JPS6152901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously manufacturing a solar heat collecting plate material having aluminum or an aluminum alloy as a base material.

For a solar heat collecting plate based on an aluminum material, the aluminum material is first anodized to form a porous oxide film on its surface, and then this is electrolytically treated in an aqueous solution containing a metal salt to form the film. Many are used in which metal is precipitated and filled into the fine pores of the solar cell, resulting in a blackened surface that selectively absorbs solar thermal energy. In terms of performance, the selective absorption film of such a heat collecting plate should have the highest possible solar thermal energy absorption rate (α), while the emissivity (ε) for dissipating heat as radiant energy should be as low as possible. is required. In view of these requirements, the selective absorption membrane is preferably formed into an extremely thin film with a thickness of 1 μm or less, and since it itself is weak in strength, it is extremely easily scratched and has poor durability. It also has poor abrasion resistance. For this reason, the plate material after the selective absorption membrane has been formed must be handled with great care, and it has been extremely difficult to mold it into a desired shape after the selective absorption membrane has been formed. Therefore, conventionally, the surface treatment for producing the selective absorption film as described above is usually performed after processing and forming the aluminum plate material in advance, and the surface treatment process is carried out continuously. As a result, the manufacturing efficiency was low.

The purpose of this invention is to solve these problems, and more specifically, to improve the efficiency of solar heat collecting plate materials, which can be processed and formed as required after forming a selective absorption film. The aim is to provide a manufacturing method that is easy to use.

Therefore, in this invention, an aluminum plate formed in a coil shape is pulled out from one end, subjected to anodizing treatment, and then electrolytically treated in an aqueous solution containing a metal salt to form a selective solar energy absorption film on the aluminum plate surface. After continuous formation, a synthetic resin protective film separately formed into a coil shape is pulled out from one end, overlaid on the selective absorption film surface, and guided between a pair of elastic pressure rolls in a state where it can be continuously and peeled off. It is characterized by being attached to.

To further explain this with reference to the illustrated embodiments, 1
is an aluminum plate formed into a coil shape, which is continuously drawn out from the coil and first led to the pretreatment section 2, where it is subjected to a predetermined pretreatment such as degreasing. This is then led to the next anodizing section 3, where it is anodized using an aqueous solution of sulfuric acid, oxalic acid, phosphoric acid, etc. as an electrolyte to form a porous anodic oxide film on the surface of the aluminum plate. Subsequently, the aluminum plate with this oxide film formed thereon is sent to the next electrolytic coloring treatment section 4.
Here, an electrolytic treatment is performed using an aqueous solution containing one or more metal salts such as nickel salts, copper salts, tin salts, cobalt salts, and iron salts as an electrolyte to precipitate metals into the micropores of the oxide film. By filling the aluminum plate, a blackened film selectively absorbing solar energy is formed on the surface of the aluminum plate. Next, after drying this to some extent, it is continuously guided between a pair of rubber pressure bonding rolls 5, 5, which are placed next to the aluminum plate, and a synthetic resin protective film 6, which is separately formed into a coil shape, is applied to the film. The protective film 6 is continuously drawn out from the coil and simultaneously introduced between the pressure bonding rolls 5, 5, and the protective film 6 is superimposed on the surface of the selective absorption membrane and crimped by the pressing force of the rolls to bond the two together. Protective film 6
is attached to an aluminum plate in a peelable manner, and the material thereof is preferably polyethylene, polypropylene, etc. The aluminum plate 1 to which the protective film 6 is bonded is wound around a coil 7 and provided as a solar heat collecting plate material.

The solar heat collecting plate material manufactured in this way is
After this is subjected to necessary processing and molding and cut to a predetermined size, the protective film 6 is peeled off to produce a final product, a solar heat collecting plate. The above-mentioned processing and forming steps include, for example, forming grooves in the heat collecting plate material for fitting heat absorption tubes, fitting and fixing heat absorption tubes made of copper pipes etc. into the grooves, and then coiling them into coils. It consists of the process of winding up and handling such as transportation.

By the way, the electrolytic treatment conditions of the anodic oxidation treatment step of the aluminum plate and the electrolytic coloring treatment step in an aqueous solution containing a metal salt are not particularly limited in the present invention. However, since the present invention involves continuously processing an aluminum plate using a coil, it goes without saying that it is desirable that the processing time of each of the above steps be as short as possible. In order to meet these demands, we have found out from the results of various experiments and research that the electrolytic conditions for each of the above steps for selective absorption membrane production are as follows:
The first step of anodizing treatment, which produces an anodic oxide film, is carried out in a phosphoric acid aqueous solution with a concentration of 50 g/min or more, and the temperature of the solution is maintained at 35 to 80°C, and The second step of metal salt treatment for blackening the film is performed using a method in which the concentration of metal salt in the electrolytic solution is relatively higher than that used in the conventional electrolytic treatment, such as nickel salt. 50~
200g/, 50-200g/ in cobalt salt,
15-100g/for copper salt, 5-100g/for tin salt
It is preferable to carry out the reaction in an aqueous metal salt solution having a concentration of 50 g/min and iron salt at a concentration of 5 to 50 g/min and keeping the liquid temperature at a high temperature of 35 to 85°C.

According to these processing conditions, the total processing time for both steps is approximately 1 to 5 minutes, and excellent selective absorption performance is achieved with film thickness t = 1 μ or less, absorption rate α = 0.9 or more, and emissivity ε = 0.1 or less. It is possible to produce a solar heat selective absorption film having the following properties.

The reason why it is especially preferable to use an aqueous phosphoric acid solution as the electrolyte in the anodizing process is that the thickness of the film that can be formed is thinner than when using an aqueous solution such as sulfuric acid or oxalic acid, and the pore size of the micropores is smaller. This is based on the fact that a large amount of metal can be obtained, and as a result, an even better selective absorption membrane can be obtained by increasing the amount of metal precipitated. Conventional general processing conditions for anodizing using a phosphoric acid aqueous solution are a solution concentration of 20 to 30 g/
, liquid temperature 20~30℃, current density 0.2~0.4A/ ^dm2
D.C., and the processing time was approximately 15 minutes. Compared to such conventional general processing conditions, the above-mentioned liquid concentration and liquid temperature are set to considerably higher values. The upper limit of the concentration of the liquid is
Considering economic efficiency and good film formation, the amount is considered to be about 800 g/approx. while 50
If the concentration is less than g/g, it takes a long time to obtain the required film thickness, and a stable film cannot be obtained in a short time. From this point of view, a particularly suitable concentration range is 80 to 300 g/g/. Also, the liquid temperature is determined by the relative relationship with the liquid concentration, but it is 35℃.
If the temperature is below 80°C, it will take a long time to obtain the required oxide film thickness and a stable film will not be obtained;
It becomes difficult to obtain the necessary film thickness, and the disadvantage is that the film becomes powdery and milky white. If we show the relative preferable range in relation to liquid concentration and temperature, the concentration is 70g/~150g/, and the liquid temperature is 45~150g/.
A range of about 55°C is preferable.

In addition, in the metal salt treatment for blackening the film, the concentration and temperature of the aqueous solution containing the metal salt are set within the above ranges.If both are below the lower limit, a good selective absorption film will be produced. However, if the concentration exceeds the upper limit, the cost will increase, the colorability will deteriorate, making it difficult to form a good selective absorption film, and if the temperature exceeds the upper limit, This is because the dissolving action of the film increases, making it impossible to obtain a good selective absorption film. A particularly preferable concentration range is
80-130g/ for nickel salt, 80-130g/ for cobalt salt, 30-50g/ for copper salt
g/, in tin salt 15-30 g/, in iron salt
The range is 60 to 100g/, and the temperature is especially 40g/
A range of ~60°C is preferred.

As described above, the present invention involves sequentially forming a selective absorption membrane on a coiled aluminum plate by sequentially subjecting it to anodizing treatment and electrolytic treatment in an aqueous solution containing a metal salt. A coiled synthetic resin protective film is continuously pasted onto the top in a peelable state by pressure bonding with an elastic roll, so the obtained solar heat collecting plate material has a selective absorption film surface protected by the film. Even if processing, molding, etc. for attaching a heat absorption tube to the selective absorption membrane are carried out, there is no risk of damaging the selective absorption membrane. In addition, it is possible to prevent other scratches from occurring during handling, resulting in easy handling and good workability. In this way, before the processing and forming process, it is possible to continuously process the aluminum plate with a coil to form a selective absorption film, so when doing it after processing and forming as in the past, The efficiency of the selective absorption film formation process can be greatly improved compared to the previous method.
As a result, it becomes possible to significantly improve the manufacturing efficiency of solar heat collecting plates and significantly reduce the manufacturing cost.

[Brief explanation of the drawing]

The drawing is a block diagram showing an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Aluminum plate coil, 2... Pretreatment section, 3... Anodizing section, 4... Electrolytic coloring section, 5... Pressing roll.

Claims (1)

[Claims] 1. An aluminum plate formed in a coil shape is pulled out from one end and subjected to anodizing treatment, and then subjected to electrolytic treatment in an aqueous solution containing a metal salt to continuously form a selective solar energy absorption film on the aluminum plate surface. , a synthetic resin protective film separately formed into a coil shape is pulled out from one end thereof, overlaid on the surface of the selective absorption film, and guided between a pair of elastic pressure rolls to be laminated continuously and in a releasable state. A continuous manufacturing method for solar heat collecting plate material.