KR101908172B1

KR101908172B1 - Method for manufacturing laminated film

Info

Publication number: KR101908172B1
Application number: KR1020147029726A
Authority: KR
Inventors: 준 후루카와; 아즈사 히로이와; 도모야스 다케우치; 에츠오 쿠메; 히사노리 야마네
Original assignee: 스미또모 가가꾸 가부시키가이샤
Priority date: 2012-06-21
Filing date: 2013-06-14
Publication date: 2018-10-15
Also published as: WO2013191095A1; TW201410473A; JPWO2013191095A1; TWI613084B; JP6404715B2; CN104272149A; CN104272149B; KR20150031409A

Abstract

An adhesive applying step of applying an active energy ray-curable adhesive onto one surface or both surfaces of at least one of the plurality of films; and a step of transporting the plurality of films in a state in which the adhesive is interposed between adjacent films And an active energy ray irradiation step of curing the adhesive by irradiating the plurality of films bonded to each other with an active energy ray in this order, Wherein the surface of the plurality of films is not coated with the adhesive in the adhesive coating step and the surface roughness of the surface to be in contact with the adhesive in the bonding step is 200 nm or less.

Description

[0001] METHOD FOR MANUFACTURING LAMINATED FILM [0002]

The present invention relates to a method of producing a laminated film used for various uses such as optical parts.

The polarizing film is widely used as a polyvinyl alcohol resin film in which a dichroic dye is adsorbed and oriented, and an iodine-based polarizing film using iodine as a dichroic dye or a dye-based polarizing film using a dichroic direct dye as a dichroic dye Film and the like are known. These polarizing films are usually polarized by bonding a transparent film such as triacetylcellulose film to one or both sides thereof with an adhesive.

A method of laminating a transparent film on one side or both sides of a polarizing film, comprising the steps of applying an active energy ray-curable resin to the surface of a transparent film in advance, joining the polarizing film and the transparent film by sandwiching them between a pair of bonding rolls, (See, for example, JP-A-2004-245925 (Patent Document 1), JP-A-2009-134190 (Patent Document 2), JP- 2011-95560 (Patent Document 3)).

As described above, in the production of a laminated film in which a plurality of films are bonded to each other through an active energy ray-curable adhesive, bubbles may be mixed between the film and the film. This is a phenomenon that does not occur when a conventional water-based tackifier or the like is used, and it is considered to be a problem peculiar to the case of using an active energy ray-curable adhesive. In recent years, it has been required to further reduce the thickness of the laminated film. Therefore, if the thickness of the active energy ray-curable adhesive is to be reduced, there is a problem that the problem of bubble inclusion tends to occur.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-245925 Patent Document 2: JP-A-2009-134190 Patent Document 3: JP-A-2011-95560

It is an object of the present invention to suppress the incorporation of bubbles between a film and a film in the production of a laminated film in which a plurality of films are bonded to each other through an active energy ray curable adhesive.

The present invention relates to a method for producing a laminated film in which a plurality of films are bonded to each other through an adhesive of an active energy ray curing type,

An adhesive applying step of applying an active energy ray-curable adhesive to one surface or both surfaces of at least one of the plurality of films;

A joining step of joining the plurality of films with each other by sandwiching the plurality of films between a pair of joining rolls which are rotated in the carrying direction in a state in which the adhesive is interposed between adjacent films,

Irradiating the plurality of films bonded to each other with an active energy ray to cure the adhesive,

Wherein the surface of the plurality of films not coated with the adhesive in the adhesive coating step has a surface roughness of 200 nm or less on a surface brought into contact with the adhesive in the bonding step.

It is preferable that the thickness of the adhesive applied in the adhesive coating process is 2 占 퐉 or less.

It is preferable that the plurality of films include an optical film and a transparent film, and the laminated film is a polarizing plate.

Wherein the plurality of films comprise one optical film and two transparent films,

In the adhesive coating step, the adhesive is applied to one surface of each of the two transparent films,

It is preferable that the optical film and the transparent film are bonded to each other by sandwiching the optical film and the transparent film between the pair of bonding rolls in a state in which the two adhesive films of the transparent film are in contact with both surfaces of the optical film in the bonding step .

Wherein the plurality of films comprise one optical film and one transparent film,

In the adhesive coating step, the adhesive is coated on one side of the transparent film,

It is preferable that the optical film and the transparent film are bonded to each other by sandwiching the optical film and the transparent film between the pair of bonding rolls so that the adhesive of the transparent film is in contact with one side of the optical film in the bonding step.

According to the present invention, in the production of a laminated film in which a plurality of films are bonded to each other through an adhesive of an active energy ray-curable type, it is possible to suppress the incorporation of air bubbles between the film and the film.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing the configuration of the entire apparatus used in the manufacturing method of Embodiment 1. FIG.
2 is a schematic diagram showing the configuration of the entire apparatus used in the manufacturing method of the second embodiment.
3 is a schematic diagram showing the configuration of the entire apparatus used in the manufacturing method of the second embodiment.

A bonding step of bonding the plurality of films to each other by sandwiching between a pair of bonding rolls rotated in a carrying direction in a state in which the adhesive is interposed between adjacent films,

And a plurality of films bonded to each other are irradiated with active energy rays to cure the adhesive.

In the present invention, in the plurality of films, the surface to which the adhesive is not applied in the adhesive coating step has a surface roughness of 200 nm or less on a surface to be brought into contact with the adhesive in the bonding step.

The surface roughness in the present invention means the ten-point average roughness (Rzjis) (in which the reference length is 2.5 mm and the evaluation length is 12.5 mm) in the revised edition JIS B 0601 in 2001, and is hereinafter abbreviated as Rz There is a case to write. The unit of surface roughness (Rz) is nm. The surface roughness Rz can be measured, for example, by using Handy's Surf E35A manufactured by Tokyo Precision Co., Ltd. as a measuring device, setting the cutoff value (reference length) to 2.5 mm and the measuring distance to 12.5 mm, The device is placed on a target film to obtain an average value when the surface roughness is measured ten times. When the surface roughness exceeds 200 nm, bubbles are likely to be incorporated between the films in the bonding step. The surface roughness is preferably 100 nm or less, and more preferably 80 nm or less. Such a film having surface roughness can be selected from commercially available products. The surface roughness of the film may be adjusted by coating a resin or the like on the surface of the film.

It is preferable that the thickness of the adhesive applied in the adhesive coating process is 2 占 퐉 or less. In the case where the thickness of the applied adhesive is 2 占 퐉 or less, the effect of suppressing the incorporation of bubbles exhibited by the present invention is remarkable because bubbles are likely to be incorporated between the films in the bonding step. When the thickness of at least one of the adhesives coated on a plurality of films is 2 mu m or less, the effect of the present invention is remarkably exhibited.

Examples of the laminated film to be produced in the present invention include a polarizing plate. In the case of producing a laminated film, a plurality of films include, for example, an optical film and a transparent film.

(Optical film)

The optical film is, for example, a polarizing film, a retardation film, or a pattern retarder film for a 3D television, and may be a single film or a laminate of a plurality of films.

In the present invention, the polarizing film to be used in the case of producing a polarizing plate as a laminated film is, for example, one in which a dichroic dye is adsorbed and aligned on a uniaxially stretched polyvinyl alcohol resin film. The polyvinyl alcohol resin is obtained by saponifying a 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 (for example, ethylene-vinyl acetate copolymer). Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. The saponification degree of the polyvinyl alcohol resin is 85 mol% or more, preferably 90 mol% or more, and more preferably 98 to 100 mol%. The average degree of polymerization of the polyvinyl alcohol resin is usually 1,000 to 10,000, preferably 1,500 to 5,000. These polyvinyl alcohol resins may be modified. For example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes may be used.

Such a polyvinyl alcohol resin film is used as the original film of the polarizing film. The method of forming the polyvinyl alcohol resin is not particularly limited, and the film can be formed by a conventionally known appropriate method. The thickness of the original film made of a polyvinyl alcohol-based resin is not particularly limited, but is, for example, about 10 to 150 mu m. It is usually supplied in a roll form and has a thickness in the range of 20 to 100 mu m, preferably 30 to 80 mu m, and an industrially practical width of 1500 to 6000 mm.

As a commercially available polyvinyl alcohol resin film, for example, Vinylon VF-PS # 7500 (manufactured by Kuraray Co., Ltd., thickness of disc 75 μm), OPL film M-7500 (Disc thickness: 60 mu m), Vylon VF-PE # 5000 (Kuraray Co., Ltd., thickness: 50 mu m), PS # 6000 And the like.

The polarizing film is usually formed by a process of dyeing a polyvinyl alcohol resin film with a dichroic dye to adsorb the dichroic dye (dyeing process), a process of treating a polyvinyl alcohol resin film adsorbed with a dichroic dye with an aqueous solution of boric acid (Boric acid treatment step) and a step of washing with water after the treatment with the aqueous solution of boric acid (water washing step).

When the polarizing film is produced, the polyvinyl alcohol resin film is usually uniaxially stretched. However, the uniaxial stretching may be performed before the dyeing process, during the dyeing process, or after the dyeing process good. In the case where uniaxial stretching is performed after the dyeing treatment step, the uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in a plurality of these steps.

Uniaxial stretching may be uniaxially stretched between rolls having different circumferential speeds, or may be uniaxially stretched using a heat roll. Further, dry stretching may be used in which stretching is performed in the atmosphere, or wet stretching in which stretching is performed in a state of being swollen with a solvent. The stretching magnification is usually about 3 to 8 times.

The dyeing by the dichroic dye of the polyvinyl alcohol resin film in the dyeing treatment step is carried out, for example, by immersing a polyvinyl alcohol resin film in an aqueous solution containing a dichroic dye. As the dichroic dye, for example, iodine, a dichroic dye and the like are used. The dichroic dye includes, for example, a dichromatic direct dye made of a disazo compound such as C.I.DIRECT RED 39, and a dichroic direct dye made of a compound such as trisazo or tetrakisazo. It is preferable that the polyvinyl alcohol resin film is immersed in water before the dyeing treatment.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing iodine and potassium iodide is generally used. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 占 폚, and the immersion time (dyeing time) for this aqueous solution is usually 20 to 1800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method in which a polyvinyl alcohol resin film is dipped in an aqueous solution containing a dichroic dye and dyed is employed. The content of the dichroic dye in the aqueous solution is usually 1 × 10 ^-4 to 10 parts by weight, preferably 1 × 10 ^{-3 to} 1 part by weight, and particularly preferably 1 × 10 ^-3 to 1 part by weight, 1 x 10 ^-2 parts by weight. The aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing aid. When a dichroic dye is used as the dichroic dye, the dye aqueous solution used for dyeing usually has a temperature of 20 to 80 캜, and the immersion time (dyeing time) for the aqueous solution is usually 10 to 1,800 seconds.

The boric acid treatment step is carried out by immersing a polyvinyl alcohol resin film dyed with a dichroic dye in an aqueous solution containing boric acid. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye in the above-described dyeing process, it is preferable that the boric acid-containing aqueous solution used in the boric acid treatment process contains potassium iodide. In this case, the amount of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight, per 100 parts by weight of water. The immersion time for the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 40 占 폚 or higher, preferably 50 to 85 占 폚, and more preferably 55 to 75 占 폚.

In the subsequent water washing treatment step, the polyvinyl alcohol resin film after the boric acid treatment is subjected to water washing treatment, for example, by immersion in water. The water temperature in the water washing treatment is usually 4 to 40 캜, and the immersing time is usually 1 to 120 seconds. After the water washing treatment, the drying treatment is usually carried out to obtain a polarizing film. The drying treatment is preferably carried out using a hot-air dryer, a far-infrared heater, or the like. The temperature of the drying treatment is usually 30 to 100 占 폚, preferably 50 to 80 占 폚. The time for the drying treatment is usually 60 to 600 seconds, preferably 120 to 600 seconds.

Thus, the polarizing film can be obtained by subjecting the polyvinyl alcohol resin film to uniaxial stretching, dyeing with a dichroic dye, boric acid treatment and washing treatment. The thickness of the polarizing film is usually in the range of 5 to 50 mu m.

(Transparent film)

In the present invention, when a polarizing plate is produced as a laminated film, a transparent film is bonded to one or both surfaces of the above-mentioned optical film. When the transparent film is bonded to both surfaces of the optical film, each transparent film may be the same or may be a different kind of film.

Examples of the material constituting the transparent film include a cycloolefin resin, a cellulose acetate resin, a polyester resin such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate, a polycarbonate resin, an acrylic resin , And polypropylene, which are conventionally widely used in the art.

The cycloolefin-based resin is, for example, a thermoplastic resin (also referred to as a thermoplastic cycloolefin-based resin) having a unit of a monomer composed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer. The cycloolefin resin may be a hydrogenated product of a ring-opening polymer of the cycloolefin or a ring-opening copolymer using two or more cycloolefins, or an addition polymer with a cycloolefin, a chain olefin, or an aromatic compound having a vinyl group. It is also effective that a polar group is introduced.

When a copolymer of a cycloolefin and an aromatic compound having a vinyl group or a chain type olefin is used, examples of the chain olefin include ethylene and propylene. Examples of the aromatic compound having a vinyl group include styrene, Substituted styrene, and the like. In such a copolymer, the unit of the monomer composed of cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). In particular, in the case of using a ternary copolymer of a cycloolefin, a chain olefin and an aromatic compound having a vinyl group, the unit of the monomer composed of the cycloolefin can be relatively small as described above. In such a terpolymer, the unit of a monomer composed of a chain olefin is usually 5 to 80 mol%, and the unit of a monomer composed of an aromatic compound having a vinyl group is usually 5 to 80 mol%.

The cycloolefin resin is preferably a commercially available product such as Topas (manufactured by Ticona), Aton (manufactured by JSR Corporation), ZEONOR (manufactured by Nippon Zeon Corporation), Zeonex (manufactured by Nippon Zeon Corporation) (Manufactured by Mitsui Chemicals, Inc.), OXIS (manufactured by Ouki Kogyo Co., Ltd.), and the like can be preferably used. When the cycloolefin resin is formed into a film, known methods such as a solvent casting method and a melt extrusion method are suitably used. Further, a pre-formed cycloolefin-based resin (for example, polyvinyl butyral) such as Essen (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.) A commercially available product of the film may also be used.

The cycloolefin-based resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be imparted to the cycloolefin-based resin film. Stretching is usually performed continuously while releasing the film roll, and is stretched in the heating furnace in the direction in which the roll advances (the longitudinal direction of the film) and in the direction perpendicular to the advancing direction (the width direction of the film) or both. The temperature of the heating furnace is usually in the range of from the vicinity of the glass transition temperature of the cycloolefin-based resin to the glass transition temperature + 100 ° C. The magnification of the stretching is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

When the cycloolefin-based resin film is in the wound roll state, the film tends to adhere to each other and tends to cause blocking. Therefore, the cycloolefin-based resin film is usually wound in a rolled form after the protective film is bonded. Since the cycloolefin resin film generally has a low surface activity, the surface to be adhered to the optical film is subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet ray irradiation treatment, frame (flame) treatment and saponification treatment desirable. Among them, a plasma treatment, particularly an atmospheric pressure plasma treatment and a corona treatment, which can be carried out relatively easily, is preferable.

As the cellulose acetate resin, a cellulose ester partially or completely esterified product, for example, a film made of an acetate ester, a propionic acid ester, a butyric acid ester, a mixed ester thereof and the like of cellulose can be mentioned. More specifically, a triacetylcellulose film, a diacetylcellulose film, a cellulose acetate propionate film, a cellulose acetate butyrate film and the like can be given. Examples of such a cellulose ester based resin film include commercially available products such as Fuji Tack TD80 (manufactured by Fuji Film), Fuji Tack TD80UF (manufactured by Fuji Film), Fuji Tack TD80UZ (manufactured by Fuji Film Co., Ltd.) , KC8UYW (manufactured by KONICA MINOLTA OPT Co., Ltd.), KC8UY (manufactured by Konica Minolta Opt Co., Ltd.), Fuji Tach TD60UL (manufactured by Fuji Film Co., Ltd.), KC4UYW Ltd.) can be preferably used.

Also, as the transparent film, a cellulose acetate resin film imparted with a retardation property is also preferably used. Examples of commercial products of the cellulose acetate based resin film to which such retardation characteristics are imparted include WV BZ 438 (manufactured by Fuji Film), KC4FR-1 (manufactured by Konica Minolta Opt), KC4CR-1 (manufactured by Konica Minolta Opt ), KC4AR-1 (manufactured by Konica Minolta Opt.), And the like. Acetate cellulose is also referred to as acetylcellulose or cellulose acetate.

These cellulose acetate based resin films are easy to absorb, and the moisture content of the polarizing plate may affect the relaxation of the end portions of the polarizing plate. The moisture content at the time of production of the polarizing plate is preferably as close as possible to the storage environment of the polarizing plate, for example, the equilibrium moisture content in a manufacturing line of a clean room or a storage room of a rolled up roll, and varies depending on the constitution of the laminated film. Is about 2.0 to 3.5%, and more preferably about 2.5% to 3.0%. The moisture content of the polarizing plate was measured by a dry weight method, and it was a weight change before and after the treatment for 120 minutes at 105 ° C using a thermostat.

The thickness of the transparent film used in the polarizing plate of the present invention is preferably as thin as possible, but if it is too thin, the strength is lowered and the workability is lowered. On the other hand, if the thickness is excessively large, the transparency deteriorates, or the curing time required after lamination becomes long. Therefore, the suitable thickness of the transparent film is, for example, 5 to 200 占 퐉, preferably 10 to 150 占 퐉, and more preferably 10 to 100 占 퐉.

A surface treatment such as corona treatment, flame treatment, plasma treatment, ultraviolet ray treatment, primer coating treatment or saponification treatment is applied to the optical film and / or the transparent film in order to improve the adhesion of the adhesive to the optical film and / It is also good.

The transparent film may be subjected to surface treatment such as anti glare treatment, anti-reflection treatment, hard coating treatment, antistatic treatment and antifouling treatment, either singly or in combination of two or more kinds. The transparent protective film and / or the transparent film surface protective layer may contain an ultraviolet absorber such as a benzophenone-based compound or a benzotriazole-based compound or a plasticizer such as a phenylphosphate-based compound or a phthalic acid ester compound.

Optical functions such as a function as a retardation film, a function as a luminance enhancement film, a function as a reflection film, a function as a transflective film, a function as a diffusion film, and an optical compensation film can be imparted to a transparent film. In this case, for example, by laminating an optical functional film such as a retardation film, a brightness enhancement film, a reflection film, a transflective film, a diffusion film, or an optical compensation film on the surface of a transparent film, This function may be given to the transparent film itself. Further, a plurality of functions may be imparted to the transparent film, such as a diffusion film having the function of a brightness enhancement film.

For example, the stretching process described in Japanese Patent No. 2841377, Japanese Patent No. 3094113, or the like is performed on the above-mentioned transparent film, or the process described in Japanese Patent No. 3168850 is performed to give a function as a retardation film . The retardation property in the retardation film can be appropriately selected, for example, in the range of the front retardation value of 5 to 100 nm and the thickness retardation value of 40 to 300 nm. Further, by forming fine holes in the above-mentioned transparent film by the method described in Japanese Patent Application Laid-Open Nos. 2002-169025 and 2003-29030, or by forming fine holes with two or more core wavelengths By superimposing the steric liquid crystal layers, a function as a brightness enhancement film can be provided.

When a metal thin film is formed on the transparent film by vapor deposition or sputtering, a function as a reflective film or a transflective film can be imparted. By coating the above-mentioned transparent film with a resin solution containing fine particles, a function as a diffusion film can be imparted. In addition, a liquid crystal compound such as a discotic liquid crystal compound is coated on the transparent film and aligned, whereby a function as an optical compensation film can be imparted. Further, the transparent film may contain a compound exhibiting a retardation. Further, various optical functional films may be directly bonded to the optical film using a suitable adhesive. Examples of commercially available optical functional films include a luminance enhancement film such as a DBEF (available from 3M Company, Japan, available from Sumitomo 3M Ltd.), a WV film (manufactured by Fuji Film Co., Ltd.) (Produced by Sekisui Chemical Co., Ltd.), VA-TAC (manufactured by Konica Minolta Opt.), Sumitomo Bakelite Co., Ltd., (Manufactured by Sumitomo Chemical Co., Ltd.), and the like.

(Active energy ray curable adhesive)

Examples of the active energy ray curable adhesive used in the present invention include an adhesive composed of an epoxy resin composition containing an epoxy resin which is cured by irradiation with active energy rays from the viewpoints of weatherability, refractive index, have. However, the present invention is not limited to this, and various types of active energy ray-curable adhesives (organic solvent adhesives, hot melt adhesives, solventless adhesives, etc.) conventionally used in the production of polarizing plates can be employed.

The epoxy resin means a compound having two or more epoxy groups in the molecule. From the standpoint of weatherability, refractive index, cationic polymerizability, and the like, it is preferable that the epoxy resin contained in the curable epoxy resin composition as the adhesive is an epoxy resin containing no aromatic ring in the molecule (for example, see Patent Document 1). As such epoxy resins, hydrogenated epoxy resins, alicyclic epoxy resins, aliphatic epoxy resins and the like can be exemplified.

The hydrogenated epoxy resin can be obtained by a method of glycidyl etherifying a nuclear hydrogenated polyhydroxy compound obtained by selectively subjecting a polyhydroxy compound as a raw material of an aromatic epoxy resin to a nucleophilic reaction under pressure in the presence of a catalyst . Examples of the aromatic epoxy resin include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol S; Novolak type epoxy resins such as phenol novolak epoxy resin, cresol novolak epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; Polyfunctional epoxy resins such as glycidyl ether of tetrahydroxyphenylmethane, glycidyl ether of tetrahydroxybenzophenone, and epoxylated polyvinyl phenol. Of hydrogenated epoxy resins, hydrogenated glycidyl ethers of bisphenol A are preferred.

The alicyclic epoxy resin means an epoxy resin having at least one epoxy group bonded to an alicyclic ring in the molecule. The "epoxy group bonded to the alicyclic ring" means a bridging oxygen atom -O- in the structure represented by the following formula. In the formula, m is an integer of 2 to 5.

The compound in which one or more hydrogen atoms of the (CH ₂ ) _m in the above formula are removed from other groups in the chemical structure may be an alicyclic epoxy resin. (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as methyl group or ethyl group. Among the alicyclic epoxy resins, an epoxy resin having an oxabicyclohexane ring (wherein m = 3 in the above formula) or an oxabicycloheptane ring (in which m = 4 in the above formula) has excellent adhesiveness is preferable . Hereinafter, the alicyclic epoxy resin which is preferably used is specifically exemplified, but is not limited to these compounds.

(a) epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(Wherein R ¹ and R ² represent, independently of each other, a hydrogen atom or a straight-chain alkyl group having 1 to 5 carbon atoms).

(b) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(Wherein R ³ and R ⁴ independently represent a hydrogen atom or a straight chain alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).

(c) epoxycyclohexylmethyl esters of dicarboxylic acids represented by the following formula (III):

(Wherein R ⁵ and R ⁶ represent, independently of each other, a hydrogen atom or a straight-chain alkyl group of 1 to 5 carbon atoms, and p represents an integer of 2 to 20).

(d) epoxycyclohexylmethyl ethers of polyethylene glycol represented by the following formula (IV):

(Wherein R ⁷ and R ⁸ independently represent a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

(e) Epoxycyclohexyl methyl ether of alkane diol represented by the following formula (V):

(Wherein R ⁹ and R ¹⁰ independently represent a hydrogen atom or a straight chain alkyl group of 1 to 5 carbon atoms, and r represents an integer of 2 to 20).

(f) a diepoxy trispyro compound represented by the following formula (VI):

(Wherein R ¹¹ and R ¹² represent, independently of each other, a hydrogen atom or a straight-chain alkyl group having 1 to 5 carbon atoms).

(g) a diepoxy monospiro compound represented by the following formula (VII):

(Wherein R ¹³ and R ¹⁴ represent, independently of each other, a hydrogen atom or a straight-chain alkyl group having 1 to 5 carbon atoms).

(h) vinylcyclohexene epoxides represented by the following formula (VIII):

(Wherein R ¹⁵ represents a hydrogen atom or a straight-chain alkyl group having 1 to 5 carbon atoms).

(i) epoxycyclopentyl ethers represented by the following formula (IX):

(Wherein R ¹⁶ and R ¹⁷ independently represent a hydrogen atom or a straight-chain alkyl group having 1 to 5 carbon atoms).

(j) diepoxytricyclodecane represented by the following formula (X):

(Wherein R ¹⁸ represents a hydrogen atom or a straight-chain alkyl group having 1 to 5 carbon atoms).

Among the alicyclic epoxy resins exemplified above, the following alicyclic epoxy resins are more preferably used because they are commercially available or the like and are relatively easy to obtain.

(A) an ester of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept- ¹ = R < ² > = H]

(B) An esterified product of 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl- [Compound wherein R ¹ = 4-CH ₃ and R ² = 4-CH ₃ in the formula (I)],

(C) an esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [compound of formula (II) wherein R ³ = R ⁴ = H, ,

(D) (7-oxabicyclo [4.1.0] hept-3-yl) methanol and adipic acid [compound of formula (III) wherein R ⁵ = R ⁶ = H, p = 4]

(E) (R ⁴ = CH ₃ , R ⁶ = CH ₃ ) in the formula (III) with an esterified product of (4-methyl- 4-CH ₃ , p = 4]

(F) (7- oxabicyclo [4.1.0] hept-3-yl) ether in the cargo [formula (V) of methanol and ^{1,2-ethanediol, R 9 = R 10 = H} , r = 2 is compound].

Examples of the aliphatic epoxy resins include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, diglycidyl ether of 1,4-butanediol; Diglycidyl ether of 1,6-hexanediol; Triglycidyl ether of glycerin; Triglycidyl ether of trimethylolpropane; Diglycidyl ether of polyethylene glycol; Diglycidyl ether of propylene glycol; And polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin.

The epoxy resin constituting the adhesive composed of the epoxy resin composition may be used singly or in combination of two or more kinds. The epoxy equivalent of the epoxy resin used in this composition is usually in the range of 30 to 3,000 g / equivalent, preferably 50 to 1,500 g / equivalent. If the epoxy equivalent is less than 30 g / equivalent, the flexibility of the composite polarizer after curing may deteriorate or the adhesive strength may decrease. On the other hand, if it exceeds 3,000 g / equivalent, compatibility with other components contained in the adhesive may be deteriorated.

In this adhesive, cationic polymerization is preferably used as a curing reaction of the epoxy resin from the viewpoint of reactivity. Therefore, it is preferable to incorporate a cationic polymerization initiator into the curable epoxy resin composition which is an active energy ray curable adhesive. The cationic polymerization initiator generates a cationic species or a Lewis acid by irradiation of an active energy ray such as visible light, ultraviolet ray, X-ray or electron ray to initiate the polymerization reaction of the epoxy group. Hereinafter, the cationic polymerization initiator for generating a cationic species or Lewis acid by irradiation of an active energy ray to initiate the polymerization reaction of the epoxy group is referred to as " photocationic polymerization initiator ".

The method of curing the adhesive by irradiation of active energy rays using a cationic ion polymerization initiator enables curing at room temperature and reduces the need to take into account distortion due to heat resistance or expansion of the optical film, It is advantageous in that it can be bonded. In addition, since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy resin.

As the cationic polymerization initiator, for example, an aromatic diazonium salt; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; Iron-allene complexes and the like.

Examples of the aromatic diazonium salt include benzene diazonium hexafluoroantimonate, benzene diazonium hexafluorophosphate, and benzene diazonium hexafluoroborate. Examples of the aromatic iodonium salt include diphenyl iodonium tetrakis (pentafluorophenyl) borate, diphenyl iodonium hexafluorophosphate, diphenyl iodonium hexafluoroantimonate, di (4- Nonylphenyl) iodonium hexafluorophosphate, and the like.

The aromatic sulfonium salts include, for example, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4'-bis (Bis (diphenylsulfonium) diphenyl sulfide bis (hexafluorophosphate), 4,4'-bis [di (? - hydroxyethoxy) phenylsulfonio] diphenyl sulfide bis (P-toluyl) sulfone, diphenylsulfone, hexafluorophosphate), 4,4'-bis [di (? - hydroxyethoxy) (Pentafluorophenyl) borate, 4- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrathiocyanate, Diphenylsulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfone-diphenylsulfide hexafluoro-diphenylsulfide hexafluorophosphate, And the like can be mentioned diphenyl sulfide tetrakis (pentafluorophenyl) borate-antimonate, 4- (p-tert- butylphenyl-carbonyl) -4'-di (p- toluyl) Pony O.

Examples of the iron-allene complexes include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron II) -tris (trifluoromethylsulfonyl) methanide, and the like.

Commercially available products of these cationic polymerization initiators can be easily obtained, and examples thereof include "Kayarad PCI-220" and "Kayarad PCI-620" (trade names, manufactured by Nippon Kayaku Co., Ltd.) CI-5102 "," CIT-1370 "," Adeka Optomer SP-150 "and" Adeka Optomer SP-170 "manufactured by Union Carbide Co., DPI-101 "," DPI-102 "and" DPI-2064S "(all manufactured by Nippon Soda Co., Ltd.)," CIP- BBI-103, BBI-105, TPS-101, BBI-101, BBI-103, DPI-105, MPI-103, MPI-105, TPS-102, TPS-103, TPS-105, MDS-103, MDS-105, DTS-102 and DTS- ), &Quot; PI-2074 " (manufactured by Lodi KK), and the like.

The cationic ion polymerization initiator may be used alone or in combination of two or more. Among them, an aromatic sulfonium salt is preferably used since it has an ultraviolet ray absorbing property even in a wavelength region of 300 nm or more, and is therefore excellent in curability and can give a cured product having good mechanical strength and adhesive strength.

The blending amount of the photocationic polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 part by weight or more, and more preferably 15 parts by weight or less based on 100 parts by weight of the epoxy resin. If the blending amount of the photocationic polymerization initiator is less than 0.5 part by weight based on 100 parts by weight of the epoxy resin, the curing becomes insufficient and the mechanical strength and the adhesive strength tend to be lowered. If the blending amount of the photocationic polymerization initiator is more than 20 parts by weight based on 100 parts by weight of the epoxy resin, the ionic substance in the cured product increases, so that the hygroscopic property of the cured product increases and the durability may be lowered.

When a photocationic polymerization initiator is used, the curable epoxy resin composition may further contain a photosensitizer, if necessary. By using the photosensitizer, the reactivity of the cationic polymerization is improved, and the mechanical strength and the adhesive strength of the cured product can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfates, redox compounds, azo and diazo compounds, halogen compounds, and photo-reducible pigments.

More specific examples of the photosensitizer include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether and?,? -Dimethoxy-? -Phenylacetophenone; Benzophenone derivatives such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; Thioxanthone derivatives such as 2-chlorothioxanthone, and 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloro anthraquinone, and 2-methyl anthraquinone; Acridone derivatives such as N-methyl acridone, and N-butyl acridone; Other examples include?,? - diethoxyacetophenone, benzyl, fluorenone, xanthone, uranyl compound, and halogen compound. The photosensitizer may be used alone, or two or more of them may be used in combination. It is preferable that the photosensitizer is contained in the range of 0.1 to 20 parts by weight in 100 parts by weight of the curable epoxy resin composition.

The epoxy resin contained in the adhesive is cured by light-ion polymerization, but may be cured by both cationic polymerization and thermal cationic polymerization. In the latter case, it is preferable to use a combination of a photo cationic polymerization initiator and a thermal cationic polymerization initiator.

Examples of the thermal cationic polymerization initiator include a benzylsulfonium salt, a thiophenium salt, a thioranium salt, a benzylammonium salt, a pyridinium salt, a hydrazinium salt, a carboxylic acid ester, a sulfonic acid ester, and an amine imide. These thermal cationic polymerization initiators can be easily obtained as commercial products, and examples thereof include trade names such as "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (manufactured by ADEKA Corporation), "CI-2639" , "SANEADE SI-80L" and "SANEADE SI-100L" (manufactured by SANSHIN CHEMICAL INDUSTRIES CO., LTD.) And the like .

The active energy ray-curable adhesive may further contain a compound that promotes cationic polymerization such as oxetanes and polyols.

Oxetanes are compounds having a 4-membered ring ether in the molecule, and examples thereof 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] , Phenol novolakoxetane, and the like. These oxetanes are commercially available and can be easily obtained by, for example, the trade names "AARON Oxetan OXT-101", "AARON Oxetan OXT-121", "AARON Oxetan OXT- AARON oxetane OXT-221 " and " AARON oxetan OXT-212 " (manufactured by TOA Corporation). These oxetanes are contained in the curable epoxy resin composition in an amount of usually 5 to 95% by weight, preferably 30 to 70% by weight.

As the polyol, it is preferable that an acid group other than the phenolic hydroxyl group is not present. For example, a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, a polyol having a phenolic hydroxyl group Compounds, polycarbonate polyols and the like. The molecular weight of these polyols is usually 48 or more, preferably 62 or more, more preferably 100 or more, and further preferably 1,000 or less. These polyols are usually contained in a proportion of not more than 50% by weight, preferably not more than 30% by weight, in the curable epoxy resin composition.

Additives such as an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a leveling agent, a plasticizer, and an antifoaming agent may be added to the active energy ray curable adhesive. Examples of the ion trap agent include inorganic compounds such as powdery bismuth, antimony, magnesium, aluminum, calcium, titanium and mixtures thereof. Examples of the antioxidant include hindered phenol antioxidants .

The active energy ray-curable adhesive can be used as a solvent-free adhesive agent substantially not containing a solvent component. However, since each coating method has an optimum viscosity range, a solvent may be added for viscosity adjustment. As the solvent, it is preferable to use an agent that dissolves an epoxy resin composition and the like well without lowering the optical performance of the optical film. For example, an organic solvent such as hydrocarbons typified by toluene, esters typified by ethyl acetate, Solvent. The viscosity of the active energy ray-curable adhesive used in the present invention is, for example, in the range of about 5 to 1,000 mPa 占 퐏, preferably 10 to 200 mPa 占 퐏, and more preferably 20 to 100 mPa 占 퐏.

Hereinafter, embodiments for producing a laminated film will be described in detail with reference to the drawings.

(Embodiment 1)

In this embodiment, the laminated film is made of one optical film and two transparent films. In the adhesive coating step, the adhesive is applied to one surface of each of the two transparent films, and in the bonding step, the two adhesive films of the two transparent films are laminated on both surfaces of the optical film, The optical film and the transparent film are bonded to each other by sandwiching the optical film and the transparent film between the pair of bonding rolls.

Next, the manufacturing method of the present embodiment will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of the entire apparatus used in the manufacturing method of the present embodiment.

In the apparatus for producing a laminated film shown in Fig. 1, adhesive coating devices 11 and 12 for applying an adhesive to one surface of transparent films 2 and 3, transparent films 2 and 3 and optical film 1 Bonding rolls (nip rolls) 51 and 52 for bonding the laminate 4 to obtain a laminate 4 and a roll 13 (nip rolls) for adhering the optical film 1 to the transparent films 2 and 3 in the laminate 4 A first active energy ray irradiating device 14 or 15 provided at a position opposed to the outer circumferential surface of the roll 13 and a second or subsequent active energy ray irradiating device 16 18 and a transport nip roll 19 are provided in this order along the transport direction.

First, an adhesive of an active energy ray-curable type is applied to one side of the transparent films 2 and 3 which are continuously unwound from the roll-wound state by means of the adhesive coaters 11 and 12 (Adhesive Coating Process).

Then, transparent films 2, 3 coated with an adhesive are laminated on both sides of the optical film 1 which is continuously unwound from the roll-wound state, and a pair of bonding rolls The optical film 1 and the transparent films 2 and 3 are bonded to each other so that the laminate 4 is formed by pressing at least one of the bonding rolls in the direction of the other bonding roll <Bonding process>.

Next, an active energy ray is irradiated from the first active energy ray irradiating device (14, 15) toward the outer peripheral surface of the roll (13) in the process of conveying the laminate (4) while adhering to the outer peripheral surface of the roll (13) And the adhesive is polymerized and cured (active energy ray irradiation step).

The second and subsequent active energy ray irradiating devices 16 to 18 disposed on the downstream side in the carrying direction are devices for completely polymerizing and curing the adhesive, and may be added or omitted as necessary. Finally, the laminate 4 passes through the nip roll 19 for conveying, and is wound on the winding roll 20 as a laminated film. Hereinafter, each step will be described in detail.

The method of coating the adhesive on the transparent films 2 and 3 is not particularly limited, but various coating methods such as doctor blade, wire bar, die coater, comma coater, and gravure coater can be used. Among them, a gravure roll is preferable as the adhesive applicators 11 and 12 in consideration of the thin film coating, the degree of freedom of the pass line, and the correspondence to the wide width.

In the case where the adhesive is applied using a gravure roll as the adhesive applicators 11 and 12, the thickness (coating thickness) of the applied adhesive is preferably about 0.1 to 10 mu m, more preferably 0.2 to 4 mu m Mu m. The coating thickness of the adhesive is adjusted by the draw ratio which is the velocity ratio of the gravure roll to the line speed of the transparent film. In general, by adjusting the draw ratio (speed / line speed of the gravure roll) to 0.5 to 10, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 mu m. More specifically, the gravure roll is rotated in the direction opposite to the conveying direction of the transparent films 2 and 3 with the line speed of the transparent films 2 and 3 set at 10 to 100 m / min, the speed of the gravure roll is set at 5 To 1000 m / min, the coating thickness of the adhesive can be adjusted to about 0.1 to 10 mu m.

After the preparation, the adhesive usually has a predetermined temperature within a range of 15 to 40 캜 (for example, 30 캜 5 캜 for a predetermined temperature of 30 캜), preferably 3 캜, more preferably 1 캜 Lt; / RTI >

In this step, transparent films 2, 3 coated with an adhesive by the above process are laminated on both sides of the optical film 1 which is continuously unwound from the roll-wound state through an adhesive. The lamination body is pressed in the direction of the bonding roll 52 while sandwiching the lamination body between a pair of bonding rolls 51 and 52 which are rotated in the carrying direction, The films 2 and 3 are bonded to each other to form the layered product 4. [

1, an adhesive is uniformly applied to one side of the transparent films 2 and 3, and the optical films 1 are laminated on the surfaces of the transparent films 2 and 3 coated with the adhesive to form bonding rolls 51 and 52 The adhesive is uniformly applied to both surfaces of the optical film 1 and the transparent films 2 and 3 are laminated on the surface of the optical film 1 coated with the adhesive to form a bonding roll 51 , 52).

The pressure applied to the laminate by pressing is not particularly limited, but in the case of using a metal roll and a rubber roll, the instantaneous pressure in the sheet-type press case manufactured by Fuji Film is preferably 0.2 to 3.0 MPa, And preferably 0.5 to 2.3 MPa. The external force of the pressing against this joining roll is usually applied to the bearing members at both ends of the joining roll.

The pair of joining rolls may have a difference in the main speed of one joining roll and the other joining roll. For example, it is preferable that the peripheral speed of the bonding roll (first bonding roll) provided on the side of the laminate 4 bonded to the liquid crystal panel is higher than the peripheral speed of the bonding roll on the opposite side (second bonding roll). Thus, when the obtained laminated film is a polarizing plate, it is possible to impart curl (positive curl) in which the surface bonded to the liquid crystal panel of the polarizing plate is convex and the surface on the opposite side is concave. When a curled surface (reverse curl) in which the surface to be bonded to the liquid crystal panel is concave and the surface opposite to the liquid crystal panel is convex is provided on the obtained polarizing plate, the polarizing plate is bonded to the liquid crystal cell, Problems are likely to occur. In this case, it is preferable to use a metal roll as the first joining roll and a rubber roll as the second joining roll.

Further, when the main speed of the second bonding roll is 1, it is more preferable that the ratio of the main speed of the first bonding roll is 1.0050 to 1.0200. When the primary velocity of the first bonding roll is higher than this range, the amount of curl of the liquid crystal becomes excessively large, and when the polarizing plate is bonded to the liquid crystal cell, there arises a problem of bubbling the end portion. Further, This is because the end of the polarizing plate may peel off from the liquid crystal cell.

The roll 13 constitutes a convex curved surface whose outer circumferential surface is mirror finished and is conveyed while closely contacting the laminated body 4 to the surface of the roll 13. During the process, the adhesive is polymerized by the active energy ray irradiating devices 14 and 15 Cure. The diameter of the rolls 13 is not particularly limited in order to polymerize and cure the adhesive and sufficiently adhere the layered product 4. [ It is preferable that the laminated body 4 in which the adhesive is in an uncured state is irradiated with an active energy ray so that the accumulated light quantity during passage through the roll 13 is 10 mJ / cm 2 or more. The roll 13 may be driven or rotated to move the line of the laminate 4, or may be fixed so that the laminate 4 slides on the surface. Further, the roll 13 may be operated as a cooling roll for dissipating heat generated in the layered product 4 at the time of polymerization curing by irradiation of active energy rays. In this case, the surface temperature of the cooling roll is preferably set to 20 to 30 占 폚.

(Embodiment 2)

In the present embodiment, the laminated film is made of one optical film and one transparent film. In the adhesive coating step, the adhesive is applied to one surface of the transparent film, and in the joining step, the optical film and the optical film are laminated so that the adhesive of the transparent film is in contact with one surface of the optical film. And the transparent film is sandwiched between the pair of bonding rolls.

Next, the manufacturing method of the present embodiment will be described with reference to the drawings. Fig. 2 is a schematic diagram showing the configuration of the entire apparatus used in the manufacturing method of the present embodiment. Fig.

The apparatus for producing a laminated film shown in Fig. 2 comprises an adhesive applicator 11 for applying an adhesive to one surface of a transparent film 2, and a transparent film 2 and an optical film 1 to form a laminate 4 A roll 13 for bringing the transparent film 2 and the optical film 1 into close contact with each other in the laminate 4 and a roll 13 for bringing the transparent film 2 and the optical film 1 into close contact with each other, The first and second active energy ray irradiating devices 14 and 15 provided at positions opposed to the outer peripheral surface of the conveying nip 16 and the second and subsequent active energy ray irradiating devices 16 to 18 provided on the downstream side in the conveying direction, Rolls 19 are provided in this order along the conveying direction.

First, an adhesive of the active energy ray curing type is applied to one side of the transparent film 2 which is continuously unwound from the rolled-up state by the adhesive coating device 11 (adhesive coating step).

A transparent film 2 on which an adhesive is applied is laminated on one side of an optical film 1 which is continuously unwound from a roll-wound state, and a pair of bonding rolls 51, The optical film 1 and the transparent film 2 are joined to form the laminate 4 by pressing at least one of the bonding rolls in the direction of the other bonding roll in a state of being sandwiched between the optical films 1 and 52 >.

Next, an active energy ray is irradiated from the first active energy ray irradiating device (14, 15) toward the outer peripheral surface of the roll (13) in the process of conveying the laminate (4) while adhering to the outer peripheral surface of the roll (13) And the adhesive is polymerized and cured (active energy ray irradiation step). The second and subsequent active energy ray irradiating devices 16 to 18 disposed on the downstream side in the carrying direction are devices for completely polymerizing and curing the adhesive, and may be added or omitted as necessary. The details of each step are the same as those of the first embodiment, and thus will not be described.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

&Lt; Example 1 >

In this embodiment, a laminated film in which two films are bonded is manufactured by using the apparatus shown in Fig. 2 described in the second embodiment.

A cycloolefin resin film "ZEONOR" (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 60 μm and a triacetyl cellulose film "KC8UX2MW" (manufactured by Konica Minolta Co., Ltd.) having a thickness of 80 μm were prepared. The surface roughness (Rz) of the cycloolefin-based resin film was 30 nm as a result of measurement with " Handysurf E35A " This value is an average value when the measurement distance is set to 12.5 mm and the surface roughness is measured ten times by placing the measuring apparatus on the target film.

An epoxy resin composition "KR-70T" (manufactured by ADEKA, viscosity: 44 mPa.s) as an ultraviolet curing type adhesive was applied to one side of a triacetyl cellulose film using an adhesive coating device. At this time, an adhesive was applied so as to have a thickness of 2.0 占 퐉 by rotating the gravure roll in the direction opposite to the conveying direction of the laminate with the line speed of the film laminate in the adhesive coater set at 25 m / min The thickness of the adhesive is 2.0 탆).

Next, a laminate in which a cycloolefin-based resin film was laminated so as to be in contact with an adhesive coated on a triacetylcellulose film was sandwiched between a pair of nip rolls (bonding rolls) having a diameter of 250 mm, pressed at a pressure of 1.0 MPa Whereby the cycloolefin-based resin film and the triacetylcellulose film were bonded.

The laminate to which the two kinds of films were bonded was transported at a line speed of 25 m / min while applying a tension of 600 N / m in the longitudinal direction, and the total accumulated light quantity (light irradiation in a wavelength range of 280 to 320 nm Ultraviolet ray (UVB) of about 250 mJ / cm 2 (measured by UV Power Puck II manufactured by Fusion UV) was irradiated to the laminate to obtain a laminated film.

With respect to the obtained laminated film, no bubbles were visually observed between the films.

&Lt; Example 2 >

In this embodiment, a laminated film in which two films are bonded is manufactured by using the apparatus shown in Fig. In the apparatus shown in Fig. 3, the cooling roll 13 and the like are omitted in the apparatus shown in Fig. 2 described in the second embodiment, and a detailed description thereof will be omitted. The reference numerals in Fig. 3 are used in the same meaning as in Fig.

A triacetylcellulose film " KC4CR-1 " (manufactured by Konica Minolta) having a thickness of 40 mu m and a composite film laminate having a thickness of 135 mu m were prepared. The surface roughness (Rz) of KC4CR-1 was measured by "Handysurf E35A" manufactured by Tokyo Precision Industries, Ltd. and found to be 50 nm. This value is an average value when the measurement distance is set to 12.5 mm and the surface roughness is measured ten times by placing the measuring apparatus on the target film.

An epoxy resin composition "KR-70T" (manufactured by ADEKA, viscosity: 44 mPa.s), which is an ultraviolet curable adhesive, was applied to one side of the composite film laminate using an adhesive coating device. At this time, an adhesive was applied so as to have a thickness of 1.0 탆 by rotating the gravure roll in the direction opposite to the conveying direction of the laminate with the line speed of the film laminate in the adhesive coater set at 25 m / min (further, The thickness of the adhesive is 1.0 탆).

&Lt; Comparative Example 1 &

(Vinylon VF-PS # 7500, manufactured by Kuraray Co., Ltd., disc thickness: 75 占 퐉) having a surface roughness (Rz) of 280 nm instead of the cycloolefin-based film was used in place of the cycloolefin- Thereby producing a laminated film. With respect to the obtained laminated film, bubbles were visually observed between the films.

From the above results, in Example 1 in which the surface constituting the laminated film had no surface coated with an adhesive in the adhesive coating process and the surface roughness of the surface brought into contact with the adhesive in the bonding step was 200 nm or less, In Comparative Example 1 using a film having a surface roughness outside the scope of the present invention without incorporation, it can be seen that air bubbles are mixed in between the films.

In Example 1, a cycloolefin-based film was used as a film having a surface roughness of 30 nm. In Comparative Example, a polyvinyl alcohol film was used as a film having a surface roughness of 280 nm. However, in a commercially available film, Are different from each other because they selected different films. That is, it is considered that the same effect difference is observed even when films having the same material and different only in surface roughness are compared. Therefore, in the present invention, each film constituting the laminated film is not limited to the material described in the above embodiment, and a laminated film can be produced using a film made of various materials.

1: optical film, 2, 3: transparent film, 4: laminate, 51, 52: bonding roll, 11, 12: adhesive coating device, 13: roll, 14, 15, 16, 17, Apparatus, 19: conveying nip roll, 20: winding roll.

Claims

A method of producing a laminated film comprising a plurality of films bonded together via an active energy beam curing type adhesive,
An adhesive applying step of applying an active energy ray-curable adhesive to one surface or both surfaces of at least one of the plurality of films;
A joining step of joining the plurality of films with each other by sandwiching the plurality of films between a pair of joining rolls which are rotated in the carrying direction in a state in which the adhesive is interposed between adjacent films,
Irradiating the plurality of films bonded to each other with an active energy ray to cure the adhesive,
Wherein the surface of the plurality of films that is not coated with the adhesive in the adhesive coating step has a surface roughness of 200 nm or less as a ten-point average roughness in a surface brought into contact with the adhesive in the bonding step.

The method according to claim 1, wherein the thickness of the adhesive applied in the adhesive coating process is 2 m or less.

The method according to claim 1 or 2, wherein the plurality of films comprise an optical film and a transparent film, and the laminated film is a polarizing plate.

The optical information recording medium according to claim 3, wherein the plurality of films comprise one optical film and two transparent films,
In the adhesive coating step, the adhesive is applied to one surface of each of the two transparent films,
Wherein the optical film and the transparent film are sandwiched between the pair of bonding rolls in a state in which the two adhesive films of the transparent film are in contact with both surfaces of the optical film in the bonding step.

The optical information recording medium according to claim 3, wherein the plurality of films comprise one optical film and one transparent film,
In the adhesive coating step, the adhesive is coated on one side of the transparent film,
Wherein the optical film and the transparent film are sandwiched between the pair of bonding rolls in a state in which the adhesive of the transparent film is in contact with one side of the optical film in the bonding step.

The method according to claim 1, wherein the viscosity of the active energy ray-curable adhesive is 20 mPa s or more.

4. The method according to claim 3, wherein the optical film is a polarizing film, and the polarizing film is a film obtained by uniaxially stretching a polyvinyl alcohol resin film having a film thickness of 10 to 80 m and adsorbing and orienting a dichroic dye.