JP2008197670A - Method for manufacturing antireflection film, or antireflection sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an antireflection film or an antireflection sheet which has an antireflection thin film layer provided on its surface and has superior surface strength and further has excellent steel wool resistance and attains pencil hardness of 3H to 4H level, by controlling the elastic modulus of a hard coated layer in a specific range, without having to change its film thickness. <P>SOLUTION: The antireflection film or the antireflection sheet is constituted by laminating a hard coated film layer and the antireflection thin-film layer, consisting essentially of a metal alkoxide and its hydrolyzate on at least one surface of a base material. Furthermore, the elastic modulus of the hard coat layer below destructive distortion is set in the range of 0.7 GPa and 5.5 GPa. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hard coat film or sheet provided with a thin film mainly composed of an antireflection effect on the surface, and particularly as various uses as a display device, specifically a liquid crystal display device, a CRT display device, a plasma. Antireflection film or sheet effective for antireflection of surfaces of various displays such as display devices, electrochromic display devices, light emitting diode display devices, EL display devices, sunglasses, goggles, show windows, window glasses, various instrument covers, etc. About.

  Conventionally, a thin film is formed by dry coating such as vapor deposition or sputtering on an inorganic oxide such as titanium oxide or silicon oxide on a substrate such as glass or plastic, and an optical multilayer film is formed by optical interference such as an antireflection film. How to do is known. However, such a dry coating process has problems that the apparatus is expensive, the film forming speed is low, and the productivity is not high.

  On the other hand, a method is known in which a metal alkoxide or the like is used as a starting composition, and a substrate is wet-coated to form an optical multilayer film. Ti or Zr is used as a high refractive material, Si or the like is used as a low refractive index material. A method using an alkoxide has been proposed.

  In order to impart performance such as scratch resistance, scratch resistance and chemical resistance to the antireflection film and sheet as described above, a hard coat layer is formed as an intermediate layer on the film and sheet base material, It is known to produce a functional film and a sheet imparted with mechanical hardware by providing an optical thin film by a method such as vapor deposition, sputtering or coating.

  However, an optical thin film produced by wet coating can achieve a certain degree of high and low refractive index, but it has insufficient physical strength such as hardness, scratch resistance, and adhesion to the substrate. Since the multilayer film is used as the outermost layer, it has a drawback that it is difficult to withstand practical use if the strength is insufficient.

JP-A-11-52103

  Even when the pencil hardness of about 2H to 3H can be realized by the hard coat layer alone, the hard coat layer and the antireflection film are formed when the antireflection film coating liquid starting from metal alkoxide or the like is provided on the surface by wet coating. There are many problems that the hardness decreases due to insufficient adhesion to the layers, poor balance in hardness between the two layers, and the like.

  Therefore, in the present invention, in producing a film or sheet having an antireflection thin film layer having excellent surface strength, the elastic modulus is controlled within a specific range without changing the film thickness of the hard coat layer. An object of the present invention is to provide an antireflection film or sheet that is excellent in steel wool resistance and realizes a pencil hardness of 3H to 4H.

  In order to solve this problem, the present invention provides a reflection obtained by laminating a hard coat film layer, a metal alkoxide, and an antireflection thin film layer mainly composed of a hydrolyzate thereof on at least one surface of a plastic film or a sheet substrate. In the prevention film or sheet, the elastic modulus is set in the range of 0.7 GPa to 5.5 GPa below the fracture strain of the hard coat layer. The antireflection film or sheet is characterized in that the coating layer has a thickness of 0.5 μm or more and 20 μm or less.

  The hard coat layer is an antireflection film or sheet characterized in that it contains inorganic or organic fine particles having an average particle diameter of 0.01 to 10 μm or both, or the surface has an uneven shape, This hard coat layer can be achieved by a method for producing an antireflection film or sheet, wherein the hard coat layer is cross-linked through a processing step using ultraviolet ray or electron beam irradiation of an active energy ray curable resin.

  The antireflection hard coat film or sheet according to the present invention is excellent in surface hardness, and in particular, by changing its elastic modulus to a specific range without changing the film thickness of the hard coat layer, the pencil hardness is 3H to 4H. Can be realized.

  Hereinafter, the constituent material and manufacturing method of the antireflection film or sheet of the present invention will be described in detail.

  The transparent plastic film or sheet used in the present invention is not particularly limited, and can be appropriately selected from known transparent plastic films or sheets.

  Specific examples include polyester, polyethylene, polypropylene, cellophane, triacetyl cellulose, diacetyl cellulose, acetyl cellulose butyrate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, polystyrene, polycarbonate, polymethylpentene, polysulfone. , Polyether ether ketone, acrylic, nylon, fluororesin, polyimide, polyether imide, polyether sulfone and the like can be mentioned, but in the present invention, triacetyl cellulose film and uniaxially stretched polyester are particularly preferred. In addition to being excellent in transparency, it is preferable in that there is no optical anisotropy.

  For the cured resin coating layer, it is particularly preferable to use an active energy ray-curable resin because of its high processing speed and low thermal damage to the support.

  The active energy ray curable resin is not particularly limited, and can be arbitrarily used as a candidate for hard coating as long as it is a resin that gives a coating film having a pencil hardness of H or more by ultraviolet ray or electron beam curing.

  Examples of such ultraviolet curable resins are synthesized from polyfunctional acrylate resins such as acrylic acid or methacrylic acid ester of polyhydric alcohol, diisocyanate, polyhydric alcohol and hydroxyalkyl ester of acrylic acid or methacrylic acid. Such polyfunctional urethane acrylate resins can be mentioned. Furthermore, 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 suitably used as necessary.

  Reactive diluents for these resins include 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol (meta ) Bifunctional or higher monomers and oligomers such as acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, neopentyl glycol di (meth) acrylate, and monofunctional monomers For example, acrylic esters such as N-vinylpyrrolidone, ethyl acrylate, propyl acrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate , Hexyl methacrylate, isooctyl methacrylate, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, methacrylic acid esters such as nonylphenyl methacrylate, tetrahydrofurfuryl methacrylate, and derivatives thereof such as caprolactone modifications thereof, styrene, α-methylstyrene, Acrylic acid and the like and mixtures thereof can be used.

  In the present invention, when the active energy ray is ultraviolet light, it is necessary to add a photosensitizer (radical polymerization initiator). Benzoins such as ketals and their alkyl ethers; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone; anthraquinones such as methylanthraquinone, 2-ethylanthraquinone, 2-amylanthraquinone Thioxanthones such as thioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone; acetophenone dimethyl ketal, benzyl dimethyl ketal, etc. Tars; benzophenone, 4,4-bis benzophenones such as methylamino benzophenone and azo compounds, and the like.

  These can be used alone or as a mixture of two or more thereof, and further, tertiary amines such as triethanolamine and methyldiethanolamine; benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate, etc. It can be used in combination with a photoinitiator aid or the like. The usage-amount of an organic peroxide or a photoinitiator is 0.5-20 weight part with respect to 100 weight part of polymeric components of the said resin composition, Preferably it is 1-15 weight part.

  Specific examples of metal alkoxide high refractive materials that can be used for an antireflection thin film layer that can be formed by a wet coating method include titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, and titanium tetra-. n-butoxide, titanium tetra-sec-butoxide, titanium tetra-tert-butoxide, zirconium tetraethoxide, zirconium tetra-i-propoxide, zirconium tetra-n-propoxide, zirconium tetra-n-butoxide, zirconium tetra-sec Examples thereof include metal alkoxides of Ti and Zr such as -butoxide and zirconium tetra-tert-butoxide.

  Silicon alkoxide is representative as a low refractive material of metal alkoxide, and specific examples thereof include tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, Tetra-sec-butoxysilane, tetra-tert-butoxysilane, tetrapentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert -Butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyl Le silane, dimethyl silane, dimethyl propoxysilane, dimethyl-butoxy silane, methyl dimethoxy silane, methyl diethoxy silane.

  These metal alkoxides may be subjected to a hydrolysis reaction with moisture in the atmosphere after coating by forming an organic acid catalyst such as P-toluenesulfonic acid in the coating liquid composition containing a solvent. In addition, water (including a catalyst such as hydrochloric acid) added in advance and hydrolyzed can also be used.

  At that time, the hydrolyzate of the metal alkoxide was partially hydrolyzed with 1/8 to 7/8 of the amount of water necessary to hydrolyze all the alkoxyl groups of the metal alkoxide. As a result, a stable composition can be obtained, and it can be used without special separation and purification without leaving excess water.

If necessary, high refractive index inorganic fine particles such as TiO ₂ , ZnO, ITO, SnO ₂ , and low refractive index inorganic fine particles such as MgF ₂ , SiO ₂ can be arbitrarily added to the metal alkoxide for adjusting the refractive index. It is. Further, in order to improve the toughness of the metal alkoxide film and the adhesion to the hard coat layer, a necessary amount of a thermosetting resin, preferably an active energy ray curable resin, may be blended.

  In addition, as an optical function by forming irregularities on the hard coat layer surface, if you want to obtain an antiglare effect, make the hard coat agent contain inorganic or organic fine particles, or form irregularities on the surface by embossing You can reach your goals.

  In particular, inorganic or organic fine particles can be arbitrarily used as long as they maintain fine transparency in the active energy ray-curable resin.

  In general, fine particles made of silica, alumina, titania, zirconia, etc. are used as the inorganic fine particles, and among them, silica particles, particularly synthetic silica particles are preferable from the viewpoint of antiglare property, resolution, hard coat property and the like.

  Conductive transparent fine particles such as tin oxide, indium oxide, cadmium oxide, and antimony oxide can also be used regardless of imparting antistatic properties.

  Further, as the organic fine particles, hard fine particles that have an appropriate crosslinking structure inside the particles and do not swell due to an active energy ray-curable resin, a monomer, a solvent, or the like can be used.

  For example, particle internal cross-linking styrene resin, styrene-acrylic copolymer resin, acrylic resin, divinylbenzene resin, silicone resin, urethane resin, melamine resin, styrene-isoprene resin, benzoguanamine resin, other reactive microgels Etc. can be used. The blending amount of the transparent fine particles is 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight per 100 parts by weight of the active energy ray-curable resin.

  Moreover, a well-known general coating additive can be mix | blended as needed. For example, a silicone-based or fluorine-based additive that imparts leveling, surface slip properties, etc. is effective in preventing scratches on the surface of the cured film. In addition, when using ultraviolet rays as active energy rays, the additive air Bleeding to the interface can reduce the inhibition of curing of the resin by oxygen, and an effective degree of curing can be obtained even under low irradiation intensity conditions.

  Appropriate amounts of these additives are 0.01 to 0.5 parts by weight per 100 parts by weight of the active energy ray-curable resin.

  Although the main constituent materials that can be used in the present invention have been described above, a method for producing a hard coat film or sheet for forming an inorganic thin film will be specifically described.

  The method for applying the hard coat layer is arbitrary, but in the production stage, a roll coater, a reverse roll coater, a gravure coater, a knife coater, a bar coater or the like is generally used.

  When ultraviolet rays are used as an active energy ray source, light sources such as high pressure mercury lamp, low pressure mercury lamp, ultra high pressure mercury lamp, metal halide lamp, carbon arc, xenon arc, etc. can be used. A metal halide lamp is generally used when a filler is included or a thick film is cured.

  In the case of curing using an electron beam, it is emitted from various electron beam accelerators such as a Cockloftwald type, a bandecraft type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type. An electron beam having an energy of ˜1000 KeV, preferably 100 to 300 KeV can be used.

  Next, the present invention will be specifically described with reference to examples.

<Example 1>
EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Parts and% are based on weight unless otherwise specified.

Formation of Hard Coat Layer With respect to the ultraviolet curable resin composition comprising the following hard components, the soft component, which is also an ultraviolet curable resin, has a weight composition ratio of 0%, 10%, 20%, 30%, 60%, A coating composition prepared by blending 100% with 2-butanone so that the resin solid content was 70 wt% was used as a hard coating agent.

(Hard ingredients)
Dipentaerythritol hexaacrylate 8 parts by weight Trimethylolpropane triacrylate 2 parts by weight 1-hydroxycyclohexyl phenyl ketone 0.3 parts by weight

(Soft ingredient)
・ Urethane acrylate oligomer (M-1600, manufactured by Toa Gosei Co., Ltd.)

Next, the ultraviolet curable hard coat agent was applied to one side of a triacetyl cellulose film having a thickness of 80 μm with a wire bar, and the solvent was evaporated to form a coating layer having a thickness of about 5 μm. A hard coat resin layer was produced by curing the ultraviolet light from a high pressure mercury UV lamp (120 W / cm) from the side under the condition of an integrated light quantity of about 400 mJ / m ² . The adhesion between the triacetyl cellulose film and the hard coat layer was good.

Formation of antireflection thin film layer <High refractive index coating composition>
9 parts of hydrolyzed tetraisopropoxide titanium, 1 part of pentaerythritol triacrylate, 0.2 part of 1-hydroxycyclohexyl phenyl ketone as a solid content in a mixed solvent of ethyl acetate / isopropyl alcohol = 1/1 (weight ratio) What was adjusted so that it might become 2 wt% was made into the high refractive index coating composition. The hydrolyzate of tetraisopropoxide titanium is prepared by mixing 2 mol of 0.1N hydrochloric acid and ethyl acetate / isopropyl alcohol = 1/1 (weight ratio) with 1 mol of tetraisopropoxide titanium at room temperature. The hydrolysis reaction was carried out by stirring for 2 hours.

<Low refractive index coating composition>
9 wt. Parts of tetramethoxysilane hydrolyzate, 1 part of pentaerythritol triacrylate, 0.2 parts of 1-hydroxycyclohexyl phenyl ketone in a mixed solvent of ethyl acetate / isopropyl alcohol = 1/1 (weight ratio) as a solid content of 2 wt% What was adjusted so that it might become was set as the low-refractive-index coating composition. The hydrolyzate of tetramethoxysilane is prepared by mixing 2 mol of 0.1N hydrochloric acid and a mixed solvent of ethyl acetate / isopropyl alcohol = 1/1 (weight ratio) with respect to 1 mol of tetramethoxysilane and stirring at room temperature for 2 hours. Thus, a hydrolysis reaction was performed.

The above high and low refractive index coating compositions were applied and stacked on the hard coat layer in the order of high and low by a bar coater, and thermally dried at 100 ° C. for 1 min. cm) of ultraviolet rays under a condition of an integrated light quantity of about 800 mJ / m ² , curing treatment is performed, and the optical film thickness (nd = refractive index n × film thickness d (nm)) is high and low nd = 550/4 nm, respectively. An antireflection thin film layer was formed so that The reflectance at a wavelength of 500 nm was about 0.8%, and the reflectance was about 1% in the range of 430 to 680 nm. The adhesion between the hard coat layer and the antireflection thin film layer was good.

Evaluation Method Table 1 shows the results of measuring and evaluating the mechanical properties of the antireflection film obtained by the above method by the following measurement method.

<Elastic Modulus of Hard Coat Layer>: The elastic modulus (Ef) of the hard coat layer was calculated using the internal stress formula shown below. The elastic modulus (Es) of the polyester film and the elastic modulus (Ec) of the composite film composed of the polyester film / hard coat layer were determined from the initial slope of the stress-strain curve using a tensile strength tester. However, since a crack easily occurs in the hard coat layer, a stress-strain curve below the fracture strain at which the crack occurs is used.

σc (b + d) = σfd + σsb
Ec (b + d) = Efd + Esb
∴Ef = (Ec (b + d) −Esb) / d
σc: internal stress of the entire composite film σf: internal stress of the hard coat layer σs: internal stress of the polyester film Ec: elastic modulus of the entire composite film Ef: elastic modulus of the hard coat layer Es: elastic modulus of the polyester film b: polyester film Thickness d: thickness of hard coat layer

<Pencil hardness>: Using a pencil having a different hardness, the presence or absence of scratches in the test method shown in JIS K5400 was determined under a 1 kg load.

<Scratch resistance>: The surface of the hard coat film was rubbed 10 times with a # 0000 steel wool while applying a load of 400 g, and the presence or absence of scratches and the extent of the scratches were visually observed, according to the following criteria. evaluated.
A: No scratches are observed.
B: Several thin scratches are observed.
C: Countless scratches are observed.

Evaluation Results Table 1 shows the evaluation results of the modulus of elasticity of only the hard coat layer, pencil hardness, scratch resistance, and pencil hardness and scratch resistance in a form in which an antireflection layer is provided on the hard coat layer.

  As the soft component ratio of the hard coat composition increases, the elastic modulus, pencil hardness, and scratch resistance of the hard coat layer decrease. On the other hand, when an anti-reflection thin film layer mainly composed of a hydrolyzate of metal alkoxide is provided on the hard coat layer, the pencil hardness decreases even if the elastic modulus of the hard coat layer is too high or too low. There are various elastic modulus ranges.

  The hard coat layer exhibits the highest pencil hardness within the range of about 0.7 to 5.5 GPa, particularly the soft component is 20 to 30%, and the elastic modulus is about 2.9 to 4.1 GPa. A hardness of 4H superior to 3H, which is the highest hardness of the hard coat layer, was obtained.

  The scratch resistance is less affected by the hard coat layer and mainly depends on the antireflection thin film layer. When the scratches with a pencil formed on the antireflection thin film layer are observed with a microscope, if the elastic modulus of the hard coat is too high, stress is concentrated on the antireflection thin film layer, and only the antireflection thin film layer is scraped off from the surface. Seemed to be.

  When the elastic modulus of the hard coat layer is too low, the entire hard coat and the antireflection thin film layer are scraped off from the triacetyl cellulose surface as a support. On the other hand, if the elastic modulus of the hard coat layer is in the optimum range, stress from the tip of the pencil can be dispersed and absorbed by deformation of the hard coat layer, and stress concentration only on the antireflection thin film layer is relaxed. Can be interpreted.

Claims (10)

  In an antireflection film or sheet in which a hard coat film layer and an antireflection thin film layer mainly composed of a metal alkoxide and a hydrolyzate thereof are laminated on at least one surface of a plastic film, the hard coat layer is destroyed. An antireflection film having an elastic modulus below a strain set in a range of 0.7 GPa to 5.5 GPa.   The antireflection film according to claim 1, wherein the hard coat layer contains fine particles having an average particle diameter of 0.01 to 10 μm.   3. The antireflection film according to claim 1, wherein the hard coat layer has an uneven surface.   4. The antireflection film according to claim 1, wherein the hard coat layer is crosslinked through a processing step by irradiation of active energy rays of an active energy ray curable resin.   The antireflection film according to claim 1, wherein the hard coat layer has a thickness of 0.5 μm or more and 20 μm or less.   An antireflection film or sheet comprising a hard coating film layer and an antireflection thin film layer mainly composed of a metal alkoxide and a hydrolyzate thereof on at least one surface of a plastic sheet substrate. An antireflective sheet, characterized in that the elastic modulus at or below the fracture strain is set in the range of 0.7 GPa to 5.5 GPa.   The antireflection sheet according to claim 6, wherein the hard coat layer contains fine particles having an average particle diameter of 0.01 to 10 μm.   The antireflection sheet according to claim 6 or 7, wherein the hard coat layer has an uneven surface.   9. The antireflection sheet according to claim 6, 7 or 8, wherein the hard coat layer is crosslinked through a processing step by irradiation with active energy rays of an active energy ray curable resin.   The antireflection sheet according to claim 6, 7, 8, or 9, wherein the hard coat layer has a thickness of 0.5 µm or more and 20 µm or less.