JP2008279438A - Laminated film production method and production apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated film production method producing a smooth film at high productivity low costs, and its production apparatus. <P>SOLUTION: The production method for a laminated film having a resin layer having a radiation curing resin includes a layer forming process for arranging a resin forming material layer containing a radiation-curing resin forming material on at least one main surface on a flexible supporter 2, a smoothing process for pressing a mirror roll 5 to the resin layer to smooth the surface of the resin forming material layer, and a curing process for fitting the resin forming material layer to the mirror roll 5 and casting radiation to the resin forming material layer in the state of face-contacting the two to cure the resin forming material layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for producing a laminated film, and more particularly to a method for producing a laminated film having a resin layer containing a radiation curable resin having a smooth surface and an apparatus for producing the same.

  In general, when trying to produce a base film with a highly smooth surface in the production of a base film used for optical films or magnetic recording media, the film surface is scratched by rolls or guides that are in contact with the production process. There is a problem that it cannot be wound well by entraining air. For this reason, a filler or the like is added to the base film to make the surface uneven, and the above problem is solved to produce a base film. However, when used in an optical film, the film surface unevenness causes an optical adverse effect such as scattering of light, and when used in a magnetic recording medium such as a magnetic tape, the film surface unevenness is a magnetic tape or the like. This may affect the smoothness of the surface of the magnetic recording medium and may adversely affect the magnetic recording.

  Magnetic tape, one of the magnetic recording media, has a variety of uses such as audio tape, video tape, and computer tape. Especially in the field of computer tape for data backup, the capacity of the hard disk to be backed up is increased. Along with this, products with a storage capacity of 100 GB or more per volume have been commercialized, and it is indispensable to increase the capacity of the backup tape in order to cope with further increase in the capacity of the hard disk in the future. In addition to the increase in capacity, the cost per storage capacity is also a very important item. The base film used in the magnetic tape is set to have a rough surface property by adding several kinds of fillers in the base film and forming protrusions in order to facilitate winding.

  A general magnetic tape manufacturing process includes a coating / drying process in which a magnetic paint is applied to a base film to form a magnetic layer, a calendar process in which the magnetic layer is smoothed, and a slit process in which the tape is cut. The surface of the magnetic layer after the coating / drying process of the magnetic layer is affected by protrusions present on the base film, and the surface properties become rough. In order to smooth the surface of the magnetic layer, in the calendering process, a smoothing process is performed in which heat and pressure are applied to the magnetic layer with a mirror-finished calender roll. However, there is a problem that the upper limit of the pressure and heat applied to the magnetic layer is subject to mechanical restrictions, and if the smoothing process conditions are excessively strong, the magnetic layer adheres to the calender roll and contaminates the calender roll. . Therefore, it is preferable to use a base film that is smooth and has few protrusions, so that a smooth magnetic layer can be obtained even under appropriate calendar conditions. Actually, it is difficult to obtain a base film that can meet this requirement, so the surface smoothness is not so good, and it is considered that the surface of a normal base film with some protrusions should be smoothed and used. It is done.

For example, as a method for smoothing a flexible support having a rough surface, a smooth coating layer is provided (laminated) on at least one surface of the flexible support, as described in Patent Document 1. Thereafter, a method of manufacturing a magnetic recording medium in which at least one magnetic layer is formed on the smoothing coating layer without winding is proposed.
JP 2004-334988 A

However, the smoothing method of the flexible support shown in Patent Document 1 is not more than a certain thickness because smoothing of the laminated surface side of the laminated film is insufficient as a result when the thickness of the smoothing layer is thin. Smoothing layer is required. In order to reduce the unit price per recording capacity, it is necessary to increase the recording area per cartridge. To that end, the tape is thinned and a longer laminated film is wound up to create a cartridge of a predetermined size. It is necessary to fit in. Therefore, it is preferable that the smoothing layer provided on the flexible support is as thin as possible. Moreover, since the method of patent document 1 is made to harden | cure as it is after apply | coating the smoothing layer on the flexible support body, the surface property of a laminated film is determined by the leveling of the smoothing layer until hardening of a coating film. Will be. Factors that contribute to leveling include the surface tension of the paint, the viscosity of the paint, the yield value of the paint, the time taken from application to curing, and the application method, etc. It is difficult to obtain a smooth surface. (Leveling means that the surface of the liquid (in this case, the coating film) naturally flattens with time according to the influence of its surface tension and other factors described above.)
Further, in the case of obtaining a smoothed laminated film by curing a smoothing layer containing the radiation-curable resin-forming material described in Patent Document 1 with ultraviolet rays that are inexpensive and easy to handle, oxygen concentration must be in an environment where the oxygen concentration is not sufficiently low. In order to inhibit the reactivity of monomers and oligomers that are the raw material of the resin and remain as low molecules, or to cure sufficiently, UV irradiation is required to damage the base film. There are problems that the production speed cannot be increased, and that the running cost is required to exclude oxygen in the ultraviolet irradiation section. The present invention can sufficiently smooth the laminated film even when the thickness of the resin layer containing the radiation curable resin is thin, and can cure the resin-forming material layer without being affected by oxygen. An object of the present invention is to provide a method for producing a laminated film having high productivity, inexpensive and smooth, and a production apparatus suitable for producing the laminated film.

  As a result of intensive studies on a method and an apparatus for producing a base film, the present inventors can achieve the above object by configuring the production method and apparatus for a laminated film as described below, thereby achieving the present invention. It was.

That is, the manufacturing method of the laminated film of the present invention is:
(1) A method for producing a laminated film having a resin layer containing a radiation curable resin, the resin forming material comprising a radiation curable resin forming material on at least one main surface on a flexible support. A layer forming step for providing a layer, a smoothing step for smoothing the surface of the resin-forming material layer by pressing a mirror-like roll against the resin-forming material layer, and contacting the resin-forming material layer with the mirror-like roll. And a curing step of forming the resin layer by irradiating the resin-forming material layer with radiation in a state where both are in surface contact to cure the resin-forming material layer.

  (2) In the method for producing a laminated film as described in (1) above, in the layer formation step, the radiation curable resin-forming material is supplied in a state containing a solvent, and the layer formation step and the smoothing step. It is preferable that the drying process for removing the said solvent is further provided between.

  (3) Moreover, in the manufacturing method of the laminated | multilayer film as described in said (1) term, in the said layer formation process, it is preferable that the said radiation curable resin forming material is supplied in the state which does not contain the solvent.

  (4) Moreover, in the manufacturing method of the laminated | multilayer film of any one of said (1)-(3) term, in the said hardening process, radiation of the resin-forming material layer which is in contact with the mirror surface roll. Irradiation is preferably made from the opposite side through a flexible support.

  (5) Moreover, in the manufacturing method of the laminated | multilayer film as described in any one of said (1), (3), (4) term, the said layer formation process is a mirror roll of resin layer forming material. The resin layer-forming material is formed by forming a liquid reservoir of the resin layer-forming material at the contact point between the mirror roll and the backup roll, which flows down or drops down and contacts through the flexible support. It is preferable to transfer the resin to a flexible support to form a resin layer.

  (6) Moreover, in the manufacturing method of the laminated | multilayer film of any one of said (1)-(3) term or (5) term, in the hardening process which hardens the said resin-forming material layer, it is a mirror surface roll. Is a mirror roll made of a material capable of transmitting radiation, and has a curing means for irradiating the radiation in the mirror roll, and the radiation is preferably irradiated from the resin-forming material layer side in contact with the mirror roll. .

  (7) Moreover, the manufacturing apparatus of the laminated | multilayer film which has a resin layer containing the radiation curable resin of this invention is resin which contains a radiation curable resin forming material on at least one main surface on a flexible support body. A layer forming means for providing a formable material layer; a smoothing means for smoothening the surface of the resin-forming material layer by pressing a mirror roll in surface contact with the resin-forming material layer; and the resin-forming material layer; And a curing means for irradiating the resin-forming material layer with radiation while the mirror roll is in surface contact to cure the resin-forming material layer to form the resin layer.

  (8) In the laminated film manufacturing apparatus according to (7), the radiation curable resin-forming material is supplied to the layer forming unit and the radiation curable resin-forming material contains a solvent. And it is preferable that the drying means for removing the said solvent is further provided between the layer formation means and the smoothing means.

  (9) In the laminated film manufacturing apparatus according to any one of (7) to (8), the resin-forming material layer and the mirror roll are in surface contact. The curing means for curing the resin-forming material layer by irradiating the resin-forming material layer in a state where the resin-forming material layer is irradiated is irradiated through the flexible support from the opposite side of the resin layer in contact with the mirror roll. It is preferable that the radiation irradiation means is installed at the position.

  (10) In the laminated film manufacturing apparatus according to any one of (7) to (8), the mirror roll is a mirror roll made of a material capable of transmitting radiation, It is preferable that the curing means for curing the resin-forming material layer is a radiation irradiation means provided in the mirror surface roll.

  According to the method for producing a laminated film of the present invention, a resin-forming material layer formed on a flexible support is pressed with a mirror roll, so that an extremely smooth surface can be obtained. Thereafter, the resin-forming material layer is irradiated with radiation in a state where the resin-forming material layer and the mirror roll are in contact with each other, so that a smooth surface having a cured resin layer is obtained. Since the resin-forming material layer is pressed with a mirror roll, smoothing is sufficient even when the smoothing layer is thin, rather than using a mirror roll and simply applying a smoothing layer and then curing with light irradiation. In addition, since the resin-forming material layer and the mirror roll are brought into contact with each other and the resin-forming material layer is irradiated with radiation in a state where both are in surface contact with each other, an oxygen exclusion effect is produced and the production efficiency is high. The flexible support can be smoothed. Moreover, in the manufacturing apparatus of the laminated | multilayer film of this invention, the manufacturing apparatus suitable for the manufacturing method of the said laminated | multilayer film of this invention can be provided. The laminated film produced by the production method and production apparatus of the present invention can be suitably used as a base film used for production of optical films, magnetic recording media and the like.

  In order to facilitate understanding of the present invention, a production method and a production apparatus of a laminated film having a resin layer containing the radiation curable resin of the present invention will be specifically described with reference to the drawings. The manufacturing method and the manufacturing apparatus are not limited to the illustrated embodiments.

  FIG. 1 is a conceptual diagram showing a laminated film manufacturing apparatus and manufacturing process according to an embodiment of the present invention.

  The laminated film manufacturing apparatus of this example flexibly supports a resin-forming material layer including a feed roll 1 for feeding a flexible support 2 and a radiation-curable resin-forming material (sometimes abbreviated as paint). Pressing the coater 3 as an application means for applying to the body 2, the dryer 4 as a drying means for removing the solvent contained in the paint for forming the resin-forming material layer, and the resin-forming material layer after application Mirror surface roll 5 that is a smoothing means for smoothing, radiation irradiation device 6 that is a curing means for irradiating and curing a resin-forming material layer containing a radiation-curable resin-forming material, and mirror surface roll 5 And a backup roll 7 that presses the resin layer in cooperation. In the present invention, the “radiation curable resin” of the “resin layer containing the radiation curable resin” is the same as the “radiation curable resin forming material” (paint and The “resin layer” is also referred to as a “resin-forming material layer” before being cured by irradiation with radiation, and the “resin layer” after the state after being cured by irradiation with radiation. In the following description, in each case, they are simplified as “radiation curable resin” and “resin layer”, respectively. Expressed. Although these are the same expressions, these meanings mean that the material before being cured by irradiation with radiation means “radiation-curable resin-forming material” and “resin-forming material layer”, respectively. Those in a state after being cured are meant to be “radiation curable resin” and “resin layer”, respectively. Since these distinctions can be easily interpreted by those skilled in the art from the description of the specification, the above simplified expressions are used unless otherwise specified.

  Next, the operation will be described.

  The flexible support 2 is fed out from the feed roll 1 [an image sectional view of the surface roughness of the flexible support at the position A (partial view: the lower side is not shown in FIG. 5), A coater 3 which is a layer forming means is provided with a resin layer 10 containing a radiation curable resin on its main surface (surface 2a of the flexible support) (see FIG. 6). (Omitted). Thereafter, after the excess solvent is removed by the dryer 4 which is a drying means, the resin layer 10 [image cross-sectional view of the surface roughness of the flexible support at position B (partial view: lower side not shown) ) Is shown in FIG. 6], the surface (the surface 10a of the resin layer) of the backup roll 7 is pressed against the mirror roll 5 which is a smoothing means, and the resin layer 10 is smoothed. The shielding plate 9 prevents the resin layer before being smoothed from being irradiated with radiation. After the smoothing treatment is performed, radiation irradiation is performed via the flexible support 2 by the radiation irradiation device 6 in a state where the resin layer and the mirror roll are in surface contact, and the flexible support 2 A laminated film having a smooth resin layer 10 on the surface is obtained [Image sectional view (partial view: lower side not shown) of the surface roughness of the flexible support at position C is shown in FIG. ]. Since the resin layer is fluid until it is irradiated with radiation, it is easy to smooth when pressed against the mirror roll 5 and is in contact with the mirror roll 5 so that the resin layer and the mirror roll are in surface contact. Since the resin layer is cured by radiation irradiation through the flexible support from the opposite side of the resin layer in contact with the mirror surface roll, an oxygen exclusion effect occurs and the resin layer is easily cured, Release from the mirror surface roll 5 is possible. The smoothed laminated film may be wound, or the next step of providing a functional layer such as an optical layer or a magnetic layer may be sent out without being wound. When heat generated by radiation irradiation damages the laminated film, the mirror roll 5 and the backup roll 7 may have a cooling function as necessary.

Next, the conceptual diagram which shows the manufacturing apparatus and manufacturing process of the laminated | multilayer film which are embodiment of another example of this invention in FIG. 2 was shown. In the manufacturing apparatus of this example, the coating material for forming the resin layer flows down or drops onto the mirror roll 5 with the coater 3, and at the contact point between the mirror roll 5 and the backup roll 7 that are in contact with each other via the flexible support 2. Then, a liquid pool of paint is formed and the paint is transferred to the flexible support 2 to form a resin layer 10 (see FIG. 6, illustration of the resin layer 10 is omitted in FIG. 2). In the present invention, “the contact between the mirror roll and the backup roll that are in contact with each other via a flexible support” (hereinafter, this expression is referred to as (A)) can be expressed strictly as “the surface thereof”. Between the mirror roll in contact with the flexible support through the resin layer-forming material and the flexible support pressed against the mirror roll by the backup roll from the back surface ”(hereinafter this expression is referred to as In the present invention, the expression (B) is abbreviated as the expression (A).
The production apparatus of this example is suitable when using a resin layer forming paint that is not diluted with a solvent, and it is not necessary to provide a special means such as a drying means when forming the layer. The configuration of the manufacturing apparatus can be simplified and the cost can be reduced. Except for the points other than the above, it is the same as the method described in FIG. 1, and the flexible support provided with the resin layer 10 (resin-forming material layer) is transferred to the surface of the resin layer 10 by the backup roll 7. Is pressed against the mirror roll 5 which is a smoothing means, and the resin layer 10 is smoothed. In a state where the resin layer and the mirror roll are in surface contact, radiation irradiation is performed by the radiation irradiation device 6 through the flexible support 2, and the smooth resin layer 10 is formed on the surface of the flexible support 2. The laminated film which has is obtained. In addition, the same parts as those in FIG.

  Next, the conceptual diagram which shows the manufacturing apparatus and manufacturing process of the laminated | multilayer film which are embodiment of another example of this invention in FIG. 3 was shown. In the manufacturing apparatus of this example, the mirror surface roll 5 is made of a material having radiation transparency, and the radiation irradiation device 6 and the shielding plate 9 are installed inside the mirror surface roll 5. In the case of this example, since the resin layer can be irradiated with radiation from the resin layer side without going through the flexible support 2, this method can be used even when the flexible support 2 is not radiolucent. When the radiation is ultraviolet, the mirror roll 5 is made of various inorganic glasses that can transmit ultraviolet rays, and organic glass made of polymethyl methacrylate, polystyrene, polyolefin, polyvinyl chloride, etc. Can do.

  As described above, in the embodiments shown in FIGS. 1 to 3, the embodiment in which the resin layer containing the radiation curable resin is formed only on one side of the flexible support 2 has been described. When a resin layer containing a radiation curable resin is formed on a laminated film in which a resin layer containing a radiation curable resin is formed only on one side of the flexible support 2 in the embodiment shown in FIGS. Once wound up, a resin layer containing a radiation curable resin may be formed on the opposite surface using the same apparatus as shown in FIGS. If it is desired to continuously form a resin layer containing a radiation curable resin on the opposite surface without winding up a laminated film in which a resin layer containing a radiation curable resin is formed only on one side of the flexible support 2 1 to 3 and the like are shown in FIGS. 1 to 3 and the like, with the same device as shown in FIGS. 1 to 3 (provided that the surface on which the resin layer is formed is on the opposite side of the flexible support 2). It is also possible to form a resin layer further containing a radiation curable resin on the opposite surface side of the flexible support 2 in the same manner using an apparatus provided in the series position in one series following the apparatus.

  A conventionally well-known thing can be used as a flexible support body used by this invention. In general, a flexible film made of various synthetic resins can be used. Specific examples include a polyethylene terephthalate film, a polyethylene naphthalate film, a polyamide film, a polyaramid film, a polyimide film, a polycarbonate film, a polyphenylene sulfide film, a polysulfone film, and a polypropylene film. Among them, a polyethylene terephthalate film is preferable from the viewpoint of mechanical strength, dimensional stability, heat resistance, price, and the like, and a biaxially stretched polyethylene terephthalate film is particularly preferable.

  Although there is no restriction | limiting in particular as the thickness of the flexible support body to be used, The thing of 3-150 micrometers is normally used according to a use.

The radiation used in the present invention has a resin curing ability such as electron beam, ultraviolet ray and visible light, and it is preferable to use ultraviolet ray and electron beam having high energy. In particular, an ultraviolet irradiator is inexpensive and easy to handle as an energy source for curing a radiation curable resin. In general, high-pressure mercury or metal halide lamps are used as ultraviolet light sources. The amount of energy required for curing varies depending on the type of lamp, the type of initiator, and the transmittance of the flexible support in the ultraviolet region, but is generally used at 10 to 1000 mJ / cm ² . Generally, ultraviolet irradiation and electron beam irradiation need to be used in an environment having an oxygen concentration of 300 ppm or less.

  When the resin layer is irradiated with ultraviolet rays through a flexible support, it is necessary to consider the ultraviolet transparency of the flexible support. As described above, when performing ultraviolet irradiation, it is necessary to consider the inhibition of curing by oxygen, but in the present invention, since the mirror roll is in close contact with the resin layer in surface contact, ultraviolet irradiation is performed. Curing inhibition by oxygen does not occur.

  Although the electron beam irradiation is expensive and the running cost is high, it is effective because it can be cured even when the flexible support does not transmit ultraviolet rays. As general electron beam irradiation conditions, an acceleration voltage is 50 kV to 500 kV, and an irradiation dose is 50 to 300 kGy. When the flexible support is thick, it is necessary to increase the acceleration voltage. In addition, when the irradiation dose is too large, the flexible support may be damaged. Therefore, it is preferable to select appropriately in accordance with the type of the flexible support within the above range.

  The thickness of the resin layer varies depending on the required level of the surface roughness (projection height) of the flexible support and the final surface roughness of the resin layer, but is preferably 0.02 μm to 5 μm. 0.05 μm to 2 μm is more preferable. If it is this range, the laminated | multilayer film which can endure practical use without excessively costing material can be obtained.

  The roughness of the resin layer surface varies depending on the application, but is preferably 0.5 nm to 5 nm in terms of average line centerline roughness Ra value.

  In addition, the evaluation method of average line centerline roughness was mentioned later.

  In the resin layer, the ratio of the radiation curable resin contained in the resin layer (in the state not containing the solvent before curing) is preferably 10% by weight or more, more preferably 30% by weight or more, and even more preferably 70% by weight or more. Most preferably, all are radiation curable resins.

  This range is preferable because the amount of radiation curable resin is less than 10% by weight and smoothing is not sufficiently performed. The more radiation curable resin, the greater the smoothing effect. The resin layer may contain a resin other than the radiation curable resin, a filler, or the like within a range that does not hinder smoothing. By using the filler in combination, the mechanical strength of the resin layer can be increased, and as a result, the mechanical strength of the base film can be increased.

  The radiation curable resin refers to a resin that reacts by irradiation and polymerizes or crosslinks to increase the molecular weight. As other resins, conventionally known thermosetting resins, thermoplastic resins, and other reactive resins can be selected.

  As the radiation curable resin, conventionally known ones can be used. Among them, it is preferable to use a combination of a low-viscosity monofunctional monomer and a bifunctional or higher monomer having good curability. In addition to the above monomers, conventionally known monomers, oligomers, and prepolymers may be used within a range in which the effects of the present invention can be achieved. Moreover, you may use a photoinitiator, a sensitizer, a promoter, a leveling agent, a mold release agent, a coloring material, a filler, etc. as needed. For example, acrylic monomers and oligomers are often used because there are many types and wide choices. Specific examples include acrylic acid esters, acrylamides, methacrylic acid esters, methacrylic acid amides, allyl compounds, vinyl ethers, vinyl esters, and the like, and these resins are used alone or in combination.

  Monofunctional monomers include N-vinylformamide, N-vinylcarbazole, N-vinylacetamide, N-vinylpyrrolidone, N-vinylcaprolactam and their derivatives, acrylic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl Acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, isooctyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate, methacrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxy acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate , Ethyl carbitol acrylate, phenoxyethyl acrylate, and the like.

  Examples of the bifunctional or higher functional monomer include ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1, 6-hexanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 2-hydroxy-1,3-dimethacryloxypropane, hydroxypioperic acid ester neopentine glycol glycol diacrylate, trimethylolpropane triacrylate, Trimethylolpropane trimethacrylate, trimethylolpropane EO adduct triac Rate, trimethylolpropane PO adduct triacrylate, glycerin EO adduct triacrylate, glycerin EO modified triacrylate, glycerin PO adduct triacrylate, pentaerythritol triacrylate, dipentaerystol hexaacrylate, dipentaerystol polyacrylate , Dipentaerystol hydroxypentaacrylate, trimethylolpropane trimethacrylate, urethane acrylate oligomer, epoxy acrylate oligomer, polyester acrylate oligomer, and the like. In the above, “EO” represents ethylene oxide, and “PO” represents propylene oxide.

  The necessity of the photopolymerization initiator depends on the type of irradiation. In particular, when using ultraviolet rays or visible light as an energy source for the curing reaction, a photopolymerization initiator is required. The photopolymerization initiator is not particularly limited as long as it can be decomposed by light irradiation to generate radicals and start a polymerization reaction, and a general one can be used.

  Among the photopolymerization initiators, examples of the radical photopolymerization agent include α-diketones such as benzyl and diacetyl, acyloins such as benzoin, acyloin ethers such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether, and benzophenone. Benzophenones such as 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, thioxanthones such as thioxanthone, 2,4-diethylthioxanthone, thioxanthone-4-sulfonic acid, Michler's ketones , Acetophenone, 2- (4-toluenesulfonyloxy) -2-phenylacetophenone, p-dimethylaminoacetophenone, α, α′-dimethoxyacetoxybenzophenone, 2,2′-dimethoxy-2- Phenylacetophenone, p-methoxyacetophenone, 2-methyl [4- (methylthio) phenyl] -2-morpholino-1-propanone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane-1 Acetophenones such as -one, quinones such as anthraquinone and 1,4-naphthoquinone, phenacyl chloride, trihalomethylphenylsulfone, halogen compounds such as tris (trihalomethyl) -s-triazine, acylphosphine oxides, di-t -Peroxides such as butyl peroxide.

  The radiation curable resin may form a coating film on a flexible support in a state containing a solvent, and in that case, as described above, a resin layer forming step and a smoothing step, In the meantime, a drying step for removing the solvent is further provided. In particular, when the film thickness of the resin layer is reduced, if a radiation curable resin is supplied in a state containing a solvent, a thin layer can be easily formed. The ratio of the solvent in this case varies depending on the type of resin used, whether it is a monomer or an oligomer, but is 1 to 3000% by weight with respect to the radiation curable resin-forming material (weight basis in the state not containing the solvent). A range is preferred.

  On the other hand, in the case of using a relatively high viscosity resin layer forming paint that is not diluted with a solvent, it is not necessary to provide a special means such as a drying means. Can be

  In the case of performing ultraviolet irradiation, for example, in the case of irradiating ultraviolet light through a flexible support as in the embodiment shown in FIGS. 1 and 2, it is possible to select a photopolymerization initiator according to the wavelength to be transmitted. Preferably, for example, when the material of the flexible support is polyethylene terephthalate or polyethylene naphthalate, each flexible support such as “Irgacure 369”, “Irgacure 819”, “Irgacure 907” (manufactured by Ciba Geigy) It is preferable to select a photopolymerization initiator having absorption in a wavelength region that does not overlap with the absorption wavelength.

Moreover, as a filler, a conventionally well-known inorganic filler and an organic filler can be included. Specific examples of the filler include, for example, carbon black, graphite, TiO ₂ , BaSO ₄ , ZnS, MgCO ₃ , CaCO ₃ , ZnO, CaO, WS ₂ , MoS ₂ , MgO, SnO ₂ , Al ₂ O ₃ , Fe, α-Fe ₂ O ₃ , α-FeOOH, SiC, CeO ₂ , BN, SiN, MoC, BC, WC, titanium carbide, corundum, artificial diamond, garnet, garnet, quartzite, triboli, diatomite, dolomite, silica And inorganic fillers such as aluminosilicate, zeolite, acid clay, activated clay, and organic fillers such as polyethylene resin particles, fluorine resin particles, guanamine resin particles, acrylic resin particles, silicone resin particles, melamine resin particles, etc. .

  There is no restriction | limiting in particular as a method of providing a resin layer on a flexible support body, A conventionally well-known layer formation means can be used. For example, the resin layer can be provided by a conventionally known coating means such as gravure coating or die coating. Further, as a layer forming method other than coating, a resin layer forming coating material is allowed to flow down or dripped onto a flexible support or a mirror roll, and the resin layer forming coating material that has flowed down or dropped is applied to the flexible support. Spreading in the width direction at the contact point between the mirror roll and the backup roll that are in contact with each other, adjusting the supply amount of the resin layer forming paint, the conveyance speed of the flexible support, the pressing condition between the mirror roll and the backup roll, etc. It is also possible to provide a resin layer on the flexible support so that a liquid pool is stably formed at the contact point between the mirror roll and the backup roll that are in contact with each other via the flexible support. Similarly, the resin layer forming coating material flows down or drops onto the mirror roll, and the width direction is applied at the contact point between the mirror roll and the backup roll that contacts the flowing or dropped resin layer forming coating material through a flexible support. The resin layer can be provided on the flexible support while spreading the resin layer, forming a liquid reservoir, and transferring the resin layer-forming coating material onto the flexible support.

As the mirror roll, a metal roll, a glass roll, a quartz roll, a resin roll, or the like can be used. The surface roughness of the roll needs to be smoother than the target surface roughness of the base film. The surface roughness of the mirror roll varies depending on the target surface roughness of the base film, but is preferably in the range of 0.5 to 5 nm in terms of the centerline average roughness Ra. Since the mirror roll used in the present invention is usually relatively large and has a cylindrical surface, it is difficult to obtain an accurate surface roughness. In the present invention, the surface roughness of the mirror surface roll was determined by the following method. That is, an appropriate ultraviolet curable resin (such as the ultraviolet curable resin used for the resin layer of the laminated film of the present invention) is allowed to flow down to the surface of the mirror roll, a transparent film is placed on the surface, and the film is pushed onto the mirror roll. After curing the resin by irradiating ultraviolet rays from above the film, the film was peeled off from the mirror roll and the surface roughness of the resin surface in contact with the mirror roll was measured using an atomic force microscope (AFM): Digital "Nano scope IIIa" manufactured by Instruments,
Measurement mode: Tapping mode Measurement conditions: Observation field of view about 10 μm × 10 μm, 512 scanning probe at an observation rate of 0.5 Hz: NCH-10V, cantilever length: 125 μm, frequency: 300-350 kHz,
The centerline average surface roughness Ra is measured under the conditions described above to obtain the surface property of the mirror roll.

  The pressing condition of the backup roll is determined by the pressure of the resin layer and the ease of plastic deformation by heat. The temperature is 5 to 100 ° C. and the pressure is in the range of 0.001 to 200 kN / m. What is necessary is just to select suitably according to the kind of press method. If these ranges are deviated, the usage conditions may be restricted, or the resin layer may not be sufficiently smoothed. Therefore, the conditions in the above ranges are preferred.

  Moreover, you may coat a mold release agent on a mirror surface roll. A well-known thing can be used as a mold release agent. For example, saturated fatty acid ester, unsaturated fatty acid ester, polyolefin wax (polyethylene wax, 1-alkene polymer, etc., which may be modified with a functional group-containing compound such as acid modification), silicone compound, fluorine compound (E.g., fluorine oil represented by polyfluoroalkyl ether), paraffin wax, beeswax and the like.

  The contact time of the resin layer to the mirror roll is the type of radiation curable resin to be used, the type of radiation to be irradiated, the irradiation intensity of the radiation, the thickness of the resin layer, and whether to irradiate radiation through a flexible support. However, since it changes depending on the type and thickness of the flexible support in that case, it cannot be defined unconditionally. Of course, it is preferable that the contact is made for a time required for the radiation curable resin to be cured by irradiation. Although not particularly limited, it is about 0.1 to 6 seconds.

  As the backup roll, a rubber roll, a metal roll, a resin roll, a carbon roll (carbon fiber reinforced plastic roll) or the like can be used as a material. The surface of the backup roll needs to be smooth to some extent. If the surface property is rough, the surface roughness of the backup roll becomes uneven pressing, resulting in uneven thickness of the resin. Further, the backup roll is not always necessary, and when the resin layer is sufficiently soft, it is sufficiently smoothed only by the wrapping pressure of the mirror surface roll.

[Example]
EXAMPLES The present invention will be described in detail below by examples, but the present invention is not limited to these.

Example 1
Using the apparatus shown in FIG. 1, a resin layer was provided on the flexible support under the conditions described in Table 1, and a smoothing step and a curing step were performed to produce a laminated film. The mirror roll 5 had a diameter of 170 mmφ, the center line average roughness Ra was 1.0 nm, and the backup rolls 7 and 7 each had a diameter of 80 mmφ. The coater 3 used a trade name “Microgravure” (manufactured by Yasui Seiki Co., Ltd.), and was applied so that the thickness after the smoothing step was 1 μm. The thickness was measured at 5 points using a Mitutoyo micrometer, and the average value was taken as the thickness. The resin layer forming paint is an acrylic ultraviolet curable paint (trade name “SEICA BEAM EXF-01B” (viscosity 130 mPa · s, manufactured by Dainichi Seika)) with organic solvent MEK (methyl ethyl ketone) to form a resin layer. The coating was performed by diluting the concentration to 60 wt%. The drying temperature in the dryer 4 was 100 ° C., and the drying time was 30 seconds. Pressurization by the backup roll 7 was performed at room temperature at 20 kN / m. The radiation irradiation apparatus 6 was performed using a UV irradiation machine (measured with a UV meter manufactured by Eye Graphics, under the condition of an irradiation amount of 100 mJ / cm ² ). The contact time of the laminated film to the mirror roll 5 was 6 seconds.

  As the flexible support, a polyethylene terephthalate film (trade name “Lumirror” thickness 6 μm, manufactured by Toray Industries, Inc.) was used.

Example 2
A laminated film was produced in the same manner as in Example 1 except that the thickness of the resin layer was changed to 0.5 μm and the solid content (resin layer) concentration was 30 wt%.

Example 3
A laminated film was produced in the same manner as in Example 1 except that the thickness of the resin layer was changed to 0.1 μm and the solid content (resin layer) concentration was 10 wt%.

Example 4
A laminated film was produced in the same manner as in Example 1 except that the thickness of the resin layer was changed to 0.05 μm and the solid content (resin layer) concentration was 5 wt%.

Example 5
The resin layer forming paint is diluted with UV-curable paint "Desolite KZ7501" (manufactured by JSR Corporation) containing inorganic filler with organic solvent MEK (the solid content concentration of the paint that forms the resin layer does not include inorganic filler) This is the same as Example 1 except that the thickness of the resin layer after drying is adjusted to 1 μm.

Example 6
Using the apparatus shown in FIG. 2, the resin layer-forming coating material was directly flowed down to a mirror surface roll without being diluted with a solvent to form a resin layer. The amount of flow down was controlled so that the thickness after the smoothing step was 1 μm. The pressure condition by the backup roll 7 is 20 kN / m, and the coating material for forming the resin layer to be used is an ultraviolet curable coating (trade name “SEICA BEAM EX-01B” (manufactured by Dainichi Seika)) as described above. Used without dilution. A laminated film was produced in the same manner as in Example 1 except for the above conditions.

Example 7
A laminated film was produced in the same manner as in Example 6 except that the flow amount was controlled so that the thickness after the smoothing step was 0.1 μm, and the pressure condition by the backup roll 7 was 200 kN / m.

Example 8
A laminated film was produced in the same manner as in Example 6 except that the flow amount was controlled so that the thickness after the smoothing step was 0.05 μm, and the pressure condition by the backup roll 7 was 400 kN / m.

Comparative Example 1
Using the apparatus for the conventional method shown in FIG. 4, the coating material for forming the resin layer is naturally leveled and smoothed between the coater 3 and the dryer 4 in FIG. 4 without performing the smoothing process by the mirror roll. The method is adopted.

  A laminated film was produced in the same manner as in Example 1 except for the drying temperature in the dryer 4, the drying time, and the conditions other than the above, such as the irradiation amount by the UV irradiation machine of the radiation irradiation device 6.

Comparative Example 2
Using the apparatus for the conventional method shown in FIG. 4, the coating for forming the resin layer is naturally leveled and smoothed between the coater 3 and the dryer 4 in FIG. 4 without performing the smoothing process by the mirror roll. A laminated film was produced in the same manner as in Comparative Example 1 except that the method was adopted and the curing step was performed with the UV irradiated portion in a nitrogen gas atmosphere.

Comparative Example 3
A laminated film was produced in the same manner as in Comparative Example 2 except that the thickness of the resin layer was changed to 0.5 μm and the solid content (resin layer) concentration was 30 wt%.

Comparative Example 4
A laminated film was produced in the same manner as in Comparative Example 2 except that the thickness of the resin layer was changed to 0.1 μm and the solid content (resin layer) concentration was 10 wt%.

Comparative Example 5
A laminated film was produced in the same manner as in Comparative Example 2 except that the thickness of the resin layer was changed to 0.05 μm and the solid content (resin layer) concentration was 5 wt%.

<Evaluation of surface roughness>
The surface roughness of the laminated film of the sample was measured under the following conditions using “Nano scope IIIa” manufactured by Digital Instruments.
Measurement mode: Tapping mode Measurement conditions: Observation field of view about 10 μm × 10 μm, 512 scanning probe at an observation rate of 0.5 Hz: NCH-10V, cantilever length: 125 μm, frequency: 300-350 kHz,
The centerline average surface roughness Ra value was used for evaluation of smoothness.
The evaluation results are shown in Table 1.

<Young's modulus measurement>
A sample for measurement having a length of 12 cm and a width of 1 cm was cut out from the longitudinal direction of the laminated film of the sample, the stress at 1% elongation was measured with a tensile tester at a measurement length of 10 cm, and the Young's modulus was obtained.

  As is apparent from Table 1, the same smoothing process was not performed by the smoothing process by the mirror roll pressing performed in Examples 1, 2, 3, 4, 5, and 6. Compared with 4, 5, a smooth resin layer could be obtained. Further, although Comparative Example 1 remained uncured, Examples 1, 2, 3, 4, 5, and 6 were irradiated with ultraviolet rays in a nitrogen gas atmosphere due to the exclusion of oxygen due to the mirror roll pressing effect of the smoothing treatment. However, it could be cured sufficiently. In order to express the effect of the smoothing treatment based on the experimental results in Table 1 in FIG. 8, graphs showing the relationship between the resin layer thickness and the surface roughness are shown in Example (black dot line graph) and Comparative Example (white). (Dot line graph). 8, a, b, and c are Examples 1, 5, 6, and d are Example 2, e is Example 3, f is Example 4, H is Comparative Example 2, I is Comparative Example 3, and J is Comparative Examples 4 and K correspond to Comparative Example 5, and L corresponds to the surface roughness of the raw material film not provided with the resin layer. Comparing f and K in the graph, it can be seen that the surface roughness is greatly improved when manufactured by the manufacturing method satisfying the configuration of the present application while having the same resin layer thickness.

  In addition, this invention is not limited only to the above-mentioned Example, Of course, it can add in the range which does not deviate from the summary of this invention.

  The present invention is capable of smoothing the laminated film even when the thickness of the resin layer containing the radiation curable resin is thin, and is capable of curing the resin layer without being affected by oxygen. Since it is possible to provide a method for producing a high, inexpensive and smooth laminated film and a production apparatus suitable for producing the laminated film, it can be effectively used for producing a magnetic recording medium, an optical film and the like.

BRIEF DESCRIPTION OF THE DRAWINGS The conceptual diagram which shows the manufacturing apparatus of a laminated film which is an embodiment of an example of this invention, and a manufacturing process. The conceptual diagram which shows the manufacturing apparatus and manufacturing process of the laminated | multilayer film which are embodiment of another example of this invention. The conceptual diagram which shows the manufacturing apparatus and manufacturing process of the laminated | multilayer film which are embodiment of another example of this invention. The conceptual diagram which shows the manufacturing apparatus and manufacturing process of a laminated | multilayer film which are embodiments of an example of the prior art which does not have a smoothing process. FIG. 2 is an image cross-sectional view (partial view) showing roughness of the surface of a flexible support at position A in FIG. 1. FIG. 2 is an image cross-sectional view (partial view) showing roughness of the surface of a flexible support at position B in FIG. 1. FIG. 2 is an image cross-sectional view (partial view) showing roughness of a surface of a flexible support at a position C in FIG. 1. The graph which shows the relationship between the resin layer thickness for expressing the effect of the smoothing process based on the experimental result of Table 1, and surface roughness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Feeding roll 2 Flexible support body 2a Surface of flexible support body 3 Coater 4 Dryer 5 Mirror surface roll 6 Radiation irradiation apparatus 7 Backup roll 9 Shielding plate 10 Resin layer 10a Surface of resin layer

Claims (10)

  A method for producing a laminated film having a resin layer containing a radiation-curable resin, wherein a resin-forming material layer containing a radiation-curable resin-forming material is provided on at least one main surface on a flexible support. A layer forming step, a smoothing step of smoothing the surface of the resin-forming material layer by pressing the mirror-like roll against the resin-forming material layer, and abutting the resin-forming material layer and the mirror-like roll, And a curing step of irradiating the resin-forming material layer in a surface contact state to cure the resin-forming material layer to form the resin layer.   In the layer forming step, the radiation curable resin-forming material is supplied in a state containing a solvent, and a drying step for removing the solvent is further provided between the layer forming step and the smoothing step. The method for producing a laminated film according to claim 1.   The method for producing a laminated film according to claim 1, wherein in the layer forming step, the radiation curable resin-forming material is supplied in a state not containing a solvent.   The manufacturing method of the laminated | multilayer film of any one of Claims 1-3 in which the radiation is irradiated through the flexible support body in the said hardening process from the opposite side of the resin layer which is in contact with the mirror surface roll.   In the layer forming step, the resin layer forming material is dropped or dropped onto a mirror roll, and the resin layer formability is formed at a contact point between the mirror roll and the backup roll which are in contact with each other via the flexible support. 5. The laminate according to claim 1, wherein a resin layer is formed by forming a liquid pool of the material and transferring the resin layer-forming material to a flexible support. A method for producing a film.   In the curing step of curing the resin-forming material layer, the mirror roll is a mirror roll made of a material capable of transmitting radiation, and has a curing means for irradiating the radiation in the mirror roll, and the radiation is in contact with the mirror roll. The manufacturing method of the laminated | multilayer film of any one of Claims 1-3 or 5 irradiated from the resin layer forming material side which is.   An apparatus for producing a laminated film having a resin layer containing a radiation curable resin, wherein a resin-forming material layer containing a radiation curable resin-forming material is provided on at least one main surface on a flexible support. Layer forming means, smoothing means for bringing the mirror-forming roll into surface contact with the resin-forming material layer and pressing the surface to smooth the surface of the resin-forming material layer, and the resin-forming material layer and the mirror roll are surfaces. A laminated film manufacturing apparatus, comprising: a curing unit configured to irradiate the resin-forming material layer in a contact state and cure the resin-forming material layer to form the resin layer.   The radiation curable resin forming material supplied to the layer forming means is a radiation curable resin forming material containing a solvent, and the solvent is interposed between the layer forming means and the smoothing means. The apparatus for producing a laminated film according to claim 7, further comprising drying means for removing the laminated film.   Curing means for curing the resin-forming material layer by irradiating the resin-forming material layer with radiation while the resin-forming material layer and the mirror roll are in surface contact with the mirror roll. The resin containing a radiation curable resin according to any one of claims 7 to 8, which is a radiation irradiation means installed at a position irradiated from the opposite side of the resin-forming material layer through a flexible support. An apparatus for producing a laminated film having a layer.   The said mirror surface roll is a mirror surface roll which consists of a material which can permeate | transmit a radiation, The hardening means to harden the said resin-forming material layer is a radiation irradiation means provided in the said mirror surface roll, Either of Claims 7-8 The manufacturing apparatus of the laminated film of 1 item | term.

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