TWI432326B - Manufacturing method of laminated film - Google Patents

Description

Method for manufacturing laminated film

The present invention relates to a method for producing a laminated film which can be used in a wide range of fields, and more particularly to a method for producing a laminated film obtained by bonding a film using a photocurable epoxy resin-based adhesive.

Laminated films are used to include automobiles, airplanes, and electrical. In a wide range of electronic instruments. Especially in recent years, electrical. The laminated film in electronic instruments is becoming more diverse and highly advanced. With the versatility and heightening of the laminated film, it is necessary to improve the productivity, the yield, the simplification of the device, the automation, and the like while maintaining the quality of the laminated film to be produced.

For example, a polarizing plate used in an optical member or a liquid crystal display device is usually produced by laminating a protective film or an optical compensation film on both sides of a polyvinyl alcohol (PVA)-based polarizer film with an adhesive. As the adhesive, a water-based adhesive or an organic solvent-based adhesive is used, but in recent years, a non-solvent-based adhesive which is a non-aqueous or non-organic solvent-based adhesive, in particular, a photocurable epoxy, has been used. Resin-based adhesive.

In the production of a laminated film using a photocurable epoxy resin adhesive as an adhesive, in order to sufficiently cure the photocurable epoxy resin adhesive, it is necessary to irradiate light with strong illuminance to irradiate heat. Alternatively, the reaction heat accelerates the curing reaction, or after the light is irradiated, it is heated by an oven or the like to complete the curing reaction (After cure). If the photocurable epoxy resin-based adhesive is irradiated with light, the photopolymerization initiator (catalyst) contained therein Will activate and produce acid. The acid reacts with the epoxy group of the photocurable epoxy resin to ring-open the epoxy group to produce carbocation. The carbocation continuously reacts with the epoxy group of the epoxy resin to cure the epoxy resin adhesive. However, the reaction of a carbocation with an epoxy group is a reaction which is difficult to occur at normal temperature, and therefore it is necessary to irradiate light of strong illuminance or to heat with an oven or the like after irradiation of light, thereby accelerating or terminating the reaction of the carbocation with the epoxy group.

If a strong illuminance is applied, the light becomes hot. For example, in the case of a polarizer film, iodine may be released from a polyvinyl alcohol film (polarizer film) dyed with iodine or the like, or the polarizer film may be protected or protected. The film or the optical compensation film is deformed, thereby deteriorating the quality.

Further, in the case of heating with an oven or the like after light irradiation, it is necessary to heat a heating device such as an oven. Especially in the case where the line speed is fast, the heating oven becomes very long, the running cost increases, and the equipment investment cost increases.

An object of the present invention is to provide a method for producing a laminated film obtained by laminating a film using a photocurable epoxy resin-based adhesive, which is not required to be sufficiently cured for curing the photocurable epoxy resin adhesive. Intense illuminance of ultraviolet light or heating (post-cure) after irradiation of light.

The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, it has been found that the above problem can be achieved by heating the photocurable epoxy resin adhesive to a specific temperature before the irradiation of light, and based on these findings, the present invention is completed. invention.

With the present invention, the following 1 to 4 inventions are provided.

(1) A method for producing a laminated film, which is a method for producing a laminated film obtained by laminating a film using a photocurable epoxy resin-based adhesive, comprising: a photocurable type existing between the films The epoxy resin-based adhesive is heated to a temperature of 40 ° C or higher, and the above-mentioned adhesive is irradiated with light to be cured to adhere the film.

(2) A film bonding method which is a method of bonding a film formed by bonding a polarizer film and a protective film and/or an optical compensation film using a photocurable epoxy resin adhesive, and is characterized by comprising The photocurable epoxy resin adhesive existing between the films is heated to a temperature lower than 40 ° C and not higher than the heat resistance temperature of the film, and the bonding agent is light-irradiated to be cured to adhere the film.

(3) The method according to (1) or (2), wherein the heating temperature is 40 to 120 °C.

(4) The method according to any one of (1) to (3) wherein the light is ultraviolet light whose at least a part of light having a wavelength of 400 nm or less is cut off.

According to the bonding apparatus of the present invention, it is not necessary to irradiate the light of the strong illuminance to sufficiently cure the photocurable epoxy resin-based adhesive or to heat (post-cure) after the irradiation of the light, so that the quality can be easily and efficiently produced. A good laminate film such as a polarizing plate.

The invention is described in detail below.

The photocurable epoxy resin-based adhesive used in the present invention contains a photocurable epoxy resin and a photopolymerization initiator, and may also contain a conventional one. Add ingredients.

The photocurable epoxy resin is not particularly limited as long as it is a commonly used photocurable epoxy resin, and includes, for example, an aromatic epoxy resin, an aliphatic epoxy resin, and an alicyclic epoxy resin.

Examples of the aromatic epoxy resin include a bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol A epoxy resin, a naphthalene skeleton epoxy resin, and a phenol novolac epoxy resin.

As the aliphatic epoxy resin, a polyglycidyl ether of an aliphatic polyol or an epoxide adduct thereof can be used. Examples of the aliphatic epoxy resin include ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, and neopentyl glycol diglycidyl ether. , 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropane diglycidyl ether, polyethylene glycol II Glycidyl ether and the like. Further, an unsaturated fatty acid epoxy resin such as a butadiene-based epoxy resin or an isoprene-based epoxy resin can also be used. Trimethylolpropane triglycidyl ether and trimethylolpropane diglycidyl ether are preferred because of their low viscosity. Commercial products of the aliphatic epoxy resin include, for example, Epolight 100MF (trimethylolpropane triglycidyl ether) manufactured by Kyoeisha Chemical Co., Ltd., and EX-321L (trimethylolpropane dicondensate) manufactured by Nagase ChemteX Co., Ltd. Glycerol ether).

The alicyclic epoxy resin is a compound having one or more epoxy groups bonded to an alicyclic ring in the molecule, and examples thereof include a vinylcyclohexene monooxide and a 1,2-epoxy group. -4-vinylcyclohexane, 1,2:8,9-diethoxylated limonene, 3,4-epoxycyclohexenylmethyl-3',4'-epoxy A cyclohexene carboxylate or the like. These are commercially available from DAICEL Chemical Industry Co., Ltd. as CEL2000, CEL3000, and CEL2021P.

As the photocurable epoxy resin in the present invention, the above epoxy resins may be used singly, or a plurality of epoxy resins may be used in combination at any mixing ratio.

The photopolymerization initiator in the present invention may be a photopolymerization initiator which generates a cation or a Lewis acid by irradiation with an activation energy ray such as visible light, ultraviolet light, X-ray or electron beam, and initiates polymerization of an epoxy group. There is no particular limitation. Examples of the photopolymerization initiator include a phosphonium salt, a phosphonium salt, and a diazonium.

Examples of the lanthanoid series include triphenyl sulfonium hexafluorophosphate, triphenyl sulfonium hexafluoroantimonate, triphenyl sulfonium tetrakis(pentafluorophenyl)borate, and 4,4'-bis[diphenyl]. Thiol]diphenyl sulfide dihexafluorophosphate, 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide dihexafluoroantimonate, 4,4 '-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide dihexafluorophosphate, 7-[bis(p-tolylmethyl)indolyl]-2-isopropylthiophene Tox keto hexafluoroantimonate, 7-[bis(p-tolylmethylhydrazino)indolyl]-2-isopropylthioxanthone tetrakis(pentafluorophenyl)borate, 4-phenylcarbonyl-4'- Diphenyldecyl-diphenyl sulfide hexafluorophosphate Salt, 4-(p-t-butylphenylcarbonyl)-4'-diphenylindenyl-diphenyl sulfide hexafluoroantimonate, 4-(p-t-butylphenylcarbonyl)- 4'-bis(p-tolylmethyl) fluorenyl-diphenyl sulfide tetrakis(pentafluorophenyl)borate.

Examples of the onium salt include diphenylphosphonium tetrakis(pentafluorophenyl)borate, diphenylsulfonium hexafluorophosphate, diphenylsulfonium hexafluoroantimonate, and di-(4-fluorenylphosphoryl)hexafluorophosphate. Phenyl) oxime and the like.

Examples of the diazonium salt include benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate, and the like.

As a commercial product of a photopolymerization initiator, ADEKA Optomer SP-150 and SP-170 manufactured by Asahi Kasei Co., Ltd., PI2074 manufactured by RHODIA Co., Ltd., and Kayarad PCI-based by Nippon Kayaku Co., Ltd. 220 and so on.

These photopolymerization initiators are used in an amount of 0.5 to 20 parts by mass, preferably 1 to 10 parts by mass, per 100 parts by mass of the photocurable epoxy resin. The photopolymerization initiators may be used alone or in combination of two or more.

The photocurable epoxy resin-based adhesive of the present invention may contain an oxetane compound as needed. The oxetane compound is a compound having a 4-membered cyclic ether (i.e., an oxetane ring) in the molecule. Examples of the oxetane compound include 3-ethyl-3-hydroxymethyloxetane and 1,4-bis[{(3-ethyl-3-oxetanyl) ) Oxy}methyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, bis(3-ethyl-3-oxetanylmethyl)ether, 3- Ethyl-3-(2-ethylhexyloxymethyl)oxetane, 3-ethyl-[{(3-triethoxymethylidenepropylpropoxy)methyl}oxeidine Alkane], oxetane sesquioxane, phenol novolac oxetane, and the like. Among these oxetane compounds, 3-ethyl-3-hydroxymethyloxetane, bis(3-ethyl-3-oxetanylmethyl)ether, and 3 are preferred. -ethyl-3-(2-ethylhexyloxymethyl)oxetane. Commercial products of oxetane compounds include, for example, the trade name OXT-101 (3-ethyl-3-hydroxymethyloxetane) and OXT-211 (3-ethyl) which are commercially available from East Asia Synthetic Co., Ltd. 3-(phenoxymethyl)oxetane), OXT-221 (bis[1-ethyl(3-oxetanyl))methyl ether), OXT-212(3- Ethyl-3-(2-ethylhexyloxymethyl)oxetane).

In the present invention, the oxetane compound is used in an amount of 50 parts by mass or less based on 100 parts by mass of the photocurable epoxy resin. The oxetane compounds may be used alone or in combination of two or more.

In the photocurable epoxy resin-based adhesive of the present invention, a photosensitizer may be used in combination as needed. By using a photosensitizer, the reaction performance is improved, and the mechanical strength or the bonding strength of the cured product can be improved. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo and a diazo compound, a halogen compound, and a photoreductive dye. Examples of the photosensitizer include benzoin methyl ether, benzoin isopropyl ether, benzoin derivatives such as α,α-dimethoxy-α-phenylethyl benzene; and diphenyl benzoate; Ketone, 2,4-dichlorobenzophenone, phthalic acid Benzophenone derivatives such as esters, 4,4'-bis(diethylamino)benzophenone; 2-chlorothioxanthone, 2-isopropylthioxanthone, 2,4 - thioxanthone derivatives such as diethyl thioxanthone; anthracene derivatives such as 2-chloroindole and 2-methylindole; N-methylacridone, N-butyl An acridine derivative such as a pyridone; an anthracene derivative such as 9,10-dibutoxyfluorene; in addition, α,α-diethoxyethyl benzene, benzoquinone ( Benzil), anthrone, xanthone, uranyl compound, halogen compound, photoreducible pigment, etc., but are not limited by these. Further, these photosensitizers may be used singly or in combination of two or more. A commercially available product of the photosensitizer is, for example, Kayacure DETX-S (manufactured by Nippon Kayaku Co., Ltd.). The amount of the photosensitizer is 0.01 to 20 parts by mass, preferably 0.1 to 5 parts by mass, per 100 parts by mass of the photocurable epoxy resin-based adhesive.

Further, in the photocurable epoxy resin-based adhesive of the present invention, additives other than the above, such as a filler, an antioxidant, and a decane coupling agent, may be blended in the range which does not impair the effects of the present invention.

Examples of the filler include inorganic fillers such as talc, cerium oxide, and mica, and resin fillers such as polypropylene and polyethylene.

Examples of the antioxidant include dibutylhydroxytoluene (BHT), Irganox 1010, Irganox 1035FF, Irganox 565, and the like.

Examples of the decane coupling agent include vinyltrimethoxydecane, vinyltriethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, and 3-epoxypropoxy group. Propyltrimethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, 3-glycidoxypropyltriethoxyhydrazine Alkane, p-styryltrimethoxydecane, 3-methylpropenyloxypropylmethyldimethoxydecane, 3-methylpropenyloxypropyltrimethoxydecane, 3-methylpropene oxime Oxypropylmethyldiethoxydecane, 3-methylpropenyloxypropyltriethoxydecane, 3-methylpropenyloxypropyltrimethoxydecane, 3-triethoxydecane Base-N-(1,3-dimethyl-butylene)propylamine and the like.

Commercial products of the decane coupling agent include, for example, epoxy (for example, KBM403, KBM303), vinyl (KBM1003), acrylic decane coupling agent (KBM503), and 3-ethyl(triethoxydecylpropoxy). Methyl) oxetane (TESOX (manufactured by Toago)).

The photocurable epoxy resin adhesive in the present invention preferably has a viscosity of 200 mPa. s (25 ° C) or less, more preferably 150 mPa. s (25 ° C) or less. The lower the viscosity, the easier the coating is, and the coating thickness of the adhesive layer can be made thin. For example, when the protective film or the optical compensation film is attached to the polarizing plate, the appearance of the polarizing plate is also good. . High viscosity adhesives can also be used, but in this case the amount of application is reduced.

The film used in the present invention must have at least one film which is a film that transmits light. Examples of such a light-transmitting film include a polyester film, a polycarbonate film, an acrylic film, a polyamide film, a polyimide film, a non-crystalline polyolefin film, and a cycloolefin system. A film, a PVA film, a cellulose film, or the like.

The non-crystalline polyolefin-based resin is usually a resin having a polymerization unit of a cyclic polyolefin such as norbornene or a polycyclic norbornene-based monomer, and may also be a copolymer of a cyclic olefin and a chain cyclic olefin. . As a commercially available non-knot The crystalline polyolefin-based resin includes the product name ARTON of JSR (share), ZEONEX, ZEONOR of Japan ZEON Co., APO, APEL of Mitsui Chemicals Co., Ltd., and the like.

In the present invention, it is possible to combine with a film that does not transmit light, and a film that does not transmit light can be used, for example, as a base film of a laminated film. Examples of such a film that does not transmit light include a resin containing a coloring pigment, a coloring dye, carbon black, inorganic particles, or polymer fine particles in order to color or block light, or no light transmittance in a wavelength region of 450 nm or less. Polyimine film and the like.

The thickness of each film in the present invention is not particularly limited, and films of various thicknesses can be used as needed.

When the laminated film is a polarizing plate, a PVA-based polarizing film or a protective film such as a cellulose-based film such as triacetyl cellulose or a cycloolefin film or an optical compensation film can be used.

In the present invention, the method of applying the photocurable epoxy resin-based adhesive to the base film is not particularly limited, and includes, for example, using a doctor blade, a wire-bar, a die coater, and a comma blade. A method of a comma coater, a gravure coater, or the like. Further, the lamination of the film in the present invention can be carried out using a metal roll, a rubber roll or the like, and the lamination pressure at this time may be 0 to 5 MPa.

The laminated film in the present invention may have a laminated structure composed of two, three, four, five, six or more films.

In the present invention, a film which is subjected to corona treatment, plasma treatment, excimer treatment, UV treatment or the like on the bonding surface of the film may be used.

The temperature at which the photocurable epoxy resin-based adhesive of the present invention is heated must be 40 ° C or higher. The upper limit of the heating temperature is the heat-resistant temperature of the adhesive film, and is not limited by the heat resistance of the adhesive film, and is, for example, 120 °C. Here, the heat-resistant temperature of the film means that when the film is placed at a certain temperature for 60 seconds, the film is not deformed (warped, deformed) and the optical properties (transmittance, polarization) of the film are not actually present before heating. Degree) The highest temperature among the temperatures at which deterioration does not occur. When the heating temperature of the adhesive is 40° C. or less, the curing of the photocurable epoxy resin by light irradiation is insufficient, and the effects of the present invention cannot be obtained. The temperature at which the adhesive is heated is preferably from 50 to 100 ° C, more preferably from 60 to 80 ° C.

The heating of the photocurable epoxy resin-based adhesive in the present invention may, for example, be a near-infrared halogen lamp, a far-infrared heater, a hot air, a hot plate, a heating roller, or the like, but is not limited thereto.

The light in the present invention means an active energy line such as visible light, ultraviolet light, X-ray, or electron beam, and is preferably ultraviolet light. The light irradiation can be carried out using a metal halide lamp, a high pressure mercury lamp, a xenon lamp, a halogen lamp or the like. In the case of using ultraviolet rays, in order to minimize the deterioration of the film, it is preferred that the ultraviolet rays do not contain at least a part of light having a wavelength of 400 nm or less (preferably 390 nm or less), and more preferably do not contain a wavelength of 400 nm or less. It is all ultraviolet rays of light of 390 nm or less. Such ultraviolet rays can be obtained, for example, by using a near-infrared cut filter or an optical filter that cuts light having a wavelength of 310 or 390 nm or less between the ultraviolet lamp and the adhesive film. Examples of such an optical filter include quartz glass, a hot line cut filter (IRCF), a cutoff filter of 310 nm or less, and a cutoff filter of 320 nm. , 340 nm cut-off filter, 390 nm cut-off filter, soda-lime glass, 400 to 450 nm bandpass filter, and the like.

The irradiation of light in the present invention is carried out when the temperature of the photocurable epoxy resin-based adhesive has a temperature of 40 ° C or higher. The irradiation intensity of light in the present invention is not particularly limited depending on the intended binder or the resin film, and the irradiation intensity in the wavelength region effective for activation of the photopolymerization initiator is preferably from 10 to 500 mW/cm ² . The irradiation time of the light is not limited as long as it is different depending on the type of the photocurable epoxy resin to be used or the material of the film, and the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is set to 100 to 3000 mJ/cm ² ( The wavelength is 405 nm), preferably 700 to 2000 mJ/cm ² (wavelength 405 nm).

[Examples]

The invention is shown by the following examples, but the invention is not limited by the examples.

Preparation of Photocuring Epoxy Resin Bonding Agents of Production Examples A to F The following raw materials were metered in a polyethylene container, mixed with a stirrer, and stirred to obtain a uniform photocurable epoxy resin-based adhesive (viscosity: 150 mPa/s (25 ° C)).

Production of laminated films (polarizing plates) of Examples 1 to 6 and Comparative Examples 1 to 3 by photocurable epoxy resin-based adhesive (symbol: A) formulated in the production example, uniaxially stretched and used The iodine-dyed polyvinyl alcohol polarizer film is bonded to the triacetyl cellulose film on one side, and the non-crystalline polyolefin resin film (ZEONOR film manufactured by ZEON Co., Ltd.) is bonded to the other side, and 3 is obtained. A film of layer structure. Using the infrared lamp, the obtained three-layer structure film is warmed to room temperature (25 ° C), 30 ° C, 40 ° C, 50 ° C, 60 ° C, 70 ° C, 80 ° C, 100 ° C, 120 ° C and 140 ° C, and then A metal halide lamp (manufactured by Eyegraphic Co., Ltd.) was used, and light irradiation was performed at an irradiation intensity of 200 mW/cm ² (405 nm) and an integrated light amount of 1000 mJ/cm ² (405 nm) to obtain a laminated film. The adhesive layer between the laminated films has a thickness of about 1 to 3 μm and is uniform. These results were confirmed using an electron microscope.

Table 2 shows the material temperature, the state of the adhesive after UV irradiation, the deformation of the laminated film after UV irradiation, the durability characteristics of the laminated film, and the optical characteristics after the moisture resistance test.

The state of the adhesive after UV irradiation: The evaluation was carried out according to the following criteria.

In the liquid state, insufficient curing: insufficient curing for liquid state, no adhesion and peeling: film peeling △: bonding, but the strength is somewhat weak (~100g/25mm) ○: bonding, strength is medium degree ( 100 to 200g/25mm) ◎: Adhesive, sufficient strength (200g/25mm~)

Deformation of the film after UV irradiation: observed with the naked eye.

Durability after moisture resistance test: The appearance (de-staining or film denaturation) after placing the laminated film in a moisture-resistant test cell at 60 ° C to 90% for 500 hours was evaluated according to the following criteria.

×: Exfoliation or deformation occurred severely, and the portion of the polarizer was decolored.

△: Peeling or deformation occurred, and the portion of the polarizer was decolored.

○: Decolorization of the polarizer portion was rarely occurred, but peeling or deformation did not occur.

◎: No peeling or deformation occurred, and the dyeing of the polarizer portion was not performed.

Optical properties after the moisture resistance test: The polarizing film and the transmittance were measured for the laminated film before and after the moisture resistance test, and the deterioration (the decrease in the value of the laminated film before the moisture resistance test) was evaluated.

^* Deterioration (deformation, durability characteristics, optical characteristics) of the adhesive material not only deteriorates due to heat, but also deteriorates under ultraviolet light.

As can be seen from Table 2, if the temperature is increased to 40 to 70 ° C, the light is carried out. When irradiated and cured, the photocurable epoxy resin-based adhesive is sufficiently cured to exhibit good adhesion and almost no deformation of the film. On the other hand, when the heating temperature is 25 ° C and 30 ° C, the photocurable epoxy resin adhesive is insufficiently cured or uncured, and the adhesiveness is extremely poor, although there is no deformation of the film. Further, when the material temperature is 80 to 100 ° C or more, the photocurable epoxy resin-based adhesive is sufficiently cured to exhibit good adhesion, but the film is slightly warped. On the other hand, when it exceeds 100 ° C, the photocurable epoxy resin-based adhesive is sufficiently cured to exhibit good adhesion, but the film is greatly denatured.

The same study was conducted on the photocurable resins B to F, and although the adhesion was more or less different, the same results were obtained.

Further, when heating is performed by a hot plate instead of an infrared lamp or by hot air, a laminated film having the same performance as described above can be obtained.

Fabrication of laminated films of Examples 7 to 13 and Comparative Examples 4 to 6 In the production of the laminated film of the first to sixth embodiments and the comparative examples 1 to 3, an optical filter (manufactured by Eyegraphics Co., Ltd.) having a light having a cutoff wavelength of 390 nm or less is disposed between the metal halide lamp and the adhesive film. Irradiation light. The laminate films of Examples 7 to 13 and Comparative Examples 4 to 6 were obtained in the same manner as in Examples 1 to 6 and Comparative Examples 1 to 3.

As is clear from Table 3, when an optical filter having a light having a cutoff wavelength of 390 nm or less is disposed between the metal halide lamp and the adherend, the polarizer and the film are less denatured than in the case of not being disposed, and it is possible to obtain a good one. A laminated film of adhesive and durable properties. Even if a filter having a cutoff wavelength of 320 nm or less, a filter having a cutoff wavelength of 340 nm or less, or a filter having a cutoff wavelength of 370 nm or less is used instead of a filter having a cutoff wavelength of 390 nm or less, the same result can be obtained. A filter having a cutoff wavelength of 390 nm or less has the least influence on the constituent film. By using an optical filter, deformation of the film when heated to 120 ° C can be suppressed, and deformation of the film when heated to 140 ° C cannot be suppressed.

Production of the laminate films of Comparative Examples 7 to 12 was carried out in the same manner as in Example 1 to obtain a film having a three-layer structure. A film of a three-layer structure obtained without heating was used, and a metal halide lamp (manufactured by Eyegraphics Co., Ltd.) was used, and an irradiation intensity of 500 mW/cm ² (405 nm), an integrated light amount of 500, 1000, 2000, and 3000 mJ/cm ² (405 nm), Light irradiation was performed to obtain a laminated film. Further, when the integrated light amount is 2,000 or 3,000 mJ/cm ² (405 nm), an optical filter (manufactured by Eyegraphics Co., Ltd.) disposed between the metal halide lamp and the adherend film and having a cutoff wavelength of 390 nm or less is used. Light irradiation was performed to obtain a laminated film.

As is clear from Table 4, even when heating is not performed before light irradiation, even if the amount of light to be irradiated is increased or decreased, a laminated film having excellent adhesion and no deformation of the film cannot be obtained.

(industrial availability)

The invention can be used in including automobiles, airplanes, and electrical. The manufacture of laminated films used in a wide range of industrial fields of electronic instruments. In addition, since it is a step having rapid curability and fast adhesion, it contributes greatly to an increase in manufacturing speed or a reduction in heating step.

Claims (5)

A method for producing a laminated film, which is a method for producing a laminated film obtained by laminating a film using a photocurable epoxy resin-based adhesive, comprising: a photocurable epoxy resin present between the films The adhesive is heated to a temperature of 40 ° C or more, and the above-mentioned adhesive is irradiated with light to cure it to adhere the film. A film bonding method for bonding a polarizing film and a protective film and/or an optical compensation film using a photocurable epoxy resin adhesive, characterized in that it comprises: The photocurable epoxy resin-based adhesive between the films is heated to a temperature lower than 40 ° C and not higher than the heat-resistant temperature of the film, and the bonding agent is light-irradiated to be cured to adhere the film. The method of claim 1 or 2, wherein the aforementioned heating temperature is 40 to 120 °C. The method of claim 1 or 2, wherein the light is ultraviolet light whose at least a portion of the light having a wavelength of 400 nm or less is cut off. The method of claim 3, wherein the light is ultraviolet light whose at least a portion of the light having a wavelength of 400 nm or less is cut off.