains a plasticizer.

(B-2) Preparation of Protective Film A film obtained by subjecting a triacetyl cellulose film having a thickness of 83 μm to saponification treatment as a protective film was prepared. A hard coat layer was formed on one side of the triacetyl cellulose film.

(C-1) Production of Laminated Film Next, in the same manner as in the above examples and comparative examples, the water-based adhesive composition obtained in the production example was formed on one surface of the resin layer in (b-1). Was applied.
Separately from this, the aqueous adhesive composition was applied to the surface of the protective film (b-2) where the hard coat layer was not formed in the same manner as the resin layer.

Using a nip roll, one surface of the polarizer layer prepared in (a-1) above and the resin layer prepared in (b-1) were bonded together via the aqueous adhesive composition. . Moreover, the other surface of the polarizer layer and the protective film prepared in the above (b-2) were bonded via the aqueous adhesive composition. In this way, a laminate was produced. At this time, the slow axis of the resin layer and the absorption axis of the polarizer layer were made substantially parallel.
Next, the obtained laminate was passed through a drying furnace while maintaining the tension, and the aqueous adhesive composition was dried. Furthermore, the laminate was cured at 40 ° C. and 23% RH for 72 hours to obtain a laminated film.

  A pressure-sensitive adhesive layer (thickness: 15 μm) having a storage elastic modulus of about 0.7 MPa was formed on the other surface of the resin layer. The laminated film was bonded to one side of the glass plate via this pressure-sensitive adhesive layer to obtain an evaluation sample. The obtained evaluation samples were left in an environment of a temperature of 65 ° C. and a humidity of 90% RH for 250 hours in the same manner as the above “Evaluation of heat and humidity resistance of laminated film”, and the visibility corrected polarization degree before and after being left was compared.

  As a result of evaluation, ΔPy in the laminated film of the reference example was 0.3% or less. From this result, when the slow axis of the resin layer and the absorption axis of the polarizer layer are substantially parallel, even if the adhesive composition does not contain an oxetane compound having an ether bond in the main chain, ΔPy is 0. .3 or less, and it was shown that a high degree of polarization was maintained even in a humid heat environment.

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

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

1, 2 ... laminated film, 11 ... polarizer layer, 21 ... stretched film, 23 ... protective film,
31, 33 ... Adhesive layer

Claims (3)

A polarizer layer in which a dichroic dye is oriented in a polyvinyl alcohol resin;
A stretched film comprising a resin film having a slow axis in a direction oblique to the absorption axis of the polarizer layer; and
An adhesive layer that bonds the polarizer layer and the stretched film;
The adhesive layer is a laminated film having an elastic modulus at 23 ° C. of 2000 N / m ² or more.   The laminated film according to claim 1, wherein the adhesive layer includes a cured product of an acetoacetyl group-modified polyvinyl alcohol resin as a forming material.   The laminated film according to claim 1 or 2, wherein the polarizer layer and the stretched film are both long.

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