JP2014224921A - Infrared intercepting sheet, and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new type infrared intercepting material and infrared intercepting sheet for use in producing windows for buildings, vehicles and refrigerating or freezing showcases and IR sensors and in preventing forgery, significantly improved over any such a conventional material or sheet in transparency in the visible light range, electric wave transmissibility and infrared interception.SOLUTION: An infrared intercepting sheet formed by stacking painted coats of high refractive index resin layers containing minute particles and of layers containing minute particles (such as ITO) lower in refractive index than the high refractive index resin layers in the infrared range is transparent, can transmit electric waves, and moreover is reduced in manufacturing cost and significantly improved in infrared interception. A manufacturing method for the sheet is also proposed.

Description

The present invention relates to a new infrared shielding sheet that efficiently absorbs and reflects infrared rays and has excellent transparency and low haze, and a method for producing the same.

In recent years, from the viewpoint of energy saving and global environmental problems, it has been demanded to reduce the load on air conditioning equipment. For example, in the field of houses and automobiles, it is required to lay an infrared shielding material capable of shielding infrared rays from sunlight on a window glass to control the temperature in a room or in a vehicle.

There are various materials having infrared shielding properties, but in Patent Document 1, a dielectric multilayer film of a high refractive index layer and a low refractive index layer and a fine particle film such as ATO are laminated in order to reflect light of a specific wavelength in the infrared region. An insulated member is disclosed. Since this heat insulating member forms the dielectric multilayer film and the fine particle layer separately, there is a problem of manufacturing cost.

Patent Document 2 discloses a heat insulating member in which a transparent conductive layer and a high refractive index layer having a relatively high refractive index in the infrared region are laminated. However, since a conductive layer is used as a low refractive index layer in the infrared region, it cannot be used for systems that require radio wave transmission performance for transmitting and receiving radio waves indoors and outdoors, such as mobile phones, TVs, and GPS. There is. Furthermore, there is a problem of manufacturing cost because vacuum equipment such as sputtering is required.

JP 2002-220262 A JP 2010-202465 A

An object of this invention is to provide the new infrared shielding sheet which improved the transparency in a visible light region, radio wave permeability, infrared shielding property, and manufacturing cost significantly.

As a result of intensive studies on such problems in the prior art, the present inventors have found that the high refractive index resin layer containing fine particles and the fine particles contained in the high refractive index resin layer in the infrared region are more relative to each other. By applying a low refractive index resin layer containing fine particles exhibiting a low refractive index to the coating, a new infrared ray having transparency, radio wave transmission, manufacturing cost, and infrared shielding properties are greatly improved. It has been found that a shielding sheet is obtained, and the present invention has been completed.

That is, the present invention is (1) a laminated film in which a high refractive index resin layer (A) and a low refractive index resin layer (B) containing fine particles are alternately laminated on a transparent support, and the high refractive index resin layer (A ) Is a value obtained by subtracting the refractive index at an arbitrary wavelength from 780 nm to 1500 nm from the refractive index at 550 nm, 0.1 or less, and the low refractive index resin layer (B) has an arbitrary wavelength from 780 nm to 1500 nm from the refractive index at 550 nm. The value obtained by subtracting the refractive index at is 0.1 or more, and in the wavelength region of the difference, the refractive index of (B) is (A) at any of the same wavelengths in (A) and (B). An infrared shielding sheet characterized by a lower refractive index,
(2) (A), (B) The surface resistance of each layer is 1 kΩ / □ or more, the total number of layers (A), (B) is 3 or more, and the optical film thickness of each layer is 195 nm to 375 nm. The infrared shielding sheet according to (1),
(3) The infrared ray shielding sheet according to (1) or (2), wherein the visible light transmittance is 50% or more and the haze is 8% or less,
(4) Fine particles contained in the high refractive index resin layer (A) are titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, tungsten oxide, niobium oxide, cerium oxide, lead oxide, diamond, zinc oxide, boride, The infrared ray shielding sheet according to any one of (1) to (3), which is at least one kind of fine particles selected from a group of nitrides,
(5) Any of (1) to (4), wherein the fine particles contained in the low refractive index resin layer (B) are at least one kind of fine particles selected from the group consisting of tin oxide, indium oxide, zinc oxide and tungsten oxide. The infrared shielding sheet according to claim 1,
(6) Fine particles contained in the low refractive index resin layer (B) are Sb-doped tin oxide (ATO), Sn-doped indium oxide (ITO), Ga-doped zinc oxide (GZO), oxygen-deficient tungsten oxide, Cs-doped oxide. The infrared shielding sheet according to any one of (1) to (5), which is at least one selected from the group of tungsten,
(7) The infrared shielding sheet according to any one of (1) to (6), wherein the low refractive index resin layer (B) includes hollow fine particles in addition to the fine particles selected from (5) or (6). ,
(8) The infrared shielding sheet according to any one of (1) to (7), wherein the content of fine particles contained in the high refractive index resin layer or the low refractive index resin layer is 90% by weight or less,
(9) The method for producing an infrared shielding sheet according to any one of (1) to (8), wherein the high refractive index resin layer and the low refractive index resin layer are formed by coating.
(10) An infrared shielding sheet according to (1) to (9), and a cholesteric liquid crystal film that selectively reflects 780 nm to 2000 nm, a birefringent multilayer film, or an infrared absorbing dye that selectively absorbs 780 nm to 2500 nm Infrared shielding sheet made by combining at least one kind,
About.

The infrared shielding sheet of the present invention has a reflection property in addition to a good absorption property for a wide infrared region, is excellent in radio wave transmission, transparency and manufacturing cost, has low haze, and has an infrared shielding effect. Therefore, both the effect of reducing the heating cost in winter and the effect of reducing the temperature in summer can be improved.

It is a graph which shows the transmittance | permeability and reflectance with respect to the wavelength of the infrared shielding sheet which concerns on Example 1 of this invention. It is a graph which shows the refractive index and reflectance with respect to the wavelength of the infrared shielding sheet which concerns on the comparative example of this invention.

The infrared shielding sheet of the present invention has a resin layer containing fine particles having a high refractive index in the infrared region on at least one surface of the transparent support, and a relatively low refractive index in the infrared region than this layer. It is a multilayer structure in which resin layers containing fine particles to be shown are alternately laminated. In addition, the infrared region in this invention shows a thing of 780 nm-2500 nm.

As the transparent support used in the present invention, various resin films and glass can be used. Polyolefin films (polyethylene, polypropylene, etc.), polyester films (polyethylene terephthalate (hereinafter referred to as PET), polyethylene naphthalate (hereinafter referred to as PEN). Etc.), polyvinyl chloride, cellulose triacetate, polyamide, polyimide and the like can be used.

Infrared shielding sheet made by alternately laminating high refractive index resin layer and low refractive index resin layer is the infrared reflection function with both refractive index difference in infrared region and absolute value of refractive index of high refractive index resin layer It is important to decide. That is, the infrared reflection function becomes larger as the refractive index difference and the absolute value of the refractive index are larger.

In the present invention, a difference in refractive index between at least two adjacent layers (a high refractive index resin layer and a low refractive index resin layer) is 0.2 or more at an infrared wavelength to be reflected. Preferably it is 0.3 or more, More preferably, it is 0.35 or more.

If the difference in refractive index is less than 0.2, the number of laminated layers is increased to make the infrared reflectance a desired value, the visible transmittance is reduced, and the production cost is increased, which is not preferable.

The infrared wavelength λ to be reflected is generally given by equation (1). n _H and d _H are the refractive index and geometric film thickness of the high refractive index resin layer, and n _L and d _L are the refractive index and geometric film thickness of the low refractive index resin layer.
Formula (1)
_{n H d H + n L d} L = λ / 2

Here, it is preferable that the high refractive index resin layer and the low refractive index resin layer have the same optical film thickness (product of the refractive index n and the geometric film thickness d) so as to be an integral multiple of λ / 4. The infrared wavelength to be reflected is preferably 780 nm to 1500 nm. If it is less than 780 nm, the visible light transmittance is lowered because it is in the visible light region, which is not preferable. On the other hand, if it is 1500 nm or more, it is not preferable because the infrared shielding effect is weakened due to absorption by fine particles contained in the low refractive index resin layer. That is, the optical film thickness at a wavelength of 780 nm to 1500 nm of the high refractive index resin layer and the low refractive index resin layer is preferably 195 nm to 375 nm.

The number of layers of the multilayer film of the present invention is preferably 3 to 30 layers, more preferably 3 to 20 layers, and particularly preferably 3 to 15 layers. If the number of layers of the multilayer film is less than 3, the infrared reflection function is insufficient, and if it exceeds 30 layers, the manufacturing cost increases, the visible light transmittance, the durability decreases, and the curl of the film due to an increase in film stress. Is not preferable because it becomes a problem.

The ideal optical performance of the infrared shielding sheet is that it has a high visible light transmittance and a low solar transmittance, but generally there is a proportional relationship between them, and the optical performance depends on which performance is important. Will be determined. As a result of various studies, the visible light transmittance of the infrared shielding sheet of the present invention is 50% or more, preferably 70% or more, in order to minimize the increase in lighting cost and winter heating cost. Furthermore, the haze value of the infrared shielding sheet needs to be such that transparency is not impaired, and should be 8% or less, preferably 3% or less.

In the case of producing a multilayer film using the difference in refractive index by coating, in the conventional technique, a high refractive index resin layer contains dielectric fine particles (such as titanium oxide) having a high refractive index, and the low refractive index resin layer has a refractive index. Low dielectric fine particles (such as silicon dioxide) were contained (for example, JP 2012-93481 A). The refractive index of the dielectric fine particles in the visible light region to the infrared region is substantially constant.

However, as a result of intensive studies, the present inventors have discovered a group of fine particles having a refractive index in the visible light region and a refractive index in the infrared region, and further have an infrared absorption capability. It was found that the infrared region can be shielded more efficiently by combining the dielectric fine particle groups.

In the high refractive index resin layer containing the fine particles, a value obtained by subtracting the refractive index at an arbitrary wavelength from 780 nm to 1500 nm from the refractive index at 550 nm is preferably 0.1 or less, and the low refractive index resin layer is 550 nm. The value obtained by subtracting the refractive index at an arbitrary wavelength from 780 nm to 1500 nm from the refractive index at 0.1 is 0.1 or more, and in the wavelength region of the difference, an arbitrary value in the high refractive index resin layer and the low refractive index resin layer It is preferable that the refractive index of the low refractive index resin layer is lower than that of the high refractive index resin layer at the same wavelength.

The fine particles contained in the high refractive index resin layer satisfying the above conditions are suitably fine particles that absorb less in the visible light region and exhibit a high refractive index in the infrared region. Examples of such fine particles include dielectric fine particles such as titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, tungsten oxide, niobium oxide, cerium oxide, lead oxide, zinc oxide, and diamond. Of these, titanium oxide, zirconium oxide, zinc oxide, and diamond are preferable. Further, although not the dielectric fine particles, borides and nitrides can be exemplified as the fine particles having a high refractive index in the infrared region and having infrared absorption ability. Specifically, lanthanum hexaboride and titanium nitride are suitable.

These fine particles exhibiting a high refractive index in the infrared region may be used singly or in combination of two or more, and separate fine particles may be used in each high refractive index resin layer in the laminated film.

The fine particles contained in the low refractive index resin layer have a low absorption in the visible light region, a good absorption in the infrared region, and a refractive index relatively lower than that of the high refractive index resin layer-containing fine particles. Those with a rate are suitable. As such, there may be mentioned electrically conductive metal oxide fine particles having a plasma wavelength in the infrared region. Specific examples include tin oxide, indium oxide, zinc oxide, tungsten oxide, chromium oxide, and molybdenum oxide. Among these, tin oxide, indium oxide, zinc oxide, and tungsten oxide having a low light absorption property in the visible light region are preferable, and indium oxide is more preferable among them.

Moreover, in order to improve the electrical conductivity of these metal oxide fine particles, it is preferable that the third component is doped or has an oxygen defect. Examples of dopants for this include Sb, V, Nb, Ta, etc. for tin oxide, and Zn, Al, Sn, Sb, Ga, Ge, etc. for indium oxide. On the other hand, Al, Ga, In, Sn, Sb, Nb, etc. are mentioned, and oxygen defects WO _x (2.45 ≦ x ≦ 2.999), Cs, Rb, K, Tl with respect to tungsten oxide. In, Ba, Li, Ca, Sr, Fe, Sn, Al, Cu and the like. Among these, Sn-doped indium oxide is preferable.

The fine particles contained in the low refractive index resin layer are fine particles having a powder resistance of 100 Ω · cm or less, preferably 10 Ω · cm or less, more preferably 1 Ω · cm or less when compressed at 60 MPa. When fine particles having a powder resistance higher than 100 Ω · cm are used, the absorption due to the plasma resonance of the fine particles is larger than 2500 nm, and the infrared shielding effect is reduced. As a method for measuring powder resistance, a powder resistance measurement system MCP-PD51 (Mitsubishi Chemical Analytech) is preferable, but is not limited thereto.

In addition to the fine particles contained in the low refractive index resin layer, hollow fine particles having a low refractive index are preferably contained. As the hollow fine particles, known hollow fine particles such as hollow silica and hollow acrylic beads can be used.

The porosity of the hollow fine particles is preferably 10% to 90% by volume. When the porosity is less than 10% by volume, the refractive index of the hollow fine particles does not decrease and cannot be used for the low refractive index resin layer. On the other hand, when the porosity is higher than 90% by volume, the mechanical strength of the hollow particles decreases, and the hollow cannot be maintained, which is not preferable.

When the metal oxide fine particles and the hollow fine particles are combined in the low refractive index resin layer, the proportion of the metal oxide fine particles in the fine particles contained in the low refractive index resin layer is preferably 10% by weight to 90% by weight, more preferably. 20% to 90% by weight. When the metal oxide fine particles are less than 10% by weight, the infrared absorption ability by the metal oxide is insufficient, which is not preferable. On the other hand, when the amount is more than 90% by weight, the ratio of hollow fine particles decreases, which is not preferable.

Further, fine particles used in the infrared shielding sheet of the present invention are those having a primary particle diameter of 300 nm or less, preferably 1 nm to 200 nm. When the primary particle diameter is larger than 300 nm, when an infrared shielding sheet is used, the haze value is increased and the visibility is deteriorated. The particle size is calculated from the specific surface area measured by the BET method.

In order to satisfy the infrared shielding performance, smoothness, low haze, and radio wave permeability of the infrared shielding sheet, it is important to appropriately disperse the fine particles. As a dispersion method, it is preferable to use a sand mill, an attritor, a ball mill, a homogenizer, a roll mill, or a bead mill. Among these, a bead mill is particularly preferable. When a bead mill is used, the peripheral speed is preferably 3 m / s to 10 m / s. If it is lower than 3 m / s, the fine particles cannot be sufficiently dispersed, and if it is higher than 10 m / s, particularly the surface of the fine particles contained in the low refractive index resin layer is damaged, and the infrared absorption performance is deteriorated. The appropriate range varies slightly depending on the apparatus used, the binder, the fine particle concentration at the time of dispersion, etc., but it is better to disperse with a relatively low dispersion energy. Furthermore, when coarse particles remain, it is preferable to remove the coarse particles by a treatment such as filtration or centrifugation.

The solvent used for dispersion is not particularly limited, but in the present invention, water or an organic solvent may be blended and used as a mixture. Examples of the organic solvent include hydrocarbon solvents (toluene, xylene, hexane, cyclohexane, n-heptane, etc.), alcohol solvents (methanol, ethanol, isopropyl alcohol, butanol, t-butanol, benzyl alcohol, etc.), ketone solvents. (Acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, acetylacetone, etc.), ester solvents (ethyl acetate, methyl acetate, butyl acetate, cellosolve acetate, amyl acetate, etc.), ether solvents (isopropyl ether, methyl cellosolve, butyl cellosolve) 1,4-dioxane, etc.), glycol solvents (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, etc.), glycol ether solvents Diethylene glycol monomethyl ether, propylene glycol monomethyl ether, etc.), glycol ester solvents (ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, etc.), glyme solvents (monoglyme, diglyme, etc.), halogenated solvents ( Dichloromethane, chloroform, etc.), amide solvents (N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone), pyridine, tetrahydrofuran, sulfolane, acetonitrile, dimethyl sulfoxide. Preferred are water, ketone solvents, alcohol solvents, amide solvents, and hydrocarbon solvents, and more preferred are toluene, methyl ethyl ketone, methyl isobutyl ketone, and acetylacetone.

Dispersants include fatty acid salts (soap), α-sulfo fatty acid ester salts (MES), alkylbenzene sulfonates (ABS), linear alkylbenzene sulfonates (LAS), alkyl sulfates (AS), alkyl ether sulfates Low molecular weight anionic (anionic) compounds such as salt (AES) and alkyl sulfate triethanol, fatty acid ethanolamide, polyoxyethylene alkyl ether (AE), polyoxyethylene alkylphenyl ether (APE), sorbitol, sorbitan Nonionic compounds, low molecular weight cationic (cationic) compounds such as alkyltrimethylammonium salt, dialkyldimethylammonium chloride, alkylpyridinium chloride, alkylcarboxyl betaine, sulfobetatai Low molecular amphoteric compounds such as lecithin, formalin condensate of naphthalene sulfonate, polystyrene sulfonate, polyacrylate, copolymer salt of vinyl compound and carboxylic acid monomer, carboxymethyl cellulose, polyvinyl alcohol, etc. Typical examples are polymeric water-based dispersants such as polyacrylic acid partial alkyl esters and polyalkylene polyamines, and polymer cationic dispersants such as polyethyleneimine and aminoalkyl methacrylate copolymers. However, as long as it is suitably applied to the particles of the present invention, those having a structure other than the ones exemplified here are not excluded.

The following are known as specific dispersants to be added. Florene DOPA-15B, Florene DOPA-17 (manufactured by Kyoeisha Chemical Co., Ltd.), Solplus AX5, Solplus TX5, Solsperse 9000, Solsperse 12000, Solsperse 17000, Solsperse 20000, Solsperse 21000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse 28000, Solsperse 32000, Solsperse 35100, Solsperse 54000, Sol Six 250, (manufactured by Nippon Lubrizol Corporation), EFKA4008, EFKA4009, EFKA4010, EFKA4015, EFKA4046, EFKA4047, EFKA4060, EFKA7440E, EFKA7440E EFKA4400, EFKA4401, EFKA4402, EFKA4403, EFKA4300, EFKA4320, EFKA4330, EFKA4340, EFKA6220, EFKA6225, EFKA6700, EFKA6780, EFKA8583, EFKA8583 PN411, Famex L-12 (manufactured by Ajinomoto Fine Techno Co., Ltd.), TEXAPHOR-UV21, TEXAPHOR-UV61 (manufactured by Cognis Japan Co., Ltd.), DisperBYK101, DisperBYK102, DisperBYK106, DisperBYK108, DisperBYK111 DisperBYK116, DisperBYK130, DisperBYK140, DisperBYK142, DisperBYK145, DisperBYK161, DisperBYK162, DisperBYK163, DisperBYK164, DisperBYK166, DisperBYK167, DisperBYK168, DisperBYK170, DisperBYK171, DisperBYK174, DisperBYK180, DisperBYK182, DisperBYK192, DisperBYK193, DisperBYK2000, DisperBYK2001, DisperBYK2020, DisperBYK2025, DisperBYK2050, DisperBYK2070, Di SuperBYK2155, DisperBYK2164, BYK220S, BYK300, BYK306, BYK320, BYK322, BYK325, BYK330, BYK340, BYK350, BYK377, BYK378, BYK380N, BYK410, BYK410, BYK410, BYK410, BYK410 , Disparon 1860, Disparon 1934, Disparon DA-400N, Disparon DA-703-50, Disparon DA-725, Disparon DA-705, Disparon DA-7301, Disparon DN-900, Disparon NS-5210, Disparon NVI-8514L, Hip LARD ED-152, Plard ED-216, Hiplard ED-251, Hiplard ED-360 (Enomoto Kasei Co., Ltd.), FTX-207S, FTX-212P, FTX-220P, FTX-220S, FTX-228P, FTX-710LL, FTX-750LL , Aftergent 212P, aftergent 220P, aftergent 222F, aftergent 228P, aftergent 245F, aftergent 245P, aftergent 250, aftergent 251, aftergent 710FM, aftergent 730FM, aftergent 730LL, aftergent 730LS, after Gento 750DM, Aftergent 750FM (manufactured by Neos Co., Ltd.), AS-1100, AS-1800, AS-2000 (manufactured by Toagosei Co., Ltd.), Kao Sera 2000, Kaosela 2100, KDH-154, MX-2045L, Homogenol L-18, Homogenol L-95, Rheodor SP-010V, Rheodor SP-030V, Rheodor SP-L10, Rheodor SP-P10 (manufactured by Kao Corporation), Evan U103, Cyanol DC902B, Neugen EA-167, Blysurf A219B, Blysurf AL (Daiichi Kogyo Seiyaku Co., Ltd.), MegaFuck F-477, MegaFuck 480SF, MegaFuck F-482 (Dic Corporation) , Sylface SAG503A, Dinol 604 (Nisshin Chemical Co., Ltd.), SN Spurs 2180, SN Spurs 2190, SN Leveler S-906 (San Nopco), S-386, S-420 (AGC Seimi Chemical Co., Ltd.) (Made by company).

The resin binder used in the present invention is not particularly limited as long as it can disperse and maintain fine particles, and examples thereof include thermoplastic resins, thermosetting resins, and photocurable resins.

The thermoplastic resins include high density polyethylene resin, low density polyethylene resin, linear low density polyethylene resin, ultra low density polyethylene resin, polypropylene resin, polybutadiene resin, cyclic olefin resin, polymethylpentene resin, polystyrene resin, ethylene acetate Vinyl copolymer, ionomer resin, ethylene vinyl alcohol copolymer resin, ethylene ethyl acrylate copolymer, acrylonitrile / styrene resin, acrylonitrile / chlorinated polystyrene / styrene copolymer resin, acrylonitrile / acrylic rubber / styrene copolymer resin, acrylonitrile / butadiene・ Styrene copolymer resins, acrylonitrile, EPDM, styrene copolymer resins, silicone rubber, acrylonitrile, styrene copolymer resins, cellulose, acetate, Rate resin, cellulose acetate resin, methacrylic resin, ethylene / methyl methacrylate copolymer resin, ethylene / ethyl acrylate resin, vinyl chloride resin, chlorinated polyethylene resin, polytetrafluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer Resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene / ethylene copolymer resin, polytrifluorinated ethylene chloride resin, polyvinylidene fluoride resin, nylon 4, 6, nylon 6, nylon 6, 6 , Nylon 6, 10, nylon 6, 12, nylon 12, nylon 6, T, nylon 9, T, aromatic nylon resin, polyacetal resin, ultrahigh molecular weight polyethylene resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyester Lena naphthalate resin, amorphous copolyester resin, polycarbonate resin, modified polyphenylene ether resin, thermoplastic polyurethane elastomer, polyphenylene sulfide resin, polyether ether ketone resin, liquid crystal polymer, polytetrafluoroethylene resin, polyfluoroalkoxy resin, polyether Examples include, but are not limited to, imide resins, polysulfone resins, polyketone resins, thermoplastic polyimide resins, polyamideimide resins, polyarylate resins, polysulfone resins, polyethersulfone resins, biodegradable resins, and biomass resins. . Also, a mixture of two or more of these resins may be used.

The thermosetting resin is not particularly limited as long as it has a functional group curable by heating, and examples thereof include a curable compound having a cyclic ether such as an epoxy group or an oxetanyl group. The photocurable resin is not particularly limited as long as it is a compound having a functional group that can be cured by light irradiation. For example, a vinyl group, vinyl ether group, allyl group, maleimide group, (meth) acryl group, etc. Examples thereof include resins having a curable compound having a saturated double bond.

It does not specifically limit as a thermosetting resin which has the said cyclic ether, For example, an epoxy resin, an alicyclic epoxy resin, an oxetane resin, a furan resin etc. are mentioned. Of these, epoxy resins, alicyclic epoxy resins, and oxetane resins are preferred from the viewpoint of reaction rate and versatility. The epoxy resin is not particularly limited, and examples thereof include novolak types such as phenol novolak type, cresol novolak type, biphenyl novolak type, trisphenol novolak type, dicyclopentadiene novolak type; bisphenol A type, bisphenol F type, 2, 2 Examples thereof include bisphenol types such as' -diallyl bisphenol A type, hydrogenated bisphenol type, and polyoxypropylene bisphenol A type. Other examples include glycidylamine.

As a commercially available product of the above epoxy resin, for example, as a phenol novolak type epoxy resin, Epicron N-740, N-770, N-775 (all of which are manufactured by Dainippon Ink and Chemicals), Epicoat 152, Epicoat 154 ( As mentioned above, all are Japan Epoxy Resin Co., Ltd.). Examples of the cresol novolac type include epiclone N-660, N-665, N-670, N-673, N-680, N-695, N-665-EXP, N-672-EXP (all of which are large. As a biphenyl novolak type, for example, NC-3000P (manufactured by Nippon Kayaku Co., Ltd.); As a trisphenol novolak type, for example, EP1032S50, EP1032H60 (all of these are manufactured by Japan Epoxy Resin); Examples of the dicyclopentadiene novolac type include XD-1000-L (manufactured by Nippon Kayaku Co., Ltd.), HP-7200 (manufactured by Dainippon Ink &Chemicals); and examples of the bisphenol A type epoxy compound include epicoat 828 and epicoat 834 Epicoat 1001, Epicoat 1004 (above, Izu Are manufactured by Japan Epoxy Resin Co., Ltd.), Epicron 850, Epicron 860, Epicron 4055 (all of which are manufactured by Dainippon Ink & Chemicals, Inc.); Commercially available bisphenol F type epoxy compounds include, for example, Epicoat 807 (Japan Epoxy Resin Co., Ltd.) ), Epicron 830 (Dainippon Ink Chemical Co., Ltd.); 2,2′-diallyl bisphenol A type, for example, RE-810NM (Nippon Kayaku Co., Ltd.); Hydrogenated bisphenol type, for example, ST -5080 (manufactured by Tohto Kasei Co., Ltd.); Examples of the polyoxypropylene bisphenol A type include EP-4000 and EP-4005 (all of which are manufactured by Asahi Denka Kogyo Co., Ltd.).

Examples of commercially available oxetane compounds include etanacol EHO, etanacol OXBP, etanacol OXTP, etanacol OXMA (all of which are manufactured by Ube Industries, Ltd.). Moreover, it does not specifically limit as said alicyclic epoxy compound, For example, Celoxide 2021, Celoxide 2080, Celoxide 3000 (all are the Daicel UCB company make) etc. are mentioned. These curable compounds having a cyclic ether group may be used alone or in combination of two or more.

The photocurable resin having an unsaturated double bond is not particularly limited, and examples thereof include resins having a vinyl group, a vinyl ether group, an allyl group, a maleimide group, a (meth) acryl group, and the like. From the viewpoint of versatility, a resin having a (meth) acryl group is preferred. In addition, in this specification, a (meth) acryl group means an acryl group or a methacryl group.

Examples of the resin having a (meth) acryl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, carbitol (meth) acrylate, and acryloyl. Morpholine, half ester which is a reaction product of hydroxyl group-containing (meth) acrylate and acid anhydride of polycarboxylic acid compound, polyethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate , Di (meth) acrylate of ε-caprolactone adduct of trimethylolpropane polyethoxytri (meth) acrylate, glycerin polypropoxytri (meth) acrylate, and neopentyl glycol hydroxypivalate (For example, KAYARAD HX-220, HX-620, etc., manufactured by Nippon Kayaku Co., Ltd.), pentaerythritol tetra (meth) acrylate, poly (meth) acrylate, dipentaerythritol and ε-caprolactone reaction product, dipenta Examples include erythritol poly (meth) acrylate (for example, KAYARAD DPHA manufactured by Nippon Kayaku Co., Ltd.), epoxy (meth) acrylate that is a reaction product of a mono- or polyglycidyl compound and (meth) acrylic acid, and the like.

There is no restriction | limiting in particular as a glycidyl compound used for the epoxy (meth) acrylate which is a reaction material of a mono- or polyglycidyl compound and (meth) acrylic acid, For example, bisphenol A, bisphenol F, bisphenol S, 4, 4'- Biphenylphenol, tetramethylbisphenol A, dimethylbisphenol A, tetramethylbisphenol F, dimethylbisphenol F, tetramethylbisphenol S, dimethylbisphenol S, tetramethyl-4,4'-biphenol, dimethyl-4,4'-biphenylphenol, 1- (4-hydroxyphenyl) -2- [4- (1,1-bis- (4-hydroxyphenyl) ethyl) phenyl] propane, 2,2′-methylene-bis (4-methyl-6-tert- Butylphenol 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol), trishydroxyphenylmethane, resorcinol, hydroquinone, pyrogallol, phenols having a diisopropylidene skeleton, 1,1-di-4-hydroxy Phenols having a fluorene skeleton such as phenylfluorene, phenolized polybutadiene, brominated bisphenol A, brominated bisphenol F, brominated bisphenol S, brominated phenol novolac, brominated cresol novolac, chlorinated bisphenol S, chlorinated bisphenol A, etc. And glycidyl etherified products of polyphenols.

The epoxy (meth) acrylate which is a reaction product of these mono- or polyglycidyl compounds and (meth) acrylic acid can be obtained by esterifying an equivalent amount of (meth) acrylic acid to the epoxy group. This synthesis reaction can be performed by a generally known method. For example, resorcin diglycidyl ether with an equivalent amount of (meth) acrylic acid, a catalyst (for example, benzyldimethylamine, triethylamine, benzyltrimethylammonium chloride, triphenylphosphine, triphenylstibine, etc.) and a polymerization inhibitor (for example, methoquinone, Hydroquinone, methylhydroquinone, phenothiazine, dibutylhydroxytoluene and the like) and, for example, an esterification reaction is performed at 80 ° C to 110 ° C. The (meth) acrylated resorcin diglycidyl ether thus obtained is a resin having a radically polymerizable (meth) acryloyl group.

Moreover, the resin binder of the infrared shielding sheet of this invention can add a photoreaction initiator and a thermosetting agent as needed. The photoinitiator is not particularly limited as long as it is for polymerizing an unsaturated double bond or an epoxy group in the curable resin by light irradiation. For example, a cationic polymerization type photoinitiator or a radical is used. A polymerization type photoinitiator is mentioned. The thermosetting agent is not particularly limited as long as it is for reacting and crosslinking the unsaturated double bond or epoxy group in the curable resin by heating. For example, acid anhydride, amines, phenol Imidazoles, dihydrazines, Lewis acids, Bronsted acid salts, polymercaptons, isocyanates, blocked isocyanates and the like.

The content of fine particles in each layer in the infrared shielding sheet is 40% to 95% by weight, preferably 50% to 90% by weight, more preferably 60% to 90% by weight. If it exceeds 95% by weight, the binder component decreases, so that the film is not cured and it becomes difficult to laminate. Furthermore, in the case of electrically conductive fine particles, the fine particles are connected to each other, so that radio wave transmission performance cannot be imparted. On the other hand, when the amount is less than 40% by weight, the refractive index of the resin binder is dominant and the infrared reflection performance cannot be imparted.

In the present invention, the surface resistance of the high refractive index resin layer and the low refractive index resin layer is 10 ³ Ω / □ or more, preferably 10 ⁴ Ω / □ or more, more preferably 10 ⁶ Ω / □ or more. If it is lower than 10 ³ Ω / □, radio waves cannot be transmitted, which is not preferable.

Further, the maximum height difference of the surface of each layer is 70 nm or less, preferably 60 nm or less, more preferably 50 nm or less. When thin film coating is performed after dispersing until the aggregated fine particles disappear, a preferable maximum height difference on the surface of the fine particle layer can be obtained. On the other hand, if there is a surface roughness of 70 nm or more, near-infrared light incident on the film surface will scatter, and good reflection performance cannot be imparted.

The infrared shielding sheet of the present invention is preferably produced by appropriately selecting a high refractive index resin layer and a low refractive index resin layer from known coating methods and applying and drying on a support. Although it does not specifically limit about a coating system, A comma coater, a spray coater, a roll coater, a knife coater, etc. are mentioned, but thin film production such as a bar coater, a spin coater, a die coater, and a micro gravure coater is preferable for the smoothness of each layer. Use a coating device suitable for

Moreover, various additives, such as a ultraviolet absorber, antioxidant, a light stabilizer, can be added to an infrared shielding sheet or a new layer as needed, for example. Furthermore, depending on the purpose, functional sheets such as an adhesive layer and a hard coat layer may be laminated on the infrared shielding sheet to form an infrared shielding laminated sheet.

For the infrared region that cannot be shielded by the infrared shielding sheet of the present invention, known materials such as an infrared absorbing dye, a cholesteric liquid crystal film, and a birefringent multilayer film may be combined.

The infrared absorbing dye to be combined with the infrared shielding sheet of the present invention is not particularly limited, and specifically, an infrared absorbing dye having an absorption maximum at 750 nm to 1100 nm, for example, a phthalocyanine dye, an anthraquinone dye, Dithiol dye, diimonium dye, anthraquinone dye, dithiol metal complex dye, squarylium dye, naphthalocyanine dye, aminium dye, organometallic complex dye, cyanine dye, azo dye, polymethine dye, quinone System dyes, diphenylmethane dyes, triphenylmethane dyes, and mercaptonaphthol dyes can be used.

Among these, phthalocyanine dyes, naphthalocyanine dyes, and anthraquinone dyes are preferably used.

In the cholesteric liquid crystal film combined with the infrared shielding sheet of the present invention, the molecular axes are aligned in a certain direction on one plane, but the molecular axes are shifted slightly from each other on the next plane, and further on the next plane. In this structure, the angles of the molecular axes are shifted one after another in the normal direction of the plane such that the angles are shifted. Such a structure in which the direction of the molecular axis is twisted is called a chiral structure. The normal line (chiral axis) of the plane is preferably substantially parallel to the thickness direction of the cholesteric liquid crystal layer.

When light is incident on the cholesteric liquid crystal material, one of the circularly polarized light in the counterclockwise direction and the clockwise direction in the specific wavelength region is reflected. When the helical axis representing the rotation axis when the molecular axis is twisted in the chiral structure and the normal line of the cholesteric liquid crystal material are parallel, the pitch length p of the chiral structure and the wavelength λ _{c of the} circularly polarized light reflected are as follows: It has the relationship of (2) and Formula (3).
Formula (2)
Formula (3)
In the formula (2) and (3), lambda _c is the center wavelength of the wavelength region to be reflected, n _o is the minor axis direction of the refractive index of the liquid crystal compounds, n _e is the refractive index of the long axis of the liquid crystal compounds, n (N _o + n _e ) / 2, θ represents the incident angle of light (angle from the surface normal).

Thus, the center wavelength of the wavelength region to be reflected depends on the pitch length of the chiral structure in the cholesteric liquid crystal material. The central wavelength to be reflected can be changed by changing the pitch length of the chiral structure.

The number of layers of the cholesteric liquid crystal material may be one or two or more. It is preferable that the number of layers is two or more because the wavelength band of infrared rays that can be reflected can be expanded.

When two or more cholesteric liquid crystal materials are used, it is preferable to combine cholesteric liquid crystal layers having different molecular axis twist directions in order to more efficiently reflect the central wavelength region to be reflected. That is, both right circularly polarized light and left circularly polarized light can be reflected, and an effective reflectance can be realized. In addition, when two or more cholesteric liquid crystal materials are used, it is preferable to combine cholesteric liquid crystal layers having different pitch lengths when combining a wide range of reflected wavelengths. A wider range of near-infrared wavelength regions can be reflected with high efficiency. As the combination of the number of layers, the right circularly polarized light, the left circularly polarized cholesteric liquid crystal layer, and the like, an appropriate combination can be used in view of manufacturing cost, visible light transmittance, and the like.

As the cholesteric liquid crystal material, a curable liquid crystal composition is preferably used. An example of the liquid crystal composition contains at least a rod-like liquid crystal compound, an optically active compound (chiral compound), and a polymerization initiator. Two or more of each component may be included. For example, a polymerizable liquid crystal compound and a non-polymerizable liquid crystal compound can be used in combination. Also, a combination of a low-molecular liquid crystal compound and a high-molecular liquid crystal compound is possible. Furthermore, in order to improve the uniformity of alignment, applicability, and film strength, it contains at least one selected from various additives such as horizontal alignment, unevenness inhibitor, repellency inhibitor, and polymerizable monomer. Also good. Further, in the liquid crystal composition, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, metal oxide fine particles, and the like are further added as necessary so as not to deteriorate the optical performance. can do.

(1) Rod-like liquid crystal compound The rod-like liquid crystal compound is a rod-like nematic liquid crystal compound. Examples of the rod-like nematic liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, phenyldioxane. Low molecular liquid crystal compounds and high molecular liquid crystal compounds such as alkenyl, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

The rod-like liquid crystal compound used in the present invention may be polymerizable or non-polymerizable. The rod-like liquid crystal compound having no polymerizable group is described in various documents (for example, Y. Goto et.al., Mol. Cryst. Liq. Cryst. 1995, Vol. 260, pp. 23-28). .
The polymerizable rod-like liquid crystal compound can be obtained by introducing a polymerizable group into the rod-like liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The polymerizable group can be introduced into the molecule of the rod-like liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable rod-like liquid crystal compound is preferably 1 to 6, and more preferably 1 to 3. Examples of the polymerizable rod-like liquid crystal compound are described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648, and 5770107, International Publication WO95 / 22586 No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081 and JP-A 2001-328773, and the like. Two or more kinds of polymerizable rod-like liquid crystal compounds may be used in combination. When two or more kinds of polymerizable rod-like liquid crystal compounds are used in combination, the alignment temperature can be lowered.

(2) Optically active compound (chiral agent)
The liquid crystal composition exhibits a cholesteric liquid crystal phase, and for that purpose, it preferably contains an optically active compound. However, when the rod-like liquid crystal compound is a molecule having an asymmetric carbon atom, the cholesteric liquid crystal layer may be formed stably without adding an optically active compound. The optically active compound is known in various known chiral agents (for example, liquid crystal device handbook, Chapter 3-4-3, TN, chiral agent for STN, 199 pages, edited by Japan Society for the Promotion of Science, 142nd Committee, 1989). ) Can be selected. The optically active compound generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as a chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The optically active compound (chiral agent) may have a polymerizable group. When the optically active compound has a polymerizable group and the rod-shaped liquid crystal compound used in combination also has a polymerizable group, the repetition is derived from the rod-shaped liquid crystal compound by a polymerization reaction between the polymerizable optically active compound and the polymerizable rod-shaped liquid crystal compound. Polymers having units and repeating units derived from optically active compounds can be formed. In this embodiment, the polymerizable group possessed by the polymerizable optically active compound is preferably the same group as the polymerizable group possessed by the polymerizable rod-like liquid crystal compound. Therefore, the polymerizable group of the optically active compound is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Is particularly preferred. The optically active compound may be a liquid crystal compound.

The optically active compound in the liquid crystal composition is preferably 0.1 mol% to 30 mol% with respect to the liquid crystal compound used in combination. A smaller amount of the optically active compound is preferred because it often does not affect the liquid crystallinity. Therefore, the optically active compound used as the chiral agent is preferably a compound having a strong twisting power so that a twisted orientation with a desired helical pitch can be achieved even with a small amount. As such a chiral agent exhibiting a strong twisting force, for example, a chiral agent described in JP-A No. 2003-287623 can be mentioned and can be preferably used in the present invention.

(3) Polymerization initiator The liquid crystal composition used for forming the light reflecting layer is preferably a polymerizable liquid crystal composition, and for that purpose, it preferably contains a polymerization initiator. In the present invention, since the curing reaction is advanced by irradiation with ultraviolet rays, the polymerization initiator to be used is preferably a photopolymerization initiator capable of starting the polymerization reaction by irradiation with ultraviolet rays. The photopolymerization initiator is not particularly limited. For example, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (“Irgacure 907” manufactured by Ciba Specialty Chemicals), 1-hydroxycyclohexyl phenyl ketone ("Irgacure 184" manufactured by Ciba Specialty Chemicals), 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone ("Irgacure" manufactured by Ciba Specialty Chemicals) 2959 "), 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one (" Darocur 953 "manufactured by Merck & Co.), 1- (4-isopropylphenyl) -2-hydroxy-2- Methylpropan-1-one (Merck "Darocur 1116"), -Hydroxy-2-methyl-1-phenylpropan-1-one ("Irgacure 1173" manufactured by Ciba Specialty Chemicals), acetophenone compounds such as diethoxyacetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether Benzoin compounds such as benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone (“Irgacure 651” manufactured by Ciba Specialty Chemicals), benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyldiphenyl sulfide, 3,3′-dimethyl-4-methoxybenzophenone (“Kayacure MBP” manufactured by Nippon Kayaku Co., Ltd.), etc. Benzophenone compound, thioxanthone, 2-chlorothioxanthone (“Kayacure CTX” manufactured by Nippon Kayaku Co., Ltd.), 2-methylthioxanthone, 2,4-dimethylthioxanthone (“Kayacure RTX” manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone, 2, 4 -Diclothiothioxanthone (“Kayacure CTX” manufactured by Nippon Kayaku Co., Ltd.), 2,4-diethylthioxanthone (“Kayacure DETX” manufactured by Nippon Kayaku Co., Ltd.), 2,4-Diisopropylthioxanthone (“Kayacure DITX” manufactured by Nippon Kayaku Co., Ltd.) ) And the like. These photoinitiators may be used independently and 2 or more types may be used together.

The content of the photopolymerization initiator in the composition is not particularly limited, but the preferred lower limit is preferably 0.5 parts by weight, preferably 100 parts by weight of the polymerizable liquid crystal compound or the (meth) acrylate monomer composition. The upper limit is 10 parts by weight or less, the more preferable lower limit is 2 parts by weight, and the more preferable upper limit is 8 parts by weight.

When the benzophenone compound or the thioxanthone compound is used as the photopolymerization initiator, it is preferable to use a reaction aid together in order to promote the photopolymerization reaction. The reaction aid is not particularly limited, and examples thereof include triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4′-diethylaminophenone, 4- Examples include amine compounds such as ethyl dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), and isoamyl 4-dimethylaminobenzoate.

The content of the reaction aid in the polymerizable liquid crystal composition is not particularly limited, but is preferably used in a range that does not affect the liquid crystal properties of the polymerizable liquid crystal composition. A preferred lower limit is 0.5 parts by weight, a preferred upper limit is 10 parts by weight or less, a more preferred lower limit is 2 parts by weight, and a more preferred upper limit is 8 parts by weight with respect to a total of 100 parts by weight of the curable polymerizable compound. is there. Moreover, it is preferable that content of the said reaction adjuvant is 0.5 to 2 times amount with respect to content of the said photoinitiator.

Furthermore, a leveling agent, an antifoaming agent, an ultraviolet absorber, a light stabilizer, an antioxidant, a polymerization inhibitor, a crosslinking agent, a plasticizer, inorganic fine particles, a filler, and the like are added to the above composition as necessary. It is also possible to impart the desired functionality. Examples of the leveling agent include fluorine compounds, silicone compounds, acrylic compounds, and the like. Examples of ultraviolet absorbers include benzotriazole compounds, benzophenone compounds, and triazine compounds. Examples of light stabilizers include hindered amine compounds and benzoate compounds. Examples of antioxidants include phenol compounds. Is mentioned.
Examples of the polymerization inhibitor include methoquinone, methylhydroquinone, hydroquinone and the like, and examples of the crosslinking agent include the polyisocyanates and melamine compounds.
Plasticizers include phthalates such as dimethyl phthalate and diethyl phthalate, trimellitic esters such as tris (2-ethylhexyl) trimellitate, aliphatic dibasic esters such as dimethyl adipate and dibutyl adipate, tributyl phosphate and triphenyl. Examples thereof include orthophosphate esters such as phosphate and acetate esters such as glyceryl triacetate and 2-ethylhexyl acetate.

The method for applying the cholesteric liquid crystal layer is not particularly limited, and examples thereof include a comma coater, a spray coater, a roll coater, a knife coater, and the like, but preferably a bar coater, a spin coater, Use of a coating apparatus suitable for thin film production such as a die coater and a micro gravure coater is preferable. Further, in order to more precisely define the alignment direction of the liquid crystal compound in the cholesteric liquid crystal layer, the surface of the layer (fine particle layer, substrate, etc.) to which the cholesteric liquid crystal layer is applied may be aligned. In order to align, it is preferable to form an alignment surface by rubbing the surface of the substrate.

The birefringent multilayer film combined with the infrared shielding sheet of the present invention includes a layer having birefringence (preferably positive birefringence) (hereinafter, birefringent layer) and a layer having isotropic refraction or negative birefringence (hereinafter, etc.). Birefringent layers), and is based on coherent interference caused by the refractive index difference between the birefringent layer and the isotropic refractive layer and the respective film thicknesses. When the in-plane refractive index is different between the birefringent layer and the isotropic refractive layer, the interface between the two layers forms a reflective surface.

Birefringence means that the refractive indices in the orthogonal x, y and z directions are not all the same. In the case of an oriented polymer, the x-axis and y-axis are in the plane of the layer, the z-axis is perpendicular to the plane of the layer, and for oriented polymers, the x-axis is chosen to be the in-plane direction with the highest refractive index, The direction corresponds to one of the directions in which the optical body is oriented (eg, stretched).

The in-plane refractive indexes of both the birefringent layer and the isotropic refractive layer are different between the layers (ie, n _1x ≠ n _2x , n _1y ≠ n _2y , where n _1x and n _1y are the in-plane refractive indices of the birefringent layer And n _2x and n _2y are the in-plane refractive indices of the isotropic refractive layer). Further, it is preferable that the z-axis refractive indexes of the birefringent layer and the isotropic refractive layer are equal, since the reflection of p-polarized light does not depend on the incident angle of light, and the reflectance becomes uniform over the range of viewing angles.

In order to increase the in-plane refractive index of the birefringent layer, a birefringent polymer (preferably a polymer having positive birefringence) that is uniaxially or preferably biaxially oriented is used, and isotropically refracted with the birefringent layer. Increase the refractive index difference of the layer.

The optical film thickness of each layer is controlled to be λ _c / 4 where λ _c is the center wavelength of the wavelength region to be reflected. As the birefringent layer material, a material that is oriented by stretching (positive birefringence) is used. For example, PEN (polyethylene naphthalate), PET, or the like is used. As the isotropic refractive material, a material that is not oriented by stretching (or a material that is negatively birefringent by stretching) is used. For example, PMMA (polymethyl methacrylate) or the like is used. In addition, the birefringent multilayer structure material can be produced by forming a multilayer film and stretching it by, for example, a co-extrusion method described in JP-T-2008-528313. Since the refractive index difference between the birefringent layer and the isotropic refractive layer is small, a large number of layers must be laminated. The number of stacked layers is preferably 3 or more and 1000 or less in view of the reflection region to be reflected, the manufacturing cost, and the like.

  Hereinafter, the present invention will be described in more detail with reference to examples. In Examples, “part” means “part by weight” and “%” means “% by weight”.

Example 1
(Preparation of high refractive index resin layer 1)
KAYARAD DPHA (trade name, dipentaerythritol hexaacrylate, Nippon Kayaku) 0.4 parts, Irgacure 184 (photopolymerization initiator, BASF Japan) 0.05 parts dissolved in methyl ethyl ketone (hereinafter MEK) 4 parts Then, 4.7 parts of zirconium oxide (NANON5 ZR-010, average particle diameter 15 nm, solid content concentration 30 wt%, manufactured by Solar) was dispersed to prepare a high refractive index resin layer coating solution 1.

Next, the high refractive index layer coating solution 1 was applied to a PET substrate with a wire bar, dried at 100 ° C. for 2 minutes to evaporate MEK, and then the high refractive index resin layer 1 was produced by UV irradiation. The refractive index and extinction coefficient for each wavelength of the produced high refractive index layer 1 were measured with a spectroscopic ellipsometer (M-2000, manufactured by JA Woollam).

(Preparation of low refractive index resin layer 1)
1.4 parts of tin-doped indium oxide (hereinafter referred to as ITO) having an average particle diameter of 25.6 nm and a powder resistance of 0.8 Ω · cm, 0.4 parts of KAYARAD DPHA, 0.05 parts of Irgacure 184, aminoalkyl methacrylate 0.3 part of the coalesced dispersant was added to 7 parts of toluene and dispersed at a peripheral speed of 10 m / s using a bead mill to prepare a low refractive index resin layer coating solution 1.

Next, the low refractive index resin layer coating solution 1 was applied to a PET substrate with a wire bar, dried at 100 ° C. for 2 minutes to evaporate toluene, and then the low refractive index resin layer 1 was produced by UV irradiation. The refractive index and extinction coefficient for each wavelength of the produced high refractive index layer were measured with a spectroscopic ellipsometer (M-2000, manufactured by JA Woollam).

(Production of laminated film)
A low refractive index is set on the base material under the condition that the wavelength to be reflected is set to 1200 nm, the optical film thickness of the high refractive index resin layer 1 is 300 nm, and the optical film thickness of the low refractive index resin layer 1 is 300 nm. The infrared ray shielding sheet of the present invention having 8 layers was produced by alternately laminating resin layers 1 to high refractive index layers 1 in this order.

Example 2
(Preparation of high refractive index resin layer 2)
1.4 parts of titanium oxide (TTO-51A, manufactured by Ishihara Sangyo) having an average particle diameter of 35 nm, 0.4 parts of KAYARAD DPHA, 0.05 parts of Irgacure 907, 0.3 parts of aminoalkyl methacrylate copolymer dispersant are added to toluene. In addition to 7 parts, it was dispersed at a peripheral speed of 10 m / s using a bead mill to prepare a high refractive index resin layer coating solution 2.

Next, the high refractive index resin layer coating solution 2 was applied to a PET substrate with a wire bar, dried at 100 ° C. for 2 minutes to evaporate toluene, and then the high refractive index resin layer 2 was produced by UV irradiation. The refractive index and extinction coefficient for each wavelength of the produced high refractive index resin layer 2 were measured with a spectroscopic ellipsometer (M-2000, manufactured by JA Woollam).

(Production of laminated film)
The wavelength to be reflected is set to 1200 nm, the optical film thickness of the high refractive index resin layer 2 on the PET substrate is 300 nm, and the optical film thickness of the low refractive index resin layer 1 prepared in Example 1 is 300 nm. A high refractive index resin layer 2 and a low refractive index resin layer 2 were alternately laminated on the material in order to produce an infrared shielding sheet of the present invention having 7 layers.

Example 3
(Preparation of high refractive index resin layer 3)
Lanthanum hexaboride (manufactured by Wako Pure Chemical Industries, Ltd.) 1.4 parts, KAYARAD DPHA 0.4 parts, Irgacure 184 0.05 parts, aminoalkyl methacrylate copolymer dispersant 0.3 parts in toluene 7 parts, bead mill Was dispersed at a peripheral speed of 10 m / s. The obtained dispersion was centrifuged for 15 minutes at a rotational speed of 5000 rpm using a centrifuge (Hitachi Koki Co., Ltd., Himac CR18) to prepare a high refractive index layer coating solution 3. The average particle size of the coating solution was 35 nm.

Next, the high refractive index layer coating solution 3 was applied to a PET substrate with a wire bar, dried at 100 ° C. for 2 minutes to evaporate toluene, and then the high refractive index resin layer 3 was produced by UV irradiation. The refractive index and extinction coefficient for each wavelength of the produced high refractive index resin layer 3 were measured with a spectroscopic ellipsometer (M-2000, manufactured by JA Woollam).

(Production of laminated film)
The wavelength to be reflected was set to 1200 nm, the optical film thickness of the high refractive index resin layer 3 on the PET substrate was 300 nm, the optical film thickness of the high refractive index layer 1 prepared in Example 1 was 300 nm, and the film was prepared in Example 1. On the condition that the optical film thickness of the low refractive index resin layer 1 is 300 nm, a high refractive index resin layer 3-a low refractive index resin layer 1-a high refractive index resin layer 1-a low refractive index resin layer 1- The infrared shielding sheet of the present invention having 5 layers was prepared by laminating in the order of the high refractive index resin layer 1.

Example 4
(Preparation of high refractive index resin layer 4)
A high refractive index resin layer 4 was produced in the same manner as in Example 2 except that the fine particles were changed to nanodiamond (average particle diameter 3.5 nm).

(Production of laminated film)
The low-refractive-index resin layer 1-high refraction is formed on the base material under the condition that the wavelength to be reflected is set to 1200 nm, the optical film thickness of the high refractive index layer is 300 nm, and the optical film thickness of the fine particle layer is 300 nm The infrared shielding sheet of the present invention having 8 layers was produced by alternately laminating in the order of the rate layers 4.

Example 5
(Preparation of low refractive index resin layer 2)
Low refractive index resin layer coating solution 2 prepared by adding 3 parts of hollow silica (V8216, average particle size 50 nm, solid content concentration 20% by weight, manufactured by JGC Catalysts & Chemicals) to low refractive index resin layer coating solution 1 prepared in Example 1 Was made.

Next, the low refractive index resin layer coating solution 2 was applied to a PET substrate with a wire bar, dried at 100 ° C. for 2 minutes to evaporate toluene, and then the low refractive index resin layer 1 was produced by UV irradiation. The refractive index and extinction coefficient for each wavelength of the produced high refractive index layer were measured with a spectroscopic ellipsometer (M-2000, manufactured by JA Woollam).

(Production of laminated film)
A low refractive index is set on the base material under the condition that the wavelength to be reflected is set to 1200 nm, the optical thickness of the high refractive index resin layer 1 is 300 nm and the optical thickness of the low refractive index resin layer 2 is 300 nm on the PET base material. The infrared ray shielding sheet of the present invention having 8 layers was produced by alternately laminating in the order of resin layer 2 -high refractive index layer 1.

Example 6
(Infrared absorbing dye synthesis example)
To 120 parts of sulfolane, 15.9 parts of naphthalic anhydride, 29 parts of urea, 0.40 part of ammonium molybdate and 3.5 parts of vanadyl chloride (V) were added, and the temperature was raised to 200 ° C. and reacted at the same temperature for 11 hours. It was. After completion of the reaction, the reaction mixture was cooled to 65 ° C., 100 parts of N, N-dimethylformamide (DMF) was added, and the precipitated solid was separated by filtration. The obtained solid was washed with 50 parts of DMF to obtain 20.3 parts of a wet cake. The obtained wet cake was added to 100 parts of DMF, heated to 80 ° C., and stirred at the same temperature for 2 hours. The precipitated solid was separated by filtration and washed with 200 parts of water to obtain 18.9 parts of a wet cake. The obtained wet cake was added to 150 parts of water, heated to 90, and stirred at the same temperature for 2 hours. The precipitated solid was separated by filtration and washed with 200 parts of water to obtain 16.1 parts of a wet cake. The obtained wet cake was dried at 80 ° C. to obtain 12.3 parts of an infrared absorbing dye.

0.03 parts of each of the synthesized infrared absorbing dyes are dispersed in the high refractive index resin layer coating solution 1 and the low refractive index resin layer coating solution 1 prepared in Example 1, respectively, and the reflection wavelength is set to 1200 nm. Under the conditions that the optical film thickness of the high refractive index resin layer is 300 nm and the optical film thickness of the low refractive index resin layer is 300 nm on the base material, the low refractive index resin layer and the high refractive index layer are alternately arranged on the base material in this order. The infrared shielding sheet of the present invention having 8 layers was laminated.

Example 7
(Cholesteric liquid crystal film production)
10 parts of LC-242 (rod-like liquid crystal compound, manufactured by BASF), 0.25 part of LC-756 (manufactured by BASF), 0.5 part of lucillin TPO (polymerization initiator, BASF) in 26 parts of cyclopentanone In addition, a liquid crystal film coating solution 1 was prepared.
Moreover, LC-756 in the liquid crystal film coating solution 1 was changed to 0.3 part to prepare a liquid crystal coating solution 2.

A cholesteric liquid crystal film was prepared by laminating liquid crystal film coating solutions 1 and 2 on a PET substrate with a wire bar so that the film thickness was 4 μm.

A condition that the optical film thickness of the high refractive index resin layer 1 prepared in Example 1 is 300 nm and the optical film thickness of the low refractive index resin layer 1 is 300 nm on the prepared cholesteric liquid crystal film (the reflection wavelength is set to 1200 nm). Thus, the infrared shielding sheet of the present invention having 6 layers was produced by alternately laminating in the order of the low refractive index resin layer 1 to the high refractive index layer 1.

Example 8
An infrared shielding sheet of the present invention was produced in the same manner as in Example 8 except that the cholesteric liquid crystal film was changed to a birefringent multilayer (nano90S, manufactured by Sumitomo 3M).

Comparative Example 1
(Preparation of low refractive index layer)
While dissolving 1 part of KAYARAD DPHA (trade name, dipentaerythritol hexaacrylate, Nippon Kayaku) and 0.01 part of Irgacure 184 (photopolymerization initiator, manufactured by BASF Japan) in 10 parts of methyl ethyl ketone (hereinafter MEK) Then, 3.8 parts of silicon oxide (MEK-ST, average particle size: 15 nm, manufactured by Nissan Chemical Industries, Ltd.) was dispersed to prepare a low refractive index layer coating solution.

Next, the low refractive index layer coating solution was applied to a PET substrate with a wire bar, dried at 100 ° C. for 2 minutes to evaporate MEK, and then a low refractive index layer was produced by UV irradiation. The refractive index and extinction coefficient with respect to each wavelength of the produced low refractive index layer were measured with a spectroscopic ellipsometer (M-2000, manufactured by JA Woollam).

(Production of laminated film)
The wavelength to be reflected is set to 1200 nm, and the optical film thickness of the high refractive index layer 1 prepared in Example 1 on the PET substrate is 300 nm and the optical film thickness of the low refractive index layer is 300 nm. A comparative infrared shielding sheet having 7 layers was fabricated by alternately laminating in the order of high refractive index layer 1 -low refractive index layer.

Visible light transmittance, haze, total solar energy, refractive index at 550 nm of each layer, refractive index at 1200 nm, refractive index difference Δn with reference to 550 nm of the infrared shielding sheets of Examples 1 to 8 and Comparative Example 1, The results of measuring the surface resistance are shown in Table 1.
(Measurement of visible light transmittance)
The visible light transmittance at a wavelength of 380 nm to 780 nm of the obtained infrared shielding sheet was measured using a spectrophotometer (UV-3100 manufactured by Shimadzu Corporation) in accordance with JIS R3106.
(Measurement of total solar energy (Tts))
Total solar energy (Tts) is a measure of how much of the thermal energy from the sun is transmitted through the target material, and was calculated using a formula defined in ISO13837. The smaller the calculated numerical value, the smaller the total solar radiation energy, and the higher the heat ray shielding property.
(Measurement of haze value)
Using a haze meter (TC-HIIIDPK manufactured by Tokyo Denshoku Co., Ltd.), the haze value of the obtained infrared shielding sheet was measured according to JIS K6714.
(Measurement of surface resistance)
The surface resistance was measured using a surface resistance meter (High Lester UP, Lorestar GP, manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

1 and 2 and Table 1, the infrared shielding sheet of the present invention absorbs the wavelength region of 1500 nm to 2500 nm in addition to efficiently reflecting the wavelength region of 780 nm to 1500 nm as compared with Comparative Example 1. As a result, Tts was greatly improved.

In Example 3, in addition to the infrared absorption of lanthanum hexaboride, the infrared rays were efficiently shielded by the high refractive index in the infrared region of the lanthanum hexaboride layer.

In Example 5, by adding hollow fine particles, the absorption wavelength by ITO could be lowered without changing the refractive index in the near infrared, so that Tts was improved as compared with Example 1.

Examples 6 to 8 were able to shield infrared rays more effectively while maintaining the transmittance by combining with the infrared shielding sheet of the present invention.

Since Comparative Example 1 has no near-infrared absorption by fine particles, Tts is insufficient, and heat rays after 1500 nm at which a person feels irritating is not shielded, so that it may feel uncomfortable. Concerned.

According to the present invention, it has been found that, by providing infrared reflectivity utilizing a difference in refractive index in addition to the infrared absorption capability of fine particles, temperature increase due to infrared rays is suppressed as compared with conventional infrared shielding sheets. As a result, the temperature rise in the space of houses and cars can be suppressed, the load on the air conditioning equipment can be reduced, and energy saving and global environmental problems can be contributed. Furthermore, since the infrared region can be selectively shielded, it can be used for IR cut filters, forgery prevention, and the like.

Claims (10)

In the laminated film in which the high refractive index resin layer (A) and the low refractive index resin layer (B) containing fine particles are alternately laminated on the transparent support, the high refractive index resin layer (A) is obtained from the refractive index at 550 nm. The value obtained by subtracting the refractive index at an arbitrary wavelength at 780 nm to 1500 nm is 0.1 or less, and the value obtained by subtracting the refractive index at an arbitrary wavelength at 780 nm to 1500 nm from the refractive index at 550 nm for the low refractive index resin layer (B) The refractive index of (B) is lower than that of (A) at any same wavelength in (A) and (B) in the wavelength region of 0.1 or more and the difference. A featured infrared shielding sheet. (A), (B) The surface resistance of each layer is 1 kΩ / □ or more, the total number of layers (A), (B) is 3 or more, and the optical film thickness of each layer is 195 nm to 375 nm. Item 15. The infrared shielding sheet according to Item 1. The infrared shielding sheet according to claim 1 or 2, wherein the visible light transmittance is 50% or more and the haze is 8% or less. Fine particles contained in the high refractive index resin layer (A) are titanium oxide, zirconium oxide, hafnium oxide, tantalum oxide, tungsten oxide, niobium oxide, cerium oxide, lead oxide, diamond, zinc oxide, boride, nitride. The infrared shielding sheet according to any one of claims 1 to 3, wherein the infrared shielding sheet is at least one kind of fine particles selected from the group. The fine particles contained in the low refractive index resin layer (B) are at least one kind of fine particles selected from the group consisting of tin oxide, indium oxide, zinc oxide, and tungsten oxide. Infrared shielding sheet. The fine particles contained in the low refractive index resin layer (B) are Sb-doped tin oxide (ATO), Sn-doped indium oxide (ITO), Ga-doped zinc oxide (GZO), oxygen-deficient tungsten oxide, and Cs-doped tungsten oxide. The infrared shielding sheet according to claim 1, wherein the infrared shielding sheet is at least one selected from the group consisting of: The infrared shielding sheet according to any one of claims 1 to 6, wherein the low refractive index resin layer (B) contains hollow fine particles in addition to the fine particles selected from claim 5 or 6. The infrared shielding sheet according to any one of claims 1 to 7, wherein the content of fine particles contained in the high refractive index resin layer or the low refractive index resin layer is 90% by weight or less. The method for producing an infrared shielding sheet according to any one of claims 1 to 8, wherein the high refractive index resin layer and the low refractive index resin layer are formed by coating. A combination of the infrared shielding sheet according to claim 1 and at least one of a cholesteric liquid crystal film that selectively reflects 780 to 2000 nm, a birefringent multilayer film, or an infrared absorbing dye that selectively absorbs 780 to 2500 nm. Infrared shielding sheet.