JP2014102320A - Optical hard coat material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical hard coat material having a hard coat layer which is excellent in flexibility, adhesive property, and surface hardness, on one surface of an acrylic substrate.SOLUTION: An optical hard coat material 1 includes a first hard coat layer 12 and a second hard coat layer 13 sequentially laminated on one surface of an acrylic substrate 11. The first hard coat layer has ultramicro indentation hardness within a range of 0.20 GPa-0.40 GPa at a depth of 50 nm, and the second hard coat layer has ultramicro indentation hardness within a range of 0.40 GPa-0.60 GPa at a depth of 50 nm.

Description

  The present invention relates to a hard coat material, and in particular, a hard coat layer applied to a display screen of a display such as a cathode ray tube display (CRT), a liquid crystal display (LCD), a plasma display panel (PDP), or an organic EL display. It is related with the optical film which provided.

  An image display surface in an image display device such as a liquid crystal display device (LCD) or a cathode ray tube display device (CRT) is required to have hardness so as not to be scratched during handling. On the other hand, it has been studied to improve the hardness of the image display surface of the image display device by using an optical laminate in which a hard coat (HC) layer is formed on a base film.

  Technologies to harden the plastic surface include coating a thermosetting resin such as organosiloxane and melamine, forming a metal thin film by vacuum deposition or sputtering, or polyfunctional acrylate-based active energy. Examples thereof include a method of coating a linear curable resin. Among the highly transparent plastic substrate films, triacetyl cellulose (TAC) films and acrylic films are mainly used as substrate films for liquid crystal displays (LCDs) because of their excellent transparency.

  However, in the conventional hard coat material used as the acrylic film supporting substrate, it is a problem that both flexibility and hardness cannot be achieved due to the poor flexibility of the acrylic substrate. Moreover, in the use of an acrylic base material, it becomes a subject that the adhesiveness of an acrylic base material and a hard-coat layer cannot be taken. In view of this, a method for achieving both flexibility and hardness and good adhesion has been proposed.

  In Patent Document 1, a hard coat containing urethane acrylate for imparting flexibility and colloidal silica for imparting hardness is formed on a transparent substrate to try to achieve both flexibility and surface hardness. . However, when the acrylic base material is used, the flexibility is insufficient.

  Patent Document 2 proposes a method of laminating two layers of a hard coat layer with a controlled elongation rate on a transparent substrate. However, this technique has a problem that the surface hardness is insufficient when an acrylic base material is used.

JP 2007-284626 A JP 2005-305383 A

  An object of the present invention is to provide an optical hard coat material having a hard coat layer excellent in flexibility, adhesion, and surface hardness on one surface of an acrylic substrate.

  The invention according to claim 1 of the present invention is

In the invention according to claim 2 of the present invention, the first hard coat layer is a functional group selected from one or more of a monofunctional or bifunctional (meth) acrylate and a trifunctional or lower urethane (meth) acrylate. An ionizing radiation curable composition containing
The second hard coat layer is composed of an ionizing radiation curable composition containing a functional group selected from one or more of trifunctional or higher functional (meth) acrylates and tetrafunctional or higher functional urethane (meth) acrylates. The optical hard coat material according to claim 1.

  In the invention according to claim 3 of the present invention, the film thickness of the first hard coat layer is in the range of 0.1 to 10 μm, and the film thickness of the second hard coat layer is in the range of 1 to 10 μm. The optical hard coat material according to claim 1 or 2.

In the invention according to claim 4 of the present invention, on the second hard coat layer, a low refractive index layer having a refractive index during curing of greater than 1.30 and less than 1.40 is formed,
The optical average reflectance according to any one of claims 1 to 3, wherein the luminous average reflectance is 0.5% or more and 1.5% or less, and the total light transmittance is 94.0% or more. Hard coat material.

  According to claim 1 of the present invention, in laminating the first hard coat layer and the second hard coat layer on one surface of the acrylic base material, the hardness after curing of the first hard coat layer is the second hard coat layer. By making it lower than the hardness after curing of the hard coat layer, the hardness of the acrylic base material, the first hard coat layer and the second hard coat layer can be inclined, and excellent in flexibility and adhesion. A hard coat material is obtained.

According to claim 2 of the present invention,
The first hard coat layer is composed of an ionizing radiation curable composition containing a functional group selected from one or more of monofunctional or bifunctional (meth) acrylate and trifunctional or lower urethane (meth) acrylate, After curing, the second hard coat layer comprises an ionizing radiation curable composition containing a functional group selected from one or more of trifunctional or higher functional (meth) acrylates and tetrafunctional or higher functional urethane (meth) acrylates. The hardness of the second hard coat layer can be made higher than that of the first hard coat layer, and the hardness of the acrylic substrate, the first hard coat layer, and the second hard coat layer can be inclined. it can.

  According to a third aspect of the present invention, the first hard coat layer is made to have an acrylic substrate and a second hard coat layer by setting the film thickness of the first hard coat layer to a range of 0.1 to 10 μm. The effect of the primer for improving adhesiveness is obtained, and sufficient hardness is obtained by setting the film thickness of the second hard coat layer, which is the decisive factor of hardness, to 1 to 10 μm.

  According to claim 4 of the present invention, on the second hard coat layer, a low refractive index layer having a refractive index at the time of curing of greater than 1.30 and less than 1.40 is formed. By setting the reflectance to 0.5% to 1.5% and the total light transmittance to 94.0% or more, an excellent antireflection effect can be obtained.

  As described above, according to the present invention, it is possible to provide a hard coat material that has excellent flexibility, excellent adhesion, and excellent surface hardness.

It is a schematic cross section of one embodiment of the hard coat material concerning the present invention. It is a schematic cross section of one embodiment of a hard coat material having an antireflection function according to the present invention. It is a schematic cross section of the polarizing plate using the hard-coat material shown in FIG. It is a schematic cross section of the transmissive liquid crystal display device using the hard-coat material shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a film cross-sectional view of one embodiment of a hard coat material according to the present invention. The hard coat material of the present invention is characterized in that a first hard coat layer 12 and a second hard coat 13 are sequentially laminated on an acrylic substrate 11.

  FIG. 2 shows a schematic cross-sectional view of an embodiment of a hard coat material having an antireflection function according to the present invention. That is, it is a hard coat material having an antireflection effect obtained by forming a low refractive index layer 14 on the second hard coat layer 13 having the configuration shown in FIG.

  The first hard coat layer 12 according to the embodiment of the present invention is a cured film of an ionizing radiation curable composition having an ultra-fine indentation hardness at a depth of 50 nm in a range of 0.20 GPa to 0.40 GPa. Have Further, the second hard coat layer 13 has a feature that it is a cured film of an ionizing radiation curable composition having an ultra-fine indentation hardness of 50 nm in a range of 0.40 GPa or more and 0.80 GPa or less. In the ionizing radiation curable composition according to the present invention, an ionizing radiation curable material such as an ultraviolet curable material or an electron beam curable material can be used.

  As the ionizing radiation curable material, monofunctional (monofunctional) or polyfunctional acrylate compounds can be used.

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

  As the polyfunctional, for example, a polyfunctional (meth) acrylate compound or a polyfunctional urethane (meth) acrylate compound synthesized from a diisocyanate and a polyhydric alcohol and a hydroxyester of acrylic acid or methacrylic acid is used. be able to. Besides these, as ionizing radiation type materials, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be used. .

  For example, bifunctional (meth) acrylate compounds include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and nonanediol di (meth) acrylate. , Ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) ) Acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol (Meth) acrylate, di (meth) acrylate, such as hydroxypivalic acid neopentyl glycol di (meth) acrylate.

  Examples of the trifunctional or higher functional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris 2-hydroxy. Ethyl isocyanurate tri (meth) acrylate, tri (meth) acrylate such as glycerin tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, etc. Trifunctional (meth) acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol te Trifunctional or higher polyfunctionality such as la (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate ( Examples thereof include a (meth) acrylate compound and a polyfunctional (meth) acrylate compound obtained by substituting a part of these (meth) acrylates with an alkyl group or ε-caprolactone.

  Further, as the urethane (meth) acrylate compound, pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate, Toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer, and the like can be used.

  Moreover, the film thickness of the first hard coat layer 12 is in the range of 0.1 to 10 μm, and the film thickness of the second hard coat layer 13 is preferably in the range of 1 to 10 μm. When the film thickness of the first hard coat layer 12 is 0.1 μm or less, flexibility cannot be obtained and the flexibility is deteriorated, and when it is 10 μm or more, the surface hardness is lowered. Further, when the film thickness of the second hard coat layer 13 is 1 μm or less, the surface hardness is low, and when it is 10 μm or more, the flexibility is deteriorated.

  The optical hard coat material of the present invention may be a hard coat layer (antistatic hard coat) in which the second hard coat layer 13 has an antistatic effect.

Further, the optical film of the present invention preferably has a high total light transmittance, and by forming the second hard coat layer 13 containing a quaternary ammonium salt material, an antireflection function is achieved without reducing the total light transmittance. An antistatic function can be further imparted to the hard coat material having As a conventional method, that is, a method for imparting antistatic performance, when metal oxide particles having conductivity are added and the surface resistance value of the antireflection film is 1 × 10 ¹¹ (Ω / cm ² ) or less, Light transmittance will deteriorate.

In the optical hard coat material of the present invention, the content of the quaternary ammonium salt in the second hard coat layer 13 is preferably in the range of 5% to less than 20% by weight. When the content of the quaternary ammonium salt is less than 5% by weight, the surface resistance value is 1 × 10 ¹¹ Ω / cm ² or more and the antistatic effect cannot be obtained. Further, when the content of the quaternary ammonium salt is 20% or more, when the low refractive index layer 14 is provided, the adhesion is lowered.

Further, when a quaternary ammonium salt is used for the first hard coat layer 12, an acrylic material containing a quaternary ammonium salt as a functional group in the molecule can be preferably used. Quaternary ammonium salt material -N ⁺ X ^- shows the structure of quaternary ammonium cation (-N ⁺⁾ and anion (X ^-) to express the conductivity in the first hard coat layer 12 by providing the. At this time, as X ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , F ⁻ , HSO ₄ ⁻ , SO ₄ ²⁻ , NO ₃ ⁻ , PO ₄ ³⁻ , HPO ₄ ²⁻ , H ₂ PO ₄ ⁻ , SO ₃ ^-, OH ^-, and the like can be given.

Examples of the acrylic material containing the quaternary ammonium salt in the molecule as a functional group include acrylic acid or methacrylic acid ester of a polyhydric alcohol containing a quaternary ammonium salt (—N ⁺ X ⁻ ) in the molecule as a functional group. Such polyfunctional or polyfunctional (meth) acrylate compounds, polyfunctional urethane (meth) acrylate compounds as synthesized from diisocyanate and polyhydric alcohol, acrylic acid or methacrylic acid hydroxy ester, and the like can be used. Besides these, as ionizing radiation type materials, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be used. .

  For example, as an acrylic material containing a quaternary ammonium salt in the molecule as a functional group, light ester DQ-100 (manufactured by Kyoeisha Chemical Co., Ltd.), NR-121X-9IPA (manufactured by Colcoat, solid content 10%) or the like is used. be able to.

  A solvent can be added to the composition forming the first hard coat layer 12 and the second hard coat layer 13 as necessary, for example, in order to improve the coating suitability. Solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane and cyclohexylbenzene, hydrocarbons such as n-hexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane, and trioxane. , Ethers such as tetrahydrofuran, anisole and phenetole, and ketones such as methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone , Ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, Esters such as acid n-pentyl and γ-ptyrolactone, cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, and ethylene glycol It is appropriately selected from water and the like in consideration of appropriate coating.

  In addition, in the composition forming the first hard coat layer 12 and the second hard coat layer 13, in order to prevent the occurrence of coating film defects such as repellency and unevenness when the composition is applied, Additives that are called may be added. Surface modifiers are also called leveling agents, antifoaming agents, interfacial tension modifiers, and surface tension modifiers, depending on their function, all of which reduce the surface tension of the coating film (antiglare layer) that is formed. Is provided.

  In addition, in the composition for forming the first hard coat layer 12 and the second hard coat layer 13, other additives may be added in addition to the surface conditioner described above. As the functional additive, an ultraviolet absorber, an infrared absorber, an adhesion improver, a curing agent, or the like can be used.

  The optical hard coat material according to the present invention is obtained by applying the composition of the first hard coat layer 12 and the second hard coat layer 13 prepared with the above-described additives onto an acrylic substrate, and drying as necessary. Then, it can be produced by irradiating with ionizing radiation such as ultraviolet rays or electron beams.

  For the application of the composition, a coating apparatus such as a roll coater, a reverse roll coater, a gravure coater, a micro gravure coater, a knife coater, a bar coater, a wire bar coater, a die coater, or a dip coater can be used. Also, two layers of the first hard coat layer 12 and the second hard coat layer 13 can be applied in succession.

  Further, as the ionizing radiation, ultraviolet rays and electron beams can be used. In the case of ultraviolet curing, a light source such as a high pressure mercury lamp, a low pressure mercury lamp, an ultrahigh pressure mercury lamp, a metal halide lamp, a carbon arc, or a xenon arc can be used. In the case of electron beam curing, electron beams emitted from various electron beam accelerators such as cockloftwald type, bandegraph type, resonant transformer type, insulated core transformer type, linear type, dynamitron type, and high frequency type can be used. .

  In addition, you may provide a drying process or a heating process before and after irradiation of the said ionizing radiation. In particular, when the composition contains a solvent, it is necessary to provide a drying step before irradiation with ionizing radiation in order to remove the solvent of the formed coating film. Examples of the drying means include heating, air blowing, and hot air.

  Further, the hard coat material having an antireflection function according to the present invention (hereinafter simply referred to as an antireflection hard coat material 2) has a low refractive index layer 14 exhibiting an antireflection function on the second hard coat layer 13. It is obtained by forming.

  As the method for forming the low refractive index layer, a wet film forming method in which a composition for forming a low refractive index layer is applied to the surface of the hard coat layer to form an antireflection layer, a vacuum deposition method, a sputtering method, or a CVD method. The method can be divided into vacuum deposition methods that form an antireflection layer in a vacuum. In particular, a method for forming a low refractive index layer by a wet film-forming method (coating) using a composition for forming a low refractive index layer containing low refractive index particles and a binder matrix should be excellent in productivity and inexpensive. It is preferable at the point which can do.

  At this time, the low refractive index layer 14 has an optical film thickness (nd) obtained by multiplying the film thickness (d) by the refractive index (n) of the low refractive index layer 14 to 1/4 of the wavelength of visible light. Designed and formed to be equal

The low refractive index layer 14 of the antireflection hard coat material 2 of the present invention has a refractive index greater than 1.30 and less than 1.40, and a luminous average reflectance of 0.5% or more and 1.5%. The following is preferred. When the refractive index is 1.30 or less, the scratch resistance becomes insufficient, and the use on the image display surface becomes difficult. Further, when the refractive index when the low refractive index layer is cured is 1.40 or more, there is a problem that the average luminous reflectance is increased and the function of preventing reflection is lowered.

  As the optical hard coat material of the present invention, for example, an antiglare layer, an ultraviolet absorption layer, an infrared absorption layer, and the like can be provided between the second hard coat layer 13 and the low refractive index layer 14. There is a possibility that the light transmittance may be lowered, and it is necessary to consider the balance.

  The optical hard coat material according to the present invention can be used for LCD, PDP, CRT, projection, EL display and the like. The case where the antireflection hard coat material 2 of the present invention is used as a member of a liquid crystal display will be described below.

  FIG. 3 shows a schematic cross-sectional view of a polarizing plate 3 using the antireflection hard coat material 2 of the present invention. That is, the polarizing plate is formed by sequentially laminating the polarizing layer 23 and the transparent substrate 21 on the other surface of the acrylic substrate 11. For example, the transparent substrate 21 may be an acrylic substrate. As the polarizing layer 23, a stretched polyvinyl alcohol film to which iodine is added can be used. These are one embodiment and are not particularly limited.

  FIG. 4 shows a schematic cross-sectional view of a transmissive liquid crystal display body provided with the antireflection hard coat material 2 of the present invention.

  FIG. 4A shows a transmissive liquid crystal display using the polarizing plate 3 shown in FIG. 3, and the backlight unit 6, the second polarizing plate 5, the liquid crystal cell 4, and the polarizing plate 3 are sequentially laminated. 1 shows a transmissive liquid crystal display configured as described above. That is, the low refractive index layer 14 side of the antireflection hard coat material 2 is the observation side (the surface of the display body).

  On the other hand, FIG. 4B shows a transmissive liquid crystal display body constructed by sequentially laminating the backlight unit 6, the second polarizing plate 5, the liquid crystal cell 4, the polarizing plate 3 ′, and the antireflection hard coat material 2. Show. The polarizing plate 3 ′ has a configuration in which the polarizing layer 23 is sandwiched between the transparent substrates 21 and 22 from both sides. The transparent substrates 21 and 22 constituting the polarizing plates 3 and 3 ′ used in FIGS. 4A and 4B and the transparent substrates 42 and 43 used in the second polarizing plate 5 may be acrylic base materials. There is no particular limitation.

  The backlight unit 6 includes a light source and a light diffusing plate. The liquid crystal cell 4 has a structure in which an electrode is provided on one transparent substrate, an electrode and a color filter are provided on the opposite transparent substrate, and liquid crystal is sealed between the electrodes.

  Hereinafter, specific examples will be described.

Seven types of compositions for forming a hard coat layer and three types of compositions for forming a low refractive index layer were prepared with the following compositions.
(Composition 1 for hard coat layer)
Trifunctional urethane acrylate: 30 parts by weight of UV7550-B
(Nippon Synthetic Chemical Co., Ltd.)
Monofunctional monomer: 70 parts by weight of isoamyl acrylate
(Kyoeisha Chemical Co., Ltd.)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
・ Solvent: 100 parts by weight of methyl ethyl ketone

(Composition 2 for hard coat layer)
・ Trifunctional urethane acrylate: 50 parts by weight of UV7550-B
(Nippon Synthetic Chemical Co., Ltd.)
Monofunctional monomer: 50 parts by weight of isoamyl acrylate
(Kyoeisha Chemical Co., Ltd.)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
・ Solvent: 100 parts by weight of methyl ethyl ketone

(Composition 3 for hard coat layer)
-Bifunctional urethane acrylate: 70 parts by weight of UV6630B
(Nippon Synthetic Chemical Co., Ltd.)
・ Polyfunctional monomer: 30 parts by weight of pentaerythritol triacrylate
(Osaka Organic Chemistry, trade name V # 300)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
・ Solvent: 100 parts by weight of methyl ethyl ketone

(Composition 4 for hard coat layer)
・ Trifunctional urethane acrylate: 70 parts by weight of UV7550B
(Nippon Synthetic Chemical Co., Ltd.)
・ Polyfunctional monomer: 30 parts by weight of pentaerythritol triacrylate
(Osaka Organic Chemistry, trade name V # 300)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
・ Solvent: 100 parts by weight of methyl ethyl ketone

(Composition 5 for hard coat layer)
・ 4- to 5-functional urethane acrylate: 70 parts by weight of UV7650-B
(Nippon Synthetic Chemical Co., Ltd.)
・ Polyfunctional monomer: 30 parts by weight of pentaerythritol triacrylate
(Osaka Organic Chemistry, trade name V # 300)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
・ Solvent: 100 parts by weight of methyl ethyl ketone

(Composition 6 for hard coat layer)
-Hexafunctional urethane acrylate: 70 parts by weight of UA306-I
(Kyoeisha Chemical Co., Ltd.)
Polyfunctional monomer: 30 parts by weight of pentaerythritol triacrylate (manufactured by Osaka Organic Chemical Co., Ltd., trade name: V # 300)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
・ Solvent: 100 parts by weight of methyl ethyl ketone

(Composition 7 for hard coat layer)
・ Decafunctional urethane acrylate: 70 parts by weight of UV1700B
(Nippon Synthetic Chemical Co., Ltd.)
Polyfunctional monomer: 30 parts by weight of pentaerythritol triacrylate (Osaka Organic Chemical Co., Ltd., trade name V # 300)
Photopolymerization initiator: 10 parts by weight (Ciba Specialty Chemicals, Irgacure 184)
Was used to prepare a hard coat forming composition 7 by dissolving in 100 parts by weight of methyl ethyl ketone.

(Low refractive index layer composition 1)
-Porous silica fine particle dispersion: 14.94 parts by weight (average particle size 50 nm, solid content 20%, solvent: methyl isobutyl ketone)
EO-modified dipentaerythritol hexaacrylate 1.99 parts by weight (manufactured by Nippon Kayaku, trade name: DPEA-12)
-Photopolymerization initiator: 0.07 part by weight (Ciba Specialty Chemicals, Irgacure 184)
・ 0.20 parts by weight of alkyl polyether-modified silicone oil (manufactured by GE Toshiba Silicone, trade name: TSF4460)
・ Solvent: 82 parts by weight of methyl isobutyl ketone

(Composition 2 for low refractive index layer)
-Porous silica fine particle dispersion: 16.12 parts by weight (average particle size 50 nm, solid content 20%, solvent: methyl isobutyl ketone)
-0.81 part by weight of EO-modified dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku, trade name: DPEA-12)
-Photopolymerization initiator: 0.07 part by weight (Ciba Specialty Chemicals, Irgacure 184)
・ 0.20 parts by weight of alkyl polyether-modified silicone oil (manufactured by GE Toshiba Silicone, trade name: TSF4460)
・ Solvent: 82 parts by weight of methyl isobutyl ketone

(Composition 3 for low refractive index layer)
-Porous silica fine particle dispersion: 13.02 parts by weight (average particle size 50 nm, solid content 20%, solvent: methyl isobutyl ketone)
-EO-modified dipentaerythritol hexaacrylate 3.91 parts by weight (manufactured by Nippon Kayaku, trade name: DPEA-12)
-Photopolymerization initiator: 0.07 part by weight (Ciba Specialty Chemicals, Irgacure 184)
・ 0.20 parts by weight of alkyl polyether-modified silicone oil (manufactured by GE Toshiba Silicone, trade name: TSF4460)
・ Solvent: 82 parts by weight of methyl isobutyl ketone

  Next, using the hard coat layer composition and the low refractive index layer composition prepared above, Examples 1 to 4 shown in Table 1 below and Optical hard coats of Comparative Examples 1 to 11 shown in Table 2 below. A material was prepared. The hard coat layer and the low refractive index layer were formed by the following method.

<Formation of hard coat layer>
The hard coat layer composition was applied to one surface of an acrylic substrate having a thickness of 80 μm so that the film thickness after curing would be the film thickness described in Tables 1 and 2 below, at 80 ° C. for 60 seconds. After drying in an oven, a hard coat layer was formed by irradiating ultraviolet rays at an irradiation dose of 300 mJ / m ² using an ultraviolet irradiation device (Fusion UV System Japan, light source H bulb).

<Formation of low refractive index layer>
On the hard-coat layer formed above, the composition for low refractive index layers described in Tables 1 and 2 was applied so that the film thickness after drying was 100 nm. Thereafter, using a UV irradiation device (Fusion UV System Japan, light source H bulb), an ultraviolet ray was irradiated at an irradiation dose of 192 mJ / m ² to form a low refractive index layer, and an antireflection hard coat material was prepared.

<Evaluation and method>
The hard coat layers and antireflection hard coat materials obtained in Examples 1 to 4 and Comparative Examples 1 to 11 were tested and evaluated by the following methods. The measurement results are shown in Tables 1 and 2 below.

"Ultra-fine indentation hardness"
A hardness of 50 nm in depth from the surface of the hard coat layer was measured using a micro indentation hardness tester (NanoIndenter SA2 manufactured by MTS Systems), indenter: triangular pyramid indenter with tip radius of curvature of 100 nm and ridge angle of 80 °, indentation speed = Measurement was performed under the condition of 2.0 nm / s.

"Pencil hardness test"
Using a Clemens type scratch hardness tester (manufactured by Tester Sangyo Co., Ltd., HA-301), a load of 500 g is applied to the surface of the low refractive index layer of the antireflection hard coat material according to JIS-K5400-1990. A test was conducted using a pencil (Mitsubishi UNI), and the change in appearance due to scratches was visually evaluated. The hardness of the upper limit pencil when no scratches were observed was taken as a measured value.

"Flexibility evaluation"
A mandrel test was performed according to K5600-5-1, and the mandrel diameter when a crack occurred was evaluated. Evaluations were made with a crack having a radius of curvature of 10 mm or less as a circle (◯) and 10 mm or more as a cross (x).

"Average luminous reflectance"
About the surface of the said low-refractive-index layer, the spectral reflectance in the incident angle of 5 degrees was measured using the automatic spectrophotometer (the Hitachi Ltd. make, U-4000). Further, the average luminous reflectance was obtained from the obtained spectral reflectance curve. In the measurement, a matte black coating amount was applied to the surface of the acrylic base material on which the low refractive index layer was not formed, and an antireflection treatment was performed.

"Total light transmittance"
About the said antireflection hard coat material, the total light transmittance was measured using the image clarity measuring device (Nippon Denshoku Industries Co., Ltd. make, NDH-2000). When the measured result was 94% or more, the evaluation was made as a circle (◯), and when it was lower than 94%, the evaluation was made as a cross (×).

"Adhesion"
The surface of the antireflective hard coat material on the low refractive index layer side was subjected to an adhesion test in accordance with the cross-cut method of JIS-K-5600-5-6. The evaluation was performed with a cut interval of 1 mm, a case where the grids and cut intersections were not peeled off at all, and a case where even a little was peeled off (X).

"Abrasion resistance"
The surface of the antireflective hard coat material on the low refractive index layer side was reciprocated 10 times while applying a load of 200 g / cm 2 using # 0000 steel wool, and the presence or absence of scratches was confirmed. The evaluation was performed with a circle (◯) indicating no scratch and a cross (×) indicating no scratch.

`` Refractive index measurement ''
The refractive index of the low refractive index layer was measured by the following method.
The low refractive index layer composition was applied on a silicon substrate so as to have a film thickness of 1.0 μm, and a coating film was formed under the conditions for forming the low refractive index layer. The produced substrate was measured with a vacuum ultraviolet multi-incidence angle spectroscopic ellipsometer (VUV-VASE, manufactured by JA Woollam). The measurement results are shown in Tables 1 and 2.

<Comparison result>
As shown in Tables 1 and 2, two different hard coat materials are laminated on one surface of the acrylic base material of (Example 1) to (Example 4), and the depth of the hard coat material is 50 nm. A cured film having a micro indentation hardness of 0.20 GPa or more and 0.40 GPa or less is formed, and the second layer has an ultra micro indentation hardness of 0.40 GPa or more and 0.60 GPa at a depth of 50 nm. By forming a cured film of the second-layer ultraviolet curable composition having the following range, a film having excellent film flexibility and surface hardness was obtained.

1 Hard Coat Material 11 Acrylic Base Material 12 First Hard Coat Layer 13 Second Hard Coat Layer 14 Low Refractive Index Layer 2 Antireflection Hard Coat Material 21 Transparent Base Material 22 Transparent Base Material 23 Polarizing Layer 3 Antireflection Hard Coat Material Integrated Type Polarizing plate 3 ′ Polarizing plate 4 Liquid crystal cell 5 Second polarizing plate 41 Polarizing layer 42 Transparent substrate 43 Transparent substrate 6 Backlight

Claims (4)

An optical hard coat material in which a first hard coat layer and a second hard coat layer are sequentially laminated on one surface of an acrylic substrate,
Ultra fine indentation hardness at a depth of 50 nm of the first hard coat layer is in a range of 0.20 GPa to 0.40 GPa,
Ultra-fine indentation hardness at a depth of 50 nm of the second hard coat layer ranges from 0.40 GPa to 0.60 GPa,
An optical hard coat material characterized by the above. The first hard coat layer is composed of an ionizing radiation curable composition containing a functional group selected from one or more of monofunctional or bifunctional (meth) acrylate and trifunctional or lower urethane (meth) acrylate,
The second hard coat layer is composed of an ionizing radiation curable composition containing a functional group selected from one or more of trifunctional or higher functional (meth) acrylates and tetrafunctional or higher functional urethane (meth) acrylates. The optical hard coat material according to claim 1.   3. The optical according to claim 1, wherein the first hard coat layer has a thickness of 0.1 to 10 μm, and the second hard coat layer has a thickness of 1 to 10 μm. Hard coat material. On the second hard coat layer, a low refractive index layer having a refractive index at curing greater than 1.30 and less than 1.40 is formed,
The optical average reflectance according to any one of claims 1 to 3, wherein the luminous average reflectance is 0.5% or more and 1.5% or less, and the total light transmittance is 94.0% or more. Hard coat material.