JP5929043B2 - Method for producing hard coat film - Google Patents

Description

  The present invention relates to a method for producing a hard coat film excellent in wet heat resistance and light adhesion, and a hard coat film.

  Plastics are used in various fields for reasons such as good processability, light weight, and low cost. However, the processability is good, but there are drawbacks such as softness and easy scratching on the surface. In order to improve this drawback, it is common to coat a hard coat material and provide a protective layer on the surface. As this hard coat material, an active energy ray-curable resin composition is useful because it is fast-curing and has low energy cost.

  In recent years, display bodies such as a liquid crystal display, a plasma display, and a touch panel display provided with a film having a hard coat material as a protective layer on the surface thereof are rapidly spreading. In particular, liquid crystal displays have become larger and are used by an unspecified number of consumers, so hard coat materials used for them have higher hardness, scratch resistance, and curling of the film when cured. It is requested. For this reason, in order to require higher hardness and scratch resistance and to improve workability, there is also a demand for an active energy ray-curable resin composition in which the curl of the cured film is small.

  For such a problem, for example, Patent Document 1 proposes a method for producing a hard coat film in which a hard coat layer forming material containing a polyfunctional acrylate is coated on a transparent film substrate.

  However, the hard coat film disclosed in the above-mentioned Patent Document 1 mainly uses a cellulose ester film having a high solvent permeability as a base film, and after the hard coat layer forming material is applied, heat treatment or the like is performed. For example, these adhesions were sufficiently maintained. However, when a polyester film is used as the base film, sufficient adhesion cannot be maintained by the method as described above, and there is room for improvement.

JP 2009-91544 A

  This invention is made | formed in view of this situation, The objective is to provide the hard coat film excellent in the adhesiveness of a hard-coat layer and a transparent film base material.

  As a result of intensive studies conducted by the inventors of the present invention in order to achieve the above object, a hard coat layer is applied to a transparent film substrate provided with an easy-contact layer, and UV curing treatment and heat treatment are performed. The inventors have found that a hard coat film with improved adhesion can be obtained by reacting the heat-reactive component with the resin component of the hard coat layer, and the present invention has been completed.

  That is, in the method for producing a hard coat film according to the present invention, a step of forming an easy-contact layer on at least one surface of a transparent film substrate, and a hard coat layer-forming material is applied on the surface of the easy-contact layer. In the method for producing a hard coat film comprising a coating step, the coating step comprises: a coating process for coating the hard coat layer forming material on a transparent film substrate; and a transparent film substrate after the coating process. Including a UV curing treatment for UV curing and a heat treatment for heating the transparent film substrate after the UV treatment, and the easy-contact layer is selected from a melamine resin as a thermal crosslinking agent, a blocked isocyanate, and an oxazoline group-containing polymer. Containing at least one kind, wherein the hard coat layer forming material contains a polyfunctional acrylate having at least one OH group That.

  The hard coat layer forming material is a polyfunctional acrylate having at least one or more OH groups, and the easy-contact layer comprises at least one selected from a melamine resin as a thermal crosslinking agent, a blocked isocyanate, and an oxazoline group-containing polymer. It is characterized by containing.

  In the heat treatment, it is preferable to react the polyfunctional acrylate and the thermal crosslinking agent.

  Moreover, it is suitable that the said heat processing is performed at 60-120 degreeC.

  The hard coat layer preferably contains at least one polyfunctional acrylate.

  In addition to the polyfunctional acrylate, isocyanuric acid-modified acrylate is preferable.

  Moreover, it is suitable that the said transparent film base material is a polyester-type film.

  According to this invention, the hard coat film excellent in the adhesiveness of a hard-coat layer and a base film can be provided.

It is the schematic which showed the coating process which concerns on the manufacturing method of this invention. It is the schematic which heat-processes the hard coat film roll after winding which concerns on this invention in the heat processing chamber A. FIG.

  Hereinafter, embodiments according to the present invention will be described, but the present invention is not limited thereto.

  The method for producing a hard coat film according to the present embodiment includes a step of forming an easy-contact layer on at least one surface of a transparent film substrate, and a coating for applying a hard coat layer-forming material on the surface of the easy-contact layer. In the method for producing a hard coat film including a coating process, the coating process includes a coating process in which the hard coat layer forming material is applied to a transparent film substrate, and a UV film is applied to the transparent film substrate after the coating process. A UV curing treatment for curing, and a heat treatment for heating the transparent film substrate after the UV treatment, wherein the easy-contact layer is at least selected from a melamine resin as a thermal crosslinking agent, a blocked isocyanate, and an oxazoline group-containing polymer. 1 type, The said hard-coat layer forming material contains the polyfunctional acrylate which has an at least 1 or more OH group, It is characterized by the above-mentioned.

《Easily accessible layer》
The constituent material of the easy-contact layer is preferably one that improves the adhesion between the polyester film and the hard coat layer, and can be reacted with the OH group of the polyfunctional acrylate contained in the hard coat layer. A crosslinking agent is preferred. Specifically, for example, a melamine-based crosslinking agent, a polyester resin, an acrylic resin, an epoxy resin, a urethane acrylic resin, a silicon acrylic resin, a polysiloxane resin, a blocked isocyanate, and an oxazoline group-containing polymer can be used. Among these, a melamine resin, a blocked isocyanate, and an oxazoline group-containing polymer are preferable from the viewpoint of good wet heat resistance. These resins may be used alone or as a mixture of two or more.

  The thickness of the easy adhesion layer is preferably 10 to 200 nm, more preferably 20 to 150 nm. If the thickness of the easy-adhesion layer is less than 10 nm, the effect of improving the adhesion is poor, and if it exceeds 200 nm, cohesive failure of the easy-adhesion layer tends to occur and the adhesion may be lowered.

《Hard coat layer》
The hard coat layer according to the present invention will be described.

  The hard coat layer according to the present invention is provided on at least one surface of the transparent film substrate via an easy-contact layer. In the present invention, after the hard coat layer is formed on the transparent film substrate, heat treatment is performed, and a functional layer such as an antireflection layer (high refractive index layer, low refractive index layer, etc.) is further provided thereon. Is preferred.

  In addition, the hard coat film in this invention means the film whose pencil hardness is H-8H. Most preferably, it is 2H-6H. The pencil hardness is evaluated by pencil hardness evaluation specified by JIS K 5400 using a test pencil specified by JIS S 6006 after the prepared hard coat film is conditioned at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours. It is the value measured according to the method.

(Polyfunctional acrylate)
In general, an actinic ray curable resin such as ultraviolet rays is used as the hard coat layer composition. However, in the present invention, such an actinic ray curable resin may contain a polyfunctional acrylate having at least one OH group. It is a feature. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups and / or methacryloyloxy groups in the molecule.

  Examples of the monomer of the polyfunctional acrylate include pentaerythritol diacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, pentaerythritol trimethacrylate, and dipentaerythritol tetramethacrylate. Preferably mentioned. Examples of the oligomer include polyfunctional hydroxy urethane acrylate and polyfunctional hydroxy epoxy acrylate.

  In addition to the polyfunctional acrylate having the OH group, other acrylate resins may be added, such as ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylol. Propane triacrylate, trimethylol ethane triacrylate, tetramethylol methane triacrylate, tetramethylol methane tetraacrylate, pentaglycerol triacrylate, pentaerythritol tetraacrylate, glycerin triacrylate, dipentaerythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate , Ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, , 6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol tetramethacrylate, glycerin tri Preferred examples include methacrylate, dipentaerythritol hexamethacrylate, and isobornyl acrylate. These compounds are used alone or in admixture of two or more. Moreover, oligomers, such as a dimer and a trimer of the said monomer, may be sufficient.

  Moreover, it is preferable to contain isocyanuric acid modified acrylate in addition to the above polyfunctional acrylate. For example, it is selected from modified isocyanuric acid EO-modified diacrylate, modified isocyanuric acid EO-modified triacrylate, and the like.

  The OH group contained in these polyfunctional acrylates and the thermal cross-linking agent in the easy-contact layer provided on the transparent film substrate, which will be described later, can maintain strong adhesion by reacting in the heat treatment step. it can.

  The addition amount of the actinic ray curable resin is preferably 15% by mass or more and less than 70% by mass in the solid content in the hard coat composition.

  In order to accelerate the curing of the actinic ray curable resin, a photopolymerization initiator and an acrylic compound having at least two polymerizable unsaturated bonds in the molecule are contained in a mass ratio of 20: 100 to 0.01: 100. It is preferable.

  Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.

In the hard coat layer according to the present invention, a binder such as a known thermoplastic resin, thermosetting resin, or hydrophilic resin such as gelatin can be mixed with the actinic ray curable resin. These resins preferably have a polar group in the molecule. Examples of the polar _{group, -COOM, -OH, -NR 2,} -NR 3 X, -SO 3 M, -OSO 3 M, -PO 3 M 2, -OPO 3 M ( wherein, M represents a hydrogen atom, an alkali A metal or an ammonium group, X represents an acid forming an amine salt, R represents a hydrogen atom or an alkyl group).

  Commercially available actinic radiation curable resins that can be used in the present invention include ADEKA OPTMER KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (Asahi) Manufactured by Denka Co., Ltd.); Koei Hard A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102 NS-101, FT-102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Co., Ltd.); Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213 , DP-10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (Daiichi Seika Kogyo Co., Ltd.) KRM7033, KRM7039, KRM7130, KRM7131, UVECRYL29201, UVECRYL29202 (manufactured by Daicel UCB); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC -5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (Dainippon Ink Chemical Co., Ltd.); 340 clear (manufactured by China Paint Co., Ltd.); Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries); SP -1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.); RCC-15C (manufactured by Grace Japan Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.); B420 (manufactured by Shin-Nakamura Chemical Co., Ltd.) or the like can be appropriately selected and used.

  Further, the hard coat layer may contain fine particles of an inorganic compound or an organic compound in order to adjust the scratch resistance, slipperiness and refractive index.

  Examples of inorganic fine particles used in the hard coat layer include silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, calcium carbonate, talc, clay, and calcined kaolin. And calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

  Organic particles include polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, melamine resin powder. An ultraviolet curable resin composition such as polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, or polyfluoroethylene resin powder can be added. Particularly preferred are cross-linked polystyrene particles (for example, SX-130H, SX-200H, SX-350H manufactured by Soken Chemical), polymethyl methacrylate particles (for example, MX150, MX300 manufactured by Soken Chemical), and fluorine-containing acrylic resin fine particles. The Examples of the fluorine-containing acrylic resin fine particles include commercial products such as FS-701 manufactured by Nippon Paint. Examples of the acrylic particles include Nippon Paint: S-4000, and examples of the acrylic-styrene particles include Nippon Paint: S-1200, MG-251.

  The average particle diameter of these fine particle powders is preferably 0.01 to 5 μm, more preferably 0.1 to 5.0 μm, and particularly preferably 0.1 to 4.0 μm. Further, it is preferable to contain two or more kinds of fine particles having different particle diameters. The proportion of the ultraviolet curable resin composition and the fine particles is desirably blended so as to be 0.1 to 30 parts by mass with respect to 100 parts by mass of the resin composition.

  In order to increase the heat resistance of the hard coat layer, an antioxidant that does not inhibit the photocuring reaction can be selected and used. Examples include hindered phenol derivatives, thiopropionic acid derivatives, phosphite derivatives, and the like. Specifically, for example, 4,4′-thiobis (6-tert-3-methylphenol), 4,4′-butylidenebis (6-tert-butyl-3-methylphenol), 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) mesitylene, di-octadecyl-4- Examples thereof include hydroxy-3,5-di-tert-butylbenzyl phosphate. The hard coat layer coating solution may contain a solvent, or may be appropriately contained and diluted as necessary. Examples of the organic solvent contained in the coating solution include hydrocarbons (toluene, xylene), alcohols (methanol, ethanol, isopropanol, butanol, cyclohexanol), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone), It can be appropriately selected from esters (methyl acetate, ethyl acetate, methyl lactate), glycol ethers, and other organic solvents, or a mixture thereof can be used. Propylene glycol monoalkyl ether (1 to 4 carbon atoms of the alkyl group) or propylene glycol monoalkyl ether acetate ester (1 to 4 carbon atoms of the alkyl group) is 5% by mass or more, more preferably 5 to 80%. It is preferable to use the organic solvent containing at least mass%.

  The hard coat layer has a center line average roughness (Ra) defined by JIS B 0601 of 0.001 to 0.1 μm, or a fine hard coat layer and Ra is adjusted to 0.1 to 1 μm. An antiglare hard coat layer may also be used. The center line average roughness (Ra) is preferably measured by an optical interference type surface roughness measuring instrument, and can be measured, for example, using a non-contact surface fine shape measuring device WYKO NT-2000 manufactured by WYKO.

  Further, the hard coat layer preferably contains a silicone surfactant or a polyoxyether compound. As the silicone surfactant, polyether-modified silicone is preferable, and specifically, BYK-UV3500, BYK-UV3510, BYK-333, BYK-331, BYK-337 (manufactured by BYK-Chemical Japan), TSF4440, TSF4445, TSF4446, TSF4452, TSF4460 (GE Toshiba Silicone), KF-351, KF-351A, KF-352, KF-353, KF-354, KF-355, KF-615, KF-618, KF-945, KF- 6004 (polyether-modified silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.) and the like are exemplified, but not limited thereto.

  Of the polyoxyether compounds, the polyoxyethylene oleyl ether compound is preferable, and is generally a compound represented by the general formula (α).

Formula _{(α) C 18 H 35 -O} (C 2 H 4 O) nH ( wherein, n represents 2-40.)

  The average addition number (n) of ethylene oxide with respect to the oleyl part is 2 to 40, preferably 2 to 10, more preferably 2 to 9, and further preferably 2 to 8. Moreover, the compound of general formula ((alpha)) is obtained by making ethylene oxide and oleyl alcohol react.

  Specific products include Emulgen 404 (polyoxyethylene (4) oleyl ether), Emulgen 408 (polyoxyethylene (8) oleyl ether), Emulgen 409P (polyoxyethylene (9) oleyl ether), Emulgen 420 (polyoxy) Ethylene (13) oleyl ether), Emulgen 430 (polyoxyethylene (30) oleyl ether) or more, Kao Corporation, NOFBLEEAO-9905 (polyoxyethylene (5) oleyl ether) manufactured by NOF Corporation.

  In addition, () represents the number of n. Nonionic polyoxyether compounds may be used alone or in combination of two or more.

  The polyoxyethylene oleyl ether compound can improve the applicability of the hard coat layer and flow. These components are preferably added in a range of 0.01 to 3% by mass with respect to the solid component in the coating solution.

  Further, the hard coat layer may contain a fluorine-siloxane graft polymer. The fluorine-siloxane graft polymer refers to a copolymer polymer obtained by grafting polysiloxane and / or organopolysiloxane containing siloxane and / or organosiloxane alone on at least a fluorine-based resin. Examples of commercially available products include ZX-022H, ZX-007C, ZX-049, and ZX-047-D manufactured by Fuji Kasei Kogyo Co., Ltd. These compounds may be used as a mixture. Fluorine-siloxane graft polymer should be used in a coating solution that has a mass ratio of actinic ray curable resin to fluorine-siloxane graft polymer: energy-active radiation curable resin = 0.05: 100 to 5.00: 100. To preferred.

  The hard coat layer may have a multilayer structure of two or more layers. One of the layers may be a so-called conductive layer containing, for example, conductive fine particles, a π-conjugated conductive polymer, or an ionic polymer. Examples of the π-conjugated conductive polymer include polythiophene, poly (3-methylthiophene), poly (3-ethylthiophene), poly (3-propylthiophene), poly (3-butylthiophene), and poly (3-hexylthiophene). , Poly (3-octylthiophene), poly (3-decylthiophene), poly (3-dodecylthiophene), poly (3-bromothiophene), poly (3-chlorothiophene), poly (3-cyanothiophene), poly (3-phenylthiophene), poly (3,4-dimethylthiophene), poly (3,4-dibutylthiophene), poly (3-hydroxythiophene), poly (3-methoxythiophene), poly (3-ethoxythiophene) , Poly (3-butoxythiophene), poly (3-hexyloxythiophene), poly (3 Octyloxythiophene), poly (3-decyloxythiophene), poly (3-dodecyloxythiophene), poly (3,4-dihydroxythiophene), poly (3,4-dimethoxythiophene), poly (3,4-di Ethoxythiophene), poly (3,4-dipropoxythiophene), poly (3,4-dibutoxythiophene), poly (3,4-dihexyloxythiophene), poly (3,4-dioctyloxythiophene), poly ( 3,4-didecyloxythiophene), poly (3,4-didodecyloxythiophene), poly (3,4-ethylenedioxythiophene), poly (3,4-propylenedioxythiophene), poly (3,4 4-butenedioxythiophene), poly (3-methyl-4-methoxythiophene), poly (3-methyl-4 -Ethoxythiophene), poly (3-carboxythiophene), poly (3-methyl-4-carboxythiophene), poly (3-methyl-4-carboxyethylthiophene), poly (3-methyl-4-carboxybutylthiophene) , Polypyrrole, poly (N-methylpyrrole), poly (3-methylpyrrole), poly (3-ethylpyrrole), poly (3-N-propylpyrrole), poly (3-butylpyrrole), poly (3-octyl) Pyrrole), poly (3-decylpyrrole), poly (3-dodecylpyrrole), poly (3,4-dimethylpyrrole), poly (3,4-dibutylpyrrole), poly (3-carboxypyrrole), poly (3 -Methyl-4-carboxypyrrole), poly (3-methyl-4-carboxyethylpyrrole), poly (3-methyl 4-carboxybutylpyrrole), poly (3-hydroxypyrrole), poly (3-methoxypyrrole), poly (3-ethoxypyrrole), poly (3-butoxypyrrole), poly (3-hexyloxypyrrole), poly ( 3-methyl-4-hexyloxypyrrole), polyaniline, poly (2-methylaniline), poly (3-isobutylaniline), poly (2-anilinesulfonic acid), poly (3-anilinesulfonic acid) and the like. . Each of these may be used alone or two types of copolymers can be suitably used.

  The ionic polymer may contain a color tone adjusting agent (dye or pigment) having a color tone adjusting function as a color correction filter for various display elements. Moreover, you may make it contain an electromagnetic wave shielding agent or an infrared absorber, etc. and to have each function.

  As a coating method of the hard coat layer coating solution, those described below can be used. The coating amount is suitably 0.1 to 40 μm, preferably 0.5 to 30 μm, as the wet film thickness. Moreover, as a dry film thickness, it is an average film thickness of 0.1-30 micrometers, Preferably it is 1-20 micrometers.

<< Transparent film substrate >>
As for the base film used for manufacture of the hard coat film of this invention, the easy-contact layer is provided in the at least one surface. Moreover, it is preferable that this transparent film base material is optically isotropic with respect to a hard-coat layer, and is optically transparent.

  Any of the above-mentioned properties may be used, for example, cellulose ester films such as cellulose diacetate film, cellulose acetate butyrate film, cellulose triacetate film, polyester film, polycarbonate film, polyarylate film, polysulfone. Film (including polyethersulfone), polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic polystyrene film, Norbornene resin film, polymethylpentene film, polyetherketone film Arm, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, a cycloolefin polymer film, polymethyl methacrylate film or there may be mentioned acrylic film or the like, but are not limited to. Among these, cellulose ester films (for example, Konica Minoltak KC8UX2M, KC4UX2M, KC4UY, KC8UT, KC5UN, KC12UR, KC8UCR-3, KC8UCR-4 (above, manufactured by Konica Minolta Opto), polycarbonate film, polysulfone (Polysulfone) A film containing ether sulfone) and a cycloolefin polymer film are preferred, and particularly preferred is a polyester-based film from the viewpoint of better achieving the object effects of the present invention, manufacturing, cost, transparency, adhesiveness, etc. It is.

  The transparent film substrate preferably has a surface roughness Ra of 1 μm or less. When Ra is larger than 1 μm, when the above-described various functional layers are provided, the surface may become uneven or remain as convex defects, and smoothness and gloss may be impaired. In order to reduce Ra to 1 μm or less, the surface of the take-up roll and the drawing roll immediately after melt extrusion is made into a mirror surface, or the surface of the take-up roll immediately after being taken by the roll is nipped between the mirror surface rolls, This is achieved by appropriately selecting the magnification and the stretching speed. It is also effective to reduce Ra by sharpening the lip edge of the melt-extrusion die or mirroring the surface in contact with the molten resin inside the die.

<< Easy-to-contact layer formation process >>
The easy-contact layer forming step in the method for producing a hard coat film of the present invention will be described. As a preferable method for providing an easy-contact layer on the transparent film substrate, a method of providing the easy-contact layer during the production process of the transparent film substrate and stretching with the film is suitable. In particular, from the viewpoint of productivity, a method of providing by a coating method during the film forming process of the transparent film substrate is most preferable. In consideration of the influence on the environment and the human body, it is preferable to use a water-based paint mainly containing water and a water-dispersible solid content, not a paint mainly containing a solvent.

  Various coating methods, for example, a reverse coating method, a gravure coating method, a rod coating method, a bar coating method, a Mayer bar coating method, a die coating method, and a spray coating method, are used as the coating method on the film substrate. be able to. Further, in consideration of the uniformity of coating film application and adhesiveness, corona discharge may be applied to the surface.

《Coating process》
Next, the coating process in the manufacturing method of the hard coat film of this invention is demonstrated.

  The coating process according to the present invention includes a coating treatment for applying a hard coat layer forming material to a transparent film substrate, a UV curing treatment for UV curing the film after the coating treatment, and a film after the UV treatment. The heat treatment which heats is included.

  Examples of the coating process include a form as shown in FIG. However, the figure is an example, and the present invention is not limited to this. Moreover, it is necessary to perform a coating process in the place where temperature and humidity can be adjusted, and it is preferable to carry out in the clean room etc. without a dust.

(Coating process)
The long film Y is unwound from the unwinding roll 1, is transported by the transport roller 2, and the hard coat layer is coated by the extrusion coater 3. At this time, the hard coat layer may be a single layer structure or a plurality of layers.

(Drying process)
The long film Y coated with the hard coat layer may then be subjected to a drying treatment in the drying zone 5. The temperature of the drying zone 5 is preferably 50 to 150 ° C. Drying is performed by blowing warm air whose temperature and humidity are controlled from the front surface, back surface, or both surfaces of the long film Y.

(UV curing treatment)
After the drying treatment, the film is cured by irradiating ultraviolet rays with an air-cooled actinic ray lamp 6 a in the light irradiation lamp unit 6. Alternatively, the half-cure state can be achieved by controlling the irradiation amount and irradiation conditions. Actinic ray irradiation can also be performed in a state where the long film Y is wound around the opposing roll 4 whose temperature is controlled in advance at 20 to 120 ° C.

At that time, it is also preferable to send cooling air from the air cooling air vent 6b to adjust the temperature of the actinic ray irradiating unit, and N ₂ gas is supplied from the N ₂ supply chamber to promote hardening of the hard coat layer. It is also preferable to do.

As examples of the light irradiation lamp, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used. These light sources are preferably air-cooled or water-cooled. The irradiation conditions vary depending on individual lamps, the dose of active ray is preferably a ^{50mJ / cm 2 ~1J / cm 2} , particularly preferably 50 to 500 mJ / cm ^2. Further, it is preferable to reduce the oxygen concentration to 0.01% to 5% by nitrogen purge in the irradiated portion.

  The irradiation time for obtaining the necessary irradiation amount of actinic rays is preferably about 0.1 second to 1 minute, and more preferably 0.1 to 10 seconds from the viewpoint of curing efficiency or work efficiency of the ultraviolet curable resin.

Moreover, it is preferable that the illuminance of these actinic ray irradiation parts is 0.05-0.2 W / m < ² >.

  When irradiating actinic radiation, it is preferably performed while applying tension in the film transport direction, and more preferably while applying tension in the width direction. The tension to be applied is preferably 30 to 500 N / m. The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. This makes it possible to obtain a film with further excellent flatness. The width tension applying method is not particularly limited, and may be a free span, a back roll or the like. Moreover, the method of providing tension | tensile_strength using a width control apparatus in the width direction is also effective, Preferably it is extending | stretching at 3.0% or less, More preferably, it is 0.05%-1.0%.

(Heat treatment)
Next, after the light irradiation, heat treatment is performed in the heating zone 7. In the heating zone 7, the long film Y is heated at a predetermined temperature for a predetermined time by the transport rollers 2 arranged above and below.

  In this heat treatment, the OH group of the polyfunctional acrylate contained in the hard coat layer forming material described above and the thermal crosslinking agent in the easy-contact layer formed on the transparent film substrate undergo a crosslinking reaction. By this crosslinking reaction, the adhesion between the transparent substrate film and the hard coat layer can be improved.

  The thermal crosslinking agent contains at least one selected from melamine-based crosslinking agents, blocked isocyanates, and oxazoline group-containing polymers. Hereinafter, these thermal crosslinking agents will be described in detail.

-Melamine type cross-linking agent It is desirable to add a blocked acid catalyst in order for the melamine type cross-linking agent to react effectively in the heat treatment after UV irradiation. By heat-reacting this blocking agent, the melamine crosslinking agent and the OH group of the hard coat resin undergo a condensation reaction and are cured.

  The type of the melamine-based cross-linking agent of the present invention is not particularly limited, but melamine, a methylolated melamine derivative obtained by condensing melamine and formaldehyde, a compound partially or completely etherified by reacting a methylolated melamine with a lower alcohol Or a mixture thereof. As the melamine-based crosslinking agent, a monomer, a condensate composed of a multimer of two or more, or a mixture thereof can be used.

  As the lower alcohol used for etherification, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, n-butanol, isobutanol and the like can be used. The functional group has an imino group, a methylol group, or an alkoxymethyl group such as a methoxymethyl group or a butoxymethyl group in one molecule, and an imino group type methylated melamine, a methylol group type melamine, or a methylol group type methylated melamine. And fully alkyl methylated melamine.

Blocked isocyanate Block isocyanate resin uses free isocyanate blocked with phenol or the like so as not to react before curing.

As a blocking agent, active methylene such as phenol, alcohol, dimethyl malonate, ethyl acetoacetate, oxime> C = N—OH, ε-caprolactam, ε-hexalactone, dimethyl malonate CH ₂ (COOCH ₃ ) ₂ , ethyl acetoacetate CH ₃ C (═O) CH ₂ COOC ₂ H ₅ , etc. is heated and volatilized to cure by a condensation mechanism of —N═CO and an alcohol group represented by the following formula (1).

-Oxazoline group-containing polymer The oxazoline group-containing polymer contains at least one monomer having an oxazoline group and is obtained by copolymerization with at least one other monomer.
The oxazoline group-containing polymer is cured by causing an addition reaction with a functional group such as an OH group and a carboxyl group by heat.

  The temperature of the heat treatment is preferably 60 to 120 ° C. or more, more preferably 80 to 120 ° C., from the viewpoint that the target effect is better exhibited. When the temperature is lower than 60 ° C., the reaction is insufficient and good adhesion cannot be obtained. When the temperature is higher than 120 ° C., the resin, the crosslinking agent, the initiator, and the like are volatilized and the performance of the coating film is deteriorated.

  Further, the heat treatment time is preferably 20 minutes or less. Even if the heat treatment is carried out for a time longer than 20 minutes, the objective effect obtained better is not changed, and the film tends to be deteriorated in appearance such as discoloration or deformation due to heat. The heat treatment time here refers to a time during which the temperature is kept constant at a desired temperature, and does not include the time when the temperature is raised and the time when the temperature is lowered.

  The temperature to be held is preferably in the range of ± 5 ° C. of the set temperature. There may be a plurality of heat treatment steps. In that case, it may be designed so that each temperature can be changed. The heat treatment is preferably performed while applying a tension in the film transport direction or the width direction, and the applied tension is preferably 50 to 500 N / m, and more preferably 300 to 500 N / m. At 300 to 500 N / m, the objective effect of the present invention is better exhibited after a more severe durability test. When it exceeds 500 N / m, it becomes difficult to maintain the flatness of the film. The width tension applying method is not particularly limited, and may be a free span, a back roll or the like. Moreover, the method of providing tension | tensile_strength using a width control apparatus in the width direction is also effective, Preferably it is extending | stretching 3.0% or less, More preferably, it is 0.05%-1.0% extending | stretching.

  The long film Y subjected to the heat treatment is taken up as a take-up roll 9 in the take-up chamber 8. In that case, it is also preferable to carry out while blowing hot air of a predetermined temperature from the hot air outlet 10. As a measure for preventing electrification and dust adhesion, the hot air is preferably adjusted to a relative humidity in the range of 10 to 70% RH, preferably 20 to 70% RH, particularly 40 to 60% RH. Moreover, it is preferable that warm air is an ion wind, and it is preferable to install a static elimination apparatus and an air cleaner in the vicinity of the winding part.

  Note that the heat treatment may be a method in which a roll of the hard coat film wound after application, drying, and light irradiation is placed on a movable carriage 12 as shown in FIG. In the heat treatment A, the temperature difference between the inside and outside of the roll of the film roll due to a rapid temperature increase is increased, and it is preferable to gradually increase or decrease the temperature in order to prevent wrinkles and the like from entering near the winding core. . Specifically, the rate of temperature increase and the rate of temperature decrease are preferably 0.3 to 5 ° C./hour.

  Moreover, in order to prevent blocking and to keep a winding form favorable, it is preferable to give a knurling process. The knurling process should just be formed in the at least one surface of the film, and may be formed in both surfaces. The thickness of the knurling part is preferably larger than the film thickness of the hard coat layer, and the thickness of the knurling part is preferably in the range of 5 to 30 μm. Preferably it is the range of 10-25 micrometers.

  In addition, as the winding core when winding the hard coat film in a roll shape, any material may be used as long as it is a cylindrical core, preferably a hollow plastic core, and a plastic material As long as it is a heat-resistant plastic that can withstand the heat treatment temperature, examples thereof include resins such as phenol resin, xylene resin, melamine resin, polyester resin, and epoxy resin. A thermosetting resin reinforced with a filler such as glass fiber is preferred. The number of windings on these winding cores is preferably 100 windings or more, more preferably 500 windings or more, and the winding thickness is preferably 5 cm or more. Moreover, when performing the said heat processing in the state which wound up the hard coat film wound up in roll shape, you may rotate this roll.

  The rotation is preferably performed at a speed of 1 rotation or less per minute, and may be continuous or intermittent. Moreover, it is also preferable to perform the roll rewinding once or more during the heating period.

  In order to rotate the long hard coat film wound around the core during the heat treatment, it is preferable to provide a dedicated turntable in the heat treatment chamber. More preferably, the hard coat film is set on a dedicated carriage having a heat-resistant rotation function and rotated during the heat treatment in the heating chamber.

  It is also preferable that the hard coat film roll after the heat treatment is carried, for example, to a rewinding step (not shown) and cooled to room temperature while the hard coat film is rewinded to obtain a rewind roll. Further, in the rewinding step, it is preferable to pass through an atmosphere having a relative humidity of 10 to 70% RH or to wind in the atmosphere. When the relative humidity is preferably 20 to 70% RH, particularly 40 to 60% RH, a good hard coat film roll can be obtained without static electricity failure or collapse of the winding shape. The film rewinding speed is 1 to 200 m / min, preferably 10 to 100 m / min. At the time of rewinding, it is also preferable to bring the film into contact with at least one roller while being drawn out in order to lower the film temperature.

  When rotating or rewinding these rolls, there is a possibility that static electricity failure or scratches may occur on the film. It is preferable to install a static eliminator or in a clean room, and the contact roller surface during rewinding is smooth. It is preferable to use one having a high value.

  As the heating means in the heat treatment step, hot air blowing, contact heat transfer using a heating roll, induction heating using a microwave, radiant heat heating using an infrared heater, or the like can be used. As the infrared heater, an electric, gas, oil or steam far infrared ceramic heater can be used. A commercially available infrared heater (for example, manufactured by Noritake Company Limited) may be used. An oil-type or steam-type infrared heater using oil or steam as the heat medium is preferable from the viewpoint of explosion prevention in an atmosphere in which an organic solvent coexists. Moreover, the film temperature and heating temperature at the time of a heating can be measured with the non-contact-type infrared thermometer generally marketed. Further, feedback control may be performed on the heating means in order to control the temperature range.

  As a coating method of these hard coat layers, it can be applied by a known method such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, or an ink jet method.

  It is preferable to apply with a wet film thickness of 0.1 to 100 μm on one surface of the base film using the coating method.

  The hard coat layer may be a single layer or a multilayer structure of two or more layers.

  The hard coat layer may be subjected to the following surface treatment. Examples of the surface treatment method include a cleaning method, an alkali saponification treatment method, a plasma treatment method, an electron beam method, an ion beam method, a sputtering method, an acid treatment, a corona treatment method, and an atmospheric pressure glow discharge plasma method.

  The alkali saponification treatment is generally carried out in a cycle in which the film is immersed in an alkali solution, washed with water and dried. Further, after the alkali treatment, neutralization in an acidic water step may be performed, followed by washing with water and drying. Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the prescribed concentration of hydroxide ions is preferably 0.1 to 3N, and more preferably 0.5N to 2N. Adhesiveness between the hard coat layer and the low refractive index layer can be obtained by setting the content in the above range. The temperature of the alkaline solution is preferably in the range of 25 to 90 ° C., more preferably 40 to 70 ° C., from the viewpoint of precipitation of the alkaline solution. The alkali treatment time is 5 seconds to 5 minutes, preferably 30 seconds to 3 minutes.

  Further, the alkali saponification treatment may be performed by applying an alkali solution to the hard coat layer surface. For example, the methods described in JP-A Nos. 2003-313326 and 2007-332253 may be used.

  Examples of the plasma treatment include flame plasma treatment, atmospheric pressure plasma treatment, and atmospheric pressure plasma treatment. As plasma treatment, plasma treatment techniques disclosed in JP-A-2004-352777, JP-A-2007-314707 and the like can also be referred to.

  Moreover, the pure water contact angle of the hard coat layer surface after the surface treatment is 60 ° or less, for example, when a low refractive index layer is provided on the hard coat layer, the adhesion between the hard coat layer and the hard coat layer is improved. preferable. The contact angle can be measured based on JIS K 2396.

  When the hard coat film manufactured by the above-mentioned manufacturing method is used as a polarizing plate protective film, the thickness of the protective film is preferably 10 to 500 μm, more preferably 20 to 150 μm, and particularly preferably 25 to 90 μm or more. If the hard coat film is thicker than the above range, the polarizing plate after polarizing plate processing becomes too thick, and is not suitable for the purpose of thin and light in liquid crystal displays used for notebook computers and mobile electronic devices. On the other hand, if it is thinner than the above-mentioned region, it is not preferable because it becomes difficult to develop retardation, the moisture permeability of the film becomes high, and the ability to protect the polarizer from humidity decreases.

  The hard coat film produced by the production method of the present invention is preferably used for a polarizing plate protective film. When using as a polarizing plate protective film, the manufacturing method of a polarizing plate is not specifically limited, It can manufacture by a general method. The obtained hard coat film was treated with an alkali, and a polyvinyl alcohol film was immersed and stretched in an iodine solution, and a polarizer protective film was attached to both sides of the polarizer using a completely saponified polyvinyl alcohol aqueous solution on both sides of the polarizer. There is a method of matching, and it is preferable that the hard coat film of the present invention is directly bonded to the polarizer on at least one side.

  Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to the examples.

Example 1
A polyester film with an easy-contact layer having a length of 2600 m, a width of 1.4 m, and a film thickness of 100 μm was prepared as follows, and then a hard coat layer was provided on one surface of the transparent substrate film. A film was prepared.

(Production of polyester film)
Polyethylene terephthalate (PET) resin was melted at 290 ° C. with an extruder, extruded into a sheet form from a T-die, and cooled with a cast drum. Thereafter, the unstretched film was stretched in the longitudinal direction using a roll stretching apparatus at a stretching temperature of 120 ° C. and a stretching ratio of 5 times. Next, a water-based coating material containing a melamine-based crosslinking agent (product number: Nicalac MW-30HM, manufactured by Sanwa Chemical Co., Ltd.) as an easy-contact layer was applied to the obtained longitudinally stretched film by a wire bar coating method. After coating, it was dried and stretched in the transverse direction at a stretching temperature of 110 ° C. and a stretching ratio of 3.0 times with a transverse stretching apparatus to produce a polyester film.

(Coating of hard coat layer)
The surface of the easy-contact layer is die-coated with the following hard coat layer coating composition, dried at 80 ° C. for 5 minutes, then irradiated with 200 mJ / cm ² of ultraviolet light, and further heated at 100 ° C. for 1 minute. A hard coat layer was provided so that the total was 10 μm, and a hard coat film was produced.

<Hard coat layer coating composition>
The following materials were stirred and mixed to obtain hard coat layer coating composition 1.

-Pentaerythritol tri / tetraacrylate (NK ester A-TMM-3L, manufactured by Shin-Nakamura Chemical Co., Ltd.) 80 parts by mass-Isocyanuric acid EO-modified triacrylate (Aronix M-315, manufactured by Toagosei Co., Ltd.) 20 masses・ Irgacure 184 (Ciba Japan Co., Ltd.) 2 parts ・ Polyether-modified polydimethylsiloxane
(BYK-UV3510, manufactured by Big Chemie Japan Co., Ltd.) 1 part by mass • 10 parts by mass of cyclohexanone • 93 parts by mass of methyl ethyl ketone

(Example 2)
A hard coat film of Example 2 was produced in the same manner as in Example 1 except that an oxazoline group-containing polymer (Epocross WS-500, manufactured by Nippon Shokubai Co., Ltd.) was used as the composition component of the easy-contact layer.

(Example 3)
A hard coat film of Example 3 was produced in the same manner as in Example 1 except that blocked isocyanate blocked isocyanate (DURANATE MFK60X, manufactured by Asahi Kasei Chemicals Corporation) was used as the composition component of the easy-contact layer.

Example 4
Melamine-based crosslinking agent (Nikalac MW-30HM, manufactured by Sanwa Chemical Co., Ltd.), oxazoline group-containing polymer (Epocross WS-500, manufactured by Nippon Shokubai Co., Ltd.), block isocyanate (Duranate MFK60X, manufactured by Asahi Kasei Chemicals Co., Ltd.) ) Was used in the same manner as in Example 1 except that the hard coat film of Example 3 was produced.

(Example 5)
A hard coat film of Example 5 was produced in the same manner as in Example 4 except that hydroxyl group-containing epoxy acrylate (Denacol Acrylate DA-314, manufactured by Nagase ChemteX Corporation) was used as the composition component of the hard coat layer. .

(Example 6)
A hard coat film of Example 6 was produced in the same manner as in Example 4 except that hydroxyl group-containing urethane acrylate (purple light, manufactured by Nippon Synthetic Chemical Co., Ltd.) was used as the composition component of the hard coat layer.

(Comparative Example 1)
The hard coat film of Comparative Example 1 was prepared in the same manner as in Example 4 except that dipentaerythritol hexaacrylate containing no hydroxyl group (A-DPH, manufactured by Shin-Nakamura Kagaku Co., Ltd.) was used as the composition component of the hard coat layer. Manufactured.

(Comparative Example 2)
Dipentaerythritol hexaacrylate (A-DPH, manufactured by Shin-Nakamura Kagaku Co., Ltd.) that does not contain a hydroxyl group is used as the composition component of the hard coat layer, and the melamine-based cross-linking agent (Nicalak MW-30HM, Sanwa Chemical Co., Ltd.) In the same manner as in Example 5, except that none of the oxazoline group-containing polymer (Epocross WS-500, manufactured by Nippon Shokubai Co., Ltd.) or blocked isocyanate (Duranate MFK60X, manufactured by Asahi Kasei Chemicals) was used. A hard coat film of Comparative Example 2 was produced.

(Comparative Example 3)
The hard coat film of Comparative Example 3 was prepared in the same manner as in Example 1 except that dipentaerythritol hexaacrylate (A-DPH, manufactured by Shin-Nakamura Scientific Co., Ltd.) containing no hydroxyl group was used as the composition component of the hard coat layer. Manufactured.

(Comparative Example 4)
The hard coat film of Comparative Example 4 was prepared in the same manner as in Example 2 except that dipentaerythritol hexaacrylate (A-DPH, manufactured by Shin-Nakamura Scientific Co., Ltd.) containing no hydroxyl group was used as the composition component of the hard coat layer. Manufactured.

(Comparative Example 5)
The hard coat film of Comparative Example 5 was prepared in the same manner as in Example 3 except that dipentaerythritol hexaacrylate (A-DPH, manufactured by Shin-Nakamura Scientific Co., Ltd.) containing no hydroxyl group was used as the composition component of the hard coat layer. Manufactured.

(Comparative Example 6)
The easy-contact layer composition includes a melamine-based crosslinking agent (product number: Nicalac MW-30HM, manufactured by Sanwa Chemical Co., Ltd.), an oxazoline group-containing polymer (product number: Epocross WS-500, manufactured by Nippon Shokubai Co., Ltd.), block isocyanate (product number: duranate). A hard coat film of Comparative Example 6 was produced in the same manner as in Example 1 except that none of MFK60X (manufactured by Asahi Kasei Chemicals Corporation) was used.

  The following evaluation was performed about the hard coat film of the above Examples 1-6 and the hard coat film of Comparative Examples 1-6.

<< Evaluation of light-resistant adhesion >>
In a method according to JIS K 5400 after light irradiation (24 hours, 48 hours) with a weather resistance tester (I Super UV Tester, manufactured by Iwasaki Electric Co., Ltd.) with the hard coat surface facing up and down at 1 mm intervals 11 cuts were made into 1 mm squares and 100 grids were prepared, and cellophane tape was applied thereto and peeled off quickly at an angle of 90 degrees, and the number of grids remaining without peeling was counted. The remaining squares were evaluated as ◎, 95 to 99 as ○, 80 to 94 as Δ, and less than 80 as ×.

◎: More than 100 remaining cells ○: 95 to 99 remaining cells △: 80 to 94 remaining cells ×: Less than 80 remaining cells

  The above results are shown in Table 1 below.

[Discussion]
From the results of Table 1, the easy-contact layer contains at least one kind selected from a melamine-based crosslinking agent as a thermal crosslinking agent, a blocked isocyanate, and an oxazoline group-containing polymer, and at least one hard coat layer forming material It became clear that Examples 1-6 which contained the polyfunctional acrylate which has OH group, and performed the heat processing after the UV hardening process to the coating process of a hard-coat layer are excellent in light-resistant adhesive evaluation.

  On the other hand, even if the easy-contact layer contains at least one kind selected from a melamine-based crosslinking agent as a thermal crosslinking agent, a blocked isocyanate, and an oxazoline group-containing polymer, the hard coat layer forming material has at least one OH group. Comparative Examples 1 to 5 that did not contain a polyfunctional acrylate having an inferior result were inferior in light-resistant adhesion. Further, Comparative Example 2 in which the easy-contact layer did not contain the above three kinds of thermal crosslinking agents was inferior in light resistance adhesion. Even in the case where a polyfunctional acrylate having at least one OH group is contained in the hard coat layer, the comparative example 6 in which the three kinds of thermal crosslinking agents are not contained in the easy-contact layer is also very light resistant. The result was inferior in adhesion.

Claims (5)

In a method for producing a hard coat film, comprising: a step of forming an easy-contact layer on at least one surface of a transparent film substrate; and a coating step of applying a hard coat layer-forming material on the surface of the easy-contact layer. ,
The coating process includes a coating process for applying the hard coat layer forming material to a transparent film substrate, a UV curing process for UV curing the transparent film substrate after the coating process, and a transparent after the UV process. Including a heat treatment for heating the film substrate,
The easy-contact layer contains at least one selected from a melamine-based crosslinking agent as a thermal crosslinking agent, a blocked isocyanate, and an oxazoline group-containing polymer,
The method for producing a hard coat film, wherein the hard coat layer forming material contains a polyfunctional acrylate having at least one OH group.   The method for producing a hard coat film according to claim 1, wherein the polyfunctional acrylate and the thermal crosslinking agent are reacted in the heat treatment.   The said heat processing are performed at 60-120 degreeC, The manufacturing method of the hard coat film of Claim 1 or 2 characterized by the above-mentioned.   The method for producing a hard coat film according to claim 3, wherein the polyfunctional acrylate is an isocyanuric acid-modified acrylate.   The said transparent film base material is a polyester-type film base material, The manufacturing method of the hard coat film in any one of Claims 1-4 characterized by the above-mentioned.

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