JP2015200815A - Hard coat film and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film made of an ionizing radiation-curable resin composition, which offers superior mechanical properties such as breaking strength and breaking strain.SOLUTION: A hard coat film is produced by coating a support medium with a coating liquid comprising an ionizing radiation-curable resin composition, drying and photocuring the coated liquid, and peeling the cured coating off from the support medium. The hard coat film has a dry film thickness of 15-50 μm, a tensile breaking strain of 30-100% and tensile strength of 40-150 MPa as indicated on a stress-strain curve stipulated in the Japanese Industrial Standards JIS K7161:1994.

Description

  The present invention relates to a hard coat film and a method for producing the same.

  In addition to optical properties, optical films for antireflection applications used in various displays use ionizing radiation curable resins on the surface of transparent substrates in consideration of scratch resistance, chemical resistance, and weather resistance. A hard coat layer was provided. As a base material used for a hard coat film or the like, a base material mainly composed of triacetyl cellulose (TAC), or in recent years, a film using an acrylic resin from the viewpoint of cost or the like is also used. Such transparent substrates and hard coat layers are also required to be thinned, and further higher pencil hardness is also required.

  Due to the thinning of the base material, breakage and wrinkles during the transport of the base material become problems, and as a result, the film thickness uniformity of the hard coat layer becomes unstable. In addition, the hard coat layer and the substrate are thinned, and the hard coat film is curled, and sufficient pencil hardness cannot be obtained.

  In Patent Document 1, in order to achieve both reduction in the thickness of the substrate and increase in hardness, the hardness of the film is increased by adding cellulose nanofibers to the film serving as the substrate. However, it is necessary to provide a hard coat on one side of the film, and it is difficult to cope with further thinning.

JP 2010-197680 A

  The TAC film and the acrylic film used as the base material of the conventional hard coat film are thinned, thereby causing problems such as breakage and wrinkles during transport of the base material. As a result, there is a problem that the film thickness uniformity of the hard coat layer provided on the substrate becomes difficult.

  As a result of intensive studies to solve the above problems, the present inventor has found that this problem can be solved by the following means, and has completed the present invention.

The invention of claim 1 is a hard coat film formed by applying a coating liquid comprising an ionizing radiation curable resin composition on a support, drying, photocuring, and peeling from the support, A hard coat film comprising cellulose nanofibers by coating a coating liquid containing nanofibers on a support, drying, and photocuring, followed by peeling from the support.
This hard coat film is easy to ensure the film thickness uniformity of the hard coat film without causing problems such as breakage and wrinkles during transportation due to the thinning of the substrate. Moreover, in this hard coat film, it is possible to improve breaking strength and elongation at break while improving hardness.

The invention according to claim 2 is the hard coat film according to claim 1, wherein the pencil hardness according to the pencil hardness evaluation method defined in Japanese Industrial Standard JIS K5600-5-4: 1999 is 2H or more. .
By using such a hard coat film, the pencil hardness of the display in which this film is used can be secured.

The invention of claim 3 has a dry film thickness of 15 to 50 μm, a tensile fracture strain of 5 to 40% and a tensile strength of 30 to 100 MPa in the stress-strain curve defined by Japanese Industrial Standard JIS K7161: 1994. The hard coat film according to claim 1 or 2, wherein the hard coat film is provided.
By using such a hard coat film, there are no problems such as breakage in subsequent web handling or single wafer processing.

The invention according to claim 4 is the hard coat film according to any one of claims 1 to 3, wherein the cellulose nanofiber is quaternary alkylamined.
In general, cellulose nanofibers are difficult to mix with water-based resins and become cloudy, but by using cellulose nanofibers that are quaternary alkylamined, they are mixed with ionizing radiation type resin compositions without clouding. Moreover, the hard coat film excellent in transparency and hardness can be provided by using such a cellulose nanofiber. Further, as a secondary effect, it is possible to impart antistatic properties to the hard coat film by adding a quaternary alkylamine.

The invention of claim 5 is a method for producing a hard coat film, comprising preparing a coating liquid comprising an ionizing radiation curable resin composition containing cellulose nanofibers, applying the coating liquid on a support, This is a production method in which a coating liquid applied on a support is dried and photocured to form a film, and a hard coat film is formed by peeling the formed film from the support.
The hard coat film produced by this production method is easy to ensure the film thickness uniformity of the hard coat film without causing problems such as breakage and wrinkles during conveyance due to the thinning of the substrate. In particular, since the transparent substrate and the hard coat formed on the surface thereof are integrally formed, a conventional transparent substrate such as a TAC or an acrylic film is not necessary, and an effect of cost reduction can be obtained. Further, in this method for producing a hard coat film, it is possible to improve the breaking strength and elongation at break while improving the hardness.

  According to the said invention, it is easy to ensure the film thickness uniformity of a hard coat film, without making the problem of the fracture | rupture, wrinkles, etc. at the time of conveyance by thickness reduction of a base material. It is also possible to improve the breaking strength and elongation at break while improving the hardness.

Sectional drawing (before peeling from a support body) of the hard coat film which concerns on one Embodiment of this invention

The present invention relates to a hard coat film 12 obtained by applying, drying and photocuring a coating liquid comprising an ionizing radiation curable resin composition, and peeling it from a support 11 (FIG. 1).
The coating liquid comprising the ionizing radiation curable resin composition forming the hard coat film of the present invention comprises at least (A) an ionizing radiation curable resin composition, (B) a photopolymerization initiator, and (C) cellulose nanofibers. Including.

  Examples of the (A) ionizing radiation curable resin composition used for forming the hard coat film of the present invention include acrylic materials, such as (meth) acrylate compounds such as acrylic acid or methacrylic acid esters of alcohol, Urethane (meth) acrylate compounds such as those synthesized from diisocyanate and alcohol and hydroxyester of acrylic acid or methacrylic acid can be used. Besides these, as ionizing radiation type materials, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be used. . In addition, polyfunctional here means having a functional group which has activity by two or more ionizing radiations in the molecule.

  In the present invention, “(meth) acrylate” refers to both “acrylate” and “methacrylate”. For example, “urethane (meth) acrylate” indicates both “urethane acrylate” and “urethane methacrylate”.

  Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl ( (Meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) ) Acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, benzyl (Meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, phenoxy (meta) ) Acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide modified phenoxy (meth) acrylate, nonylphenol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, propylene oxide modified nonylphenol (meth) acrylate, methoxydiethylene glycol (meth) Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl hydrogen phthalate, 2- (meth) acryloyloxypropyl hydrogen Phthalate, 2- (meth) acryloyloxypropyl hexahydrohydrogen phthalate, 2- (meth) acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate , Hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, 2 -Adamantane derivatives mono (meth) acrylates such as adamantyl acrylate having a monovalent mono (meth) acrylate derived from adamantane and adamantanediol.

  Examples of the bifunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and nonanediol di (meth). Acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di ( (Meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol Di (meth) acrylate, di (meth) acrylate, such as hydroxypivalic acid neopentyl glycol di (meth) acrylate, and the like.

  Examples of the trifunctional or higher functional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris 2-hydroxyethyl. 3 such as tri (meth) acrylate such as isocyanurate tri (meth) acrylate and glycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate Functional (meth) acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra Trifunctional or more polyfunctional (meth) such as (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate Examples thereof include acrylate compounds and polyfunctional (meth) acrylate compounds in which a part of these (meth) acrylates is substituted with an alkyl group or ε-caprolactone.

  Besides these, as ionizing radiation type materials, polyether resins, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. having acrylate functional groups can be used. The material is not particularly limited.

  In addition, since the ionizing radiation curable material is cured by ultraviolet rays, (B) a photopolymerization initiator is added to the coating liquid composed of the ionizing radiation curable resin composition. Any photopolymerization initiator may be used as long as it generates radicals when irradiated with ultraviolet rays. For example, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones are used. Can do. The addition amount of the photopolymerization initiator is 0.1 to 10 parts by weight, preferably 1 to 7 parts by weight, more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the ionizing radiation curable material. Parts by weight.

[Cellulose nanofibers and production method thereof]
(C) Cellulose nanofibers used in the present invention need only have a fiber diameter within the following range, and the adjustment method is not particularly limited. That is, the number average minor axis diameter in the minor axis diameter may be 1 nm or more and 100 nm or less, preferably 2 nm or more and 50 nm or less, more preferably 3 nm or more and 20 nm or less. When the number average minor axis diameter is less than 1 nm, a highly crystalline, rigid and finely divided cellulose fiber structure cannot be obtained, and the hardness of the hard coat film becomes insufficient. On the other hand, when the number average minor axis diameter exceeds 100 nm, transparency is impaired and it becomes difficult to obtain good coating surface properties. As for the major axis diameter, the number average major axis diameter is preferably 20 nm or more, and more preferably 40 nm or more. If the number average major axis diameter is less than 20 nm, the fiber entanglement effect is insufficient and sufficient ductility cannot be obtained. Further, from the viewpoint of improving the effect of the present invention, the number average major axis diameter is more preferably 10 times or more than the number average minor axis diameter.

  The number average minor axis diameter of cellulose nanofibers is obtained as an average value obtained by measuring the minor axis diameter (minimum diameter) of 100 fibers (cellulose nanofibers) through observation with a transmission electron microscope and atomic force microscope. . On the other hand, the number average major axis diameter of cellulose nanofibers is determined by measuring the major axis diameter (maximum diameter) of 100 fibers (cellulose nanofibers) through transmission electron microscope observation and atomic force microscope observation. Desired.

  The type of cellulose that can be used as a raw material for cellulose nanofibers is not particularly limited. For example, in addition to wood-based natural cellulose, non-wood such as cotton linter, bamboo, hemp, bagasse, kenaf, bacterial cellulose, squirt cellulose, and valonia cellulose Natural cellulose, and regenerated cellulose represented by rayon fiber and cupra fiber can be used. From the viewpoint of easy material procurement, it is preferable to use wood-based natural cellulose as a raw material.

  The method for producing cellulose nanofiber is not particularly limited. For example, in addition to mechanical treatment with a grinder, oxidation treatment using N-oxyl compounds such as TEMPO, dilute acid hydrolysis treatment, enzyme treatment, etc. are used in combination with mechanical treatment. Methods for obtaining nanofibers are known. Bacterial cellulose can also be used as the cellulose nanofiber. Furthermore, regenerated cellulose nanofibers obtained by dissolving various natural celluloses in various cellulose solvents and then performing electrospinning may be used. In particular, in an oxidation reaction using an N-oxyl compound such as TEMPO, -CH2OH at the 6th position of the glucopyranose unit of the cellulose molecular chain on the crystal surface is oxidized with high selectivity, and a carboxy group via an aldehyde group. Is converted to Thus, since electrostatic repulsion acts between the cellulose nanofibers having a carboxy group introduced on the crystal surface, cellulose single nanofibers dispersed in microfibril units can be obtained.

  The content of the carboxy group in the cellulose single nanofiber is preferably in the range of 0.1 mmol to 5.0 mmol, and preferably 0.5 mmol to 3.0 mmol, per 1 g of the cellulose single nanofiber. More preferred. When the carboxy group amount is 0.1 mmol / g or more, the dispersion stability is good. When the amount of carboxy group is 5.0 mmol / g or less, the crystal structure of the cellulose single nanofiber is sufficiently retained, and the hardness of the hard coat film to be produced is good.

  Hereinafter, an example of a method for preparing a dispersion of cellulose single nanofibers having a carboxy group introduced by an oxidation reaction using an N-oxyl compound from wood-based natural cellulose will be described. It is not limited to the method. The adjustment method of this example includes a step of oxidizing wood-based natural cellulose with an N-oxyl compound to obtain oxidized cellulose (oxidation step), a step of ammonium chlorinating the carboxyl group of oxidized cellulose (ammonium chloride step), And a step of refining the oxidized cellulose in an aqueous medium to prepare a cellulose single nanofiber dispersion (a refining step).

(Oxidation process)
The wood-based natural cellulose is not particularly limited, and those generally used for producing cellulose nanofibers such as softwood pulp, hardwood pulp, and waste paper pulp can be used. Softwood pulp is preferred because it is easily refined and refined. Examples of N-oxyl compounds include TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy radical), 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, 4 -Methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamido-2,2,6,6 -Tetramethylpiperidine-N-oxyl and the like. Among these, TEMPO is preferable. The amount of the N-oxyl compound used is not particularly limited, and may be an amount as a catalyst. Usually, it is about 0.01-5.0 mass% with respect to solid content of the wood type natural cellulose to oxidize.

  Examples of the oxidation method using an N-oxyl compound include a method in which wood-based natural cellulose is dispersed in water and oxidized in the presence of the N-oxyl compound. At this time, it is preferable to use a co-oxidant together with the N-oxyl compound. In this case, in the reaction system, the N-oxyl compound is sequentially oxidized by a co-oxidant to produce an oxoammonium salt, and cellulose is oxidized by the oxoammonium salt. According to such oxidation treatment, the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of the carboxy group is improved. When the oxidation treatment is performed under mild conditions, it is easy to maintain the crystal structure of cellulose. As the above-mentioned co-oxidant, halogen, hypohalous acid, halous acid, perhalogen acid, or salts thereof, halogen oxide, nitrogen oxide, peroxide, etc. should be able to promote the oxidation reaction. Any oxidizing agent can be used. Sodium hypochlorite is preferred because of its availability and reactivity. The amount of the co-oxidant used is not particularly limited, and may be an amount that can promote the oxidation reaction. Usually, it is about 1-200 mass% with respect to solid content of the wood type natural cellulose to oxidize.

  Along with the N-oxyl compound and the co-oxidant, at least one compound selected from the group consisting of bromide and iodide may be further used in combination. Thereby, an oxidation reaction can be advanced smoothly and the introduction efficiency of a carboxyl group can be improved. As the compound, sodium bromide or lithium bromide is preferable, and sodium bromide is more preferable from the viewpoint of cost and stability. The amount of the compound used is not particularly limited, and may be an amount that can promote the oxidation reaction. Usually, it is about 1-50 mass% with respect to solid content of the wood type natural cellulose to oxidize.

  The reaction temperature of the oxidation reaction is preferably 4 to 50 ° C, more preferably 10 to 40 ° C. When the reaction temperature is less than 4 ° C., the reactivity of the reagent is lowered and the reaction time is prolonged. On the other hand, when the reaction temperature exceeds 50 ° C., the side reaction is promoted to lower the molecular weight of the sample and cause a decrease in viscosity. The reaction time of the oxidation treatment can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy group, and the like, and is not particularly limited, but is usually about 1 to 5 hours.

  The pH of the reaction system during the oxidation reaction is preferably 9-11. When the pH is 9 or more, the reaction can be efficiently carried out. If the pH exceeds 11, side reactions may progress and the decomposition of the sample may be accelerated. In the above oxidation treatment, as the oxidation proceeds, the pH in the system decreases due to the formation of a carboxy group, and therefore the pH of the reaction system is preferably maintained at 9 to 11 during the oxidation treatment. Examples of a method for maintaining the pH of the reaction system at 9 to 11 include a method of adding an alkaline aqueous solution in accordance with a decrease in pH. Examples of alkaline aqueous solutions include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrabutylammonium hydroxide aqueous solution, benzyltrimethylammonium hydroxide aqueous solution, etc. Organic alkalis, and the like.

  The oxidation reaction with the N-oxyl compound can be stopped by adding alcohol to the reaction system. At this time, the pH of the reaction system is preferably maintained at 9-11. The alcohol to be added is preferably a low molecular weight alcohol such as methanol, ethanol or propanol in order to quickly terminate the reaction, and ethanol is particularly preferred from the viewpoint of the safety of by-products produced by the reaction.

  In order to remove a catalyst such as an N-oxyl compound, impurities, and the like, the oxidized reaction solution is recovered from the oxidized cellulose contained in the reaction solution and washed with a cleaning solution. Oxidized cellulose can be collected by a known method such as filtration using a glass filter or a nylon mesh having a 20 μm pore size. In addition, as a cleaning liquid used for cleaning oxidized cellulose, it is preferable to wash in order of hydrochloric acid and distilled water in order to once acidify the alkalized carboxyl group when controlling the pH during the oxidation reaction.

(Ammonium chloride process)
Thereafter, in order to increase the affinity between the produced cellulose single nanofiber and the ionizing radiation curable resin composition, the recovered cellulose single nanofiber is dispersed in distilled water or the like, and then a quaternary alkyl ammonium salt is added. Examples of the quaternary alkylammonium salt at this time include monoalkyltrimethylammonium salt, dialkyldimethylammonium salt, trialkylmonomethylammonium salt, and alkylbenzyldimethylammonium salt, but are not particularly limited.

(Miniaturization process)
Subsequently, the cellulose single nanofiber dispersion is subjected to a physical defibrating treatment to refine the oxidized cellulose. For physical fibrillation treatment, high pressure homogenizer, ultra high pressure homogenizer, ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic homogenizer, nanogenizer, underwater facing collision, etc. Mechanical treatment is mentioned. By performing such physical fibrillation treatment, the oxidized cellulose in the suspension is refined, and a dispersion of cellulose nanofibers having a carboxy group on the fiber surface can be obtained. The number average minor axis diameter and number average major axis diameter of the cellulose single nanofibers contained in the obtained cellulose single nanofiber dispersion liquid can be adjusted by the time and number of times of physical fibrillation treatment at this time.

  The cellulose single nanofiber dispersion liquid thus refined is mixed with an ionizing radiation curable resin composition and a photopolymerization initiator to complete a coating liquid comprising the ionizing radiation curable resin composition.

  Alternatively, after following the ammonium chlorination step and the miniaturization step as described above, the oxidation step is performed, and then the ionizing radiation curable resin composition, the quaternary ammonium salt and the initiator are added, and the above physical fibrillation treatment is performed. May be applied. The number average minor axis diameter and number average major axis diameter of the cellulose single nanofiber can be adjusted depending on the treatment conditions.

  The addition amount of the cellulose single nanofiber in the present invention is preferably 0.1% by mass or more and 40% by mass or less with respect to the ionizing radiation curable resin composition. When the addition amount is 0.1% by mass or less, the effect of addition does not appear, and when the addition amount is 40% by mass or more, the transparency and smoothness of the hard coat film are lost.

  A thermoplastic resin may be added to the coating liquid made of the ionizing radiation curable resin composition used to form the hard coat film of the present invention. Examples include polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, Teflon (registered trademark), ABS resin, polyamide, polyacetalol, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene, polyolefin, polyamide, Polyetheretherketone, polyamideimide, vinyl alcohol and the like can be used, and the material is not particularly limited. In addition, a functional group such as fluoride, sulfonate, or nitride of these materials may be provided as appropriate.

  Furthermore, a solvent can be added to the coating liquid comprising the ionizing radiation curable resin composition as necessary. Solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane and cyclohexylbenzene, hydrocarbons such as n-hexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane, and trioxane. , Ethers such as tetrahydrofuran, anisole and phenetole, and ketones such as methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone , Ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, From esters such as acid n-pentyl and γ-ptyrolactone, cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, cellosolve acetate, alcohols such as methanol, ethanol, isopropyl alcohol, butanol, water, etc. It is appropriately selected in consideration of solubility, coating suitability, drying speed and the like.

  In addition, a surface adjusting agent, a refractive index adjusting agent, an adhesion improver, a curing agent, an antifoaming agent, and the like can be added as an additive to the coating liquid composed of the ionizing radiation curable resin composition. In addition, silica fine particles, acrylic fine particles, metal fine particles, and the like can be added as additives to the coating liquid made of the ionizing radiation curable resin composition in order to further increase the hardness. In addition, a functional material such as an antistatic agent may be added.

  The viscosity of the coating liquid made of the ionizing radiation curable resin composition depends on the selected coating method, but is preferably about 30 to 2000 mPa · sec. When it exceeds 2000 mPa · sec, the flatness of the coating cannot be ensured, and the filtering of the coating liquid and the defoaming process become difficult. If it is less than 30 mPa · sec, the fluidity of the coating film immediately after coating is so great that flatness of coating cannot be ensured. Furthermore, about 50 to 800 mPa · sec is preferable.

  Examples of the defoaming treatment method for the coating liquid comprising the ionizing radiation curable resin composition in the present invention include, but are not particularly limited to, stationary treatment, centrifugal separation, membrane permeation, and defoaming with a multi-screw extruder.

  Examples of the coating method of the coating liquid comprising the ionizing radiation curable resin composition according to the present invention on the support 11 include existing coating methods such as a screen printing method, a doctor blade method, a gravure printing method, a die coating method, and an inkjet method. Can be mentioned. Preferably, a die coating method is used. A coating liquid made of an ionizing radiation curable resin composition is applied to the support 11, dried and photocured, and then peeled from the support 11 to obtain the intended hard coat film 12.

  The hard coat film 12 of the present invention may be formed from a plurality of layers. For example, when formed from two layers, the first layer is applied to the support 11 and dried and cured, and then the second layer is applied, dried and cured, and the first and second layers are simultaneously applied in multiple layers. After drying, there is a method of drying and curing at the same time, but any method may be used. In the case of coating, drying, and curing for each layer, when the first to second layers are cured, the semi-cured structure improves the adhesion at the interface between the layers. In the case of multilayering, the functionality may be changed depending on the layer. For example, the addition amount of cellulose nanofibers may be changed for each layer to adjust the hardness, or an antistatic agent such as quaternary alkylamine may be increased only on the outermost layer.

  For the support 11 in the present invention, a resin film such as a PET film, a smooth and flat drum-type roll, an endless belt, or the like is used.

Moreover, the hard coat film 12 according to the present invention is excellent in tensile and elongation properties, and can be developed for uses other than optical films. For example, it is possible to provide gas barrier properties by forming a SiO ₂ film on the surface. Moreover, use as a transparent conductive film is also possible by forming a transparent conductive film on the surface.

  Cellulose nanofibers used in the following examples were prepared as follows.

(TEMPO oxidation of wood cellulose)
70 g of softwood kraft pulp was suspended in 3500 g of distilled water, and a solution of 0.7 g of TEMPO and 7 g of sodium bromide dissolved in 350 g of distilled water was added and cooled to 20 ° C. 450 g of sodium hypochlorite aqueous solution having a concentration of 2 mol / L and a density of 1.15 g / mL was added dropwise thereto to initiate an oxidation reaction. The temperature in the system was always kept at 20 ° C., and the decrease in pH during the reaction was kept at pH 10 by adding a 0.5N aqueous sodium hydroxide solution. When sodium hydroxide reached 3.00 mmol / g based on the mass of cellulose, an excessive amount of ethanol was added to stop the reaction. Then, it wash | cleaned with 1 mol / L hydrochloric acid using the glass filter, the filtration washing | cleaning by distilled water was repeated, and the oxidized pulp was obtained.

(Example 1)
20 parts by mass of UA122P manufactured by Shin-Nakamura Chemical Co., Ltd., 20 parts by mass of Light Acrylate 9EG-A manufactured by Kyoeisha Chemical Co., Ltd. 5 parts by mass of photopolymerization initiator), 5 parts by mass of oxidized pulp, 1 part by mass of dimethylaminopropylacrylamide methyl chloride quaternary salt manufactured by Kojin Co., Ltd., and 1-methoxy-2-propanol using a planetary ball mill The mixture was dispersed in a mixed solution of propanol and isopropanol and defoamed by applying ultrasonic waves to prepare a coating solution. This coating solution is applied on one side of a PET film (Toray: 75 μm thickness) using a die coater, dried in an oven at 100 ° C. for 60 seconds, and irradiated with ultraviolet rays at an irradiation dose of 300 mJ / m ² using an ultraviolet irradiation device. Was performed to form a transparent hard coat film having a dry film thickness of 45 μm. This formed hard coat film had a tensile fracture strain of 15% and a tensile strength of 45 MPa in a stress-strain curve defined by Japanese Industrial Standard JIS K7161: 1994. The formed hard coat film had a pencil hardness of 2H as defined in Japanese Industrial Standard JIS K5600-5-4: 1999.

(Example 2)
50 parts by weight of epoxy ester 3002A (N) manufactured by Kyoeisha Chemical Co., 50 parts by weight of purple light UV-7605B manufactured by Nippon Synthetic Chemical Co., Ltd., 5 parts by weight of Irgacure 184 (photopolymerization initiator) manufactured by BASF, oxidized pulp 5 parts by mass and 1 part by mass of dimethylaminopropylacrylamide methyl chloride quaternary salt manufactured by Kojin Co., Ltd., each of which is dispersed in a mixture of 1-methoxy-2-propanol and methyl ethyl ketone, and a PET film (Toray Industries, Inc .: The film is coated on one side with a film thickness of 75 μm using a die coater, dried in an oven at 100 ° C. for 60 seconds, and then irradiated with ultraviolet rays at an irradiation dose of 300 mJ / m ² using an ultraviolet irradiation device to obtain a transparent film having a dry film thickness of 45 μm. A film was formed. The formed hard coat film had a tensile fracture strain of 6% and a tensile strength of 50 MPa in a stress-strain curve defined by Japanese Industrial Standard JIS K7161: 1994. The formed hard coat film had a pencil hardness of 2H according to the pencil hardness evaluation method defined in Japanese Industrial Standard JIS K5600-5-4: 1999.

(Comparative Example 1)
The triacetyl cellulose film (film thickness: 40 μm) manufactured by Fuji Film Co., Ltd. had a tensile fracture strain of 15% and a tensile strength of 130 MPa in the stress-strain curve defined by Japanese Industrial Standard JIS K7161: 1994. The triacetyl cellulose film (film thickness 40 μm) manufactured by Fuji Film Co., Ltd. had a pencil hardness of 3B according to the pencil hardness evaluation method defined in Japanese Industrial Standard JIS K5600-5-4: 1999.

  The film thickness uniformity of the hard coat film could be ensured without causing problems such as breakage and wrinkles during conveyance due to the thinning of the substrate. In addition, the transparent base material and the hard coat formed on the surface thereof are integrally produced, and a conventional transparent base material is not required, so that an effect of cost reduction can be obtained. Further, the breaking strength and elongation at break could be improved while improving the hardness.

  The hard coat film of the present invention can be used for an optical film for antireflection used for various displays.

DESCRIPTION OF SYMBOLS 1 ... Hard coat film and support body 11 ... Support body 12 ... Hard coat film

Claims (5)

A hard coat film created by applying a coating liquid comprising an ionizing radiation curable resin composition on a support, drying, photocuring, and peeling from the support,
A hard coat film comprising cellulose nanofibers by coating the coating liquid containing cellulose nanofibers on a support, drying, and photocuring, followed by peeling from the support.   The hard coat film according to claim 1, wherein the pencil hardness according to the pencil hardness evaluation method defined in Japanese Industrial Standard JIS K5600-5-4: 1999 is 2H or more.   The dry film thickness is 15 to 50 μm, the tensile fracture strain in the stress-strain curve defined by Japanese Industrial Standard JIS K7161: 1994 is 5 to 40%, and the tensile strength is 30 to 120 MPa, The hard coat film according to claim 1 or 2.   The hard coat film according to any one of claims 1 to 3, wherein the cellulose nanofiber is quaternary alkylamined. A method for producing a hard coat film, comprising:
Prepare a coating liquid consisting of ionizing radiation curable resin composition containing cellulose nanofibers,
Applying the coating solution onto a support;
The coating liquid applied on the support is dried and photocured to form a film,
The manufacturing method which creates a hard coat film by peeling the formed film from a support.

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