FI70179B - FRONT REFLECTOR FOR REFLECTOR-LIGHT REFLECTOR LAMINERAD REFLECTOR WITH BAODFORM - Google Patents

Description

70179

The present invention relates to a method for manufacturing a reflector according to the preamble of claim 1.

Such a concentrating reflector can be used to reflect the sun or other radiant energy in the desired direction under conditions where moisture, air currents, impurities accumulating on the surface of the device, and radiation harmful to some materials, e.g., UV radiation, may occur. With the aid of a reflector shaped as a parabolite, for example, the radiant energy of the sun can be applied to one point in order to achieve the desired centering effect. Correspondingly, by means of a known elongate reflector with a parabolic cross-section, the radiation reflected from the reflector can be concentrated in a linear area. It should be mentioned that in the USA, for example, this type of reflector is sold annually for about 1,000,000 m ^.

20

In the manufacture of centering solar collectors, the mirror reflection surface can be fabricated in several ways. Often a smooth-surfaced base structure of approximately parabolic cross-section is used, to which an adhesive-surfaced material 25 is attached to a plastic film having a thin metallic reflective surface. In this case, however, the reflector surface is exposed to the weather, oxidizes before long and dims. To avoid this detrimental phenomenon, a variety of lacquer materials or coatings have been developed to improve the weatherability of the coated reflective surface. In this case, it is often difficult to obtain a suitably thick, even application of the surface layer, since the surface layer adversely affects the reflectivity. The surface layer is also susceptible to damage if the surface is improperly cleaned.

A method known for silvering a glass sheet for making a reflector has long been known. However, it is technically more difficult to manufacture a benign concave reflector than a planar reflector.

35 2 70179

It is possible to make a concave reflector using a metal plate mirrored by the vacuum evaporation method, but often the surface dims in a short time if moisture is present. The protective surface layer, on the other hand, impairs the reflection properties of the mirror-5.

Disadvantages of current reflector constructions include their generally poor weather resistance, the difficulty of cleaning without damaging the surface, the high cost of coated reflector film materials 10, and thus the material and labor costs associated with periodic replacement of the reflector surface.

The object of the present invention is to obviate the drawbacks of the previous manufacturing methods and structures and to provide a completely new type of method for manufacturing a laminated reflector.

The invention is based on the fact that the reflective film is produced by a technique known from the capacitor film technique 20 as a separate uniform composite film, which is hermetically sealed between two support layers by means of adhesive layers known from windscreen manufacturing.

More specifically, the method according to the invention is mainly characterized by what is stated in the characterizing part of claim 1.

The main advantage of the method according to the invention is that the durability of the reflector surface and the stability of the reflection ability are substantially increased so that the reflector lasts for several years of use and cleaning without any other measures. In addition, the structure achieves very good shape stability.

35

In the following, the invention will be examined in more detail by means of embodiments according to the accompanying drawings.

Figure 1 is a partially schematic cross-sectional view of the edge portion of a reflector manufactured by the method of the invention prior to compression and heat treatment.

70179

Figure 2 shows the edge part according to Figure 1 after the pressing and heat treatment.

In the exemplary case, two layers of radiation-permeable and thermosetting adhesive 3/4, each with a thickness of about 0.3 mm, are arranged between two glass plates 1, 2 of parabolic shape and at least approximately identical in cross section. Suitable adhesives are, for example, polyvinyl butyral (PVB) and polyvinyl alcohol (PVA). A composite film 5, 6 consisting of a flexible core layer 5 and a reflective thin metal layer 6 deposited thereon is further interposed between the layers 3, 4 of the adhesive layer 10. The core layer 5 having a thickness of about 250 μm is made of a polyester film. The metal layer 6 is preferably aluminum-15a, which according to the capacitor film technique is deposited on the core layer 5 by vacuum evaporation. The thickness of this aluminum layer is about 40 nm.

A piece of the composite film thus prepared is cut, which is dimensioned so that its edges extend at most at the level of the edges of the adhesive layers 3, 4. In the exemplary case according to Figure 1, the adhesive layers 3, 4 extend somewhat over the edge of the composite film 5, 6 so as to form a groove 11 based on the outer edge of the composite film 5, 6 and the outer parts of the adhesive layers 3, 4 as walls. The depth of this groove 11 is suitably at least 200 nm.

The combination thus obtained is then subjected to a compression treatment known from the windscreen technique by subjecting the edge area between the layers 1, 2 of the support layer to a vacuum so that the support layers 1, 2 are pressed together to remove excess air.

The laminate structure is then subjected to infrared heating at a temperature of 35 to 120 ° C, preferably about 100 ° C. The laminate is then transferred to a pressure autoclave having a treatment temperature of 130 to 170 ° C, preferably about 150 ° C, a pressure of 8 to 13 bar, preferably about 10.5 bar, and a treatment time of 35 to 55 min. , fit my streak for about 45 min. When heated, the adhesive layers 3 and 4 partially melt, whereby their outer edges gradually fuse together over the edges of the composite film 5,6, hermetically sealing the composite film 5,6 together. In this case, the groove 11 disappears completely and the structure according to Fig. 2 is created, in which the adhesive layers 3 and 4 form the support layers 1 and 2 connecting the edges of these to a single edge surface 12.

10

Since the composite film 5, 6 shrinks to some extent during the heat treatment, the groove 11 according to Fig. 1 is not necessarily needed per se, but the composite film 5, 6 can extend approximately up to the outer edge of the adhesive layers 3, 4. Due to the shrinkage mentioned, the result according to Figure 2 is obtained in this case as well. However, the shrinkage does not unduly impair the reflective properties of the reflective metal layer 6.

As layers 3 and 4, polyvinyl butyral (PVB) can be used very advantageously, since it is also commonly used in other laminate structures, e.g. in the manufacture of automotive windshields.

When the light beam 7 hits the glass plate 1 at the point 8 of the finished reflector, it penetrates through the glass plate 1 and the adhesive layer 3 to the point 9, where it is mirror-reflected and passes through the layers 3 and 1 again. The surface 10 of the glass sheet 1 can be easily cleaned, e.g. with water, of dust or dirt accumulated therein. The metal coating 6, on the other hand, is very shielded, and the glass sheet 1 alone silences the UV radiation, which is so harmful to the coating 6, effectively.

The following is a summary of the thicknesses of the various layers of the reflector produced by the method according to the invention in the exemplary embodiment and the typical ranges of (in parentheses):

Glass sheets 1 and 2 2.2 mm (1 ... 3 mm) 40 Adhesive layers 3 and 4 0.3 mm (0.1 ... 1.0 mm) 5 70179

Heart floor 5 250 is (10 ... 500 is)

Coating layer 6 40 nm (20 ... 60 nm)

The significance of the core layer 5 is that the coating layer 6 can be easily formed on it.

It should be noted that the method according to the invention is also easily applicable to bidirectionally bent structures, since the adhesive layers 3 and 4 and the core layer 10 with their coatings 6 can be modified into permanent surfaces with constant cross-section, e.g. paraaboloid surfaces or the like.

Claims (9)

A method of manufacturing a straining and, in particular, solar energy reflecting laminated reflector (1-6) having a baking surface, according to which a method is provided between two straining transmitting and the desired baking mold (1, 2), e.g. glass layer, in turn, provides a first strain-permeable and heat-curing adhesive layer (4), a combination film (5, 6) consisting of a flexible central layer (5) and a reflective thin metal layer stored thereon (6), and a second straining permeable and heat-curing adhesive layer (3), characterized in that the edges of the combination film (5, 6) extend most in line with the edges of the adhesive layer (3, 4) and subject to the laminate so obtained. (1-6) a press and heat treatment said that when the combination film (5, 6) in each other assembles, the adhesive layers (3, 4) melt together over the edges of the combination film (5, 6), the closing combination film (5). 5, 6) in its entirety hermetically within. 2. A method according to claim 1, characterized in that the press treatment is carried out by moving the edge area between the support layers (1, 2) under the influence of vacuum, so that the flow layers (1, 2) are pressed against each other to remove excess air. 3. A method according to claim 1, characterized in that the heat treatment comprises an infrared heating at a temperature of 80 ... 120 ° C, preferably about 100 ° C, and a subsequent autoclave heating at