JPH0430344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a multilayer system according to the preamble of claim 1. A multilayer thermal insulation system of this kind is known, for example, from DE 30 27 256 A1. This document describes, for example, a multilayer system consisting of a support layer made of polyester, a dielectric layer above it and a metal layer above it, which dielectric layer acts to prevent the reflection of the metal layer. By appropriate selection of the thickness and refractive index of the dielectric layer, interference effects occur so that the light rays in the visible spectral band incident through the support layer are only partially reflected and their passage through the multilayer system is almost impeded. I can't do it. On the other hand, heat rays in the infrared band hitting the metal layer from the side opposite to the support layer, for example from inside the room, are highly reflected. The described arrangement has on the side opposite the support layer of the metal layer another dielectric layer similar to said dielectric layer, which layer further increases the transmission power of visible light and almost reduces the reflection power of infrared radiation. It acts as anti-corrosion to some extent.

Another heating arrangement for the opening of a light-transmissively closed chamber is known from DE 27 03 688 A1. This arrangement comprises a plastic protective layer with a low absorption capacity in the infrared spectral range on the interior side that is to reflect the infrared rays, so that the infrared rays do not heat the plastic protective layer and are reflected almost unhindered into the warm interior. Metal layer on plastic protective layer,
A cover layer likewise made of a plastic sheet, for example polyethylene, is supported thereon. This cover layer has the function of mechanically supporting the multilayer system.
This layer is on the outside and touches, for example, a glass plate. Such an arrangement has a high reflection power in the infrared spectral range, but a relatively low transmission power in the visible spectral range. First of all, no provision has been made for the reflection of visible light in the metal layer, and furthermore the outwardly facing supporting cover layer has not been modified to have a high transmission power in the visible spectral range.

On the contrary, the multilayer system according to the invention having the features described in claim 1 has a very good transmittance in the visible spectral range and very good transmission on the surface not protected by the support layer of the metal layer. Good mechanical protection and corrosion protection are achieved. To improve corrosion protection on the side opposite the support layer and prevent reflections on this side,
A further dielectric cover layer is preferably inserted between the metal layer and the protective layer on this side of the metal layer as well. Advantageous formations and improvements of the multilayer system according to claim 1 are set out in the claims 2 to 12 and in the description below.

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

The drawing shows in particular a support layer 10 consisting of a polyester sheet with a thickness of 10 to 200 μm. Alternatively, it is possible to use as support layer 10, for example an acetate sheet with a thickness of 10 to 50 μm or a PVC sheet with a thickness of 20 to 100 μm. This support layer has a thickness of 10
A first dielectric cover layer 11 of ~40 μm is supported, which layer comprises at least one metal oxide, in particular a mixture of titanium oxide and bismuth oxide or optionally a separate layer of these metal oxides. Supported on the first dielectric cover layer 11 is a metal layer 12, in particular a silver layer with a thickness of 5 to 20 μm, which layer is covered by a second dielectric cover layer 13 having the same composition as the first dielectric cover layer 11. Protective layer 14
forms the outer closure layer opposite the support layer 10.
The structure and material composition of the stacks 10 to 13 substantially correspond to the formation described in the earlier German Patent Application No. P3140100.
In this case the support layer 10 faces the incident light and the protective layer 14
is supported on the indoor side of the multilayer system, and is exposed to infrared rays from this side. If the light passage is reversed so that the support layer 10 is exposed to long wavelength infrared radiation, the sheet will be significantly heated by absorption within the support layer. In this case, the effectiveness of the heat-insulating layer is based on its low emission capacity for long-wavelength light.

The functionality of the multilayer system is achieved by ensuring overall high reflection in the infrared spectral band and high transmission in the visible spectral band. For this reason, a material having a high transmittance to visible light, such as a polyester sheet with a thickness of 10 to 200 μm, is selected for the support layer 10. In particular, a metal layer 12 consisting of silver
are anti-reflective by dielectric cover layers 11 and 13, whose thickness and material are such that interference with the refractive index occurs and the proportion of visible light reflected at the interface of metal layer 12 is reduced. is selected so that almost all of the incident light, except for a small portion, can be transmitted through the multilayer system. The dielectric cover layer 11 is formed with the same composition as the cover layer 13 and contains in particular two metal oxides: titanium oxide and bismuth oxide. In this case, the purpose of titanium oxide is to increase the UV stability of the silver layer, and bismuth oxide has a strong anticorrosion effect. Although the illustrated layers 11 and 13 are a mixed layer of two metal oxides, the two cover layers 11 and 13 can also each be formed in two layers with separate layers of metal oxide.

The dielectric cover layer 13 provides protection against UV radiation and corrosion protection for the metal layer and is thus supplemented by a protective layer 14 which serves in particular for mechanical protection of the multilayer system. Since layers 13 and 14 must be transparent with little absorption of infrared radiation, their formation and material selection must be carried out in the infrared band, i.e. 5.
One must note the low absorption power in the ~40 μm wavelength band. In this case, it has become clear that, together with the formation of the dielectric cover layer 13, a polymer film is particularly suitable for the protective layer 14. The layer thickness and material of the polymer film are selected in such a way that they absorb very little infrared radiation. In particular, thin polymer film protective layers can be produced from siloxane polymers, the polymerization preferably taking place in a plasma. Hexamethyldisiloxane (HMDS) has proven particularly advantageous in this case.
HMDS has a sufficient vapor pressure and can therefore be introduced as a vapor into the evacuated coating equipment and polymerized as a protective layer 14 on the dielectric cover layer 13 in a glow discharge without large equipment outlays. The protective layer 14 produced in this way preferably has a thickness of less than 0.2 .mu.m, in the maximum case this layer reaches a layer thickness of less than 1 .mu.m and lies underneath as a completely pore-free and dense hydrophobic protective layer. Satisfactory protection of the layer system is guaranteed. Furthermore, the protective layer 14 is particularly applied to the dielectric cover layer 13.
A coating with a thickness of 5 μm can be formed, for example, from a sprayed Lutzka film.

If the protective layer 14 is desired to be thicker and thicker to increase its mechanical stability, the material chosen for the protective layer 14 is a material with low absorption in the infrared spectral range, in particular polyethylene or polypropylene. In this case, the protective layer 14 is combined with the remaining layer system as a laminate, and the protective layer 14 itself is formed as a plastic sheet. Another method of coating large thicknesses of such protective layers is flame spraying.

The multilayer system according to the invention thus relates to a series of layers 11, 12, 13 applied in a vacuum manner, in which at least one metal layer 12 and in particular a number of dielectric cover layers 11 and 13 are deposited or sputtered onto the support layer 10. coated. The composition and layer structure of the dielectric cover layers 11 and 13 are optimized in such a way that the highest possible stability against environmental effects is achieved. Although the protective effect of the dielectric layers 11 and 13 is generally sufficient when the multilayer system is incorporated between glasses, it is especially important to add protection against mechanical damage when the multilayer system is used on top of the glass or in the form of a rolled-up curtain or a plain curtain. protection is necessary.
For this purpose, the coated support layer 10, i.e. the dielectric cover layer 13 in the exemplary embodiment, is coated as a protective layer 14 with a polymer film which ensures very good additional mechanical protection without significantly reducing the optical properties of the layer system. Ru. The layer thickness of the polymer film is adjusted in such a way that a sufficient mechanical protective effect is achieved, but very little infrared radiation is absorbed, and/or the material of this additional coating is as good as possible in the infrared band of the protective layer 14. Selected to provide transparency.

Coating methods include plasma polymerization, coating with a plastic melt by one of the customary continuous coating methods or lamination, for example with another plastic sheet.

Organosilicone films formed by plasma polymerization already meet the requirements of low infrared absorption as protective layer 14 due to the layer thickness of less than 1 μm, which arises due to technical reasons in this coating method. Due to its dense nature and its mechanical properties, such a protective layer 14, despite its small thickness, serves as a protection against mechanical effects and as an additional protection against corrosive effects. Details of the production and properties of such films can be found at, for example, the ACS Symposium.
Described in the publication "Plasma-Polymerisation", Series 108, Washington DC 1979. It has become clear that among the siloxanes obtained, hexamethyldisiloxane is advantageous as the protective layer 14. Already with a thickness of less than 2 μm, this layer ensures good protection and the optical properties are hardly changed.

A thicker protective layer 14 is obtained when coating the Lutzka film from the liquid phase. This is because Lutzka films cannot be coated with such small thicknesses. When using an acrylic resin coated by a spray method, the infrared absorption of the protective layer 14 increases rapidly as the thickness increases, and at a protective layer thickness of 20 μm, about 50% of the infrared absorption occurs in the protective layer 14. This absorption value must not be exceeded in any case, but if other rays with lower infrared absorption are used,
It has become clear that even larger protective layer thicknesses are acceptable. In addition to acrylates, fluorohydrocarbon resins, polyester resins or epoxy resins are also used. However, since all Raduka systems have a strong absorption band in the infrared region, the metal layer 1
If it is desired to avoid deterioration of the infrared reflection properties of No. 2, the thickness must be carefully controlled. Experiments have shown that the thickness of the protective layer 14 should not be less than 1 μm if a lacquer layer is used, so that a closed coating without pores is obtained. On the other hand, the thickness of the coating layer should not exceed 5 μm, so that the infrared reflectance of the metal layer 12 is not lower than about 80% of the value of the multilayer system without the protective layer 14. In this layer thickness range, the degradation of the optical properties occurring in the visible spectral range, in particular due to scattering, Schilleren formation and absorption, is still negligible.

In order to produce the laminate of the protective layer 14 and the layers of the multilayer system below it using a plastic sheet, polyethylene, which has a particularly good transmission in the infrared rays, is used as sheet material. Polypropylene also has good properties.

[Brief explanation of drawings]

The drawing is a cross-sectional view of the multilayer system of the invention. 10... Support layer, 11, 13... Dielectric cover layer, 12... Metal layer, 14... Protective layer.

Claims (1)

[Claims] 1. A support 10, a metal layer 12, and a cover layer 11, 13 comprising a dielectric metal oxide that reduces reflection.
and a polymeric film protective layer 14 disposed on the opposite side of the metal layer 12 from the support layer 10 and having a low absorption capacity in the infrared spectral band, with high absorption capacity in the infrared spectral band and high transmission in the visible spectral band. 1. A multilayer system for heat retention, characterized in that the polymer film protective layer 14 is made of a siloxane polymer. 2. A multilayer system according to claim 1, wherein the siloxane polymer is a plasma polymer. 3. Multilayer system according to claim 1 or 2, in which the polymer film protective layer 14 comprises hexamethyldisiloxane (HMDS). 4 Polymer film protective layer 14 has a layer thickness ≦1 μm
A multilayer system according to any one of claims 1 to 3 having the following.