JP2006098666A - Optical laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical laminate which effectively prevents generation of interfacial reflection and interference fringes on the interface between a light-transmitting substrate and a hard coat layer. <P>SOLUTION: The optical laminate has a hard coat layer on a light-transmitting substrate. The light-transmitting substrate is made of triacetate cellulose, and the hard coat layer is made of a mixture of (1) a modified pentaerythritol acrylate resin having over four functional groups, (2) an isocyanuric acid-modified acrylate resin or bisphenol-modified acrylate resin having three or less functional groups, and a permeable solvent. The refractive index, near the interface between the light-transmitting substrate and the hard coat layer, is varied in a stepwise manner. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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, the present inventors have confirmed that a specific light-transmitting substrate and a hard coat layer are combined, and the refractive index near the interface between the light-transmitting substrate and the hard coat layer changes continuously. An optical laminate characterized by this has not been proposed yet.
JP 2003-131007 A

  The inventors have improved the interface state between the light-transmitting substrate and the hard coat layer by combining the composition constituting the hard coat layer with a specific combination at the time of the present invention. The inventors have obtained knowledge that an optical laminate having improved mechanical strength and curl resistance of the optical laminate can be 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 provides visibility, mechanical strength, and curl resistance. An object of the present invention is to provide an optical layered body with improved performance.

Therefore, the optical laminate according to the present invention is
A hard coat layer is provided on a light transmissive substrate,
The light transmissive substrate is triacetate cellulose;
The hard coat layer is
(1) a modified pentaerythritol acrylate resin having more than 4 functional groups;
(2) formed of a mixture of an isocyanuric acid-modified acrylate resin or bisphenol-modified acrylate resin having a functional group of 3 or less, and a penetrating solvent;
The refractive index in the vicinity of the interface between the light-transmitting substrate and the hard coat layer is changed stepwise.

An optical laminate according to another aspect of the present invention is provided.
An optical laminate comprising a hard coat layer on a light transmissive substrate,
The light-transmitting substrate is polyethylene terephthalate;
The hard coat layer is
(1) a modified pentaerythritol acrylate resin having more than 4 functional groups;
(2) formed of a mixture of an isocyanuric acid-modified acrylate resin or bisphenol-modified acrylate resin having a functional group of 3 or less, and a penetrating solvent;
The refractive index in the vicinity of the interface between the light-transmitting substrate and the hard coat layer is changed stepwise.

1. Optical laminate The optical laminate according to the present invention is characterized in that the refractive index in the vicinity of the interface between the light-transmitting substrate (TAC or PET substrate) and the hard coat layer is changed stepwise. It is. By making the refractive index in the vicinity of this interface different in steps, interface reflection and interference fringes at this interface can be effectively prevented.

  According to a preferable aspect of the present invention, the refractive index in the vicinity of the interface between the light-transmitting substrate and the hard coat layer is changed stepwise so that the interface is substantially absent. Is preferred. In the present invention, “substantially no interface” means that the two layer surfaces overlap each other but the actual interface does not exist, and that there is no interface on both surfaces in terms of the refractive index. This includes things that are included.

Light transmissive substrate The light transmissive substrate uses triacetate cellulose (TAC) or polyethylene terephthalate (PET). These light-transmitting substrates are preferable because of their high transparency and little difference in refractive index from the resin constituting the hard coat layer described later. 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 may be formed of a resin, a permeable solvent, and an optional component.

1) Resin resin (1)
Specific examples of the modified pentaerythritol acrylate (1) having a functional group exceeding 4 are selected from pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, and modified products thereof.
Resin (2)
Examples of the isocyanuric acid-modified acrylate resin or bisphenol-modified acrylate resin having a functional group of 3 or less include modified isocyanuric acid EO-modified diacrylate, modified isocyanuric acid EO-modified triacrylate, bisphenol F EO-modified diacrylate, bisphenol A EO-modified diacrylate, It is selected from epoxy-modified bisphenol A diacrylate and the like.

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; halogenated hydrocarbons; Aromatic hydrocarbons such as toluene and xylene; phenols; or a mixture thereof.

  When the light-transmitting substrate is triacetate cellulose (TAC), the permeable solvent is 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 or a mixture thereof. Preferable examples include methyl acetate, ethyl acetate, butyl acetate, and methyl ethyl ketone.

When the light transmissive substrate is polyethylene terephthalate (PET), the penetrating solvent is phenol, chlorobenzene, nitrobenzene, chlorophenol, hexafluoroisopropanol, 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 or mixtures thereof are preferably mentioned, more preferably phenol, Chlorobenzene, nitrobenzene, chloro phenol, hexafluoroisopropanol.
The amount of penetrating solvent added is 20% by weight or more, preferably 30% by weight or more, based on the total weight of the mixture.

3) Antistatic agent and / or antiglare agent The hard coat layer according to the present invention may comprise other agents, and preferably comprises an antistatic agent and / or an antiglare agent. It's okay.

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 section of 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. As the resin, a thermoplastic resin can also be used, but it is more preferable to use a thermosetting resin, and more preferable is an ionizing radiation curable composition containing an ionizing radiation curable resin or an ionizing radiation curable compound. It is.

  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. Further, 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 appropriately selected from those 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), and the maximum value from the substrate surface in the vertical direction of the convex portions of the antiglare layer is Hmax (μm). When the average unevenness interval of the antiglare layer is Sm (μm) and the average inclination angle of the unevenness portion is θa, the following formula:
8R ≦ Sm ≦ 30R
R <Hmax <3R
1.3 ≦ θa ≦ 2.5
1 ≦ R ≦ 8
It is preferable to satisfy all of these simultaneously.

  According to another preferred embodiment of the present invention, when the refractive indexes of the fine particles and the resin are n1 and n2, respectively, Δn = | n1−n2 | <0.1 is satisfied, and An antiglare layer having a haze value inside the antiglare layer of 55% or less is preferred.

1) Anti-glare agent Examples of the anti-glare agent include fine particles, and the shape thereof may be a true sphere or an ellipse, preferably a true sphere. The fine particles may be inorganic or organic, but those formed of an organic material are preferred. The fine particles exhibit anti-glare properties and are preferably transparent. Specific examples of the fine particles include plastic beads, and more preferably those having transparency. 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 20 μm. When the film thickness is within this range, the function as an antiglare layer can be sufficiently exhibited.

2) 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, etc. .

  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. Cellulose resin is mentioned.

  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.

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.

2. Method for producing optical laminate
Preparation of liquid composition Each liquid composition for hard coat layer (antistatic layer, antiglare layer, low refractive index layer if necessary) is mixed and dispersed according to the general preparation method. It may be adjusted by processing. 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, slide coating, bar coating, and roll coater method. Various methods such as a meniscus coater method, a flexographic printing method, a screen printing method, and a speed coater method can be used.

  As a curing method of the curable resin composition, it is cured by irradiation with an electron beam or ultraviolet rays. In the case of electron beam curing, an electron beam having energy of 100 KeV to 300 KeV is used. In the case of ultraviolet curing, ultraviolet rays or the like emitted from light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, or a metal halide lamp are 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. 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.

Example 1
A wet weight of 15 g / m ² (dry weight of 6 g / m ² ) was applied to one side of a cellulose triacetate film (thickness: 40 μm) according to the composition for hard coat layer prepared according to the composition table of Table 1 below. It dried for 30 seconds at 50 degreeC, and irradiated the ultraviolet-ray 100mJ / cm < ² >, and prepared the optical laminated body.

Table 1
Modified dipentaerythritol hexaacrylate 5 parts by weight (KAYARAD DPCA30; manufactured by Nippon Kayaku Co., Ltd.)
Isocyanuric acid EO-modified triacrylate 5 parts by weight (M315; manufactured by Toagosei Co., Ltd.)
Polymerization initiator 0.3 parts by weight (Irgacure 184)
Methyl acetate 5 parts by weight Methyl ethyl ketone 5 parts by weight

A wet weight of 15 g / m ² (dry weight of 6 g / m ² ) was applied to one side of a polyethylene terephthalate film (thickness of 188 μm PET) according to the composition for hard coat layer prepared in accordance with the composition table shown in Table 2 below. It dried for 30 seconds at 50 degreeC, and irradiated the ultraviolet-ray 100mJ / cm < ² >, and prepared the optical laminated body.

Table 2
Modified dipentaerythritol hexaacrylate 5 parts by weight (KAYARAD DPCA30; manufactured by Nippon Kayaku Co., Ltd.)
5 parts by weight of isocyanuric acid EO-modified triacrylate (M315; manufactured by Toagosei)
Polymerization initiator 0.3 parts by weight (Irgacure 184)
9 parts by weight of methyl ethyl ketone 1 part by weight of hexafluoroisopropanol

Comparative Example 1
A wet weight of 15 g / m ² (dry weight of 6 g / m ² ) was applied to one side of a cellulose triacetate film (thickness 40 μm) according to the composition for hard coat layer prepared in accordance with the composition table shown in Table 3 below. It dried for 30 seconds at 50 degreeC, and irradiated the ultraviolet-ray 100mJ / cm < ² >, and prepared the optical laminated body.

Table 3
Pentaerythritol triacrylate 5 parts by weight (M305; manufactured by Toagosei Co., Ltd.)
Dipentaerythritol hexaacrylate 5 parts by weight (Nippon Kayaku Co., Ltd.)
Polymerization initiator 0.3 parts by weight (Irgacure 184)
Methyl acetate 5 parts by weight Methyl ethyl ketone 5 parts by weight

Comparative Example 2
A wet weight of 15 g / m ² (dry weight of 6 g / m ² ) was applied to one side of a polyethylene terephthalate film (thickness of 188 μm PET) according to the composition shown in Table 4 below. It dried for 30 seconds at 50 degreeC, and irradiated the ultraviolet-ray 100mJ / cm < ² >, and prepared the optical laminated body.

Table 4
Pentaerythritol triacrylate 5 parts by weight (M305; manufactured by Toagosei Co., Ltd.)
Dipentaerythritol hexaacrylate 5 parts by weight (Nippon Kayaku Co., Ltd.)
Polymerization initiator 0.3 parts by weight (Irgacure 184)
9 parts by weight of methyl ethyl ketone 1 part by weight of hexafluoroisopropanol

The following tests were conducted on the optical laminates of the evaluation test examples and comparative examples, and the results are shown in Table 5 below.
Evaluation 1: Interference fringe presence / absence test The surface opposite to the hard coat layer of the optical laminate is rubbed with sandpaper, and then black tape is applied for matting, and the optical laminate is visually observed from the surface of the hard coat layer. Evaluation was made according to the following evaluation criteria.
Evaluation criteria Evaluation A: No interference fringes were generated.
Evaluation x: Interference fringes were generated.

Evaluation 2: Scratch resistance evaluation test The surface of the low refractive index layer was subjected to 10 reciprocating frictions using # 0000 steel wool with a predetermined friction load (changed every 200 g within a range of 200 to 1000 g). Thereafter, 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.

Evaluation 3: Curling Generation Presence Test The maximum curl width (as shown in FIG. 1) when the antiglare film was cut into 10 cm × 10 cm was measured. The measurement was performed on the antiglare film in an environment of a temperature of 25 degrees and a humidity of 55%, and then the presence or absence of curling of the optical laminate was visually observed and evaluated according to the following criteria.
Evaluation standard evaluation A: Curling hardly occurred.
Evaluation x: Curling occurred, and the optical laminate was rolled.

Table 5
Evaluation 1 Evaluation 2 Evaluation 3
Example 1 ◎ ◎ ◎
Example 2 ◎ ◎ ◎
Comparative Example 1 × × ×
Comparative Example 2 × × ×

FIG. 1 is a schematic view showing a curl occurrence test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical laminated body 3 Center point of a hard-coat layer 4 Edge part of a hard-coat layer 5 Hard-coat layer 7 Curl width 9 Light-transmitting base material (TAC or PET base material)

Claims (6)

An optical laminate comprising a hard coat layer on a light transmissive substrate,
The light transmissive substrate is triacetate cellulose;
The hard coat layer is
(1) a modified pentaerythritol acrylate resin having more than 4 functional groups;
(2) formed of a mixture of an isocyanuric acid-modified acrylate resin or bisphenol-modified acrylate resin having a functional group of 3 or less, and a penetrating solvent;
An optical laminate in which a refractive index in the vicinity of an interface between the light transmissive substrate and the hard coat layer is changed stepwise. An optical laminate comprising a hard coat layer on a light transmissive substrate,
The light-transmitting substrate is polyethylene terephthalate;
The hard coat layer is
(1) a modified pentaerythritol acrylate resin having more than 4 functional groups;
(2) formed of a mixture of an isocyanuric acid-modified acrylate resin or bisphenol-modified acrylate resin having a functional group of 3 or less, and a penetrating solvent;
An optical laminate in which a refractive index in the vicinity of an interface between the light transmissive substrate and the hard coat layer is changed stepwise.   The optical lamination according to claim 1 or 2, wherein the permeable solvent is one or a mixture of two or more selected from the group consisting of phenols, alcohols, ketones, esters, and halogenated hydrocarbons. body.   The optical laminated body according to any one of claims 1 to 3, wherein the hard coat layer comprises an antistatic agent and / or an antiglare agent.   The optical laminate according to any one of claims 1 to 4, wherein an antistatic layer, an antiglare layer, a low refractive index layer, or two or more of these layers are formed on the hard coat layer. body.   The optical laminate according to any one of claims 1 to 5, which is used as an antireflection laminate.

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