JP2006293279A - Optical laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical laminate in which occurrence of interface reflection and interference fringes can be prevented effectively, by substantially eliminating the interface between a translucent base material and a hardcoat layer. <P>SOLUTION: The optical laminate comprises the hardcoat layer provided on the light translucent base material, the interface between the translucent base material and the hardcoat layer having been rendered substantially absent. Further a composition for the hardcoat layer contains a permeable solvent, having permeability to a resin and the translucent base material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical laminate that prevents interface reflection and interference fringes.

  An image display surface in an image display device such as a liquid crystal display (LCD) or a cathode ray tube display device (CRT) is required to reduce reflection due to light rays emitted from an external light source and to improve its visibility. On the other hand, by using an optical laminate (for example, an antireflection laminate) in which an antiglare layer or an antireflection layer is formed on a light transmissive substrate, reflection of the image display surface of the image display device can be achieved. It is common to reduce and improve visibility.

  However, in an optical laminated body in which layers having a large difference in refractive index are laminated, it has often been observed that interface reflection and interference fringes occur at the interface between the layers that overlap each other. In particular, it has been pointed out that when black is reproduced on the image display surface of the screen display device, interference fringes are conspicuously generated, and as a result, the visibility of the image is lowered and the appearance of the image display surface is impaired. Yes. In particular, when the refractive index of the light-transmitting substrate is different from the refractive index of the hard coat layer, interference fringes are likely to occur.

  On the other hand, according to Japanese Patent Laid-Open No. 2003-131007 (Patent Document 1), the refractive index in the vicinity of the interface between the base material and the hard coat layer continuously changes in order to suppress the generation of interference fringes. An optical film characterized by this has been proposed.

However, as a result of confirmation by the present inventors, an optical laminate that substantially eliminates the interface state between the light transmissive substrate and the hard coat layer has not yet been proposed.
JP 2003-131007 A

  At the time of the present invention, the present inventors paid attention to the interface state between the light-transmitting substrate and the hard coat layer, and obtained the knowledge that an optical laminate having substantially no interface was obtained. . Therefore, the present invention effectively prevents the occurrence of interface reflection and interference fringes by substantially eliminating the interface between the light-transmitting substrate and the hard coat layer, and improves visibility and mechanical strength. The object is to provide an optical laminate.

Therefore, the optical laminate according to the present invention is
Comprising a hard coat layer on a light transmissive substrate,
The interface between the light-transmitting substrate and the antistatic layer is substantially absent.

1. Optical laminate
Substantial disappearance of the interface The optical layered body according to the present invention has substantially no interface between the light-transmitting substrate and the hard coat layer. In the present invention, “the interface is (substantially) nonexistent” means that the two layer surfaces overlap each other but there is actually no interface, and there is no interface on both surfaces in terms of the refractive index. This includes cases where it is determined that. As a specific criterion that “the interface is (substantially) absent”, for example, the cross section of the optical laminate is observed with a laser microscope, and there is an interface in the cross section of the laminate where the interference fringes are visually observed. This can be done by measuring that there is no interface in the cross section of the laminate where no interference fringes are visible. Since the laser microscope is capable of non-destructively observing a cross section with a difference in refractive index, a measurement result that there is no interface between materials having no great difference in refractive index occurs. From this, it can be determined that there is no interface between the base material and the hard coat layer from the viewpoint of the refractive index.

  In the present invention, when a mixture of a resin and a permeable solvent is applied onto a light transmissive substrate, the mixture penetrates (wet) into the light transmissive substrate. After that, the resin in the mixture is cured and dried, whereby the permeable solvent evaporates and a hard coat layer is formed on the light-transmitting substrate. It seems not to. Although the mechanism cannot be easily understood, it may be caused by forming a hard coat layer by applying a mixture of the above-described resin and a permeable solvent.

Light-transmitting substrate The light-transmitting substrate may be transparent, translucent, colorless, or colored as long as it transmits light, but is preferably colorless and transparent. Specific examples of the light-transmitting substrate include glass plate; triacetate cellulose (TAC), polyethylene terephthalate (PET), diacetyl cellulose, acetate butyrate cellulose, polyethersulfone, acrylic resin; polyurethane resin; polyester; polycarbonate Polysulfone; polyether; trimethylpentene; polyether ketone; and a thin film formed of (meth) acrylonitrile. According to a preferred embodiment of the present invention, triacetate cellulose (TAC) is preferably mentioned. The thickness of the light-transmitting substrate is about 30 μm to 200 μm, preferably 40 μm to 200 μm.

The hard coat layer “hard coat layer” refers to a layer having a hardness of “H” or higher in a pencil hardness test defined by JIS 5600-5-4 (1999). The thickness of the hard coat layer (during curing) is in the range of 0.1 to 100 μm, preferably 0.8 to 20 μm. The hard coat layer is formed of a resin and an optional component.

1) The resin resin is preferably transparent, and specific examples thereof include an ionizing radiation curable resin that is a resin curable by ultraviolet rays or an electron beam, a mixture of an ionizing radiation curable resin and a solvent-drying resin, Or, there are three types of thermosetting resins, preferably ionizing radiation curable resins.

  Specific examples of the ionizing radiation curable resin include those having an acrylate functional group, for example, a polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene having a relatively low molecular weight. Resins, polythiol polyene resins, oligomers or prepolymers such as (meth) allylates of polyfunctional compounds such as polyhydric alcohols, and reactive diluents, and specific examples thereof include ethyl (meth) acrylate, ethylhexyl (meta ) Monofunctional monomers such as acrylate, styrene, methylstyrene, N-vinylpyrrolidone and polyfunctional monomers such as polymethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) Acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, isocyanuric acid modified Examples include diacrylate, isocyanuric acid-modified triacrylate, and bisphenol F-modified diacrylate.

  Polyfunctional oligomers and polyfunctional polymers can also be preferably used. Examples thereof include urethane acrylate and urethane methacrylate.

  When using an ionizing radiation curable resin as an ultraviolet curable resin, it is preferable to use a photopolymerization initiator. Specific examples of the photopolymerization initiator include acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylchuram monosulfide, and thioxanthones. Further, it is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine and the like.

  The solvent-drying resin used by mixing with the ionizing radiation curable resin mainly includes a thermoplastic resin. As the thermoplastic resin, those generally exemplified are used. By adding the solvent-drying resin, coating film defects on the coated surface can be effectively prevented. According to a preferred embodiment of the present invention, when the material of the transparent substrate is a cellulose resin such as TAC, as a preferred specific example of the thermoplastic resin, a cellulose resin such as nitrocellulose, acetylcellulose, cellulose acetate propionate, Examples thereof include ethyl hydroxyethyl cellulose.

  Specific examples of the thermosetting resin include phenol resin, urea resin, diallyl phthalate resin, melanin resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation resin, silicon resin. And polysiloxane resin. When a thermosetting resin is used, a curing agent such as a crosslinking agent and a polymerization initiator, a polymerization accelerator, a solvent, a viscosity modifier and the like can be further added as necessary.

2) Penetrating solvent The penetrating solvent uses a solvent that is permeable to the light-transmitting substrate. Therefore, in the present invention, the “permeability” of the osmotic solvent is intended to include all concepts such as permeability, swelling property, and wettability with respect to the light transmissive substrate. Specific examples of the permeable solvent include alcohols such as isopropyl alcohol, methanol, and ethanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; chloroform, methylene chloride, Halogenated hydrocarbons such as tetrachloroethane; or a mixture thereof, preferably esters and ketones.

  Specific examples of the osmotic solvent include acetone, methyl acetate, ethyl acetate, butyl acetate, chloroform, methylene chloride, trichloroethane, tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, nitromethane, 1,4-dioxane, dioxolane, N -Methylpyrrolidone, N, N-dimethylformamide, methanol, ethanol, isopropyl alcohol, butanol, isobutyl alcohol, diisopropyl ether, methyl cellosolve, ethyl cellosolve, butyl cellosolve, preferably methyl acetate, ethyl acetate, butyl acetate, methyl ethyl ketone, etc. Is mentioned.

3) Antistatic agent and / or antiglare agent The hard coat layer according to the present invention preferably comprises an antistatic agent and / or an antiglare agent.

Antistatic agent (conductive agent)
Specific examples of the antistatic agent that forms the antistatic layer include quaternary ammonium salts, pyridinium salts, various cationic compounds having a cationic group such as first to third amino groups, sulfonate groups, and sulfate esters. Anionic compounds having anionic groups such as bases, phosphate ester bases, phosphonate bases, amphoteric compounds such as amino acids and aminosulfate esters, nonionic compounds such as amino alcohols, glycerols, and polyethylene glycols, tin And organic metal compounds such as titanium alkoxides and metal chelate compounds such as acetylacetonate salts thereof, and compounds obtained by increasing the molecular weight of the compounds listed above. Coupling having a tertiary amino group, a quaternary ammonium group, or a metal chelate moiety, and a monomer or oligomer polymerizable by ionizing radiation, or a polymerizable functional group polymerizable by ionizing radiation Polymerizable compounds such as organometallic compounds such as agents can also be used as antistatic agents.

Moreover, electroconductive ultrafine particles are mentioned. Specific examples of the conductive fine particles include those made of a metal oxide. Examples of such metal oxides include ZnO (refractive index 1.90, the numerical value in parentheses below represents the refractive index), CeO ₂ (1.95), Sb ₂ O ₂ (1.71), SnO. ₂ (1.997), indium tin oxide (1.95) often referred to as ITO, In ₂ O ₃ (2.00), Al ₂ O ₃ (1.63), antimony-doped tin oxide (abbreviation) ATO, 2.0), aluminum-doped zinc oxide (abbreviation: AZO, 2.0), and the like. The fine particles refer to those having a so-called submicron size of 1 micron or less, and preferably those having an average particle size of 0.1 nm to 0.1 μm.

The antiglare agent may be the same as that described in the section of the antiglare layer described later.

Other Layers The optical layered body according to the present invention is basically composed of a light-transmitting substrate and a hard coat layer formed thereon as described above. However, one or two or more layers described below may be formed on the hard coat layer in consideration of the function or application as an optical laminate.

Antistatic layer The antistatic layer comprises an antistatic agent and a resin. The antistatic agent and the solvent may be the same as described in the hard coat layer.

As specific examples of the resin resin, a thermoplastic resin, a thermosetting resin, an ionizing radiation curable resin, or an ionizing radiation curable compound (including an organic reactive silicon compound) can be used. Although a thermoplastic resin can be used as the resin, it is more preferable to use a thermosetting resin, and more preferably an ionizing radiation curable composition containing an ionizing radiation curable resin or an ionizing radiation curable compound. .

  The ionizing radiation curable composition is a mixture of a polymerizable unsaturated bond or a prepolymer, an oligomer, and / or a monomer having an epoxy group in a molecule. Here, the ionizing radiation refers to an electromagnetic wave or a charged particle beam having an energy quantum capable of polymerizing or crosslinking molecules, and usually an ultraviolet ray or an electron beam is used.

  Examples of prepolymers and oligomers in ionizing radiation curable compositions include unsaturated polyesters such as unsaturated dicarboxylic acid and polyhydric alcohol condensates, and methacrylates such as polyester methacrylate, polyether methacrylate, polyol methacrylate, and melamine methacrylate. Acrylates such as polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polyol acrylate, and melamine acrylate, and cationic polymerization type epoxy compounds.

  Examples of the monomer in the ionizing radiation curable composition include styrene monomers such as styrene and α-methylstyrene, methyl acrylate, 2-ethylhexyl acrylate, methoxyethyl acrylate, butoxyethyl acrylate, and butyl acrylate. Acrylic esters such as methoxybutyl acrylate and phenyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methoxyethyl methacrylate, ethoxymethyl methacrylate, phenyl methacrylate, lauryl methacrylate, etc. , 2- (N, N-diethylamino) ethyl acrylate, 2- (N, N-dimethylamino) ethyl acrylate, 2- (N, N-dibenzylamino) methyl acrylate, acrylic acid- 2- (N, N-diethyla B) Unsaturated substituted amino alcohol esters such as propyl, unsaturated carboxylic acid amides such as acrylamide and methacrylamide, ethylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol di Compounds such as acrylate, triethylene glycol diacrylate, polyfunctional compounds such as dipropylene glycol diacrylate, ethylene glycol diacrylate, propylene glycol dimethacrylate, diethylene glycol dimethacrylate, and / or two or more thiol groups in the molecule Polythiol compounds having, for example, trimethylolpropane trithioglycolate, trimethylolpropane trithiopropylate, pentaerythritol tet And lathioglycolate.

  Usually, as the monomer in the ionizing radiation curable composition, the above compounds are used alone or in combination of two or more as required, but in order to give ordinary application suitability to the ionizing radiation curable composition. In addition, the prepolymer or oligomer is preferably 5% by weight or more, and the monomer and / or polythiol compound is preferably 95% by weight or less.

  When flexibility is required when an ionizing radiation curable composition is applied and cured, it is preferable to reduce the amount of monomer or use an acrylate monomer having 1 or 2 functional groups. When wear resistance, heat resistance, and solvent resistance are required when an ionizing radiation curable composition is applied and cured, ionizing radiation curing such as using an acrylate monomer with three or more functional groups It is possible to design a sex composition. Here, 2-hydroxy acrylate, 2-hexyl acrylate, and phenoxyethyl acrylate are exemplified as those having one functional group. Examples of those having 2 functional groups include ethylene glycol diacrylate and 1,6-hexanediol diacrylate. Examples of the functional group having 3 or more include trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate.

  In order to adjust physical properties such as flexibility and surface hardness when an ionizing radiation curable composition is applied and cured, a resin that is not cured by ionizing radiation irradiation can be added to the ionizing radiation curable composition. . Specific examples of the resin include the following. Thermoplastic resins such as polyurethane resin, cellulose resin, polyvinyl butyral resin, polyester resin, acrylic resin, polyvinyl chloride resin, and polyvinyl acetate. Among these, addition of a polyurethane resin, a cellulose resin, a polyvinyl butyral resin, or the like is preferable from the viewpoint of improving flexibility.

  When hardening after application | coating of an ionizing radiation curable composition is performed by ultraviolet irradiation, a photoinitiator and a photoinitiator are added. As the photopolymerization initiator, in the case of a resin system having a radical polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether and the like are used alone or in combination. In the case of a resin system having a cationic polymerizable functional group, an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a metatheron compound, a benzoin sulfonic acid ester or the like is used alone or as a mixture as a photopolymerization initiator. . The addition amount of a photoinitiator is 0.1-10 weight part with respect to 100 weight part of ionizing radiation-curable compositions.

  In the ionizing radiation curable composition, the following organic reactive silicon compound may be used in combination.

1 of the organosilicon compound can be represented by the general formula R _m Si (OR ′) _n , R and R ′ represent an alkyl group having 1 to 10 carbon atoms, a subscript m of R and a subscript n of OR ′ Each is an integer satisfying the relationship m + n = 4.

  Specifically, tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, tetrapenta Ethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltri Butoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane, methyl Silane, methyl diethoxy silane, hexyl trimethoxy silane and the like.

  The organosilicon compound that can be used in combination with the ionizing radiation curable composition is a silane coupling agent. Specifically, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ- Aminopropyltriethoxysilane, γ-methacryloxypropylmethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropylmethoxysilane / hydrochloride, γ-glycidoxypropyltrimethoxysilane, aminosilane, methyl Methoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, vinyltris (β-methoxyethoxy) silane, octadecyldimethyl [3- (trimethoxysilyl) propyl ] Ammonium chloride, methyltrichlorosilane, dimethyldichlorosilane and the like.

  The thickness of the antistatic layer is preferably about 30 nm to 1 μm.

Antiglare layer The antiglare layer may be formed between the transparent substrate and the hard coat layer or the low refractive index layer. The antiglare layer may be formed of a resin and an antiglare agent, and the resin may be the same as that described in the section of the hard coat layer.

According to a preferred embodiment of the present invention, the antiglare layer has an average particle size of R (μm), a ten-point average roughness of the unevenness of the antiglare layer as Rz (μm), and an unevenness average interval of the antiglare layer. Is Sm (μm), and the average inclination angle of the concavo-convex part is θa, the following formula:
30 ≦ Sm ≦ 600
0.05 ≦ Rz ≦ 1.60
0.1 ≦ θa ≦ 2.5
0.3 ≦ R ≦ 15
It is preferable to satisfy all of these simultaneously.

  According to another preferred embodiment of the present invention, Δn = | n1-n2 | <0.1 is satisfied when the refractive indexes of the fine particles and the transparent resin composition are n1 and n2, respectively. And the anti-glare layer whose haze value inside an anti-glare layer is 55% or less is preferable.

Anti- glare agent Anti-glare agent includes fine particles, and the shape thereof may be spherical or elliptical, and preferably spherical. The fine particles include inorganic and organic particles. The fine particles exhibit anti-glare properties and are preferably transparent. Specific examples of the fine particles include silica beads for inorganic materials and plastic beads for organic materials. Specific examples of plastic beads include styrene beads (refractive index 1.59), melamine beads (refractive index 1.57), acrylic beads (refractive index 1.49), acrylic-styrene beads (refractive index 1.54), Examples thereof include polycarbonate beads and polyethylene beads. The addition amount of the fine particles is about 2 to 30 parts by weight, preferably about 10 to 25 parts by weight with respect to 100 parts by weight of the transparent resin composition.

  It is preferable to add an antisettling agent when adjusting the composition for the antiglare layer. This is because by adding an anti-settling agent, precipitation of the resin beads can be suppressed and the resin beads can be uniformly dispersed in the solvent. Specific examples of the anti-settling agent include silica beads having a particle size of 0.5 μm or less, preferably about 0.1 to 0.25 μm.

  The film thickness (when cured) of the antiglare layer is 0.1 to 100 μm, preferably 0.8 to 10 μm. When the film thickness is within this range, the function as an antiglare layer can be sufficiently exhibited.

Low refractive index layer The low refractive index layer is composed of a resin containing silica or magnesium fluoride, a fluorine resin which is a low refractive index resin, silica or a fluorine resin containing magnesium fluoride, and has a refractive index of It can be composed of a thin film of 1.46 or less, also about 30 nm to 1 μm, or a thin film of silica or magnesium fluoride by chemical vapor deposition or physical vapor deposition. The resin other than the fluororesin is the same as the resin used for constituting the antistatic layer.

  More preferably, the low refractive index layer can be composed of a silicone-containing vinylidene fluoride copolymer. Specifically, this silicone-containing vinylidene fluoride copolymer is a monomer containing 30 to 90% vinylidene fluoride and 5 to 50% hexafluoropropylene (including percentages below, all in terms of mass). It is obtained by copolymerization using the composition as a raw material, and comprises 100 parts of a fluorine-containing copolymer having a fluorine content of 60 to 70% and 80 to 150 parts of a polymerizable compound having an ethylenically unsaturated group. A low refractive index having a refractive index of less than 1.60 (preferably 1.46 or less) which is a thin film having a film thickness of 200 nm or less and is provided with scratch resistance by using this resin composition. Form a layer.

  In the silicone-containing vinylidene fluoride copolymer constituting the low refractive index layer, the proportion of each component in the monomer composition is such that the vinylidene fluoride is 30 to 90%, preferably 40 to 80%, particularly preferably 40 to 40%. 70% and hexafluoropropylene is 5 to 50%, preferably 10 to 50%, particularly preferably 15 to 45%. This monomer composition may further contain 0 to 40%, preferably 0 to 35%, particularly preferably 10 to 30% of tetrafluoroethylene.

  In the above monomer composition, other copolymer components are, for example, in the range of 20% or less, preferably in the range of 10% or less, within the range in which the intended purpose and effect of the silicone-containing vinylidene fluoride copolymer are not impaired. Specific examples of such other copolymerization components are fluoroethylene, trifluoroethylene, chlorotrifluoroethylene, 1,2-dichloro-1,2-difluoroethylene, 2-bromo-3,3,3-trifluoroethylene, 3-bromo-3,3-difluoropropylene, 3,3,3-trifluoropropylene, 1,1,2-trichloro-3,3,3-tri Examples thereof include polymerizable monomers having fluorine atoms such as fluoropropylene and α-trifluoromethacrylic acid.

  The fluorine-containing copolymer obtained from the monomer composition as described above needs to have a fluorine content of 60 to 70%, preferably a fluorine content of 62 to 70%, particularly preferably 64 to 68. %. When the fluorine content is in such a specific range, the fluorine-containing polymer has good solubility in a solvent, and contains such a fluorine-containing polymer as a component. Since it has excellent adhesion to various substrates, it forms a thin film with high transparency and low refractive index and sufficiently excellent mechanical strength, so the scratch resistance of the surface on which the thin film is formed The mechanical properties such as the above can be made sufficiently high, which is extremely suitable.

  The fluorine-containing copolymer preferably has a molecular weight of 5,000 to 200,000, particularly 10,000 to 100,000 in terms of polystyrene-equivalent number average molecular weight. By using a fluorine-containing copolymer having such a molecular weight, the viscosity of the resulting fluorine-based resin composition becomes a suitable size, and therefore surely has a suitable coating property. It can be. The fluorine-containing copolymer preferably has a refractive index of 1.45 or less, particularly 1.42 or less, more preferably 1.40 or less. When a fluorine-containing copolymer having a refractive index exceeding 1.45 is used, a thin film formed from the obtained fluorine-based paint may have a small antireflection effect.

In addition, the low refractive index layer also can be formed of a thin film made of SiO _2, an evaporation method, a sputtering method, or a plasma CVD method or the like, or to form a SiO ₂ gel film from the sol solution containing SiO ₂ sol It may be formed by a method. The low refractive index layer, in addition to SiO ₂ also, the or a thin film MgF _2, but may be configured in other materials, in terms of high adhesion to the lower layer, it is preferable to use a SiO ₂ thin film. Among the above methods, when the plasma CVD method is used, it is preferable to use organosiloxane as a raw material gas under the condition that there is no other inorganic vapor deposition source, and to maintain the deposition target as low as possible. It is preferable.

  According to a preferred embodiment of the present invention, it is preferable to use “fine particles having voids”. The “fine particles having voids” can reduce the refractive index while maintaining the layer strength of the low refractive index layer. In the present invention, the term “fine particles having voids” refers to a structure in which a gas is filled with gas and / or a porous structure containing gas, and the gas in the fine particle is compared with the original refractive index of the fine particle. It means fine particles whose refractive index decreases in inverse proportion to the occupation ratio. The present invention also includes fine particles capable of forming a nanoporous structure inside and / or at least part of the surface depending on the form, structure, aggregation state, and dispersion state of the fine particles inside the coating film. It is.

  As specific examples of the inorganic fine particles having voids, silica fine particles prepared by using the technique disclosed in Japanese Patent Application Laid-Open No. 2001-233611 are preferably exemplified. Since silica fine particles having voids are easy to manufacture and have high hardness, when a low refractive index layer is formed by mixing with a binder, the layer strength is improved and the refractive index is 1.20-1. It is possible to prepare within the range of about 45. In particular, as specific examples of the organic fine particles having voids, hollow polymer fine particles prepared by using the technique disclosed in JP-A-2002-80503 are preferably exemplified.

  The fine particles capable of forming a nanoporous structure inside and / or at least part of the surface of the coating film are manufactured for the purpose of increasing the specific surface area in addition to the silica fine particles, and the packing column and the surface porosity Examples include controlled release materials that adsorb various chemical substances on the mass part, porous fine particles used for catalyst fixation, or dispersions and aggregates of hollow fine particles intended to be incorporated into heat insulating materials and low dielectric materials. it can. As such a specific example, an aggregate of porous silica fine particles and a silica fine particle manufactured by Nissan Chemical Industries, Ltd. were linked in a chain form from the product names Nippon and Nippon manufactured by Nippon Silica Kogyo Co., Ltd. as commercial products. From the colloidal silica UP series (trade name) having a structure, those within the range of the preferable particle diameter of the present invention can be used.

  The average particle diameter of the “fine particles having voids” is 5 nm or more and 300 nm or less, preferably the lower limit is 8 nm or more and the upper limit is 100 nm or less, more preferably the lower limit is 10 nm or more and the upper limit is 80 nm or less. When the average particle diameter of the fine particles is within this range, excellent transparency can be imparted to the low refractive index layer.

Antifouling Layer According to a preferred embodiment of the present invention, an antifouling layer may be provided for the purpose of preventing the outermost surface of the low refractive index layer from being stained, and preferably the light transmissive substrate on which the low refractive index layer is formed. It is preferable that an antifouling layer is provided on the side opposite to one side. The antifouling layer can further improve the antifouling property and scratch resistance with respect to the antireflection laminate.

  Specific examples of the antifouling layer agent include fluorine compounds that have low compatibility with ionizing radiation curable resin compositions having fluorine atoms in the molecule and are difficult to add to the low refractive index layer, and Examples thereof include silicon compounds, ionizing radiation curable resin compositions having fluorine atoms in the molecule, and fluorine compounds and / or siliceous compounds having compatibility with fine particles.

2. Method for producing optical laminate
Adjustment of Liquid Composition Each liquid composition for the antistatic layer, thin layer, hard coat layer and the like may be adjusted by mixing and dispersing the components described above according to a general preparation method. For mixing and dispersing, it is possible to appropriately disperse with a paint shaker or a bead mill.

Specific examples of the coating method of each liquid composition on the surface of the coating light transmissive substrate and the surface of the antistatic layer include spin coating, dipping, spraying, die coating, bar coating, roll coater, Various methods such as a meniscus coater method, a flexographic printing method, a screen printing method, and a speed coater method can be used.

3. Use of optical laminate The optical laminate according to the present invention is used as a hard coat laminate, preferably as an antireflection laminate (including an antiglare laminate). The optical laminate according to the present invention is used for a transmissive display device. In particular, it is used for display displays of televisions, computers, word processors and the like. In particular, it is used on the surface of displays such as CRTs and liquid crystal panels.

  The contents of the present invention will be described in detail with reference to the following examples, but the scope of the present invention should not be construed as being limited to these examples.

Preparation of Hard Coat Layer Composition A hard coat layer composition was prepared by mixing and filtering according to the following composition.
5 parts by weight of urethane acrylate (UV1700B; molecular weight 2000; manufactured by Nihon Gosei Co., Ltd.)
5 parts by weight of polyester acrylate (M9050; molecular weight 418; manufactured by Toagosei Co., Ltd.)
Polymerization initiator 0.4 part by weight (Irgacure 184)
15 parts by weight of methyl acetate

Preparation of optical laminate
Example 1
A wet weight 15 g / m ² (dry weight 6 g / m ² ) of the composition for a hard coat layer was applied to one side of a cellulose triacetate film (thickness 80 μm). It dried for 30 seconds at 50 degreeC, and irradiated the ultraviolet-ray 100mJ / cm < ² >, and prepared the optical laminated body.

Example 2
An optical laminate was prepared in the same manner as in Example 1 except that a cellulose triacetate film having a thickness of 40 μm was used and that methyl acetate was changed to 10 parts by weight of methyl ethyl ketone in the hard coat layer composition.

Comparative Example 1
An optical layered body was prepared in the same manner as in Example 1 except that methyl acetate was changed to 10 parts by weight of toluene in the hard coat layer composition.

Comparative Example 2
An optical laminate was prepared in the same manner as in Example 1 except that methyl acetate was changed to 10 parts by weight of xylene in the composition for hard coat layer.

Evaluation Tests The following evaluation tests were performed on the optical laminates prepared in Examples and Comparative Examples. The results were as described in Table 1 below.

Evaluation 1: Interference fringe presence / absence test On the surface opposite to the hard coat layer of the optical laminate, a black tape for preventing back surface reflection was applied, and the optical laminate was visually observed from the surface of the hard coat layer. Evaluation was based on criteria.
Evaluation criteria Evaluation A: No interference fringes were generated.
Evaluation x: Interference fringes were generated.

Evaluation 2: Interface presence / absence test Using a confocal laser microscope (LeicaTCS-NT: Leica Co., Ltd .: magnification “500 to 1000 ×”), the cross section of the optical laminate was observed through transmission to determine the presence or absence of the interface, and the following evaluation criteria Judged. Specifically, in order to obtain a clear image without halation, a wet objective lens is used for the confocal laser microscope, and about 2 ml of oil having a refractive index of 1.518 is placed on the optical laminate. Judged. The use of oil was used to eliminate the air layer between the objective lens and the optical stack.
Evaluation Criteria Evaluation A: No interface was observed (Note 1).
Evaluation x: An interface was observed (Note 2).
Note 1 and Note 2
Note 1: In all the examples according to the present invention, as shown in FIG. 1, only the interface of the oil surface (upper layer) / hard coat layer (lower layer) is observed, and the interface between the hard coat layer and the light transmissive substrate is observed. Was not.
Note 2: In all of the comparative examples, as shown in FIG. 2, an interface was observed at the boundary between each of the oil level (upper layer) / hard coat layer (middle layer) / light-transmitting substrate (lower layer).

Evaluation 3: Scratch resistance evaluation test The surface of the hard coat layer of the optical laminate was changed to 10 with a predetermined friction load (changed every 200 g within a range of 200 to 1000 g) using # 0000 steel wool. After reciprocating friction, the presence or absence of peeling of the coating film was visually observed and evaluated according to the following criteria.
Evaluation Criteria Evaluation A: There was no peeling of the coating film.
Evaluation x: There was peeling of the coating film.

Table 1
Evaluation 1 Evaluation 2 Evaluation 3
Example 1 ◎ ◎ ◎
Example 2 × ◎ ◎
Comparative Example 1 × × ◎
Comparative Example 2 × × ◎

It is a laser micrograph of the cross section of the optical laminated body by this invention. It is a laser micrograph of the cross section of the optical laminated body by a comparative example.

Claims (6)

An optical laminate comprising a hard coat layer on a light transmissive substrate,
An optical laminate, wherein an interface between the light transmissive substrate and the hard coat layer is substantially absent.   The hard coat layer is formed by using a composition for a hard coat layer that is permeable to the light transmissive substrate, whereby an interface between the light transmissive substrate and the hard coat layer is substantially reduced. The optical layered body according to claim 1, which is not present in a conventional manner.   The optical laminate according to claim 1 or 2, wherein the composition for a hard coat layer comprises a resin and a permeable solvent having permeability to the light transmissive substrate.   The optical laminate according to any one of claims 1 to 3, wherein the hard coat layer comprises an antistatic agent and / or an antiglare agent.   The antistatic layer, the antiglare layer, the low refractive index layer, the antifouling layer, or two or more of these layers are formed on the hard coat layer. Optical laminate.   The optical laminate according to any one of claims 1 to 5, which is used as an antireflection laminate.