JPS6193404A - Carbon fiber reinforced plastic mirror - Google Patents

Abstract

PURPOSE:To obtain a CFRP mirror having less tendency to absorbing a moisture in an atmosphere of air at a room temp., thereby less releasing a gas in a vacuum by forming a metallic coating layer for preventing the moisture absorption over a whole surface of the CFRP substrate. CONSTITUTION: The titled mirror is prepared by coating the CFRP substrate with the metallic coating layer and by providing a mirror surface of a vapor- deposited aluminum layer 4 which is transcribed on a concave side by an adherent 3 and also by providing a black coating layer 5 on a back of the mirror to cover a glossiness of the metallic coating layer 2 and to accelerate an absorption and a radiation of a radiant heat. The metallic coating layer is formed by chemical plating a metallic nickel and cupper etc. or by dipping the preheated CFRP substrate plate in a molton metal composed of a low melting point metal and then lefting it. If the CFRP substrate plate is sufficiently dried before forming the metallic coating layer on the substrate, the generation of gas is small in a space chamber, thereby making the vacuum easy for a short period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to carbon fiber reinforced plastic (CFRP) mirrors.

(Prior technology) A collimator mirror is placed in a laboratory (space chamber) that simulates the space environment on the ground, and has a certain curvature to reflect light from a window into uniform parallel light. It is a concave mirror with a radius. diameter is 3
When it comes to a large mirror of m or more in size, it is difficult to make a single mirror, so a large mirror is constructed by arranging a plurality of small hexagonal mirrors without gaps. For example, the diameter is 10
A large mirror of approximately 100 m in size would be constructed by arranging nearly 100 small mirrors.

Conventionally, mirrors like this are made using an aluminum alloy as a substrate, which is then plated with nickel and polished.

Aluminum was vapor-deposited as a mirror surface. With this metal mirror, it was necessary to polish and finish each small mirror one by one, which required a long period of time to manufacture and was also expensive. Furthermore, the inside of the space chamber is close to -200℃ when it is dark, and the mirror surface is close to +100℃ when illuminated9. The range of temperature changes is very large. Therefore, when combining small mirrors made of aluminum alloy (linear thermal expansion coefficient of about 25 x 10-'+m/an'c), the gap can be reduced to 0 at the maximum temperature (about 100'C).
However, at the lowest temperature (approximately -200℃) it is about 0.75%
There may be gaps. If such a gap is formed, the uniformity of the parallel light will be poor, and the light will be scattered on the end face of the small mirror, causing a rise in temperature.

Therefore, the coefficient of linear thermal expansion (in the creeping direction) is almost 0 (according to actual measurements, it is less than 1 x 10-'a+/m''c).

Mirrors using CFRP as a substrate have been proposed.

When configuring a combination of small CFRP mirrors.

If the gap is set to O near room temperature, almost no gap will occur at either high or low temperatures. However, one of the problems with CFRP mirrors is that it is difficult to form a mirror surface with good light reflectance on one surface. That is, even if a CFRP surface or a top coat layer of synthetic resin is applied to the surface and polished, it is easily scratched, and the aluminum mirror surface deposited thereon cannot be cleaned.

Of course, like aluminum alloy mirrors, CFRP may be plated with nickel, this hard surface polished, and aluminum deposited, but this requires the same effort as with conventional mirrors. The inventors have previously developed a method for efficiently forming a good mirror surface on a CF-P substrate. This is called the ``transfer method,'' and first a polished glass or metal blade is prepared, and an aluminum vapor-deposited layer is formed on its surface. Next, a preferably solvent-free adhesive is applied to the CFRP substrate or the mold, the two are put together, the adhesive is cured, and the mold is released. The aluminum vapor deposition layer is transferred to the CFRP substrate side, creating a good mirror surface. I can do it. With this method, only one accurately polished mold is required for transfer, and since the adhesive is clogged between the CFRP substrate and the aluminum deposited layer, the concave surface of the CPRP substrate does not need to be roughened. Alternatively, if a CFRP substrate is molded using a metal that has almost the same shape as the polished disk and one surface may be rough, then the surface can be roughened with sandpaper to improve adhesion, and transfer can be performed. efficient and efficient.

However, another problem with CFRP-based mirrors is outgassing. In other words, CFRP materials are generally exposed to room temperature air for long periods of time.

When placed in the space chamber, moisture will continue to be released forever, and the chamber will maintain a predetermined degree of vacuum (I
(on the order of 10-'Torr) will take a long time.

(Purpose of the Invention) The present invention provides a flexible substrate that absorbs water even when exposed to the atmosphere at room temperature. The temperature can be controlled.

The purpose is to provide a CFRP mirror.

(Structure of the Invention) The present invention provides a carbon fiber reinforced plastic mirror in which a metal coating layer is provided on the entire surface of a CFRP substrate, an aluminum vapor deposition layer is transferred to the mirror side of this surface, and a black coating layer is provided on the back surface. Regarding.

Transfer of the aluminum vapor deposition layer is performed by the transfer method described above.

FIG. 1 is a longitudinal sectional view showing an example of the CFRP mirror of the present invention. The CPRP substrate 1 is surrounded by a metallization layer 2 . The concave side has a mirror surface of the aluminum vapor deposited layer 4 transferred with adhesive 3, and the back side has a black coating layer 5 to hide the luster of the metal coating layer 2 and improve the absorption and dissipation of radiant heat on the back side. It's profitable.

The CFRP substrate 1 is generally made by laminating carbon fiber base materials,
Obtained by impregnating and curing a thermosetting resin composition.

The metal coating layer 2 is generally formed by chemically plating nickel, copper, or the like, or by melting a low melting point alloy, dipping a preheated CFRP substrate, and pulling it up. At this time, in order to improve the wetting of the low melting point alloy and the CFRP surface,
It is best to plate the P surface with a thin layer of copper or nickel in advance. Low melting point alloys include an, 37Pb (melting point 18
3℃) *Bs 142Sn (138℃), In, 5
0Sn (125°C), Bi.

4+PB (124°C) is reasonable. The black coating layer 5 can be formed by impregnating and pasting a carbon fiber base material with a synthetic resin composition, or by applying a carbon-filled synthetic resin paint.

The thickness of the metal coating layer 2 is such that it completely covers the protrusions of carbon fibers (thickness: 7 to 10 μm) on the CFRP surface, and the thickness exceeds about 50 μm.

Due to the difference in thermal expansion with CFRP, temperature changes (-2006C to +
Since peeling is likely to occur due to repeated heating at 100° C., a range of 15 μm to 5011 m is preferable. In chemical plating, this level of thickness can be freely obtained by adjusting the immersion time in the plating solution. In the case of low melting point alloys, they can be obtained freely by reducing the degree of immersion.

In the CF RP mirror of the present invention, the CFRP substrate 1
Since the entire surface of the CFRP substrate is covered with the metal coating layer 2, if the CFRP substrate is sufficiently dried before forming the metal coating layer, there will be less gas released in the space chamber. The degree of vacuum can be increased. In addition, since there is a spot-colored coating layer 5 on the iron surface, even in a high vacuum, by changing the temperature of the chamber wall, CFRP can be formed by radiation.
The mirror can be heated or cooled from the back side. That is, if you want to quickly create a high vacuum inside the chamber and start operation, it is recommended to heat (baking) to speed up gas release. Also, to suppress the eccentric rise of the CFRP mirror during light irradiation in a high vacuum.

Just cool it down.

(Example) Next, an example will be described. In the example, the amount of υ gas released was compared using a model sample. The presence or absence of a mirror surface has no particular effect, so
A comparison was made between a case where a metal coating layer and a black coating layer were provided on a CFRP substrate (example) and a case where a metal coating layer and a black coating layer were not provided (comparative example).

The CFRP board is made of plain weave carbon cloth.

18 trading cards (φ6343) were stacked and pressed to a thickness of 4 mm, and alicyclic epoxy resin composition (U3O's j1
"iI cyclic epoxy resin E 4221.100 parts, hexahydrophthalic anhydride 90 parts, and benzyldimethylamine 1 part) was impregnated under reduced pressure at 70° C., OiTorr, and then impregnated at 120° C. under atmospheric pressure. It was cured at 160°C for 3 hours and then at 160°C for 5 hours.

In the implementation, a 30cm square CFRP board was used.

First, the thickness of the nickel chemical plating layer is 5 μm.

Next, after drying at 160℃ for 12 hours, the low melting point alloy +
Bi t 428n was immersed in a melt at 160° C. and pulled up to form a metal coating layer with a thickness of 25 μm. Next, a carbon layer was added to sodium silicate (water glass) and applied to one side to form a black coating layer with a thickness of 5 μm. In the comparative example, the CFRP substrate was used as it was and heated at 160°C and 12
After drying for a while, the conditions were adjusted. Approximately 20% after drying
After leaving it in a room at 70 SRH for one month, measurements were taken.

Measurement is performed in a small vacuum chamber to determine the amount of gas released (
(per unit surface area) was observed over time. This is shown in Figure 2. A is a CFRP board of a comparative example, and B is a CFRP board of an example.
It is an FRP board. All results were measured at room temperature. The example has a smaller amount of gas released than the comparative example,
It is thought that high vacuum will be reached more quickly. Next, B' is a case where a hot plate with a temperature of 80°C is placed in parallel at a position 20 cm away from the back surface of the FRP board of the example, and the temperature of the plate is about 73°C, which is higher than B' at the initial stage of degassing. Since gas release is active and reverses after 3 hours after degassing, it is thought that high vacuum will be reached even earlier.

(Effects of the Invention) As explained by the examples, the CFR of the present invention,
The P mirror has a metal coating layer on the entire surface of the CFB and P substrate to prevent moisture absorption, so it absorbs less moisture during suspension of operation, and has the advantage of quickly creating a high vacuum in the chamber when restarting operation. be. Furthermore, since a black coating layer is provided on the back surface, the temperature of the CFRP mirror can be controlled by radiation by arranging this and a heating plate or cooling plate facing each other. By heating, gas release can be promoted and the mirror can be brought into operation quickly, and the temperature increase of the mirror due to light irradiation during operation can be suppressed by cooling.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an example of the CFRP mirror of the present invention, and FIG. 2 is a diagram showing the relationship between the degassing time in vacuum and the amount of gas released for the CFRP mirror models of Examples and Comparative Examples. Explanation of symbols 1... CF'RP board 2... Metal coating layer 3.
... Adhesive 4 ... Mirror surface (aluminum vapor deposited layer) 5 ... Black coating layer

Claims (1)

[Claims] 1. A carbon fiber reinforced plastic mirror made by forming a metal coating layer on the entire surface of a carbon fiber reinforced plastic substrate, transferring an aluminum vapor deposition layer to the mirror side of this surface, and forming a black coating layer on the back side.