JP2005511292A - Infrared reflecting lacquer layer - Google Patents

Abstract

  The present invention relates to a method for producing a transparent IR shielding film. According to this method, the carrier carries the active substance and is placed in the irradiation path. To achieve this, a lacquer system containing nanoparticles and a normal lacquer solvent is applied to the substrate by a wet process.

Description

  The present invention relates to the claimed object, ie an infrared shielding film.

  Infrared shielding films are becoming increasingly important in various fields. In the architectural field, for example, on large glass surfaces in high-rise buildings, often the amount of infrared radiation into the building is kept to a minimum, and in southern countries the maximum amount of sunlight is maintained while keeping the building at a low temperature. It is required to do. Similarly, in the field of automotive glass industry, there is a need to make aerodynamic improvements and maintain a wider range of glass with similar visibility. In any case, it is desirable to avoid an internal temperature rise. If the radiant heat cannot be adequately eliminated, air conditioners must be used in homes and cars. This therefore requires high energy consumption.

  In still other cases, it is required with regard to radiant heat behavior, which is particularly required in green houses, etc., in the north region. At that time, the radiant heat in the green house should be maintained and should not be lost. This applies to specific sheet materials such as, for example, greenhouses, tent materials, clothing and the like. On the other hand, if excessive temperature rise itself should be avoided, it is possible to release the internal heat, and heat incidence should be prevented in the preferred case. Each should not always be achieved because it is desirable only in certain cases. Furthermore, it can be considered that the heat flow is completely suppressed, that is, heat exchange from the inside to the outside or from the outside to the inside is completely suppressed. For example, in automobiles, the interior should be protected from sunlight during the summer, while in the winter the heat from the heater is kept inside as much as possible to support a rapid temperature rise. , Cooling state must be avoided.

A laminated glass including an intermediate layer in the first and second transparent glass plates has been proposed (EP 0727306A2), and functional ultrafine particles having a particle diameter of up to 0.2 μm are dispersed in the intermediate layer. This layer may in particular consist of plastic PVB (polyvinyl butyral) or ethylene vinyl acetate copolymer (EVA). The functional particles are selected from the group consisting of metals, metal-containing compounds and composite materials as shown in EP0727306A2. These metals consist of Sn, Ti, Si, Zn, Zr, Fe, Al, Cr, Co, Ce, In, Ni, Ag, Cu, Pt, Nn, Ta, W, V, and Mo. Metal compounds may include oxides, nitrides, oxynitrides and sulfides; the composite material may be doped with at least one substance, and the compound may be doped with at least one substance. It may be. As an _{oxide, SnO 2, TiO 2, SiO} 2, ZrO 2, ZnO 2, FeO 3, Al 2 O 3, FeO, Cr 2 O 3, CO 2 O 3, CeO 2, In 2 O 3, NiO, MnO And CuO. It is considered how much amount should be added into the starting resin for the intermediate layer, and that the resulting film has maximum conductivity to achieve sufficient radio wave transmission.

  Conventional methods lead to properties that are suitable for a particular use, but in all cases are not completely satisfactory. This is especially true for obtaining antistatic properties or providing a dissipative layer where it is desirable to have improved conductivity in addition to good IR-shielding properties. Furthermore, it is difficult to produce an infrared shielding composite molded body such as a strongly bent windshield.

Another method known in the state of the art is vapor phase coating on sheet glass, which can be carried out by sputtering, CVD, PVD or the like. The film material can be a very thin phase of conductively or semiconductively doped oxide, for example ATO (SnO ₂ : Sb), FTO (SnO ₂ : F), AZO (ZnO: Al) or ITO ( It is obtained by sputtering In ₂ O ₃ : Sn). These layers are very thin, transparent to visible light, and reduce infrared transmission. A continuous layer can be used as the conductive layer. However, the equipment used to apply such thin layers is very expensive, which in this case is unsuitable for coating with a large supply, i.e. a large number of materials. Means. In addition, essentially a lot of target material is required and eventually separates on the substrate. The residue must generally be removed in order to accumulate in the device, in which case this is highly undesirable as well as incomplete availability of expensive targets.

  Such a type of sputtering device is extremely difficult to use to apply the layers in small quantities or in a specific order on the composite compact, despite being technically very complex, This is because each change in geometry requires a significant reconstruction in the main part of the system. Attempts to planarly cover an automotive windshield and then bend it into the desired aerodynamic shape have been unsuccessful and have already been long. Furthermore, polymer or foil coating, as often desired, is only possible conditionally.

  The object of the present invention is to introduce new technology for commercial use.

  This object is made clear in the characterizing part of the independent claim. Preferred embodiments can be found in the following claims.

  The invention thus provides, according to a first aspect, a method for producing a transparent IR-blocking layer, in which the carrier is coated with an agent for placement in an irradiation pass, in which case these Was produced by applying nanoparticles and a normal lacquer solvent, which is free of nanoparticles and contained in a lacquer system applicable to a thin film, onto a substrate by a wet method.

  Surprisingly, it was confirmed that the nanoparticles produced a good infrared shielding effect even when mixed in a lacquer system. This makes it possible to apply nanoparticles to the lacquer system in a wet process. These advantages are, on the one hand, a small technological investment for the application, which opens up new applicability and, on the other hand, even complex shapes can be handled. More materials, in particular polymers and / or foils, can be handled according to the state of the art.

  Preferably, the nanoparticles are dispersed in a lacquer system. The nanoparticles used in the production of the lacquer system are those that are once dispersed or redispersed in the lacquer system for this purpose. Methods for achieving preferred redispersion are known to those skilled in the art. However, a good IR shielding film obtained by using known methods is important.

  In order to broaden the range of application, it is possible to achieve the infrared shielding action of nanoparticles with a variety of lacquer solvents, since the lacquer system is based on specific substrates and / or conditions of use, for example internal, external This is because it can be optimized for aircraft, especially cockpit glass, automobiles, etc. under different typical climatic conditions, for example under humidity and heavy rainfall. A particularly temperature-resistant lacquer system is selected when infrared shielding is to be achieved in high temperature applications, in which case this is a hot space, for example an oven, which must be heated without losing heat .

  It is possible to use a mixture of various conventional lacquer solvents to achieve various optimized properties such as abrasion and strength, resistance to peeling or flaking, heat resistance, UV-resistance, etc. It is.

  Lacquer systems can be used in particular as binders in the form of organic components. This organic component may be used in the form of a monomer, oligomer or polymer and is a polyacrylate, in particular PMMA, polyvinyl pyrrolidone (PVP), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyethylene glycol, polyurethane At least one from the group of polymers which are polymers based on bisphenols and polyesters, and oligomers and / or monomers of said polymers and / or cellulose derivatives, in particular methylcellulose, hydroxypropylcellulose and / or nitrocellulose and / or metals It is an organic compound. Furthermore, silicones and / or silanes can be added in the form of monomers, oligomers and / or polymers.

  Nanoparticles are typically 1 to 200 nm in size. This ensures good handling in the production process and ensures that the properties of the lacquer system are appropriately defined.

  In the case of particles below 200 nm, the transparency is not affected within the range of visible light, so that a high proportion of particle sizes below 100 nm results in good uniformity in all particles. Cause an increase in sex. As nanoparticles, those described in EP 0727306 can be taken into account.

  As the substrate, in addition to mineral glass such as silicate glass typically used for plate glass, PMMA, PVB, and the like can be used. This makes it possible for a lacquer system comprising a polymer according to the invention to advantageously reduce the weight of the glass and open up new applicability. In this way, it is possible to easily impart infrared shielding to the beverage container, in which case they are advantageous if the beverage in the container is left cooled. The layer obtained according to the invention ensures this.

  The present invention can be applied using many different technologies that are economically advantageous. At the same time it is completely covered by techniques such as impregnation, the shape pattern can be further embossed on the object, for example this is particularly advantageous in combination with improved conductivity. In this way, an antenna part that is electrically conductive, transparent and at the same time IR-shielded in an automotive windshield for receiving radio waves and / or for transmitting and receiving automotive radio signals. Can be incorporated into. Furthermore, this can be applied over a wide range.

  When applied to very complex shapes, or when a separate pattern is embossed and not repeated between objects, or only for a small amount of product, eg serial number, batch When embossing numbers or the like, it is applied using an ink-jet method. Since the layer is not visible, it can generate invisible encryption. In this case, the surface layer of the object to be coated can be scanned for conductivity, for example to incorporate electrodes at predetermined locations, and / or scan hidden information by infrared irradiation. In which case heat can be recorded in the transmission behind the substrate or coated substrate. In such a case, the coating can be further inserted between the two surfaces, for example, inside the heat-resistant glass or the like. The predetermined combination of conductivity and IR shielding is particularly reliable.

  Drying is typically slow and is carried out at a temperature below, for example, 100 ° C. Drying may be performed at room temperature or heated at an elevated temperature at 50-70 ° C. without compromising any advantageous characteristics of the layer.

  It is particularly advantageous to achieve an improved or totally conductive layer, at least the antistatic properties being achieved in the coating or layer and further induced thereby. This is particularly possible when nanoparticles with high conductivity are used. The use of ITO, which has a relatively higher conductivity than doped ITO, is particularly preferred. It is noteworthy that expensive ITO materials have high conductivity even in fairly small amounts, and the target action can occur especially at the penetration limit.

  As indicated at the outset, many applications require a type in the case of thermal radiation or a diode-like behavior for thermal radiation, ie radiant heat in only one direction and not in the reverse direction. In one preferred variant of the invention, the absorption constant is selected such that the coating is transparent at maximum solar energy incidence. This solar energy incidence shows its maximum value in the range of about 800 nm to 1100 nm. This range is therefore related to heating. It has been found that by selecting the absorption limit position, it is possible to increase the thermal solar radiation incidence to a high level, while the radiation from the inside can be sufficiently reduced. This is because the heat radiation to be dissipated is not possible in the present invention but is generally longer in wavelength than the incident one. Thus, in a particularly preferred variant, the absorption limit is between the near-infrared (NIR) and far-infrared (FIR) of radiation, thereby reflecting and / or absorbing immediately and subsequently transmitting. Let Therefore, particularly preferably, the absorption limit is separated, but close to 1100 nm, in particular in the range 1120 to 1350. By having an absorption limit in the shorter wavelength range, it shields more of the thermal solar radiation preferred in the present invention. The layer according to the invention is visually completely or at least almost completely transparent, and in this case it is not related to the yellow value of the base material.

  In other variations, for other purposes, preferably ITO with an absorption limit at about 1100 nm should be used, followed by other absorptions in the coating that absorb within 900 nm. Mix the ingredients. Particularly preferably, UV resistant absorbers are used. At the same time, organic absorbers should be used, in which case they can be introduced without problems in common lacquer systems. Phthalocyanine dyes are particularly suitable and have been found to be visually transparent and UV resistant. A particularly suitable absorber is referred to as YKR 50/10 phthalocyanine dye, which is available from Yamamoto Chemicals. It was determined that only 10% of the dye amount relative to the ITO mass was sufficient to achieve a broad band absorption layer.

The present invention is illustrated by the following figure:
FIG. 1a. The transmittance of an uncoated glass substrate;
FIG. 1 b Transmittance of the coated glass substrate;
Fig. 2a Permeability of uncoated PC board;
Figure 2b Permeability of the coated PC (polycarbonate) substrate;
3a Permeability of uncoated PMMA substrate 3b Permeability of coated PMMA substrate 4a Permeability of uncoated borosilicate glass substrate 4b Permeation of coated borosilicate glass substrate 5 Borosilicate Glass transmission Figure 6 Transmission curve of the coating (layer), various methods for producing ITO were used.

  Indium tin oxide powder was produced in the form of nanocrystals. Particle size analysis shows that the resulting nanoparticles are largest in the 100 nm particle size spectrum, and this maximum is nearly 0% at 200 nm, while below 1 nm. ITO-particles no longer exist. Thereafter, the conductivity of the ITO-powder is poured into a weighing glass of 45 ml volume, in this case having a diameter of 35 mm and a height of 70 mm, and half of the powder is poured into a suitable press stamp in a loose powder form. And a 1 kg mass was loaded for 30 seconds. The stamp was removed and a pin-shaped measuring electrode having a diameter of 1.5 mm was pressed into the powder packed to a width of 1 cm and a depth of 0.7 cm. The electrical DC resistance was measured between the electrodes. The selected powder showed good conductivity within the range of 30-50 Ω powder resistance.

  The powder is used in the following examples.

Example 1
50 g of a dispersion of nanocrystalline ITO in n-butanol (solid content 25% by weight) was mixed together with 25 g of 15% polymer solution Paraloid B72 in ethyl acetate. Glass was spray coated with this coating solution and the resulting coating was dried at 70 ° C. The layer thickness was 1 μm. This layer was completely transparent. This recorded a transmission curve. This is shown in FIG. Measuring the conductivity of the layer was 8x10 ⁴ Ω ^2.

Example 2
50 g ethanol dispersion of nanocrystalline ITO powder (solid content 25% by weight) was mixed with 50 g 15% polymer solution Paraloid B72 in ethyl acetate. A glass plate was spin coated with the coating solution. Thereafter, the glass was dried. The layer thickness was 1 μm. This transmission curve was obtained from FIG. The conductivity of the layer was 10 ⁵ Ω ^2.

Example 3
The lacquer system from Example 2 was used and sprayed onto PMMA plates. The layer thickness was adjusted to 1 μm and drying was performed at 70 ° C. The transmittance is shown in FIG. The conductivity was 8x10 ⁴ Ω ^2.

Example 4
50 g of ethanol dispersion of nanocrystalline ITO (solid content 25% by weight) was mixed with 32 g of a 10% by weight polymer solution of polyvinyl butyral (PVB) in isopropanol. This coating solution was applied on a glass plate and dried at 50 ° C. The resulting layer had a thickness of 3 μm and high transparency. The transmittance curve is shown in FIG. The conductivity was 8x10 ³ Ω ^2.

  The figure shows that the transmittance in the infrared region is significantly reduced compared to the uncoated substrate.

Thereafter, the conductivity of the resulting layer was measured. For Example 2, the conductivity was ² × 10 ⁵ Ω2. With respect to Examples 1 and 3 was 8x10 ⁴ Ω ^2. Comparison between Example 2 and Example 4 showed that the surface resistance was dependent on the binder. The amount of nanocrystalline ITO in the layer showed a concentration below the penetration limit.

  In another example, the transmission of pure ITO with a layer thickness of 1 μm was obtained in this case by spraying an aqueous dispersion and finally heating to 500 ° C. Compared. The preferred coating according to the invention shown in FIG. 5 showed a decrease in transmission at shorter wavelengths, i.e. improved infrared shielding.

Other examples show that the absorption limit can be shifted:
Nanocrystalline In ₂ O ₃ / SnO ₂ (ITO-) powder is produced from an aqueous solution using a coprecipitation method, in which soluble In or Sn components are precipitated by increasing the pH value. In this example, the concentration of these compounds is selected such that the Sn-concentration is 5% by weight with respect to In, but in principle the Sn-concentration can be arbitrarily determined.

  This choice is due to the fact that various Sn concentrations have been shown to have a strong influence on the absorption behavior of ITO; in this example, the concentration of Sn is kept constant, so that the ITO-material It was shown that the absorption characteristics of can be determined with a certain formulation. After separation of the reaction product, it was dried and heated at a temperature of 300 ° C. for 1 hour under normal atmospheric conditions to adjust the crystalline phase.

Thereafter, the crystalline In ₂ O ₃ / SnO ₂ was distributed into two samples, and the individual samples were heated again for different times under forming gas at 300 ° C. (see Table 1). ).

  Each powder sample (60 g) was dispersed in 100 g of isopropyl ethanol (IPE), respectively, and the dispersion was replaced with 39 g of nitrocellulose, respectively. Thereafter, the dispersion was applied onto glass using an average 50 μm coating scraper. After heating at 120 ° C., the layer thickness was 4 μm.

  Thereafter, color values and transmission curves were measured for the layers obtained with the powder. For both layers, according to DIN 6167 and ASTM D1925, the yellow value was measured using a color pen (Dr. Lange) (reference light source C; normal viewer 2 °). Powders having color values included in the maximum values listed in Table 1 (IT-50 HCB and IT-05-HCG) and layers having yellow values included in the respective values in Table 1 are It can be included in a mixture of powders.

  The corresponding x and y color values of the powder and the yellow value of the layer are shown in Table 1 and the transmission was found in FIG.

  A correlation was observed between the yellow value and the position of the absorption limit. From this result, it was found that ITO powders having a yellow value greater than 0.15, in particular a yellow value greater than 0.5, are good over the absorption limit in IR. This is preferred in certain applications.

  In another variation, the resulting powder IT-05HCG was replaced with 10% YKR-50 / 10-phthalocyanine-dye (Yamamoto-Chemicals). In this way, the layers were made to be particularly suitable for applications where complete IR blocking is desired.

a diagram showing the transmittance of an uncoated glass substrate, b diagram showing the transmittance of a coated glass substrate a Diagram showing the transmittance of an uncoated PC board, b Diagram showing the transmittance of a coated PC (polycarbonate) substrate a a diagram showing the transmittance of an uncoated PMMA substrate, b a diagram showing the transmittance of a coated PMMA substrate The figure which shows the transmittance | permeability of the borosilicate glass board | substrate which is not coat | covered, b Diagram showing transmittance of borosilicate glass Diagram showing transmission curves of coatings or layers using various methods for ITO production

Claims (27)

  In a method for producing a transparent IR-shielding film in which an active substance is supported on a carrier for the purpose of placing in an irradiation path, nanoparticles and a normal lacquer solvent are applied to a substrate by a wet method. A method for producing a transparent IR-shielding film, characterized in that   The method according to claim 1, wherein the lacquer system is formed by dispersed nanoparticles.   Usual lacquer solvents include water, alcohols, especially ethanol, propanol, isopropanol, butanol and / or other alkyl- or isoalkyl alcohols, ketones, especially acetone and / or MEK, diketones, diols, carbitols, glycols, diesters. Glycols, triglycols, glycol ethers, especially ethoxy-, propoxy-, isopropoxy-, butoxyethanol-acetate, esters, especially glycol esters, especially ethyl acetate, butyl acetate, butoxyethyl acetate, butoxyethoxyethyl acetate, alkanes and / or The process according to claim 1 or 2, wherein at least one of alkane-containing mixtures, aromatic compounds, in particular toluene, xylene is used.   4. The process according to claim 1, wherein one or more mixtures from the substances are used as the usual lacquer solvents.   5. A method according to any one of claims 1 to 4, wherein the lacquer system contains a binder.   6. A method according to any one of the preceding claims, wherein the binder system contains at least one organic component.   As organic components, at least one from the group of polyacrylates, in particular PMMA, polyvinylpyrrolidone (PVP), polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyethylene glycol, polyurethane, polymers based on bisphenol, polyester polymers , And oligomers and / or monomers of the polymers and / or cellulose derivatives, in particular methylcellulose, hydroxypropylcellulose and / or nitrocellulose and / or metal organic compounds. The method described.   8. The process according to claim 5, wherein at least one silicone and / or silane is included in the lacquer system in the form of monomers, oligomers and / or polymers.   9. The method according to any one of claims 1 to 8, wherein nanoparticles with a particle size> 1 nm are used.   10. The method according to any one of claims 1 to 9, wherein only nanoparticles with a particle size> 1 nm are used.   The method according to any one of claims 1 to 10, wherein nanoparticles having a particle size of <200 nm are used.   The method according to any one of claims 1 to 11, wherein only nanoparticles with a particle size of <200 nm are used.   13. A method according to any one of claims 1 to 12, wherein> 70%, in particular> 90% of the nanoparticles have a particle size below 100 nm.   As substrates, PVC (polyvinyl chloride), PE (polyethylene), PU (polyurethane), PC (polycarbonate), PET (polyethylene terephthalate), PMMA, PVB and / or transparent polymer materials and / or binder materials and / or 14. A method according to any one of the preceding claims, wherein mineral glass, in particular silicate glass, for example flat glass, is selected.   15. The method according to any one of claims 1 to 14, wherein the wet application is performed by pressing, spin dip coating, spreading, dipping and / or spraying, in particular an ink jet method.   The method according to claim 15, wherein wet coating is performed by an ink jet method, which enables ink jet application by adding a rheology modifier known to those skilled in the art to the lacquer system.   The method according to any one of claims 1 to 16, wherein the coating is dried at a temperature lower than 100 ° C.   The process according to any one of claims 1 to 17, wherein the drying is carried out at a temperature below 70 ° C.   The process according to any one of claims 1 to 18, wherein the drying is carried out at a temperature above 50 ° C.   20. A method according to any one of the preceding claims, wherein a layer having at least antistatic properties, preferably at least a dissipative layer, is produced.   21. A method according to any one of claims 1 to 20, wherein the nanoparticles are produced at least partially from ITO.   The method according to any one of claims 1 to 21, wherein an amount of ITO below the penetration limit is added.   23. A method according to any one of claims 1 to 22, wherein the absorption limit is between 1100 nm and 1350 nm.   24. In addition to an inorganic absorber exhibiting long-wavelength absorption, particularly ITO, in addition, another absorber exhibiting absorption in the near-infrared region of 900 nm or less is used. The method described.   25. Coating according to any one of claims 1 to 24, in which organic absorbers, in particular phthalocyanine-dyes, are used as other absorbers, in particular in a mass of less than 10% with respect to ITO.   26. A coating according to any one of claims 1 to 25, wherein ITO having a yellow value of at least 0.15, preferably at least 0.5 is used.   ITO-powder having a yellow value of at least 0.5.

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